<SYSTEM>This document contains comprehensive information about Syed Moinuddin's professional profile, portfolio, and blog content. It includes personal details, work experience, projects, achievements, certifications, research papers, and all published blog posts. This data is formatted for consumption by Large Language Models (LLMs) to provide accurate and up-to-date information about Syed Moinuddin's background, skills, and expertise as a Software Development Engineer.</SYSTEM>

# syedmoinuddin.com

> A minimal, pixel-perfect dev portfolio and blog showcasing my work as a Software Development Engineer.

## About

- Passionate about exploring new technologies and turning ideas into reality through polished, thoughtfully crafted work.
- Obsessed with the details. How something looks, feels, and performs matters to me as much as the fact that it works.
- Happiest when I own a problem end to end. I would rather understand the whole picture than be handed a piece of it.
- Building toward a future where AI products are trusted the way good infrastructure is: quietly, completely, without anyone having to think about it. That's the work I want my name on.

### Personal Information

- First Name: Syed
- Last Name: Moinuddin
- Display Name: Syed Moinuddin
- Location: Bangalore, India
- Website: https://syedmoinuddin.com

### Social Links

- [X](https://x.com/SyedMoin)
- [GitHub](https://github.com/SyedMoin-lab)
- [LinkedIn](https://www.linkedin.com/in/syed-moinuddin106/)
- [Cal.com](https://cal.com/syed-moinuddin)
- [WakaTime](https://wakatime.com/@SyedMoin)
- [Resume](#)

### Tech Stack

- [TypeScript](https://www.typescriptlang.org/)
- [JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript)
- [React](https://react.dev/)
- [Next.js](https://nextjs.org/)
- [Tailwind CSS](https://tailwindcss.com/)
- [Radix UI](https://www.radix-ui.com/)
- [shadcn/ui](https://ui.shadcn.com/)
- [Framer Motion](https://motion.dev/)
- [Three.js](https://threejs.org/)
- [Node.js](https://nodejs.org/)
- [Express](https://expressjs.com/)
- [Redis](https://redis.io/)
- [MongoDB](https://www.mongodb.com/)
- [Zod](https://zod.dev/)
- [Claude](https://claude.ai/)
- [OpenAI](https://openai.com/)
- [Gemini](https://gemini.google.com/)
- [Perplexity](https://www.perplexity.ai/)
- [Groq](https://groq.com/)
- [Kimi](https://www.kimi.com/)
- [Turborepo](https://turbo.build/)
- [pnpm](https://pnpm.io/)
- [AWS](https://aws.amazon.com/)
- [Cloudflare](https://www.cloudflare.com/)
- [Linux](https://www.kernel.org/)
- [Vercel](https://vercel.com/)
- [Docker](https://www.docker.com/)
- [Git](https://git-scm.com/)

## Experience

### Software Development Engineer | Virallens

Duration: 06.2025 - Present

Skills: TypeScript, Next.js 16, React 19, Tailwind CSS, shadcn/ui, Framer Motion, Three.js, Node.js, Redis, MongoDB, Vercel AI SDK, Anthropic Claude, Google Gemini, Turborepo

- Built Citera, an AI claim-verification engine that checks every claim in a text, link, or file against trusted sources and quotes the evidence word for word.
- Built L-K Firmwide Publisher, which turns dense legal complaints into fully sourced shareholder alerts, with automatic fact-checking, a multi-model fallback chain, and a per-alert cost dashboard.
- Built the front end of L-K Drop Analysis, a legal-tech platform, with hover-to-source citations, a live AI chat that streams its reasoning, and an in-house design system.
- Shipped Perssonify Website 3, an animated site for four brands from one codebase, with a shared design system, 3D backgrounds, and CMS-driven content.
- Rebuilt the Blog Creator dashboard with a rich-text editor for AI posts and a live pipeline dashboard for speed, success rate, and cost per post.
- Led the front end of the EllaVox website, with a custom animation system and an interactive product demo.
- Built the L-K Text-to-SQL chat that answers plain-English questions with data tables, streaming reasoning, and a one-line embeddable widget.

### Founder | Cortexcn

Duration: 02.2025 - Present

Skills: Design Systems, shadcn/ui, Component Design, UI Design, Design Tokens, Tailwind CSS, Motion Design, Data Visualization, Accessibility, shadcn Registry

- Founded Cortexcn, a design system built on shadcn/ui: components, blocks, charts, and templates that companies and product teams build their interfaces with.
- Design every component end to end, from layout, spacing, and type to motion, dark mode, and accessible interaction states, so it fits into any shadcn/ui project.
- Keep the system consistent through shared design tokens for color, radius, and spacing, and document every component at [ui.cortexcn.dev](https://ui.cortexcn.dev) with a live preview, its props, and usage notes.
- Made every item install with one shadcn CLI command, or through AI agents like Claude Code, Cursor, and Codex via the shadcn MCP server.
- Ship new components, blocks, and chart updates from [cortexcn.dev](https://cortexcn.dev), with a public changelog.

### Full-stack Developer | Freelance

Duration: 01.2025 - 08.2026

Skills: Next.js, React, TypeScript, Tailwind CSS, shadcn/ui, Redux, WooCommerce, PayPal, Firebase, Vercel

Client Project: [CallKaro AI](https://app.callkaro.ai)
- Designed and built the first marketing website (May to June 2025), then redesigned the entire site in Next.js (July to August 2026).
- Set up Strapi as the CMS, so the team publishes blog posts and edits landing page content without a developer.
- Designed an agent builder prompt and a live demo where visitors talk to a voice agent in the browser.

Client Project: [ClothVillage](https://clothvillage.com)
- Built a headless WooCommerce store with a Next.js front end for a Canadian client.
- Integrated the WooCommerce REST API, CoCart for the cart, PayPal checkout, and Firebase Auth.

### Bachelor of Technology | REVA University

Duration: 08.2019 - 08.2023

Skills: C++, Python, MATLAB, Simulink, Control Systems, Robotics, Embedded Systems, Arduino, SolidWorks, AutoCAD

Mechatronics, Robotics, and Automation Engineering.

## Projects

### syedmoinuddin.com

Project URL: https://syedmoinuddin.com

Skills: Next.js 16, React 19, TypeScript, Tailwind CSS v4, Base UI, shadcn/ui, shadcn registry, MDX, Motion, Vercel

My personal site: a portfolio, a blog, and a shadcn registry of the components I build.
- Experience, projects, testimonials, and a blog written in MDX
- Live panels for GitHub contributions, WakaTime coding time, LeetCode stats, and site insights
- A components section with Cortexcn components that install with the shadcn CLI
- Command menu (Ctrl K), light and dark themes, and llms.txt for AI agents

### Cortexcn

Project URL: https://www.cortexcn.dev

Skills: Next.js 16, React 19, TypeScript, Tailwind CSS v4, shadcn/ui, shadcn registry, MDX, Motion, visx, Turborepo, Vercel

Cortexcn is a shadcn/ui registry of React components, charts, and blocks for developers, freelancers, and startups who ship fast.
- 17 charts, plus UI components grouped as Neurons (core UI) and Cortex (custom components)
- Every item installs with one shadcn CLI command, or through AI agents via the shadcn MCP server
- Docs at [ui.cortexcn.dev](https://ui.cortexcn.dev) with live previews, llms.txt, and a markdown copy of every page
- Ready-made blocks for landing pages and dashboards, and a public changelog

### Anavo Attorneys

Project URL: https://anavo-attorneys-legal.vercel.app

Skills: Next.js, React, Tailwind CSS, Framer, Vercel

The website for Anavo Attorneys, a corporate law practice for tech startups and founders. Moved the site from Framer into a Next.js codebase the client owns and can host anywhere.
- Rebuilt every section of the Framer design in Next.js and Tailwind CSS
- Hero with a Book Online Consultation button and an industries graphic for manufacturing, financial services, life sciences, and retail
- Legal services, Why Anavo Attorneys, and About sections, plus a contact form for new enquiries
- SEO metadata and light and dark favicons, deployed on Vercel

### CallKaro AI v2

Project URL: https://app.callkaro.ai

Skills: Next.js, React, TypeScript, Tailwind CSS, shadcn/ui, Radix UI, Strapi

A full redesign of the CallKaro AI website, live at app.callkaro.ai. CallKaro AI (RKSMS Technologies) runs voice AI agents that answer calls, book appointments, and qualify leads 24/7.
- Rebuilt the site in Next.js with a new look, light and dark themes, and Industries and Company menus
- Set up Strapi as the CMS, so the team publishes blog posts and edits most landing page sections themselves, without hiring a developer for content changes
- Agent builder prompt, and a live demo where visitors pick a use case and talk to a voice agent in the browser
- Sections for the in-house Arjuna 2.5 and Krishna 2.5 models, capabilities like 40+ languages and ~600 ms latency, case studies, integrations, a blog, and an FAQ

### CallKaro AI v1

Project URL: https://callkaro-ai.syedmoinuddin.com

Skills: React, Vite, TypeScript, Tailwind CSS, shadcn/ui, Radix UI, Vercel

The first website for CallKaro AI, a 24/7 AI receptionist for business calls.
- A React single-page app built with Vite and hosted on Vercel
- Hero with Test a Call and Book a Demo actions, and a customer logo marquee
- Six capability highlights, from multilingual, accent-adaptive voice to simple API integration
- How It Works steps, demo booking, and pricing plans

### ClothVillage

Project URL: https://clothvillage.com

Skills: Next.js, React, Redux, Redux Toolkit, TypeScript, Tailwind CSS, shadcn/ui, Radix UI, Framer Motion, Zod, WordPress, WooCommerce REST API, CoCart, Firebase Auth, PayPal SDK, Vercel

A headless WooCommerce store with a Next.js front end, built for a Canadian client.
- Products from the WooCommerce REST API, with CoCart for cart operations
- PayPal checkout and Firebase Auth for sign-up, login, and sessions
- Catalog with category filters, search, and product pages
- Redux for state, Tailwind CSS and shadcn/ui for the UI, deployed on Vercel
- Separate local, staging, and production config

## Awards



## Certifications



## Research

---
title: "VeRDiCT: Verifying Real Docket Citations in Tiers"
description: "VeRDiCT checks case citations in AI-drafted court filings with deterministic tiers over open legal data, before any model reads them. It reaches 62.5 precision at 90 ms per excerpt with no model calls and flags 46.6% of the fabrications documented by US courts."
last_updated: "October 11, 2026"
source: "https://syedmoinuddin.com/research/verdict"
---

# VeRDiCT: Verifying Real Docket Citations in Tiers

Syed Moinuddin, Independent Researcher, Bengaluru, India

Preprint · v1 · October 11, 2026

PDF: https://syedmoinuddin.com/research/verdict.pdf

## Abstract

Court filings drafted with generative AI increasingly cite authorities that do not exist, misquote real opinions, or misstate what they hold. A public tracker's export of 10 October 2026 lists 2,185 court decisions addressing such material, 1,248 of them dated 2026. Recent detectors hand the whole task to language-model agents that search legal databases step by step, and they are evaluated mostly on errors injected into pre-2022 briefs rather than on errors that courts have found. The authors propose **VeRDiCT**, a cascade of deterministic checks over open data that settles what can be settled before any model reads a citation: reporter series that never existed, citations that resolve to no case, captions that do not match the case found, pin cites outside the cited pages, and quotations that are not in the cited opinion on the cited page. Propositions that survive every check are passed on for reading. On the 390-excerpt test split of Legal_Phantom_Citation, VeRDiCT reaches 62.5 precision, 29.0 recall and 39.6 F1 at 90 ms per excerpt on two CPU cores with no model calls; a GPT-5 agent that averages 15.3 steps per excerpt reaches 40.8 precision and 55.0 F1. VeRDiCT finds 80.6% of non-existent citations and 41.3% of altered quotations, and by design none of the misrepresented holdings, which are 40% of the gold spans. On 7,515 citations drawn from US court decisions that addressed hallucinated authority, it flags 46.6% of the documented fabrications and 5.9% of the authorities those courts relied on. None of the documented fabrications uses a reporter series that does not exist, unlike the benchmark's, and 32.8% cite Westlaw or Lexis numbers that open data cannot check. Code and data are available at https://github.com/SyedMoin-lab/verdict.

## 1 Introduction

Citation to authority is the load-bearing structure of legal argument, and generative models break it in ways that are expensive to discover. When asked verifiable questions about federal cases, general-purpose models produced legal hallucinations between 58% of the time for ChatGPT 4 and 88% for Llama 2 (Dahl et al., 2024), and retrieval-augmented legal research products marketed as reliable still hallucinated between 17% and 33% of the time (Magesh et al., 2025). The consequences now reach the courts. The AI Hallucination Cases Database (Charlotin, 2026) recorded 2,185 decisions in its export of 10 October 2026, of which 1,492 list the United States alone; the yearly count rose from 16 in 2023 and 61 in 2024 to 859 in 2025 and 1,248 in 2026 up to 8 October. Pro se litigants are the sole party responsible in 885 of the US entries and lawyers in 579.

![Two authorities cited in the Affirmation in Opposition in Mata v. Avianca: (a) Varghese v. China Southern Airlines Co., Ltd., 925 F.3d 1339 (11th Cir. 2019) and (b) Zicherman v. Korean Air Lines Co., Ltd., 516 F.3d 1237 (11th Cir. 2008). T0 format: both reporter series exist. T1 existence flags (a), because no case named Varghese begins at or just before page 1339, and flags (b), because the cases beginning just before page 1237 include Miccosukee Tribe v. United States (page 1235) and none is Zicherman. The control, 516 U.S. 217, is found and its caption matches the real Zicherman v. Korean Air Lines Co. (1996), so its proposition would be escalated for reading.](https://images.syedmoinuddin.com/research/verdict/fig-1-mata-avianca-light-5e90d0bc.svg)

_Figure 1: VeRDiCT on two fabricated authorities from a widely reported 2023 sanction (United States District Court for the Southern District of New York, 2023). Both use real reporter series and real volume numbers; (b) borrows the volume of the genuine Supreme Court decision and moves it to the Federal Reporter. An index lookup with a caption check flags both in milliseconds, while the genuine decision passes and only its proposition would be left for a model or a person to read._

In this work, _citation verification_ is defined as answering four questions about each authority a filing relies on: whether a case exists at the cited location, whether it is the case the filing names, whether quoted language appears in that case at the cited page, and whether the case supports the proposition it is cited for. The first three questions have deterministic answers given the right data; the fourth requires reading. The study is restricted to United States case law: statutes, regulations, secondary sources and the record are out of scope.

Existing approaches treat all four questions as one reading task. Closed-book models are not a remedy: on LegalCiteBench, even the strongest of 21 models scored below 7 out of 100 on closed-book citation retrieval and completion, and for 20 of them more than 94% of the low-scoring answers on retrieval-heavy tasks named a concrete authority rather than abstaining (Chen et al., 2026). Agentic verifiers do better at a cost. On the Legal_Phantom_Citation benchmark, a GPT-5 agent with legal-database and web tools reached 84.4 recall but 40.8 precision (55.0 F1), averaged 15.3 steps per excerpt and exhausted its 30-step budget in 29.5% of episodes; Claude Code with Opus 4.8 reached 68.8 F1 with 15.4 tool calls per excerpt (Liu et al., 2026). Both rely on the CourtListener lookup service, and 19.9% of the opinions the agents retrieved had no usable text or pagination (Liu et al., 2026). Claim-level work isolates the fourth question and supplies the full opinion to the model (Demir and Canbaz, 2026), and pinpoint-level work finds that even strong models miss many wrong page references (Verma, 2026). These benchmarks share a further limit: their errors are constructed, by injection or by prompting a model, rather than found in filings. Legal_Phantom_Citation, for example, generates non-existent citations from a list of reporter names that do not exist (Liu et al., 2026), a pattern that does not occur among the fabrications courts have documented (Section 5).

The authors propose VeRDiCT, which answers the first three questions with deterministic checks over open legal data and passes only the residue to a reader. The cascade checks reporter series and their publication dates, resolves each citation against an index of 18,130,235 CourtListener citations with an explicit abstention when the index does not cover a volume, matches the caption party by party, bounds pin cites by the cited case's pages, and locates quoted language in page-labelled opinion text from the Caselaw Access Project. Each tier sees only what earlier tiers could not settle.

The contributions of this work are as follows:

- A deterministic, open-data verification cascade for court filings, with coverage-aware abstention, that runs on two CPU cores without model calls.
- A test set of 7,515 citation instances from US court decisions that addressed hallucinated authority: 869 citations from the curated hallucination items of a public tracker and 6,646 authorities that the deciding courts themselves relied on.
- An evaluation on Legal_Phantom_Citation against eleven published agent and model configurations, with ablations of each tier and of the main thresholds, and a held-out check on test entries never inspected during development.
- Evidence that benchmark and real-world difficulty diverge: every non-existent citation in Legal_Phantom_Citation that VeRDiCT finds is caught by the reporter-series rule alone, whereas none of the 588 fabricated citations extracted for Dataset A uses a non-existent series, 32.8% cite proprietary numbers, and the open index misses some genuine authority that courts rely on.

## 2 Related Works

### 2.1 Hallucinated Authority in Legal Practice

Dahl et al. (2024) profiled legal hallucinations across models and tasks and found them pervasive for questions about real federal cases, and Magesh et al. (2025) showed that commercial retrieval-augmented tools reduce but do not remove the problem. Charlotin (2026) catalogues the decisions in which courts addressed hallucinated material, with the party, the tool where known, the nature of each item and the sanction. These works measure the problem; VeRDiCT is a check that a filer, a clerk or an opposing party can run before the problem reaches a judge.

### 2.2 Benchmarks for Citation Verification

LegalCiteBench evaluates closed-book citation retrieval, completion and verification over opinions from the Caselaw Access Project (Chen et al., 2026). Legal_Phantom_Citation injects five error types into excerpts of 245 federal appellate briefs filed between 2012 and 2021, adds model-generated holdings from Dahl et al. (2024), and evaluates agentic and non-agentic detectors (Liu et al., 2026). Demir and Canbaz (2026) frame support checking as three-way inference over 3,396 parenthetical claims, and Verma (2026) corrupts citations by replacing the case or the pinpoint page. None of the four draws its errors from filings that courts have examined. VeRDiCT is evaluated on one of them and on citations recorded in such decisions.

### 2.3 Citation Infrastructure

eyecite extracts and normalises case citations (Cushman et al., 2021); reporters-db records reporter series and their date ranges (Free Law Project, 2026c); CourtListener publishes a citation lookup service and quarterly bulk data (Free Law Project, 2026b,a); and the Caselaw Access Project publishes page-labelled opinion text (Harvard Law School Library Innovation Lab, 2024). These are components rather than detectors and have not, to the authors' knowledge, been evaluated as a verification system against labelled hallucinations.

### 2.4 Cascades and Cost-Aware Routing

Attentional cascades reject easy negatives with cheap tests before expensive ones (Viola and Jones, 2001), and FrugalGPT applies the idea to language models by routing queries through models of increasing cost (Chen et al., 2024). VeRDiCT places deterministic, zero-cost tiers before any model and routes by what each tier can decide rather than by model confidence. To our knowledge, no publicly available method verifies citations in court filings with deterministic open-data checks evaluated on real sanctioned filings, or reports the cost of each verification stage.

## 3 Methodology

VeRDiCT processes a document in five tiers (Figure 2). Offline, it builds three resources from open data. Online, each citation passes through the tiers in order, and each tier either flags it, clears it, or leaves it undecided for the next tier.

![The VeRDiCT pipeline. Offline setup indexes three open resources once: reporters-db series and dates, CourtListener bulk data with 18.1M citations and 10.2M case names, and Caselaw Access Project static data with page ranges and page-labelled text. Each citation then passes five deterministic tiers in order: T0 format (series exists; year after series began; reporters-db), T1 existence (case at citation; abstain if volume not indexed; CourtListener, CAP), T2 identity (caption matches party by party; CourtListener, CAP), T2b pin range (pin inside the case's pages; CAP) and T3 quotation (quote present, on the pin page; CAP). Each tier can emit flagged spans: non-existent, name mismatch, wrong pin cite, altered quotation. What survives forms the T4 support escalation set for a reading tier that is not evaluated: propositions whose citations survived T0 to T3, and quotations absent from the cited opinion.](https://images.syedmoinuddin.com/research/verdict/fig-2-pipeline-light-8c61f464.svg)

_Figure 2: The VeRDiCT pipeline. Offline (blue), three open resources are indexed once: reporter series with their date ranges, 18,130,235 CourtListener citations with 10,174,551 case names from the snapshot of 30 September 2026, and Caselaw Access Project page ranges and text, cached on first use. Online (pink), each citation passes the tiers in order; a flag ends its path, and anything a tier cannot decide moves on. What survives every deterministic tier, together with quotations absent from the cited opinion, forms the escalation set for a reading tier (grey), which this paper sizes but does not evaluate._

### 3.1 Problem Formulation

A document $d$ contains citation instances $c_1, \ldots, c_n$. Each instance carries a volume $v$, a reporter $r$, a first page $p$, an optional pin cite $\pi$, the caption $w$ written before it, and any quotations $Q(c)$ attached to it. A short form ("Smith, 437 U.S. at 587") or an _Id._ citation inherits $(v, r, p)$ from its antecedent. Gold labels mark spans as non-existent citations, case-name mismatches, incorrect pin cites, altered quotations or misrepresented holdings. A system outputs flagged spans; Section 4.4 gives the matching rule.

### 3.2 T0: Reporter Series and Dates

Let $\mathcal{E}$ be the set of reporter editions in reporters-db and $\mathcal{B}$ the set of their base names ("N.E." for "N.E.2d"). A string of the form "volume, abbreviation, page" whose abbreviation has a base in $\mathcal{B}$ but is not itself in $\mathcal{E}$, such as "N.E.4th", is flagged. A citation to a numbered later series whose parenthetical year precedes the series' start by more than a year is also flagged. Year checks are limited to numbered series because start dates for unnumbered reporters are unreliable in the source data.

### 3.3 T1: Existence with Coverage-Aware Abstention

Let $I$ be the set of $(v, r, p)$ triples in the citation index and $V_I$ the set of indexed $(v, r)$ volumes. The existence decision is

$$
\mathrm{T1}(c) =
\begin{cases}
\text{\footnotesize FOUND} & (v, r, p) \in I \text{ or in CAP} \\
\text{\footnotesize ABSTAIN} & r \in R_{\mathrm{prop}} \text{ or } (v, r) \notin V_I \\
\text{\footnotesize FOUND} & s\big(w, N(v, r, p)\big) \ge \theta_n \\
\text{\footnotesize FLAG} & \text{otherwise,}
\end{cases}
\tag{1}
$$

where $R_{\mathrm{prop}}$ is the set of proprietary reporters (Westlaw and Lexis numbers), $N(v, r, p)$ is the set of names of the up to four cases that begin within 150 pages before $p$ in the same volume, and $s$ is the caption similarity of Eq. 2. The third case admits a common drafting habit, citing a pin page in full form ("467 U.S. 842" for a case that begins at 837), provided the written caption matches a case that contains the page. Without a caption, such citations abstain. For closed series with at least 200 indexed volumes, a volume beyond the last indexed one is flagged. Abstention is reported, never counted as a flag.

### 3.4 T2: Party-wise Caption Identity

For a citation found in the index, let $C$ be the names CourtListener and CAP give the case. Captions are split into parties at "v.", parties that are generic ("United States", a state, "People", "Commonwealth") are dropped, abbreviations are expanded with a table of common reporter abbreviations, and dotted initialisms are collapsed ("E.P.A." to "epa"). The similarity is

$$
s(w, C) = \max_{c \in C} \; \max_{a \in P(w),\, b \in P(c)} \sigma(a, b),
\tag{2}
$$

where $P(\cdot)$ is the set of distinctive parties and $\sigma$ is the token-set ratio of RapidFuzz (Bachmann, 2026), set to 100 when $a$ is the initialism of $b$. A citation is flagged as a case-name mismatch when $s(w, C) < \theta_n$. Matching on either party tolerates the substitution of public officials across a case's history, while requiring a distinctive party prevents "United States v. Smith" from matching "United States v. Jones".

### 3.5 T2b: Pin-Cite Range

For a full or short citation with pin $\pi$ resolving to a case with first page $p$ and last page $\ell$ from CAP metadata, the citation is flagged when $\pi < p$ or $\pi > \ell$. Short forms whose antecedent lies outside the excerpt are resolved by their short name within the cited volume, and are skipped when the name does not identify a unique case. _Id._ citations are excluded from this tier because they frequently refer to record documents that the extractor cannot see.

### 3.6 T3: Quotation Location

Each quotation of at least $m$ words is attached to a citation by one of three rules, tried in order: the quotation sits inside a parenthetical that opens after a citation; the next citation follows within 220 characters with no record cite, statute or other quotation between; or the quotation follows a citation in the same sentence. A quotation $q$ is split into fragments $f_1, \ldots, f_k$ at ellipses and bracketed alterations, and each fragment is located in the cited opinion's normalised text $T$. If $f_j$ is a substring of $T$ it is found. Otherwise let $a_j$ be the best partial alignment score of $f_j$ against $T$ and $\delta_j$ the number of content words that differ between $f_j$ and the aligned window, ignoring word pairs whose similarity is at least $\omega$ (optical-character-recognition noise). The verdict for $q$ is

$$
\mathrm{T3}(q) =
\begin{cases}
\text{\footnotesize ABSENT} & \exists j : a_j < \theta_q \\
\text{\footnotesize ALTERED} & \exists j : \delta_j \ge k_\delta \\
\text{\footnotesize VERBATIM} & \text{otherwise.}
\end{cases}
\tag{3}
$$

Altered quotations are flagged. Absent quotations are escalated rather than flagged, because a deterministic attachment rule cannot distinguish a fabricated quotation from one drawn from another source. For verbatim quotations with a pin cite, CAP page labels give the pages on which each fragment occurs; when no occurrence lies on the pin page or the page before it, the citation is flagged as an incorrect pin cite.

### 3.7 Escalation Set

Citations that survive all deterministic tiers contribute their proposition, the text from the start of the citing sentence to the citation, to an escalation set, together with every absent quotation. This set is what a reading tier, whether a model or a person, must examine. The paper reports its size; evaluating a reading tier is left to future work.

## 4 Experiments

### 4.1 Datasets

**Legal_Phantom_Citation.** The benchmark of Liu et al. (2026) provides a 390-entry test split (`eval`) and a 910-entry auxiliary split (`aux_train`), released under CC BY 4.0. Of the test entries, 90 are model-generated holdings from Dahl et al. (2024) rather than brief excerpts; they hold 77 of the misrepresented-holding spans. The test split contains 331 gold spans: 131 misrepresented holdings, 68 case-name mismatches, 55 incorrect pin cites, 46 altered quotations and 31 non-existent citations, plus 22 optional spans. All rules and thresholds were developed on `aux_train`. The first 60 test entries were inspected while debugging citation extraction early in development, so results on the remaining 330 entries are reported separately as a held-out check.

**Court decisions on hallucinated authority (Dataset A).** The authors built a citation-level set from the AI Hallucination Cases Database (Charlotin, 2026), downloaded on 10 October 2026. Its entries are decisions that addressed hallucinated material in a filing, from warnings to monetary and professional sanctions. Of its 2,185 rows, 1,492 are from the United States and 1,365 record at least one hallucinated item about case law. Positives are citations that appear inside the curated item descriptions, labelled with the item's category: fabricated, false quotation or misrepresented. The primary set keeps items that contain exactly one citation, so the label attaches without ambiguity, giving 869 positives (588 fabricated, 192 misrepresented, 89 false quotations); 331 citations from multi-citation items form an extended set. Negatives are authorities that the deciding court relied on in its own decision. The authors converted 1,267 of the source decisions to text, removed every sentence (and the sentence after it) that discusses fabricated, false, misattributed or AI-generated authority, removed citations matching any positive, sampled up to six distinct citations per decision, and excluded decisions in which a judge was among the parties who used AI, giving 6,646 negatives. Appendix B lists the exclusion vocabulary and counts.

### 4.2 Implementation Details

All experiments ran on a cloud container with two virtual CPU cores and 7 GB of memory, Python 3.13, eyecite 2.7.8, RapidFuzz 3.14.6, PySBD (Sadvilkar and Neumann, 2020) for sentence boundaries, and SQLite. The CourtListener bulk snapshot of 30 September 2026 was indexed into 18,130,235 citation rows (139 s) and 10,174,551 case-name rows (389 s). CAP volume metadata and opinion HTML were fetched on first use at no more than four requests per second and cached. Hyperparameters, selected on `aux_train` (Appendix A), are: caption threshold $\theta_n = 80$; quotation absence threshold $\theta_q = 70$; OCR word similarity $\omega = 80$; minimum changed words $k_\delta = 1$; minimum quotation length $m = 8$ words; proprietary reporters $R_{\mathrm{prop}}$ = WL and the four LEXIS forms. No component is trained, so results are deterministic and no seeds apply.

### 4.3 Baselines

Six cascade variants isolate each tier: T0 alone; T0 and T1; T0 and T1 without coverage-aware abstention (misses in proprietary reporters and unindexed volumes are flagged); T0 to T2; T0 to T2b; and the full cascade T0 to T3. External baselines are the eleven configurations reported by Liu et al. (2026) on the same split with the same matching rule: Gemini 2.5 Flash, GPT-5, GPT-OSS 120B, Qwen3-8B and Qwen3.6-27B, each with and without their agentic harness, and Claude Code with Opus 4.8. Their numbers are quoted from that paper, not re-run.

### 4.4 Metrics

On Legal_Phantom_Citation a gold span is found when it is a substring of a predicted span or the reverse, case-insensitively, with ellipsis fragments allowed (Liu et al., 2026). Precision is the share of predicted spans matching any gold span, recall the share of required gold spans found, micro-averaged over entries; optional spans count as true positives when predicted and are not required (Liu et al., 2026, App. A1.4). Under the released evaluation code, which counts optional spans as required, the full cascade scores 62.5 precision, 28.0 recall and 38.7 F1. Ninety-five per cent intervals come from 1,000 bootstrap resamples of entries. On Dataset A the unit is the citation: the flag rate on positives, the false-alarm rate on negatives, and the abstention rate.

## 5 Results

**Against published systems.** Table 1 compares VeRDiCT with the published configurations. The full cascade reaches 62.5 precision and 29.0 recall (39.6 F1, 95% interval 33.3 to 45.6). Its precision is second only to Claude Code with Opus 4.8 (76.1) and above every other configuration, agentic or not; its recall is the lowest of all, because it makes no attempt on the 131 misrepresented holdings. Its F1 is above seven of the eleven configurations and below GPT-5 with and without tools, Claude Code, and the Qwen3.6-27B agent (40.0). Liu et al. (2026) report ± values of 2.2 to 7.8 points for these rows without stating what they denote, so gaps of a few points should be read with care. Restricted to the four citation-level types, VeRDiCT finds 48.0% of gold spans. The 330 held-out entries give 39.0 F1, against 39.6 on all 390. One post-hoc change to the output format, reporting a flagged citation's caption and parenthetical with it, lets a flag match case-name spans that the benchmark marks on the caption alone (16 of the 68); it raises case-name matches from 40 to 44, F1 to 41.3 on the test split and F1 from 50.2 to 50.9 on `aux_train`, but was chosen after the first test run and is not part of the main result.

| Family                        | System                  | Precision ↑         | Recall ↑            | F1 ↑                |
| ----------------------------- | ----------------------- | ------------------- | ------------------- | ------------------- |
| Deterministic, no model calls | T0 format               | 100.0               | 7.9                 | 14.6                |
|                               | T0 to T1 existence      | 82.0                | 12.1                | 21.1                |
|                               | T0 to T1, no abstention | 37.6                | 12.1                | 18.3                |
|                               | T0 to T2 identity       | 82.5                | 19.6                | 31.7                |
|                               | T0 to T2b pin range     | 79.1                | 20.2                | 32.2                |
|                               | **VeRDiCT** (T0 to T3)  | 62.5 (54.2 to 70.2) | 29.0 (23.6 to 34.7) | 39.6 (33.3 to 45.6) |
| Model, no tools (reported)    | Gemini 2.5 Flash        | 25.3                | 43.5                | 32.0                |
|                               | GPT-5                   | 36.9                | 58.2                | 45.2                |
|                               | GPT-OSS 120B            | 14.9                | 30.7                | 20.0                |
|                               | Qwen3-8B                | 14.6                | 35.1                | 20.7                |
|                               | Qwen3.6-27B             | 45.9                | 31.5                | 37.4                |
| Agent, 30 steps (reported)    | Gemini 2.5 Flash        | 16.9                | 66.9                | 27.0                |
|                               | GPT-5                   | 40.8                | **84.4**            | 55.0                |
|                               | GPT-OSS 120B            | 21.1                | 55.1                | 30.5                |
|                               | Qwen3-8B                | 12.0                | 41.1                | 18.6                |
|                               | Qwen3.6-27B             | 28.9                | 65.0                | 40.0                |
|                               | Claude Code, Opus 4.8   | **76.1**            | 62.8                | **68.8**            |

_Table 1: Legal_Phantom_Citation test split (390 excerpts). Deterministic rows are the authors' runs; parentheses give 95% bootstrap intervals for the full cascade. Model and agent rows are quoted from Liu et al. (2026, Table 2), which reports ± values of 2.2 to 7.8 points without defining them. In bold: the best published value per column._

**By error type.** Table 2 sets VeRDiCT's recall beside the agents' per-type recall (Liu et al., 2026, Table A6). VeRDiCT finds 80.6% of non-existent citations, all through the reporter-series rule of T0, which reflects how the benchmark generates them (Liu et al., 2026) rather than a property of real fabrications; the six it misses all use "Mass. App. 4th", whose base is not a reporter series in reporters-db, so neither T0 nor the extractor recognises them. It finds 58.8% of case-name mismatches, below every agent except Qwen3-8B, partly because 16 of the 68 gold spans mark the caption alone. It finds 41.3% of altered quotations, close to GPT-OSS 120B (42.9) and well below GPT-5 (95.2). Incorrect pin cites remain hard for every system: VeRDiCT finds 21.8%, against 52.8 for GPT-5 and 3.6 for Claude Code, because a small change of page is detectable only when a quotation fixes the true page.

| Error type             | n   | VeRDiCT | Tier       | Gemini 2.5 Fl. | GPT-5 | GPT-OSS | Qwen3-8B | Qwen3.6-27B | Claude Code |
| ---------------------- | --- | ------- | ---------- | -------------- | ----- | ------- | -------- | ----------- | ----------- |
| Non-existent citation  | 31  | 80.6    | T0         | 100.0          | 100.0 | 83.9    | 58.1     | 100.0       | 93.5        |
| Case-name mismatch     | 68  | 58.8    | T2, T1, T0 | 100.0          | 100.0 | 84.2    | 49.1     | 96.5        | 83.8        |
| Incorrect pin cite     | 55  | 21.8    | T3, T2b    | 18.9           | 52.8  | 26.4    | 18.9     | 50.9        | 3.6         |
| Altered quotation      | 46  | 41.3    | T3         | 78.6           | 95.2  | 42.9    | 31.0     | 64.3        | 71.7        |
| Misrepresented holding | 131 | 0.0     | none       | 60.3           | 83.2  | 51.1    | 45.8     | 48.9        | 66.4        |

_Table 2: Recall (%) by error type on the test split. VeRDiCT is the authors' run; Tier lists the tiers that produced its matches, most frequent first. Agent columns are the agentic configurations of Liu et al. (2026, Table A6), which reports recall only because its systems do not label error types._

**Cost.** Table 3 reports the cost per excerpt. The full cascade takes 90 ms per excerpt and makes no model calls: extraction and tiers T0 to T2 take 25 ms, the pin-range tier adds 31 ms and the quotation tier 34 ms, and a warm cache fetches nothing. The GPT-5 agent averages 15.3 steps per excerpt, each a model turn with a growing context, and Claude Code 15.4 tool calls, which its harness can issue several per turn; the source paper reports no dollar costs. On the test split, the deterministic tiers leave 956 propositions for a reading tier, an average of 2.5 per excerpt.

| System                | ms per excerpt | Model calls |
| --------------------- | -------------- | ----------- |
| T0                    | 21             | 0           |
| T0 to T1              | 22             | 0           |
| T0 to T2              | 25             | 0           |
| T0 to T2b             | 56             | 0           |
| VeRDiCT (T0 to T3)    | 90             | 0           |
| GPT-5 agent           | n/r            | 15.3 steps  |
| Claude Code, Opus 4.8 | n/r            | 15.4 calls  |
| Qwen3-8B agent        | n/r            | 7.5 steps   |
| Index build (once)    | 528 s          | 0           |

_Table 3: Cost per excerpt on the test split, two virtual CPU cores, warm cache, median of three runs. Agent figures are averages reported by Liu et al. (2026): model steps, or tool calls for Claude Code, whose harness can issue several per turn; n/r: not reported. Index build covers both CourtListener tables._

**Court decisions on hallucinated authority.** Table 4 reports Dataset A. VeRDiCT flags 46.6% of the 588 fabricated citations in the primary set and abstains on 44.4%. Of the fabrications, 32.8% cite Westlaw or Lexis numbers, which open data cannot confirm or refute; on the remaining fabrications that cite published reporters, the flag rate is 69.1%. None of the fabrications uses a reporter series that does not exist, the pattern behind every non-existent citation that VeRDiCT finds in Legal_Phantom_Citation. Misrepresented and falsely quoted authorities are flagged at 13.0% and 3.4%: these are real cases, and the citation-level tiers are not meant to catch them. On the 6,646 authorities the courts relied on, the alarm rate is 5.9%, with 29.0% abstentions. A random sample of 59 of these alarms was categorised by reading each decision's text with AI assistance (the categories are released for confirmation by a person): 35 were genuine authorities that the 30 September snapshot does not hold at the cited location (Mata v. Avianca's own sanctions opinion, at 678 F. Supp. 3d 443, accounts for four); 14 came from text-extraction noise in the PDF orders; 3 were negatives mislabelled by the construction rules, sentences in which a court discussed a fabricated citation without the excluded vocabulary; 2 were Arizona paragraph cites read as pages; 2 were caption variants below the threshold; and 3 had other causes. The coverage-aware rule of Eq. 1 assumes that an indexed volume is complete, and in this sample it often was not.

| Category                  | n    | Flagged | Abstained | Passed |
| ------------------------- | ---- | ------- | --------- | ------ |
| Fabricated                | 588  | 46.6    | 44.4      | 9.0    |
| Misrepresented            | 192  | 13.0    | 14.1      | 72.9   |
| False quotation           | 89   | 3.4     | 9.0       | 87.6   |
| Court-relied (neg.)       | 6646 | 5.9     | 29.0      | 65.0   |
| _Fabricated, by reporter_ |      |         |           |        |
| Published reporter        | 395  | 69.1    | 17.7      | 13.2   |
| Westlaw or Lexis number   | 193  | 0.5     | 99.0      | 0.5    |

_Table 4: Dataset A, primary set: citation-level tiers T0 to T2b on citations recorded in US decisions that addressed hallucinated authority (%). The 95% bootstrap interval for the fabricated flag rate is 42.7 to 50.5._

### 5.1 Ablations

Table 5 varies one component at a time on the test split, with the other settings fixed at the values selected on `aux_train`; Appendix A gives the full sweeps on `aux_train`. These ablations isolate three findings. First, coverage-aware abstention is what makes an open index usable: flagging lookup misses in proprietary reporters and unindexed volumes lowers precision from 82.0 to 37.6 for T0 and T1 without finding any additional error, because Westlaw and Lexis citations and unindexed volumes are common in real briefs. Second, the quotation tier contributes the largest share of the recall beyond format and existence checks, and its precision depends on treating absent quotations as escalations: flagging them adds 6 true and 23 false positives. Third, the pin-range tier is nearly neutral on this benchmark, 39.4 F1 without it against 39.6 with it, because the benchmark draws each injected pin from between the case's first page and the original pin (Liu et al., 2026, App. A1.2), so it always lies inside the case.

| Variant                          | P ↑  | R ↑  | F1 ↑     |
| -------------------------------- | ---- | ---- | -------- |
| VeRDiCT, selected settings       | 62.5 | 29.0 | 39.6     |
| Flag absent quotations           | 56.1 | 30.5 | 39.5     |
| No coverage-aware abstention     | 45.5 | 29.0 | 35.4     |
| Without T2b pin range            | 62.7 | 28.7 | 39.4     |
| T2b bound from next indexed case | 62.5 | 29.0 | 39.6     |
| Without T3 quotation             | 79.1 | 20.2 | 32.2     |
| $\theta_n = 60$                  | 62.2 | 28.1 | 38.7     |
| $\theta_n = 90$                  | 61.7 | 29.0 | 39.5     |
| $m = 6$                          | 62.6 | 29.3 | **39.9** |
| $m = 12$                         | 64.7 | 28.4 | 39.5     |
| $k_\delta = 2$                   | 63.5 | 28.7 | 39.5     |

_Table 5: Ablations on the test split, one change at a time from the settings selected on `aux_train`. Best F1 in bold._

## 6 Conclusion and Future Works

VeRDiCT shows that a large share of citation verification needs no model. Over open data, five deterministic tiers find non-existent citations, mismatched captions and altered quotations at 90 ms per excerpt and no model cost, with precision above every published configuration but one. On citations from court decisions that addressed hallucinated authority, the same tiers catch 46.6% of documented fabrications and expose three limits that synthetic benchmarks hide: fabrications cite valid reporter series, a third cite proprietary numbers that no open resource can check, and the open index is incomplete even for well-known decisions. The practical implication is to place deterministic tiers in front of any agent, so that model calls are spent on the propositions and absent quotations that only reading can settle. Future work will evaluate reading tiers on the escalation set, replace the quarterly snapshot with the live lookup service and a density test for partly indexed volumes, extend coverage to Westlaw and Lexis citations through licensed lookups, label quotation and proposition errors in the filings these decisions address, and release the verifier as a filing-time check.

## Limitations

The authors outline several limitations of VeRDiCT and its evaluation, and encourage future work to address them.

**No reading tier.** VeRDiCT does not judge whether a case supports a proposition. Misrepresented holdings are 40% of the gold spans in Legal_Phantom_Citation and 22% of the primary positives in Dataset A, and VeRDiCT finds almost none of them. Its recall is therefore capped at the share of gold spans that are citation-level errors, and the comparison in Table 1 should be read per error type.

**Labels in Dataset A.** Positives come from a curator's summary of each decision, not from the filing itself, and negatives assume that a deciding court's own authorities are real; the inspected sample shows that the exclusion vocabulary misses some sentences in which a court discusses a fabricated citation. Neither assumption has been audited by hand; an audit sample of 100 positives and 100 negatives is released with the data and is pending. Quotation and proposition checks cannot be evaluated on Dataset A because the database does not carry the filings' text.

**Coverage of open data.** The CourtListener snapshot ends on 30 September 2026, does not index every volume, and is incomplete within volumes it does index; CAP text ends with its digitisation. VeRDiCT abstains on proprietary citations and missing volumes, which leaves 44.4% of real fabrications undecided: 191 of the 193 Westlaw and Lexis citations, and published-reporter citations amounting to 11.9% of the fabrications. It cannot detect a missing case inside an indexed volume, which caused most of the inspected alarms on genuine authority.

**Development on the test split.** The first 60 test entries were inspected during early debugging of extraction. The held-out 330 entries give 39.0 F1, close to the full-split figure, but the risk of tuning to the test split is not zero.

**Comparison with published numbers.** Agent results are quoted from Liu et al. (2026) rather than re-run, and their models, harnesses and search services may have changed since. The benchmark's labels also assume that the original briefs are free of errors: T1 raises 9 flags that no gold span covers, and for 5 of them a case with the written caption begins one digit away (Appendix A), so measured precision understates the share of flags that point at real mistakes.

**Scope.** Only United States case law in English is covered. Statutes, regulations, secondary sources, record citations and foreign authority are out of scope, although the same tracker lists decisions from more than 40 other jurisdictions (Charlotin, 2026).

## Use of AI Assistants

The authors used Claude (Anthropic) as a research and engineering assistant: to search the literature, write and debug the code, run the experiments and draft the text. Every experimental result in the paper is written into the text by a script from the released results files; figures quoted from other work and dataset construction counts were typed by hand and checked against their sources. The sample of alarms in Section 5 was categorised with AI assistance and is released for confirmation by a person.

## References

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## A Detailed Ablation Analysis

### A.1 Selection on aux_train

All thresholds were chosen on the 910-entry `aux_train` split before the first test run. Table 6 sweeps the caption threshold with tiers T0 to T2 only; $\theta_n = 80$ gave the best F1 and was kept. Table 7 compares quotation settings with the full cascade (these runs used $\theta_n = 60$, the setting at the time). Treating absent quotations as escalations raised F1 by 1.5 points, and requiring two changed words instead of one traded recall for precision with no gain in F1, so $m = 8$ and $k_\delta = 1$ were kept. With every selected setting, the cascade reaches 70.1 precision, 39.1 recall and 50.2 F1 on `aux_train`.

| $\theta_n$ | T2 TP | T2 FP | F1 (T0 to T2) |
| ---------- | ----- | ----- | ------------- |
| 60         | 46    | 7     | 37.2          |
| 70         | 50    | 8     | 38.2          |
| 80         | 52    | 9     | 38.6          |
| 90         | 53    | 20    | 38.4          |

_Table 6: Caption threshold on `aux_train`, tiers T0 to T2._

| Quotation setting                  | P    | R    | F1   |
| ---------------------------------- | ---- | ---- | ---- |
| $m = 8, k_\delta = 1$              | 69.8 | 37.9 | 49.1 |
| $m = 8, k_\delta = 2$              | 72.0 | 37.0 | 48.9 |
| $m = 6, k_\delta = 2$              | 70.9 | 37.3 | 48.9 |
| $m = 8, k_\delta = 2$, flag absent | 63.6 | 37.8 | 47.4 |

_Table 7: Quotation settings on `aux_train`, full cascade with $\theta_n = 60$._

### A.2 Coverage-aware Abstention

A lookup miss is weak evidence on its own. On the test split, flagging every miss lowers the precision of T0 and T1 from 82.0 to 37.6 without finding any additional error, because briefs cite Westlaw and Lexis numbers ("2015 WL 1240182, \*8") and volumes the open index does not hold. Liu et al. (2026) report the same pressure on agents: 132 correct citations in the test split return no CourtListener result, and weaker models flagged up to 65.9% of them.

### A.3 Unlabelled Errors Found by T1

T1 raises 9 flags on the test split that match no gold span. For 5 of them, a case with the written caption begins at a citation one digit away in the volume or the page (a digit changed, added, removed or transposed), which marks the flag as a likely typing error in the original brief rather than a false alarm. Examples are "216 F.3d 659" where the captioned case is at 276 F.3d 659, "616 F.2d 153" for 616 F.2d 1153, and "553 S.W.2d 903" for 554 S.W.2d 903. Liu et al. (2026, App. A1.4, Table A1) list "216 F.3d 659" among the typos they added to the gold labels after inspecting GPT-5's false positives, but the released labels do not contain it; the other four are not listed.

### A.4 Caption Matching

Party-wise matching mainly guards against generic parties. "United States v. Smith" cited where "United States v. Jones" begins scores 50 on whole-caption similarity but 20 party-wise, and "People v. Garcia" against "People v. Martinez" scores 71 and 43. Abbreviation expansion and the initialism rule let "Nat'l Lime Ass'n v. EPA" match "National Lime Association v. Environmental Protection Agency" (93 whole, 100 party-wise), and matching on either party accepts "Heartland Regional Med. Ctr. v. Sebelius" against the indexed "Heartland Regional Medical Center v. Leavitt", where the Secretary changed between the decision and the brief. The rule has a blind spot: when one party is a frequent litigant that is not on the generic list, a fabricated opponent passes, so "Smith v. City of Chicago" cited where "Jones v. City of Chicago" begins scores 100 party-wise (80 whole). On `aux_train`, raising $\theta_n$ from 80 to 90 more than doubles T2's false alarms (20 against 9) for one more true positive.

### A.5 Quotation Location

On the test split, for example, the altered quotation "constitutional torts, like their common law kin, require a showing of both actual cause and proximate cause" aligns with the cited opinion at a score of 79, with five content words counted as changed. Inspection of its false positives on `aux_train` found three recurring sources: quotations the brief itself altered without brackets, quotations attached to the wrong authority when a sentence cites several, and page labels that place a quotation spanning a page break on the earlier page. On the test split, the tier's misquotation flags are 22 correct and 25 incorrect, and its pin-cite flags 10 correct and 17 incorrect. Disabling the pin check gives 37.5 F1 against 39.6.

### A.6 Pin-Cite Range

CAP metadata occasionally records a case's last page as equal to its first; such ranges are ignored. Bounding a case by the next indexed case in the volume instead of CAP's last page made no difference on the test split (39.6 F1): the benchmark draws each injected pin from between the case's first page and the original pin (Liu et al., 2026, App. A1.2), so a range check cannot catch it by construction.

## B Dataset A Construction

**Source.** The AI Hallucination Cases Database (Charlotin, 2026) was exported as CSV on 10 October 2026 (2,185 rows; the web page reported 2,180 cases and a last update of 9 October 2026). Each row lists one or more hallucination items in the form "Category: Subcategory | description", separated by double bars. Only US rows and items with the subcategory Case Law and the categories Fabricated, False Quotes or Misrepresented were used.

**Positives.** Citations were extracted from each item's description with eyecite and with the reporter-series rule of T0, and deduplicated by volume, reporter and page within the item. Of 4,116 case-law items in US rows, 1,029 contain at least one citation, giving 1,200 citations. Items with exactly one citation form the primary set (588 fabricated, 192 misrepresented, 89 false quotations); the remaining 331 citations form the extended set, which is released but not used in Table 4.

**Negatives.** For each US row whose source is a PDF decision hosted by the database and whose items include case law, the decision was converted to text with pdftotext and unwrapped. Of the 1,272 such decisions, 1,271 downloaded; two came from rows in which a judge was the party who used AI and were not used, two yielded no readable text, and 1,267 were converted. A sentence was excluded, together with the sentence after it, when it matched the pattern below; 3,834 candidate citations fell in such sentences, and a further 1,729 matched a positive by volume, reporter and page. Up to six distinct remaining citations per decision were sampled with a fixed seed. Finally, the 18 sampled citations from three decisions in which a judge was among the parties who used AI were removed, leaving 6,646 negatives.

```text
fictitious, fabricat*, hallucinat*, non-existent,
nonexistent, does / do / did not exist, no such
case, no such opinion, could not / unable to /
cannot locate or find, not exist, misrepresent*,
mischaracteri*, does / did not stand for, support,
say or contain, not appear in, not found in,
inaccurate, incorrect citation, wrong citation,
miscit*, phantom, fake, bogus, generative,
artificial intelligence, AI, ChatGPT
```

**Presentation to the verifier.** Each instance is presented as "Caption, volume reporter page, pin." using the caption written before the citation in its source text, or "See volume reporter page." when no caption was found. Only tiers T0 to T2b apply; quotation and proposition checks need the filing's own text, which the database does not carry.

**Audit sample.** A fixed-seed sample of 100 primary positives and 100 negatives, with the source text of each, is released for independent annotation. At the time of writing it has not been annotated.

## C Reproduction

The code, the processed Dataset A, the audit sample and every results file behind this paper's numbers are released with it. Rebuilding the indexes from the 30 September 2026 CourtListener snapshot takes 139 s and 389 s on the hardware above; the CAP cache is filled on the first run. `src/run_phantom.py` reproduces Tables 1 to 5, `src/eval_dataset_a.py` reproduces Table 4, and `paper/make_numbers.py` writes every number in the text from those results.

Last updated on October 11, 2026

## Blog

---
title: "The Brief and the Inventory: What I Learned Researching DESIGN.md and Design-System MCP Servers"
description: "DESIGN.md tells an agent what your brand means. It cannot say which components exist today or which props are real; MCP servers do. I linted 74 community files, read the Figma, Storybook and shadcn docs, and found the client's seat now decides what a freelancer's agent can do."
last_updated: "October 10, 2026"
source: "https://syedmoinuddin.com/blog/design-md-mcp-design-systems-2026"
---

# The Brief and the Inventory: What I Learned Researching DESIGN.md and Design-System MCP Servers

DESIGN.md tells an agent what your brand means. It cannot say which components exist today or which props are real; MCP servers do. I linted 74 community files, read the Figma, Storybook and shadcn docs, and found the client's seat now decides what a freelancer's agent can do.

Here is the whole argument up front. A `DESIGN.md` is a brief: one Markdown file with design tokens in YAML on top and plain-language rationale below, so an agent learns what a color is for and not only its hex value \[1]\[2]. It answers "why", and it is static. It cannot answer what an agent needs halfway through a screen: which `Button` exists in this codebase today, which props it really takes, and whether the thing it just built passes the tests. Those are live facts, and in 2026 they arrive over MCP, from Figma, Storybook or a component registry \[3]\[4]\[5]. Figma's own docs say its MCP server does not understand your design system by default \[6]. So the setup that works is both: a brief the agent reads and an inventory it can query. For freelancers, that pair is also the deliverable that outlives the contract, and whether your agent can use half of it depends on the seat the client gives you.

I started this thinking `DESIGN.md` was the whole story, a better handoff file that would retire the Figma link and the PDF style guide. Three things changed my mind. A vendor-run eval found that with the design system out of an agent's reach, 73% of style decisions bypassed tokens and none of 60 runs flagged a problem \[7]. Mature systems already ship both halves: Cognite's Aura pairs a `DESIGN.md` with an MCP server for its docs \[8], and Atlassian publishes its MCP server while keeping its `design-md` skill internal \[9]. And when I ran Google's own linter over 74 community `DESIGN.md` files, 13 had no tokens it could read.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/brief-and-inventory-light-eb5d2e53.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/brief-and-inventory-dark-0ed76fc2.svg" alt="Diagram: on the left, DESIGN.md as the brief, with YAML tokens, eight Markdown sections and a home in the repo, answering what a color is for. On the right, MCP servers as the inventory: Figma, Storybook and shadcn, answering which components and props exist today. Both feed one coding agent, the file read once and the servers queried live." />

*FIG. 01 · The brief and the inventory · the file carries intent, the servers carry what exists right now \[2]\[6]\[4]*

## What is actually inside a DESIGN.md?

Google's Stitch team open-sourced the draft spec on April 21, 2026, so any tool could read the same design rules \[1]. YAML front matter holds the tokens in five groups, `colors`, `typography`, `rounded`, `spacing` and `components`, and a component can reference another token, such as `{colors.primary}` \[2]. The Markdown body holds up to eight `##` sections in a fixed order, from Overview to Do's and Don'ts. Tokens give exact values; prose says why they exist and when to use them \[2].

The tooling surprised me. The `@google/design.md` package ships a linter with nine rules: one error, `broken-ref`, for a reference that resolves to nothing; six warnings, including a WCAG AA `contrast-ratio` check at 4.5:1; and two info rules \[2]. It also diffs versions for token regressions and exports to Tailwind or W3C DTCG JSON \[2], and DTCG reached its first stable version, 2025.10, last October \[10]. The format itself is still `alpha`, at release 0.3.0 from June 15, 2026 \[2].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/anatomy-light-bcdfcce3.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/anatomy-dark-dd9171e6.svg" alt="Anatomy of a DESIGN.md: five YAML token groups (colors, typography, rounded, spacing, components), eight Markdown sections in fixed order from Overview to Do's and Don'ts, and the linter's nine rules drawn to scale: 1 error (broken-ref), 6 warnings and 2 info rules." />

*FIG. 02 · Two layers, eight sections, nine lint rules · only a broken token reference is an error \[2]*

## How well do the community files hold up?

Adoption ran ahead of the spec. On October 10 the official repo had 26.3k stars, and VoltAgent's collection of brand files had 101k, up from the 71k Mejba Ahmed counted in early May \[2]\[11]\[12]. Most people meet the format through that collection, so I cloned it at its October 5 commit, 74 files, and ran `@google/design.md` 0.3.0 against every one.

None produced an error, which is narrower than it sounds. In 13 files the linter found no machine-readable tokens: 10 had no YAML and 3 had YAML it could not parse, so to an agent they are prose. 36 files had at least one component text and background pair under 4.5:1, 89 findings in all, including the primary button in six. I excluded another 89 findings on fully transparent backgrounds, which the linter scores against black. 61 files defined tokens no component used.

Two caveats. These files are extracted from public websites, and the repo disclaims ownership of any site's visual identity \[11]. And WCAG accepts 3:1 for large or bold text, so some of those buttons pass on the live site. The finding is about the file: an agent that copies one inherits its contrast misses unless something checks.

The number I got wrong first was section order. The collection uses nine sections of its own, such as an Agent Prompt Guide \[11], so I expected `section-order` warnings. There were none, because the spec preserves headings it does not know rather than rejecting them \[2].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/lint-74-light-14bb46ad.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/lint-74-dark-1cfe58e7.svg" alt="Bar chart of Google's DESIGN.md linter run on 74 community files: 0 files with a lint error, 13 with no machine-readable tokens, 36 with a component color pair under 4.5:1, 61 with color tokens no component uses, 20 with component props outside the spec, and 0 section-order warnings." />

*FIG. 03 · Google's linter against 74 community files · zero errors, 13 with no readable tokens, 36 with color pairs under 4.5:1 · my run, October 10, 2026 \[2]\[11]*

## Why isn't the file enough on its own?

Because a file is read once and drifts quietly. TJ Pitre, who maintains the open source Figma Console MCP, puts it simply: an agent does not know your design system exists unless someone puts it in its context, and left alone it generates a component rather than finding the governed one \[13]. A `DESIGN.md` puts the rules in context, not the inventory. It cannot tell the agent that `Card` gained a variant on Tuesday.

Knapsack's eval is the sharpest evidence I found, with caveats up front: Knapsack sells design system tooling, and the test covers 60 runs against one system, Meta's open source Astryx \[7]. Out of reach, 73% of style decisions bypassed tokens, one in three component choices built something new, and 0 of 60 runs reported a problem \[7]. In reach, 60 of 60 runs used the system and decisions the compiler could check rose from 49% to 78% \[7]. The post does not say whether "in reach" meant a file, an MCP server or both, so I read it as evidence for live context in general.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/drift-eval-light-a2429dbd.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/drift-eval-dark-2d382c90.svg" alt="Knapsack's vendor-run evals on Meta's Astryx design system, 60 runs. With the system out of reach: 73% of style decisions bypassed tokens, 1 in 3 component choices built a new one, about 31 token violations per build, and 0 of 60 runs reported a problem. With it in reach: 60 of 60 runs used the system, compiler-checkable decisions rose from 49% to 78%, and invented token names fell 95%." />

*FIG. 04 · Out of reach, agents improvise; in reach, they use the system · vendor-run, 60 runs, one design system \[7]*

Practitioners report the same split. Mejba Ahmed shipped four products on `DESIGN.md`; a 412-line file took him about three hours and then produced a landing page in 40 minutes, and his warning is about forks, where a file copied from a sibling project builds the other brand's UI \[12]. He also writes that Claude Design launched with deep `DESIGN.md` support. I could not confirm it: Anthropic's announcement says Claude Design builds a design system by reading your codebase and design files, and never mentions `DESIGN.md` \[14]. I treat that claim as secondhand.

## What does MCP add that the file can't?

Live answers to narrow questions. Figma's server lists 18 read tools and 12 write tools, not counting its Weave tools \[3]. `search_design_system` finds components and variables across libraries, `get_variable_defs` returns the tokens a selection uses, and with Code Connect the response carries your real component's import and usage snippet instead of generic React and Tailwind \[3]\[15]. Since March 24, 2026, `use_figma` also writes native frames, components and variables back to the canvas \[16]\[17].

Storybook's addon serves MCP from the dev server at `/mcp`: `docs-list` and `docs-show` for documented components and props, and `test-run` for interaction and accessibility tests on what the agent built \[4]. Its suggested `AGENTS.md` rule is the best one-line case for MCP I read: never hallucinate component properties, check them through the tools first \[4]. The shadcn server does the same for component registries, including private ones \[5].

The protocol grew up this year too. The July 28, 2026 revision made MCP stateless, so any request can land on any server instance, and the maintainers report close to half a billion SDK downloads a month \[18]. Figma's VP of Engineering, Josh Clemm, is quoted in that release saying more builders use Figma's MCP server and the stateless core lets it scale with them \[18].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/timeline-light-3b7c0d36.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/timeline-dark-4303afd5.svg" alt="Timeline from June 2025 to October 2026: Figma MCP server launches read-only in June 2025, DTCG tokens spec stable at 2025.10 in October 2025, MCP November 2025 spec revision, Figma code to canvas in February 2026, use_figma writes to the canvas on March 24, 2026, Claude Design launches April 17, DESIGN.md spec open-sourced April 21, design.md CLI 0.3.0 on June 15, and the stateless MCP 2026-07-28 spec on July 28, 2026." />

*FIG. 05 · Read-only to read-write to stateless in just over a year · the pieces this post depends on \[16]\[10]\[18]\[14]\[1]\[2]*

Figma is honest about the limit. Its docs say the server does not generate final code, does not understand your design system by default, and does not fix problems for you \[6]. That is the gap the brief fills. The file supplies intent, the server supplies inventory, and neither does the other's job.

## What does the client actually see?

Mostly the output. On Upwork's August earnings call, CEO Hayden Brown said clients increasingly assume AI will be used without saying so: nearly half of freelancers in a company survey said their latest project involved AI, while 16% of job posts mentioned it \[19]. Upwork also sees clients hiring people to finish or fix projects started with AI, including turning AI-generated code into production websites \[19].

What changes is what the client keeps. The old handoff was a Figma link and a style guide a person had to read. The 2026 handoff is a linted `DESIGN.md` in their repo, plus endpoints their own agents can call after you leave: a Figma library with Code Connect mappings, a published Storybook MCP, a component registry \[2]\[15]\[4]\[5]. The file is portable and free. The endpoints are only as good as the seats and upkeep behind them.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/handoff-light-dfd50908.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/handoff-dark-90485b54.svg" alt="Before and after handoff: before, a Figma file link, a PDF or wiki style guide and specs in tickets, all read by people. In 2026, a linted DESIGN.md in the client's repo that needs no seat, plus a Figma library with Code Connect that needs Dev or Full seats, a Storybook MCP on a dev server or published Storybook, a component registry over MCP, and an AGENTS.md routing rule." />

*FIG. 06 · What the client keeps after you leave · a file any agent can read, and endpoints that need seats and upkeep \[2]\[15]\[4]\[5]*

Designers already work this way. In UX Tools' independent survey of 1,478 designers this spring, Claude was the second most-used weekly tool at 50.8%, behind Figma at 82.6%, and design systems and tokens ranked third among next-year investments at 40.2% \[20]. Among the 17.9% who work independently, 36.2% said AI is now central to their workflow, against 28.6% at agencies \[20].

## Why does the client's seat decide what your agent can do?

This is the part I would put in a statement of work. View and Collab seats get up to 20 Figma MCP tool calls a month on every plan. Dev and Full seats get 200 a day on Professional and Organization and 600 a day on Enterprise \[21]. Writing is narrower: the developer docs say agents need a Full seat to write to Figma files, and the help center adds that Dev seats can write only in drafts \[22]\[23]. Only clients listed in Figma's MCP catalog can connect at all \[21].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/access-light-38f2b639.svg" srcDark="https://images.syedmoinuddin.com/blogs/design-md-mcp-design-systems-2026/access-dark-71dfa072.svg" alt="Matrix of maximum Figma MCP tool calls by plan and seat: View and Collab seats get 20 a month on Starter, Professional, Organization and Enterprise; Dev and Full seats get 200 a day with 10 a minute on Professional, 200 a day with 15 a minute on Organization, and 600 a day with 20 a minute on Enterprise. Full seats can write to Figma files, Dev seats only in drafts." />

*FIG. 07 · The client's seat decides what your agent can do · 20 calls a month on a View seat, and writing needs a Full seat \[21]\[22]\[23]*

A freelancer on a client's View seat has 20 calls for the month, which one agent session can spend. Figma also says writing will become a usage-based paid feature after the free beta \[23]\[17]. And a catalog listing is not proof of working support: in April, a Windsurf user on a Professional Full seat reported that read tools loaded but `use_figma` never appeared \[24]. Ask for a Dev or Full seat before the first sprint, and test the exact editor you will use.

## How would I wire one project?

Three pieces: the brief, a routing rule, and a lint gate. I ran the `DESIGN.md` below through the 0.3.0 linter and got zero errors and zero warnings. Change one letter in the `{colors.accent}` reference and it becomes a `broken-ref` error with exit code 1, which is what makes it usable as a CI gate \[2].

```md
---
version: alpha
name: Client Brand
colors:
  primary: "#1A1C1E"
  on-primary: "#FFFFFF"
  accent: "#B8422E"
  surface: "#F7F5F2"
typography:
  body-md:
    fontFamily: Inter
    fontSize: 1rem
  label-caps:
    fontFamily: Inter
    fontSize: 0.75rem
rounded:
  sm: 4px
spacing:
  sm: 8px
  md: 16px
components:
  button-primary:
    backgroundColor: "{colors.accent}"
    textColor: "{colors.on-primary}"
    rounded: "{rounded.sm}"
    padding: 12px
  page:
    backgroundColor: "{colors.surface}"
    textColor: "{colors.primary}"
---

## Overview

Quiet and editorial. Dense tables, generous margins. The accent is reserved
for the single most important action on a screen.

## Colors

- **Primary (#1A1C1E):** body text and headings.
- **Accent (#B8422E):** primary buttons only. Never links or decoration.

## Do's and Don'ts

- Never hardcode a hex value in a component; use a token.
- Never invent a component prop. Look it up first.
```

The inventory goes in `.mcp.json` for Claude Code: Figma's remote server and a local Storybook. I have not run this exact pairing end to end, so treat it as a starting point \[3]\[4].

```json
{
  "mcpServers": {
    "figma": { "type": "http", "url": "https://mcp.figma.com/mcp" },
    "storybook": { "type": "http", "url": "http://localhost:6006/mcp" }
  }
}
```

The routing rule in `AGENTS.md` tells the agent which source answers which question. The second line is adapted from Storybook's own suggestion \[4].

```md
## UI work

- Read DESIGN.md before generating any UI. It is the source of truth for tokens and intent.
- Before using a component or a prop, look it up with docs-list and docs-show. Never guess a prop.
- For a Figma link, call get_design_context and reuse components that come back through Code Connect.
- After building, run test-run on the new stories and fix what fails before reporting done.
```

The lint gate is one script. The `designmd` alias is the README's own suggestion for `package.json`, because the `.md` in the main binary name confuses Windows \[2].

```json
{
  "scripts": {
    "design:lint": "designmd lint DESIGN.md"
  }
}
```

## What does the side-by-side look like?

|           | `DESIGN.md`                                | Figma MCP (remote)                                | Storybook MCP                                                            | shadcn MCP                                            |
| --------- | ------------------------------------------ | ------------------------------------------------- | ------------------------------------------------------------------------ | ----------------------------------------------------- |
| Answers   | Why a value exists and when to use it \[2] | What is in the design file and its libraries \[3] | Which documented components and props exist, and whether tests pass \[4] | What is in a component registry \[5]                  |
| Lives     | Repo root, versioned with the code \[2]    | Figma's hosted endpoint \[3]                      | Storybook dev server at `/mcp`, or published \[4]                        | Locally, reading registries in `components.json` \[5] |
| Freshness | As of the last edit                        | Live                                              | Live                                                                     | Live                                                  |
| Writes    | Nothing                                    | Canvas, via `use_figma` on a Full seat \[22]      | Stories and test runs \[4]                                               | Installs components \[5]                              |
| Access    | Apache-2.0, free \[2]                      | 20 calls a month to 600 a day, by seat \[21]      | Open source addon \[4]                                                   | Public or token-protected registries \[5]             |
| Status    | `alpha`, release 0.3.0 \[2]                | Write tools in free beta \[17]                    | AI features in preview \[4]                                              | Not stated                                            |

## Which one should you reach for?

**`DESIGN.md` alone is enough if:**

* [ ] The project is small and has no component library yet \[12]
* [ ] The client has no Figma seat to give you and you need something portable and free \[2]\[21]
* [ ] You can gate it in CI so a broken token reference fails the build \[2]

**Add the Figma MCP server if:**

* [ ] The source of truth is a Figma library with variables and components \[3]
* [ ] The client can give you a Dev or Full seat, since a View seat gets 20 calls a month \[21]
* [ ] Someone will keep Code Connect mappings current as component APIs change \[15]

**Add Storybook or a registry server if:**

* [ ] The components already exist in code and agents keep inventing props \[4]
* [ ] You want the agent to run interaction and accessibility tests before it says done \[4]\[7]
* [ ] The team ships a private component registry \[5]

**If you are the freelancer, put these in the contract:**

* [ ] Which plan and seat you will work on, and who pays once agent writes stop being free \[21]\[23]
* [ ] A linted `DESIGN.md` written for the client's brand, not forked from a public file \[11]\[12]
* [ ] Who keeps the MCP endpoints running after handoff \[4]\[15]

## What would I do differently next time?

1. Run the tool before writing about it. My guess about section-order warnings was wrong, and the 13 community files with no readable tokens did not come up in anything I read.
2. Read the vendor's "what it does not do" page first. Figma's three-line list framed this post better than its launch blog did.
3. Keep format support apart from product claims. Several write-ups say Claude Design reads `DESIGN.md`; Anthropic's announcement does not. A support claim needs the tool's own docs.

## Sources

1. Google, Cassia Xu, "Stitch's DESIGN.md format is now open-source so you can use it across platforms," April 21, 2026, [blog.google](https://blog.google/innovation-and-ai/models-and-research/google-labs/stitch-design-md/)
2. Google Labs, "google-labs-code/design.md" README and release 0.3.0 (June 15, 2026), accessed October 10, 2026, [github.com](https://github.com/google-labs-code/design.md)
3. Figma, "Tools and prompts," Figma MCP server developer docs, accessed October 10, 2026, [developers.figma.com](https://developers.figma.com/docs/figma-mcp-server/tools-and-prompts/)
4. Storybook, "MCP server," Storybook 10.6 docs, accessed October 10, 2026, [storybook.js.org](https://storybook.js.org/docs/ai/mcp/overview)
5. shadcn/ui, "MCP Server," accessed October 10, 2026, [ui.shadcn.com](https://ui.shadcn.com/docs/mcp)
6. Figma, "What the MCP sends vs. what the agent does," Figma MCP server developer docs, accessed October 10, 2026, [developers.figma.com](https://developers.figma.com/docs/figma-mcp-server/mcp-vs-agent/)
7. Knapsack, "Your AI Builder Has Changed, And Your Design System Needs to Know," August 19, 2026, [knapsack.cloud](https://www.knapsack.cloud/blog/your-ai-builder-has-changed--and-your-design-system-needs-to-know)
8. Cognite, "About Aura," Aura design system docs, accessed October 10, 2026, [docs.cognite.com](https://docs.cognite.com/aura-design-system/what-is-aura)
9. Atlassian Design, "Develop: With AI," accessed October 10, 2026, [atlassian.design](https://atlassian.design/get-started/develop/with-ai)
10. Design Tokens Community Group, "First stable version 2025.10 now available," designtokens.org home page, accessed October 10, 2026, [designtokens.org](https://www.designtokens.org/)
11. VoltAgent, "awesome-design-md," commit 13be5c0 of October 5, 2026, accessed October 10, 2026, [github.com](https://github.com/VoltAgent/awesome-design-md)
12. Mejba Ahmed, "DESIGN.md: The AI Design Framework Hiding In Plain Sight," May 5, 2026, [mejba.me](https://www.mejba.me/blog/design-md-ai-design-framework)
13. TJ Pitre, Southleft, "The Design System Was Fine Until the Agents Moved In," August 17, 2026, [southleft.substack.com](https://southleft.substack.com/p/the-design-system-was-fine-until)
14. Anthropic, "Introducing Claude Design by Anthropic Labs," April 17, 2026, [anthropic.com](https://www.anthropic.com/news/claude-design-anthropic-labs)
15. Figma, "Code Connect integration," Figma MCP server developer docs, accessed October 10, 2026, [developers.figma.com](https://developers.figma.com/docs/figma-mcp-server/code-connect-integration/)
16. Vannarot Roeung, Creative AI News, "Figma Opens Canvas to AI Design Agents," March 24, 2026, [creativeainews.com](https://www.creativeainews.com/blog/figma-canvas-ai-agents-mcp/)
17. Figma, Matt Colyer, "Agents, meet the Figma canvas," March 2026, [figma.com](https://www.figma.com/blog/the-figma-canvas-is-now-open-to-agents/)
18. Model Context Protocol Blog, David Soria Parra and Den Delimarsky, "The 2026-07-28 Specification," July 28, 2026, [blog.modelcontextprotocol.io](https://blog.modelcontextprotocol.io/posts/2026-07-28/)
19. PYMNTS, "Upwork Navigates Cross-Currents as AI Reshapes Freelance Demand," August 10, 2026, [pymnts.com](https://www.pymnts.com/earnings/2026/upwork-navigates-cross-currents-as-ai-reshapes-freelance-demand/)
20. UX Tools, Tommy Geoco, "State of Prototyping: Spring 2026," survey run March 14 to April 6, 2026, [uxtools.co](https://www.uxtools.co/survey/2026/state-of-prototyping)
21. Figma, "Rate limits & access," Figma MCP server developer docs, accessed October 10, 2026, [developers.figma.com](https://developers.figma.com/docs/figma-mcp-server/rate-limits-access/)
22. Figma, "Write to canvas," Figma MCP server developer docs, accessed October 10, 2026, [developers.figma.com](https://developers.figma.com/docs/figma-mcp-server/write-to-canvas/)
23. Figma Help Center, Figma MCP server help article 39216419318551, accessed October 10, 2026, [help.figma.com](https://help.figma.com/hc/en-us/articles/39216419318551)
24. Figma Forum, "Figma MCP for Windsurf Says Read and Write Access. However, Write to Canvas is not working," April 2, 2026, [forum.figma.com](https://forum.figma.com/ask-the-community-7/figma-mcp-for-windsurf-says-read-and-write-access-however-write-to-canvas-is-not-working-52569)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on October 10, 2026

---
title: "One Flag Away From Root: What I Learned Researching the LMCache Pickle RCE"
description: "CVE-2026-105192 lets one unauthenticated ZeroMQ message run code on an LMCache multiprocess server, and no fixed version exists. The default bind is safe; LMCache's own Kubernetes example is not. Who can reach the port, why this bug keeps recurring, and four checks to run today."
last_updated: "October 8, 2026"
source: "https://syedmoinuddin.com/blog/lmcache-pickle-rce-cve-2026-105192"
---

# One Flag Away From Root: What I Learned Researching the LMCache Pickle RCE

CVE-2026-105192 lets one unauthenticated ZeroMQ message run code on an LMCache multiprocess server, and no fixed version exists. The default bind is safe; LMCache's own Kubernetes example is not. Who can reach the port, why this bug keeps recurring, and four checks to run today.

Here is the whole argument up front. CVE-2026-105192 lets anyone who can open a TCP connection to an LMCache multiprocess server run code on it with a single message, as root on the official images, and there is no patched version to install \[1]\[2]. The bug is not exotic. LMCache hands bytes from an unauthenticated ZeroMQ socket to Python's `pickle`, the same mistake that has now shipped in eight LLM serving projects since 2024 \[3]\[4]\[5]. So for the next few weeks the fix is not a version number, it is one flag. With the default `--host localhost`, nothing off the machine can reach the port. With `--host 0.0.0.0`, which is what LMCache's own Kubernetes example uses next to `hostNetwork: true`, anything that can reach the node can \[1]\[6].

I started this as a quick "upgrade now" note, like my [Next.js security post](https://syedmoinuddin.com/blog/nextjs-16-3-7-is-not-the-patch). Then PyPI showed there is nothing to upgrade to: twenty stable releases carry the bug, and the release candidate published the day before disclosure still has it \[7]\[1]. What changed the post was the example DaemonSet, which puts the port on the node IP, where most network plugins do not apply pod policy selectors \[6]\[8]. "My reading" below means the 0.5.5 and 0.5.6rc3 wheels I pulled from PyPI on October 8. I read the code. I did not run the exploit.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/exposure-light-f8101eac.svg" srcDark="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/exposure-dark-08626765.svg" alt="Table of four ways to run LMCache: in-process inside vLLM opens no port; --host localhost on port 5555 is reachable only from the same machine; --host 0.0.0.0 on the pod network is reachable from anything routable to the pod IP; the example DaemonSet with hostNetwork and 0.0.0.0 on port 6555 is reachable from anything that can reach the node IP, where pod selectors usually do not apply." />

*FIG. 01 · One flag decides who can reach the cache server · the default is local, the example DaemonSet is not \[1]\[6]\[8]*

## What does one message actually do?

LMCache is a KV cache layer for vLLM and other engines. In multiprocess mode it runs as a separate server, one per node, that vLLM workers reach over ZeroMQ or gRPC \[9]. The ZeroMQ side is a ROUTER socket with no CURVE, ZAP, password or message authentication \[1]. One msgpack extension type, code 1, carries a `DeviceIPCWrapper`, the handle to GPU memory a worker wants to share, and the server rebuilds it with `pickle.loads` so the concrete subclass survives the trip \[1]\[10].

The order is the problem. The pickle runs inside `ext_hook` while the server is still decoding a `REGISTER_KV_CACHE` message, before any handler looks at what arrived \[1]. In JFrog's proof of concept, one DEALER message to port 5555 makes the server write `uid=0(root)` to a file, and only then does it log a type error \[1]. Yuval Moravchick of JFrog found the bug, and JFrog scores it 9.8 for a server bound to a routable address \[1].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/decode-path-light-342b979d.svg" srcDark="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/decode-path-dark-e7cbdd44.svg" alt="Six-step flow: a DEALER message reaches the ZeroMQ ROUTER on port 5555 with no authentication, msgpack decodes the message arguments, ext_hook code 1 hands the bytes to DeviceIPCWrapper, pickle.loads runs the attacker's code, and only then does the handler's type check log an error. Affected 0.3.9 to 0.5.5 and 0.5.6rc1 to rc3, with no fixed release as of October 7, 2026." />

*FIG. 02 · The pickle runs before the server knows what it received · the failed type check comes after the command \[1]\[10]*

## Who can actually reach the port?

This is the part worth an afternoon. JFrog is careful about scope: the request server binds `localhost` unless the operator passes a routable `--host`, a stock single-host install is not reachable from other machines, and LMCache inside a vLLM process opens no port at all \[1]. My reading of both wheels agrees: `--host` defaults to `localhost` and `--port` to 5555.

The example people copy does not use the default. LMCache's v0.5.5 `lmcache-daemonset.yaml` starts the server with `--host "0.0.0.0"` and `--port "6555"`, sets `hostNetwork: true`, and pulls `lmcache/standalone:nightly` \[6]. Host networking puts the socket on the node's own interfaces, so the question becomes who can reach the node IP on 6555. The usual Kubernetes answer, a NetworkPolicy, is the wrong tool. The docs call policy behavior for `hostNetwork` pods undefined, and say the most common implementation ignores those pods when matching selectors and treats their traffic as node traffic \[8]. An `ipBlock` rule against node IPs can still work. A policy that selects `app: lmcache-server` probably does nothing. Note the port, too: a scanner keyed to JFrog's 5555 walks past a server started from the example on 6555 \[1]\[6].

## Is there a fixed version yet?

No. JFrog lists 0.3.9 through 0.5.5, the 0.5.6 release candidates through rc3, and the dev branch as of October 7, with no fixed release \[1]. The PyPI dates make the window concrete: 0.3.9 shipped on October 29, 2025 and 0.5.5 on September 12, 2026, which is twenty stable releases, not counting four post releases, in the 343 days before disclosure \[7]. LMCache had not published a security advisory when The Hacker News checked \[2], and PyPI still listed 0.5.6rc3 as the newest release when I checked on October 8 \[7].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/release-window-light-bba85b81.svg" srcDark="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/release-window-dark-02ccdebe.svg" alt="Timeline of 20 stable LMCache releases from 0.3.9 on October 29, 2025 to 0.5.5 on September 12, 2026, all affected, followed by 0.5.6rc1 to rc3 and disclosure of CVE-2026-105192 on October 7, 2026: 343 days from the first affected release, 25 days from 0.5.5, and zero fixed versions." />

*FIG. 03 · Twenty stable releases in 343 days, none fixed · hollow dots are the 0.5.6 release candidates, still affected \[7]\[1]*

I compared the two wheels to see what the release candidate does change. One thing got safer: the default `--http-host` of the multiprocess HTTP server moved from `0.0.0.0` in 0.5.5 to `127.0.0.1` in 0.5.6rc3, which matches what The Hacker News reported \[2]. That matters because a separate report says the same HTTP server on 0.5.5 will clear the cache, rewrite tenant quotas and return the whole process environment from `GET /env`, all without authentication \[11]. That report and five others came from one GitHub account on October 6, with proofs of concept but no maintainer reply or CVE, so I treat them as claims \[2]\[11]\[12].

One thing did not change, and it is wider than the advisory. Both wheels contain a second server-side `pickle.loads` in the engine-driven transfer code, on the bytes a worker sends with `COMMIT_STORE`. LMCache's docs describe that route as the "pickle path" \[9]. It only loads when `--supported-transfer-mode` is `engine_driven` or `auto`, JFrog does not mention it, and I did not test whether it is reachable without first registering a context. I am flagging it for one reason: when a fix ships, check that pickle left the transport, not only `DeviceIPCWrapper`.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/rc-diff-light-6c55fa18.svg" srcDark="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/rc-diff-dark-20ef591b.svg" alt="Comparison of LMCache 0.5.5 and 0.5.6rc3 wheels: the HTTP server default bind changed from 0.0.0.0 to 127.0.0.1, the request server still binds localhost on port 5555, DeviceIPCWrapper.Deserialize still calls pickle.loads, and the engine-driven commit_store path also still calls pickle.loads, which the advisory does not mention." />

*FIG. 04 · What 0.5.6rc3 changed, and what it did not · my reading of the PyPI wheels, not a test run \[7]\[1]\[9]*

I also looked for practitioner discussion and found none on Hacker News in the first day, so the record so far is a security vendor, a news write-up and one GitHub reporter. The most useful dissent is JFrog's own scoping: on a default single-host install, this is not a remote bug at all \[1].

## Why does this keep happening in LLM serving?

Because the code travels. Oligo's ShadowMQ research in November 2025 traced pickle over unauthenticated ZeroMQ TCP sockets through Meta's Llama Stack, vLLM, NVIDIA TensorRT-LLM, Modular Max Server, Microsoft's Sarathi-Serve and SGLang, and found that SGLang's vulnerable file opened with a note saying it was adapted from vLLM \[3]. Oligo's Avi Lumelsky summed it up as different maintainers at different companies making the same mistake \[3]. Since then SGLang picked up more pickle CVEs in March 2026, addressed in 0.5.10 \[4], and LMDeploy's disaggregated serving path got CVE-2025-66455, fixed in 0.16.0 by moving that channel from pickle to JSON \[5]. LMCache is the eighth.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/shadowmq-timeline-light-464feca2.svg" srcDark="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/shadowmq-timeline-dark-82f6308b.svg" alt="Timeline from 2024 to 2026 of pickle over unauthenticated ZeroMQ flaws in eight serving projects: Meta Llama Stack CVE-2024-50050 fixed with JSON, vLLM CVE-2025-30165 fixed with a new default engine, NVIDIA TensorRT-LLM CVE-2025-23254 fixed with HMAC, Modular Max Server CVE-2025-60455 fixed with msgpack, Microsoft Sarathi-Serve unpatched, SGLang CVE-2026-3059 and 3060 fixed in 0.5.10, LMDeploy CVE-2025-66455 fixed in 0.16.0 with JSON, and LMCache CVE-2026-105192 with no fix." />

*FIG. 05 · Eight serving projects, one mistake, two years · hollow dots had no fix when reported \[3]\[4]\[5]\[1]*

The library warned everyone. PyZMQ's docs say `recv_pyobj` is a thin wrapper over `pickle.loads` that trusts incoming messages with arbitrary code execution, and point to CURVE, IPC socket permissions or an HMAC checked before deserializing \[13]. LMCache never calls `recv_pyobj`. It reached pickle through a msgpack extension hook, which is exactly why a grep for `recv_pyobj` misses it. The projects that fixed this picked JSON, msgpack, HMAC validation or, for vLLM, a new default engine \[3]\[5]. vLLM's security guide is the honest summary for operators: every inter-node channel, KV cache transfer included, is insecure by default and belongs on an isolated network \[14].

## How would I check mine this afternoon?

Four checks, in this order. They assume Linux nodes and `kubectl` access, and they only read state. I tested the `jq` filter against sample pod JSON, not against your cluster.

```bash
# 1. Is multiprocess mode running anywhere? Read pod specs, not Helm values.
kubectl get pods -A -o json | jq -r '.items[]
  | select([.spec.containers[] | ((.command // []) + (.args // [])) | join(" ")]
           | any(test("lmcache(\\.v1\\.multiprocess| server)")))
  | "\(.metadata.namespace)/\(.metadata.name) hostNetwork=\(.spec.hostNetwork // false)"'

# 2. On each node that runs one: what is actually bound?
#    Anything other than 127.0.0.1 or ::1 is reachable off-host.
sudo ss -ltnp | grep -E ':(5555|6555|8080)\b'

# 3. From a different node: does the port accept a connection?
#    Connecting proves exposure. Do not send anything.
nc -vz -w 3 NODE_IP 6555

# 4. Who would injected code run as?
kubectl exec -n NAMESPACE POD -- id
```

If check 2 shows a routable bind, the fix depends on where your workers live. If they share the host's network, bind to `127.0.0.1` \[1]. If they reach the server through the node IP, as the DaemonSet layout implies, filter the port at the host. This is a sketch I have not run against a real CNI, and eBPF-based plugins may bypass `iptables` entirely:

```bash
# On each LMCache node: allow 6555 only from loopback and this node's pod range.
# .spec.podCIDR is empty on plugins that manage their own IP ranges; use your pod subnets then.
POD_CIDR=$(kubectl get node "$(hostname)" -o jsonpath='{.spec.podCIDR}')
sudo iptables -I INPUT -p tcp --dport 6555 -j DROP
sudo iptables -I INPUT -p tcp --dport 6555 -s "$POD_CIDR" -j ACCEPT
sudo iptables -I INPUT -p tcp --dport 6555 -s 127.0.0.1 -j ACCEPT
```

Keep JFrog's caveat in mind: anything that can still connect can still run code \[1]. On a node that also runs workloads you do not trust, turn multiprocess mode off until a release takes pickle out of the transport.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/four-checks-light-8b6807f2.svg" srcDark="https://images.syedmoinuddin.com/blogs/lmcache-pickle-rce-cve-2026-105192/four-checks-dark-a9518610.svg" alt="Four read-only checks in order: whether LMCache multiprocess mode is running, checked with kubectl; what it binds to on ports 5555, 6555 or 8080, checked with ss; who can reach it, checked with nc from another node; and which user it runs as, checked with id in the container. Until a fixed release ships, the bind address and the host firewall are the patch." />

*FIG. 06 · Four read-only checks, in order · the bind address and the host firewall are the patch for now \[1]\[6]\[8]*

## What does the side-by-side look like?

| Deployment shape                                             | Who can reach the request port           | Does a NetworkPolicy help?                         | What I would do now                               |
| ------------------------------------------------------------ | ---------------------------------------- | -------------------------------------------------- | ------------------------------------------------- |
| LMCache inside the vLLM process                              | No port is opened \[1]                   | Not needed                                         | Nothing for this CVE                              |
| `lmcache server` with the default `--host localhost`         | Processes on the same machine \[1]       | Not needed                                         | Keep the default and check nobody overrides it    |
| `--host 0.0.0.0` on the pod network                          | Anything that can route to the pod IP    | Yes, if your plugin enforces policy \[8]           | Bind narrower and add an ingress policy           |
| The example DaemonSet, `hostNetwork: true` on `0.0.0.0:6555` | Anything that can reach the node IP \[6] | Usually not, selectors skip host-network pods \[8] | Filter at the host, or turn multiprocess mode off |

## What should you do this week?

**If you run LMCache multiprocess mode:**

* [ ] Read `--host` and `--port` from every running server, and treat any non-loopback bind as exposed \[1]
* [ ] Check ports 6555 and 8080 as well as 5555 \[6]\[11]
* [ ] Upgrade vLLM to 0.30.0 or later, which fixes a one-request engine crash on LMCache multiprocess deployments \[15]
* [ ] Watch the LMCache security advisories page for the fix \[2]

**If you copied the example DaemonSet:**

* [ ] Do not count on a NetworkPolicy that selects the pod \[8]
* [ ] Filter the port on the node, or move the server off host networking \[6]
* [ ] Confirm which user the container runs as \[1]

**If you only use LMCache inside vLLM:**

* [ ] Nothing to patch for this CVE, but run check 1 to confirm no multiprocess server exists \[1]

**If you maintain anything that speaks ZeroMQ:**

* [ ] Grep for `pickle.loads` and `recv_pyobj` anywhere socket bytes flow, including codec hooks \[13]
* [ ] Authenticate before you deserialize: CURVE on the socket or an HMAC on each message \[13]\[1]

## What would I do differently next time?

1. Read the example deployment before the severity score. The 9.8 is conditional on a routable bind, and the example YAML is what tells you whether your cluster meets the condition.
2. Search for the class, not the CVE. Grepping a dependency tree for `pickle.loads` near socket code finds this bug and the next one, without waiting for a feed to catch up.
3. Treat "localhost by default" as a property of the binary, not of the deployment. Every exposed server in this story is a safe default plus one flag that someone added for a good reason.

## Sources

1. JFrog Security Research, "LMCache is vulnerable to Unauthenticated Remote Code Execution via Pickle Deserialization on the Multiprocess ZMQ Transport, JFSA-2026-001694382," October 7, 2026, [research.jfrog.com](https://research.jfrog.com/vulnerabilities/lmcache-is-vulnerable-to-unauthenticated-remote-code-execution-via-pickle-deserialization-on-the-multiprocess-zmq-transport-cve-2026-105192-jfsa-2026-001694382/)
2. The Hacker News, "Unpatched Critical LMCache Flaw Lets Unauthenticated Attackers Run Code Remotely," October 7, 2026, [thehackernews.com](https://thehackernews.com/2026/10/unpatched-critical-lmcache-flaw-lets.html)
3. Oligo Security, Avi Lumelsky, "ShadowMQ: How Code Reuse Spread Critical Vulnerabilities Across the AI Ecosystem," November 13, 2025, [oligo.security](https://www.oligo.security/blog/shadowmq-how-code-reuse-spread-critical-vulnerabilities-across-the-ai-ecosystem)
4. CERT/CC, "SGLang (sglang) is vulnerable to code execution attacks via unsafe pickle deserialization, VU#665416," March 12, 2026, [kb.cert.org](https://kb.cert.org/vuls/id/665416)
5. OSV, "CVE-2025-66455: LMDeploy has Remote Code Execution by Pickle Deserialization via handle_zmq_recv," September 18, 2026, [osv.dev](https://osv.dev/vulnerability/CVE-2025-66455)
6. LMCache, "examples/multi_process/lmcache-daemonset.yaml at v0.5.5," accessed October 8, 2026, [github.com](https://github.com/LMCache/LMCache/blob/v0.5.5/examples/multi_process/lmcache-daemonset.yaml)
7. PyPI, "lmcache release history," accessed October 8, 2026, [pypi.org](https://pypi.org/project/lmcache/#history)
8. Kubernetes, "Network Policies," updated April 14, 2026, [kubernetes.io](https://kubernetes.io/docs/concepts/services-networking/network-policies/)
9. LMCache, "Overview, multiprocess mode," accessed October 8, 2026, [docs.lmcache.ai](https://docs.lmcache.ai/mp/index.html)
10. LMCache, "lmcache/v1/platform/base/ipc_wrapper.py at v0.5.5," accessed October 8, 2026, [github.com](https://github.com/LMCache/LMCache/blob/v0.5.5/lmcache/v1/platform/base/ipc_wrapper.py)
11. yyymk, "Unauthenticated cache control plane and process environment disclosure on LMCache multiprocess HTTP server," GitHub issue 5511, October 6, 2026, [github.com](https://github.com/LMCache/LMCache/issues/5511)
12. yyymk, "Unauthenticated cross-tenant KV cache read, write, and unbounded storage on LMCache server," GitHub issue 5507, October 6, 2026, [github.com](https://github.com/LMCache/LMCache/issues/5507)
13. PyZMQ, "Serializing messages with PyZMQ," PyZMQ 27.2.0 documentation, accessed October 8, 2026, [pyzmq.readthedocs.io](https://pyzmq.readthedocs.io/en/latest/howto/serialization.html)
14. vLLM, "Security," updated October 6, 2026, [docs.vllm.ai](https://docs.vllm.ai/en/latest/usage/security/)
15. vLLM, "Loose cache_salt validation lets a single request kill EngineCore on LMCache-MP deployments, GHSA-2823-qmq8-rwvj," September 23, 2026, [github.com](https://github.com/vllm-project/vllm/security/advisories/GHSA-2823-qmq8-rwvj)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on October 8, 2026

---
title: "16.3.7 Is Not the Patch: What I Learned Researching the Next.js September Security Release"
description: "The September notice named 16.3.7. It shipped as a bug fix, and the seven fixes landed in 16.3.8. Five days later npm audit still called 16.3.7 clean, and a release cooldown installed it on its own. What applies to your app, and the five places an old Next.js keeps running."
last_updated: "October 5, 2026"
source: "https://syedmoinuddin.com/blog/nextjs-16-3-7-is-not-the-patch"
---

# 16.3.7 Is Not the Patch: What I Learned Researching the Next.js September Security Release

The September notice named 16.3.7. It shipped as a bug fix, and the seven fixes landed in 16.3.8. Five days later npm audit still called 16.3.7 clean, and a release cooldown installed it on its own. What applies to your app, and the five places an old Next.js keeps running.

Here is the whole argument up front. The version number in a Next.js security notice is a forecast, and this month it was wrong. The September 23 notice said the fixes would ship in 16.3.7 \[1]. 16.3.7 shipped on September 29 as a bug fix with none of them, and the seven fixes landed in 16.3.8 and 15.5.27 on September 30, with one critical and one high postponed \[1]\[2]. Five days later, three tools I would normally trust still treated 16.3.7 as fine: `npm audit` reported zero vulnerabilities, a one-day release cooldown installed it on its own, and bumping `next` in a lockfile left an older image library behind. The only floor worth trusting is the one in the release post, checked against what is actually running.

I started this as a ten-minute patch reminder for a week with three Next.js security posts in it. What changed my mind was running `npm audit` against a lockfile pinned to 16.3.7 and getting a clean bill of health. The second surprise was worse, because it came from my own advice: the release cooldown I recommended in [my keyv worm post](https://syedmoinuddin.com/blog/keyv-shai-hulud-npm-worm-check) is exactly the setting that picks 16.3.7 for you. Everything marked "my test" below I reproduced in a sandbox on October 5, with the configs included so you can rerun them.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/timeline-light-png-ddc7bfa7.png" srcDark="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/timeline-dark-56ff63db.svg" alt="Timeline of Next.js 16 security floors from July to October 2026: monthly releases announced Jul 13, 16.2.11 on Jul 21 with 4 high and 5 medium fixes, 16.3.3 on Aug 25 with 2 critical, 16.3.6 out of band on Sep 22 for 1 critical RCE, 16.3.7 on Sep 29 with bug fixes only and newest for 31 hours, 16.3.8 on Sep 30 with seven fixes and 1 critical and 1 high postponed, and npm audit calling 16.3.7 clean on Oct 5." />

*FIG. 01 · The patched version moved four times in ten weeks · filled dots are floors, the dashed one is 16.3.7 \[2]\[3]\[4]\[5]\[6]\[7]*

## Why did the safe version keep moving?

Next.js moved to a formal security release program on July 13: advance notice roughly once a month, the highest expected severity in each notice, and time to coordinate firewall rules with hosting providers for apps that are not patched yet \[3]. The stated reason is volume. The team says LLM-assisted vulnerability research is rising fast, pointing to Mozilla disclosing 271 issues in a single Firefox release, all found by Anthropic's Mythos Preview \[3].

The floor on the 16.x line has moved four times since. July's 16.2.11 fixed four high and five medium issues \[4]. August's 16.3.3 was pulled forward a day after a second critical turned up in an upstream dependency, and it fixed two criticals, including remote code execution through `sharp`'s libheif when optimizing an attacker-controlled AVIF image \[5]. On September 22, an out-of-band 16.3.6 fixed a critical remote code execution in the Node.js `ImageResponse` from `next/og` \[6]. Then came 16.3.8 \[2]. August and September only patched 16.3 and 15.5, so anyone still on 16.2 had to take a minor upgrade to get the fixes \[5]\[2].

The npm registry shows how narrow the trap was. 16.3.7 was published at 09:04 UTC on September 29, and 16.3.8 at 16:07 UTC on September 30, so for 31 hours the newest 16.3 release was the one the notice had named, without the fixes \[7]\[1].

## What changed between the notice and the release?

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/notice-vs-release-light-png-ffaf9f44.png" srcDark="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/notice-vs-release-dark-d9763176.svg" alt="Bar chart of September fixes by severity, shipped of announced: critical 0 of 1, high 1 of 2, medium 5 of 5, low 1 of 1. The September 23 notice promised nine fixes in 16.3.7; 16.3.8 and 15.5.27 shipped seven on September 30, with one critical and one high postponed for upstream dependency delays." />

*FIG. 02 · Nine fixes in 16.3.7 became seven in 16.3.8 · one critical and one high postponed, not cancelled \[1]\[2]*

The Next.js team did correct the record, with dated updates at the top of the notice \[1]. The problem is everything that copied the original. A daily.dev summary of the notice still lists 16.3.7 and nine fixes when I checked it on October 5 \[8]. The careful version of this response looks like Dayopt's ticket from September 29, whose first pre-release step is not to treat 16.3.7 as the fixed version \[9]. Even that ticket still counts nine advisories, because it was written before the count dropped. This is not new, either. After React2Shell in December 2025, a Vercel Community thread was titled after Next.js docs that suggested the wrong version to patch to \[10].

## Why does my scanner say 16.3.7 is clean?

Because the scanner has not heard about September yet. On October 5, about five days after disclosure, I ran `npm audit` with npm 12.2.0 against three lockfiles (my test). With `next@16.3.5` it reported one critical, the September 22 `next/og` advisory. With `next@16.3.7` and `next@16.3.8` it reported zero vulnerabilities each. The results link to the GitHub Advisory Database, and that is where the gap is: all seven September 30 advisories returned 404 there when I checked, while the September 22 one resolved.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/scanner-lag-light-png-d8b4dd9f.png" srcDark="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/scanner-lag-dark-82767902.svg" alt="npm audit on October 5, 2026: a lockfile on next 16.3.5 shows 1 critical, while 16.3.7 and 16.3.8 show 0 found, even though all seven September 30 advisories apply to 16.3.7. The September 22 critical took 8 days to reach the GitHub Advisory Database, and the seven September 30 advisories were still missing after 5 days." />

*FIG. 03 · npm audit said zero on 16.3.7 · the September 22 critical took 8 days to reach the database, the September 30 seven were still missing on October 5 \[11]\[12]\[13]*

The lag has a precedent from the same month. The September 22 critical was published in the Next.js repository that day, but the GitHub Advisory Database lists it as published and reviewed on September 30, with a CVSS score of 9.5 \[13]. For eight days, a lockfile on 16.3.5 would have passed `npm audit` with that remote code execution in it. The September advisories may be stuck for a mundane reason: the two I opened in the vercel/next.js repository still show their patched versions as "16.3.?" and "15.5.?", and one has no upper bound on its affected range \[11]\[12]. I am inferring that the placeholders are why they have not been imported. I cannot see GitHub's review queue.

## Which of the seven actually apply to my app?

Not all of them, and where you host changes the answer. Here is the September 30 set, with conditions from the release post and hosting notes from the Next.js and Netlify write-ups \[2]\[14]:

| Advisory                                                | Severity | You are exposed if                                                                  | Hosting notes                                     |
| ------------------------------------------------------- | -------- | ----------------------------------------------------------------------------------- | ------------------------------------------------- |
| GHSA-cjq9, SSRF in Image Optimization (CVE-2026-94483)  | High     | 16.x, with a host in `images.remotePatterns` you would not trust with its DNS \[11] | Not affected on Netlify \[14]                     |
| GHSA-4jqv, SSG and ISR cache poisoning (CVE-2026-94543) | Medium   | Self-hosted Pages Router with SSG or ISR pages \[2]                                 | Not affected on Vercel \[2]                       |
| GHSA-mcj8, catch-all cache poisoning (CVE-2026-94484)   | Medium   | A root-level catch-all page plus SSG or ISR routes \[2]                             | An availability issue (HTTP 500) on Netlify \[14] |
| GHSA-f87g, metadata image bypass (CVE-2026-94485)       | Medium   | App Router built with webpack, using `opengraph-image` or `twitter-image` \[2]      | Turbopack builds not affected \[2]                |
| GHSA-h694, nested `use cache` leak                      | Medium   | Cache Components, with a nested `use cache` reading a root param \[2]               | Applies to 16.3.x \[14]                           |
| GHSA-3w37, Draft Mode leak (CVE-2026-94544)             | Medium   | Cache Components plus Draft Mode with draft-dependent cached content \[2]           | Not affected on Netlify \[14]                     |
| GHSA-39w2, dev MCP endpoint (CVE-2026-94486)            | Low      | Running `next dev` on 16.x \[2]                                                     | Production never serves it \[2]                   |

Two things stood out. First, the low-severity one is the only one that reaches every 16.x developer regardless of hosting: `next dev` exposes a Model Context Protocol endpoint that does not check which website a request comes from, so a malicious page you visit can read your project's path on disk, source snippets from error reports, your route inventory and dev logs \[2]. Second, the sources disagree on scope for GHSA-4jqv. Netlify's table limits it to apps with a root catch-all route, while the Next.js post and advisory describe any self-hosted Pages Router app with SSG or ISR pages \[14]\[2]\[12]. I would go with the broader reading from the people who wrote the fix.

For the SSRF, the advisory's workaround is worth doing even after you patch: audit `images.remotePatterns` for any host you would not trust with its own DNS entries \[11].

## Why did my own cooldown pick 16.3.7?

In the keyv post I suggested a one-day release cooldown, so freshly hijacked packages never reach you. pnpm now ships that by default: since v11, `minimumReleaseAge` defaults to 1440 minutes, and it only fails loudly when you set it yourself, because an explicit setting turns on strict mode \[15]. A cooldown cannot tell a worm from a security patch, though, and with a caret range it does something quieter than failing.

I reproduced the moment 16.3.8 shipped by shifting the cooldown so the cutoff fell between the two releases' publish times, then resolved a lockfile with pnpm 12.9.1 (my test).

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/cooldown-light-png-5f44796f.png" srcDark="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/cooldown-dark-81f116bf.svg" alt="Timeline at 16:07 UTC on September 30 with a 1440 minute cooldown: 16.3.6 and 16.3.7 are past the cutoff and 16.3.8 is too new, so a ^16.3.6 range resolves to 16.3.7. The exact pin 16.3.8 fails with ERR_PNPM_NO_MATURE_MATCHING_VERSION, exempting next alone fails because 9 @next packages are also too new, and exempting next plus the 9 @next packages at 16.3.8 resolves 16.3.8." />

*FIG. 04 · A one-day cooldown resolves ^16.3.6 to 16.3.7 · the exact pin fails loudly, the caret range does not \[7]\[15]*

With `"next": "^16.3.6"`, pnpm resolved `next@16.3.7` and exited 0. npm 12.2.0 with `min-release-age` did the same. With an exact `"next": "16.3.8"`, pnpm stopped with `ERR_PNPM_NO_MATURE_MATCHING_VERSION`, which is the behavior you want. Exempting only `next@16.3.8` also failed, because `@next/env` and eight `@next/swc-*` binaries were published minutes earlier and were just as new. What worked was exempting exact versions, which pnpm has supported since v10.19 \[15]:

```yaml
# pnpm-workspace.yaml
minimumReleaseAge: 1440
minimumReleaseAgeExcludePrune: true
minimumReleaseAgeExclude:
  # Next.js September 2026 floor. Exact versions only, never whole packages.
  - next@16.3.8
  - '@next/env@16.3.8'
  - '@next/swc-darwin-arm64@16.3.8'
  - '@next/swc-darwin-x64@16.3.8'
  - '@next/swc-linux-arm64-gnu@16.3.8'
  - '@next/swc-linux-arm64-musl@16.3.8'
  - '@next/swc-linux-x64-gnu@16.3.8'
  - '@next/swc-linux-x64-musl@16.3.8'
  - '@next/swc-win32-arm64-msvc@16.3.8'
  - '@next/swc-win32-x64-msvc@16.3.8'
```

`minimumReleaseAgeExcludePrune` removes those entries once your lockfile moves past them, according to the docs; I did not test that part \[15]. Clerk's team does the same bookkeeping in public: when they bumped `next` for a security fix in May, the pull request also updated the minimum-release-age exclusion in their `pnpm-workspace.yaml` \[16]. On npm I only tested the caret case, so the practical check there is that your lockfile actually says 16.3.8 after the bump.

## What does bumping next leave behind on a self-hosted box?

This one came from a practitioner. In a pull request merged on October 2, a developer upgrading a self-hosted shop to 16.3.8 pinned `sharp` at 0.35.4, turned off AVIF in `images.formats`, and wrote down the risk left open: sharp 0.35.4 bundles libheif 1.23.2, which has open advisories including a critical one \[17]. Their note says it matters only off Vercel, in Docker or `output: standalone`, where sharp processes images on your own server \[17].

I checked the parts I could. The libheif advisory is real: critical, CVSS 9.8, affecting 1.18.0 through 1.23.2 and fixed in 1.23.3 \[18]. But the pull request's claim that no stable sharp closes it was already out of date. sharp 0.35.5, published September 27, ships a libvips build with libheif 1.23.5 \[19]\[20]. The catch is in the lockfile. When I bumped only `next` from 16.3.6 to 16.3.8 in an existing lockfile, pnpm kept sharp at 0.35.4, because it still satisfies the `^0.35.4` range `next` asks for (my test). A fresh resolve picked 0.35.5.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/sharp-drift-light-png-478981bf.png" srcDark="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/sharp-drift-dark-322fb684.svg" alt="Three lockfile cards: before, next 16.3.6 with sharp 0.35.4, libvips build 1.3.3 and libheif 1.23.2; after bumping only next, next 16.3.8 but sharp still 0.35.4 and libheif still 1.23.2; a fresh resolve gives sharp 0.35.5, libvips build 1.3.4 and libheif 1.23.5. libheif advisory GHSA-x8r2-mggj-j6wr is critical, CVSS 9.8, affecting 1.18.0 to 1.23.2 and fixed in 1.23.3." />

*FIG. 05 · Bumping next left sharp, and its libheif, where they were · a fresh resolve gets 1.23.5 \[17]\[18]\[19]\[20]*

What I could not establish is whether Next's image optimizer can reach this particular libheif bug after August's AVIF change \[5]. Treat it as open, and bump `sharp` with `next` if you self-host.

## How would I check every app this afternoon?

The floors are 16.3.8 on 16.x and 15.5.27 on 15.x \[2]. 14.x is outside the support policy, so no patches are coming for it \[21]. I check the artifact rather than the repo, because a merged pull request is not a rebuilt image, and a rebuilt image is not a deploy. This script reads `next` and `sharp` from inside each image in a list and compares against the floor. I tested the comparison logic, not your images, and it assumes a Node base image with `node` on the path:

```bash
#!/usr/bin/env bash
# images.txt: one image reference per line, the tags you actually deploy
check() {
  case "$1" in
    16.*) floor=16.3.8 ;;
    15.*) floor=15.5.27 ;;
    none) echo "no next in image"; return ;;
    *)    echo "unsupported line, no patches coming"; return ;;
  esac
  lowest=$(printf '%s\n%s\n' "$1" "$floor" | sort -V | head -n1)
  if [ "$1" != "$floor" ] && [ "$lowest" = "$1" ]; then echo "BELOW FLOOR $floor"; else echo "ok"; fi
}

while read -r image; do
  next=$(docker run --rm --entrypoint node "$image" -p "require('next/package.json').version" </dev/null 2>/dev/null || echo none)
  sharp=$(docker run --rm --entrypoint node "$image" -p "require('sharp/package.json').version" </dev/null 2>/dev/null || echo none)
  echo "$image next=$next sharp=$sharp $(check "$next")"
done < images.txt
```

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/five-places-light-png-5ca5ef2d.png" srcDark="https://images.syedmoinuddin.com/blogs/nextjs-16-3-7-is-not-the-patch/five-places-dark-ed9d8be8.svg" alt="Five places to check after a Next.js security bump: the repo lockfile, the built image, the running deploy, old public previews that stay vulnerable until deleted, and developer laptops running next dev on 16.x. One floor for all five: 16.3.8 on 16.x and 15.5.27 on 15.x." />

*FIG. 06 · The lockfile is the first of five places to check · old previews and dev laptops are the two people forget \[2]\[8]\[14]*

The last two boxes are the ones that slip. Netlify warns that public deploy previews and branch deploys stay vulnerable until they are deleted, and that its Next.js adapter must reach 5.16.1, which a redeploy picks up unless you pinned it \[14]. A commenter on the daily.dev thread put the process well: the upgrade ticket should name every deployed Next.js app, reachable previews included, with an owner for each before patch day \[8].

## What does the side-by-side look like?

| Signal                            | What it said                  | What was true                                  | What to trust instead                            |
| --------------------------------- | ----------------------------- | ---------------------------------------------- | ------------------------------------------------ |
| The advance notice and its copies | Fixes ship in 16.3.7 \[1]\[8] | 16.3.7 was a bug fix, fixes in 16.3.8 \[1]\[2] | The release post, on release day                 |
| `npm audit` on October 5          | 0 vulnerabilities on 16.3.7   | Seven September advisories apply \[2]          | The floor, compared yourself                     |
| A cooldown with `^16.3.6`         | Install succeeded             | It resolved 16.3.7                             | An exact pin plus exact-version exemptions \[15] |
| Bumping only `next`               | Patched                       | sharp stayed at 0.35.4, libheif 1.23.2 \[18]   | `sharp` 0.35.5 or later \[19]                    |
| A merged pull request             | Done                          | Images, deploys and previews can lag \[14]     | The version read from the artifact               |

## What should you do this afternoon?

**If you self-host with Docker or `output: standalone`:**

* [ ] Read `next` and `sharp` from every deployed image, not the repo
* [ ] Reach 16.3.8 or 15.5.27, and `sharp` 0.35.5 or later \[2]\[19]
* [ ] Audit `images.remotePatterns` for hosts you would not trust with DNS \[11]
* [ ] Treat GHSA-4jqv as yours if you run Pages Router with SSG or ISR \[2]\[12]

**If you deploy on Vercel or Netlify:**

* [ ] Upgrade anyway, since Vercel is listed as unaffected for only one of the seven \[2]
* [ ] On Netlify, redeploy for adapter 5.16.1 and delete stale public previews \[14]

**Everyone on 16.x:**

* [ ] Update every laptop that runs `next dev` \[2]
* [ ] Pin the exact floor in security bumps so a cooldown fails loudly
* [ ] Watch for the postponed critical and high, which have no date yet \[2]
* [ ] Do not close the ticket on a green `npm audit` this week

## What would I do differently next time?

1. Read the version from the release post, not the notice. The notice is a forecast that the Next.js team updates; copies of it do not update.
2. Treat a green scanner during disclosure week as a sign the database is behind, not as proof that you are safe. Compare against the floor yourself for at least the first week.
3. Pair every cooldown with a second rule. My cooldown advice in the keyv post was incomplete: security bumps should pin the exact version and exempt that exact version, so the install fails loudly instead of quietly picking the decoy.

## Sources

1. Next.js, "Upcoming Next.js September Security Release" (updated September 29 and 30), September 23, 2026, [nextjs.org](https://nextjs.org/blog/upcoming-nextjs-security-release-september-2026)
2. Next.js, "September 2026 Security Release," September 30, 2026, [nextjs.org](https://nextjs.org/blog/september-2026-security-release)
3. Next.js, "Next.js Security Release and Our Next Patch Release," July 13, 2026, [nextjs.org](https://nextjs.org/blog/next-security-release-program)
4. Next.js, "July 2026 Security Release," July 20, 2026, [nextjs.org](https://nextjs.org/blog/july-2026-security-release)
5. Next.js, "August 2026 Security Release," August 25, 2026, [nextjs.org](https://nextjs.org/blog/august-2026-security-release)
6. Next.js, "Next.js Security Update for a Critical Upstream Issue," September 22, 2026, [nextjs.org](https://nextjs.org/blog/nextjs-security-update-september-22-2026)
7. npm registry, "next" package metadata and publish times, accessed October 5, 2026, [registry.npmjs.org](https://registry.npmjs.org/next)
8. daily.dev, "Upcoming Next.js September Security Release" (summary and comments), September 23, 2026, [daily.dev](https://daily.dev/posts/upcoming-next-js-september-security-release-wycfl3t7c)
9. Dayopt, "security(next): 16.3.8 September Security Release," GitHub issue 2970, September 29, 2026, [github.com](https://github.com/Dayopt/dayopt/issues/2970)
10. Vercel Community, "Misleading warning about react2shell CVE (suggested wrong Next.js version to patch to)," December 15, 2025, [community.vercel.com](https://community.vercel.com/t/misleading-warning-about-react2shell-cve-suggested-wrong-next-js-version-to-patch-to/29978)
11. vercel/next.js, "Server-Side Request Forgery in Image Optimization," GHSA-cjq9-62q9-8jv4, September 30, 2026, [github.com](https://github.com/vercel/next.js/security/advisories/GHSA-cjq9-62q9-8jv4)
12. vercel/next.js, "Cache poisoning of SSG and ISR pages in self-hosted Next.js applications," GHSA-4jqv-mc3x-m676, September 30, 2026, [github.com](https://github.com/vercel/next.js/security/advisories/GHSA-4jqv-mc3x-m676)
13. GitHub Advisory Database, "Next.js: Remote Code Execution in next/og ImageResponse," GHSA-vcvr-r3jv-pc5j, reviewed September 30, 2026, [github.com](https://github.com/advisories/GHSA-vcvr-r3jv-pc5j)
14. Netlify, "Security Update: Multiple vulnerabilities in Next.js," September 30, 2026, [netlify.com](https://www.netlify.com/changelog/2026-09-30-nextjs-react-security-vulnerabilities/)
15. pnpm, "Dependency Resolution Settings," accessed October 5, 2026, [pnpm.io](https://pnpm.io/settings/dependency-resolution)
16. Clerk, "chore(nextjs): Update next to patched versions for GHSA-26hh-7cqf-hhc6," GitHub PR 8547, May 14, 2026, [github.com](https://github.com/clerk/javascript/pull/8547)
17. d-Alvhor, "fix(seguridad): sube Next a 16.3.8 y desactiva AVIF," GitHub PR 12, October 2, 2026, [github.com](https://github.com/d-Alvhor/lasernex/pull/12)
18. libheif, "Heap buffer overflow in unci mixed-interleave decoding with unequal chroma bit depths," GHSA-x8r2-mggj-j6wr, September 1, 2026, [github.com](https://github.com/strukturag/libheif/security/advisories/GHSA-x8r2-mggj-j6wr)
19. npm registry, "sharp" package metadata, accessed October 5, 2026, [registry.npmjs.org](https://registry.npmjs.org/sharp)
20. npm registry, "@img/sharp-libvips-linux-x64" package metadata and tarballs, accessed October 5, 2026, [registry.npmjs.org](https://registry.npmjs.org/@img%2Fsharp-libvips-linux-x64)
21. Next.js, "Support Policy," accessed October 5, 2026, [nextjs.org](https://nextjs.org/support-policy)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on October 5, 2026

---
title: "You Already Gave It the Keys: What I Learned Researching Apple's Full Disk Access Crackdown on AI Agents"
description: "On October 2, Apple said macOS Full Disk Access will need very explicit user action because of AI agents. The bigger finding: if your terminal has it, every coding agent you start there inherits it. What it exposes, who asks for it, and a 10-minute audit, with 12 sources."
last_updated: "October 4, 2026"
source: "https://syedmoinuddin.com/blog/apple-full-disk-access-ai-agents"
---

# You Already Gave It the Keys: What I Learned Researching Apple's Full Disk Access Crackdown on AI Agents

On October 2, Apple said macOS Full Disk Access will need very explicit user action because of AI agents. The bigger finding: if your terminal has it, every coding agent you start there inherits it. What it exposes, who asks for it, and a 10-minute audit, with 12 sources.

Here is the whole argument up front. On October 2, 2026, Apple said Full Disk Access on the Mac will soon require "very explicit user action," because AI agents make that permission more dangerous \[1]. Most coverage reads this as a story about desktop agent apps like Meta's Muse. The more useful lesson for developers is quieter. macOS ties a privacy permission to the app responsible for a process, and when you run a tool from Terminal, Apple's developer support says Terminal is that app \[2]. So if your terminal or IDE has Full Disk Access, every coding agent you start there, and everything that agent spawns, runs with it. Apple has not said when its new controls will arrive \[3]. You do not need to wait for them to find out what your agents can already read.

I started this expecting to write about Muse and a disputed magazine column. What changed my mind was a 2024 answer from Apple's Developer Technical Support on the developer forums, read next to a Ghostty thread from June in which developers describe granting Full Disk Access to their terminal so Claude Code can reach their project folders \[2]\[4]. The honest answer to "did I give an agent Full Disk Access?" is often different from the one we would give from memory. This post is the research, the dissent, and a 10-minute audit. No code required.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/access-inheritance-light-png-1c9c89e8.png" srcDark="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/access-inheritance-dark-f5acdc48.svg" alt="Diagram: a terminal or IDE with Full Disk Access switched on launches a shell, which launches a coding agent CLI that runs with the same grant, and the agent's MCP servers, build scripts and dependency install hooks inherit it too. The grant reaches files, mail, messages and browsing history, per Apple's October 2, 2026 notice." />

*FIG. 01 · Grant it to the terminal, and every agent inherits it · macOS checks the responsible app, not the tool you typed \[1]\[2]*

## What did Apple actually announce?

The notice is two paragraphs on Apple's developer news site, titled "Updates to Full Disk Access in macOS" \[1]. Apple says the permission largely sidesteps the privacy controls behind its APIs so that backup apps can work, and that some developers are using it in ways that expose files, mail, messages and browsing history without users fully understanding what they agreed to \[1]. For communication apps, Apple adds, that also exposes the people on the other side of the conversation \[1]. Going forward, granting it will take explicit action, and Apple ties the urgency directly to agents becoming more capable and autonomous \[1].

What the notice leaves out matters as much. It names no app, no macOS version and no date, and Engadget notes that Apple did not say what exactly will change from the current setup \[3]. TechCrunch reported that Apple did not respond to its questions about the change \[5]. Everything after "additional controls" is speculation, including mine.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/timeline-light-png-f25ed56b.png" srcDark="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/timeline-dark-0ee93835.svg" alt="Timeline from September 19 to October 2, 2026, drawn to scale: Jason Aten's column on Muse on September 19, Meta disputing it on September 30, then Apple's developer notice and Microsoft's Digital Defense Report 2026 on October 2, thirteen days later. A dashed extension ends at the new controls shipping, which has no announced date. Chips list what the notice leaves out: no app named, no macOS version, no date, no design details." />

*FIG. 02 · Thirteen days from one column to a platform notice · and still no date for the controls themselves \[1]\[3]\[6]\[7]*

## Why did Muse become the test case?

Apple named no one, but the timing points at Meta's Muse. According to The Next Web's account, Inc. columnist Jason Aten wrote on September 19 that he installed Muse on an iPhone and a Mac mini, chose not to give it access to his messages, and then got a column suggestion built on a conversation he had just had with his podcast co-host \[6]. When he asked how it knew, Muse said it only saw notification banners. Aten then found Muse had synced his Messages database up to row 187,462, while its settings showed Full Disk Access switched off \[6].

Meta disputes this. Its communications chief Andy Stone said Muse cannot read Messages unless the user turns on both Full Disk Access and the Messages connector inside the app, and Meta Superintelligence Labs executive David Singleton said the macOS protections cannot be bypassed even if the app had a bug \[6]. I cannot settle that, and nobody can without a forensic look at Aten's Mac, so I am treating it as disputed. I did not open Aten's original column myself; the details above come from The Next Web.

The part nobody disputes is the onboarding pattern. Engadget reports that desktop clients for agents like OpenClaw, Dots and Muse often encourage users to grant Full Disk Access, and that some people now run agents on dedicated machines instead, which helped fuel Mac mini shortages this year \[3].

## Why does my coding agent probably have it already?

This is the section I wish I had read first. macOS privacy checks (Apple calls the system TCC) are not made against whichever program touches the file. They are made against what Apple's developer support calls the responsible code \[2]. Quinn, an engineer in Apple's Developer Technical Support, lists the common cases: when a user runs a tool from Terminal, Terminal is the responsible code, and when an app spawns a helper tool, the app is \[2]. He also warns that the exact algorithm is not documented, has changed before and may change again \[2].

Follow that through. If Terminal, iTerm2, Ghostty or any other terminal has Full Disk Access, a coding agent CLI you start inside it runs with that access, and so does everything the agent launches: the MCP servers it starts, the scripts it runs, and any install hook buried in a dependency tree. That last one is not hypothetical. A dependency's install hook is exactly how [the keyv worm I wrote about](https://syedmoinuddin.com/blog/keyv-shai-hulud-npm-worm-check) ran on developer machines, and started from a terminal with Full Disk Access, a hook like that would inherit it.

Developers are granting it in practice. In a Ghostty discussion from June, a user describes giving Ghostty Full Disk Access and expecting Claude Code sessions inside it to keep access to project directories, and other commenters report the same setup with Codex \[4]. A VS Code issue describes the same rule for IDEs: when the integrated terminal spawns a process, macOS treats VS Code as responsible for it, and one commenter notes those commands are increasingly run by coding agents such as Claude Code and Codex \[8].

There is one more path people forget. With Remote Login on, Quinn notes that the SSH server becomes the responsible code, and macOS has a separate setting that gives remote sessions Full Disk Access \[2].

## What does Microsoft's report add?

Microsoft's Digital Defense Report 2026, whose page is dated October 2, reads like the other half of the argument \[7]. Microsoft says attackers already treat AI as an attack surface, exploiting it to run malicious commands and exfiltrate data, and it lists five risk classes for agents \[7]. Two of them map straight onto Full Disk Access: sensitive data exposure, where an attacker drives an agent to read beyond its sanctioned scope, and excessive agency, where an agent is coaxed into tools and actions beyond what it was allowed \[7]. Full Disk Access does not create either risk. It decides how far each one can reach.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/mddr-risks-light-png-769bc4a8.png" srcDark="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/mddr-risks-dark-22c84626.svg" alt="Microsoft's five risk classes for the 2026 agentic attack surface: prompt and intent manipulation, sensitive data exposure, identity and privilege compromise, excessive agency, and operational integrity. Sensitive data exposure and excessive agency are highlighted as the two where Full Disk Access sets the reach. A side panel shows figures from the same report: 88% of enterprises experimenting with AI agents, and a malicious extension with 600,000+ installs that harvested ChatGPT and DeepSeek history and affected almost 10,000 organizations." />

*FIG. 03 · Two of Microsoft's five agent risks are about reach · filled rows are my read, the names and descriptions are Microsoft's \[7]*

Two figures from the report set the scale. Microsoft says 88% of enterprises are already experimenting with AI agents \[7]. It also describes a malicious browser extension with more than 600,000 installs that harvested ChatGPT and DeepSeek conversation history and affected almost 10,000 organizations before it was mitigated, and it notes that this kind of history now routinely holds source code, architecture, customer data and leaked credentials \[7]. These are Microsoft's own numbers, and I have no independent count. Its advice is the boring kind that works: reduce oversharing, apply least privilege, and treat agents as identities in their own right \[7].

## Is Apple right that this was built for backups?

Not everyone accepts Apple's framing. John Voorhees at MacStories looked at his own MacBook Pro and found that only a handful of the apps holding Full Disk Access were backup tools; the rest included Alfred, PopClip, Hazel, Pixelmator Pro and even an Apple Arcade game \[9]. He agrees the agent concerns are well founded, but worries that the backup framing signals Apple may restrict which kinds of apps can use the permission at all \[9].

John Gruber at Daring Fireball shares that worry as a power user who relies on Full Disk Access, then makes the counterpoint I find hardest to argue with \[10]. On an iPhone, no permission lets a third-party app read your email or your end-to-end encrypted messages. On a Mac, saying yes to everything an agent asks for hands over most of the startup drive, and many Mac users do not know the difference \[10].

My read is that both are right. The new controls will add friction for power users, and the way to avoid fighting them is to need the permission less.

## How would I audit this in 10 minutes?

Open System Settings, then Privacy and Security, then Full Disk Access, and go down the list with these questions.

| Step | Look for                     | Why it matters                                                            |
| ---- | ---------------------------- | ------------------------------------------------------------------------- |
| 1    | Every app with the switch on | That list is your real exposure, not the apps you remember approving \[1] |
| 2    | Terminals and IDEs           | Everything launched inside them inherits the grant \[2]\[8]               |
| 3    | Desktop agent apps           | Many ask for it during setup \[3]                                         |
| 4    | Backup tools                 | The case Apple says the permission exists for, so usually keep \[1]       |
| 5    | Remote Login                 | A separate setting can give SSH sessions full access \[2]                 |

For every row that is not a backup tool, switch it off and see what breaks. If an agent only needs a project folder, it should not need the disk. If you do want an agent to have broad access, the dedicated machine Engadget describes, or at least a separate macOS user account with nothing sensitive in it, is a cleaner boundary than a toggle on your daily Mac \[3].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/audit-light-png-ab2a8bb7.png" srcDark="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/audit-dark-6b4ead25.svg" alt="A generic Full Disk Access settings pane with five rows, all switched on, each with a verdict: Terminal or IDE that launches coding agents, turn off; desktop agent app that asked during setup, turn off; backup app, keep; launcher or file utility, decide; Remote Login (SSH) with full disk access for remote users, check. A side panel asks of every row: does it launch programs, does it need the disk or one folder, and would you notice if it read files, mail, messages and browsing history." />

*FIG. 04 · The 10-minute audit in one settings pane · a generic example, not a screenshot \[1]\[2]\[3]\[11]*

## What should agent builders do before Apple ships the change?

Design as if the new controls are already here. There is no API to request Full Disk Access; the user has to switch it on, and Quinn's long-standing advice is to defer the request until there is a concrete failure, then explain it and suggest the permission as the remedy \[11]. Apple's documentation says the same from the other side: an app cannot gain full disk access through an entitlement or with code, so it should handle the failure gracefully \[12].

The narrower path is already documented. When a user picks a file or folder in a standard open panel, macOS extends the app's sandbox to it, and for a folder that includes everything nested inside; a security-scoped bookmark keeps that access across launches \[12]. For an agent, that means asking for the project folder, not the drive.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/access-ladder-light-png-8a4c3e3b.png" srcDark="https://images.syedmoinuddin.com/blogs/apple-full-disk-access-ai-agents/access-ladder-dark-ccf233dc.svg" alt="Five macOS file access paths drawn as bars from narrowest to widest, in order rather than to scale: the app container; a user-selected folder, including nested items; a security-scoped bookmark that keeps the same pick across launches; Files and Folders, with per-user consent for protected folders; and Full Disk Access, the widest bar, covering files, mail, messages and browsing history, with no API to request it. The user-selected folder and bookmark rows are shaded as where an agent should usually live." />

*FIG. 05 · Ask for a folder, not the disk · order, not scale; the last step is granted only in System Settings \[1]\[11]\[12]*

## What does the side-by-side look like?

| Access path                  | What it reaches                                                         | How it is granted                                        |
| ---------------------------- | ----------------------------------------------------------------------- | -------------------------------------------------------- |
| Full Disk Access             | Files, mail, messages and browsing history \[1]                         | A user switch in System Settings, with no API \[11]\[12] |
| Files and Folders            | Protected folders, per user, skipped entirely by Full Disk Access \[11] | User consent, per user \[11]                             |
| User-selected file or folder | Only what the user picked, nested items included \[12]                  | A standard open or save panel \[12]                      |
| Security-scoped bookmark     | The same pick, kept across launches \[12]                               | Created by the app after the pick \[12]                  |

## Which one should you reach for?

**Keep Full Disk Access on if:**

* [ ] The app is a backup tool that has to read everything \[1]
* [ ] You have checked that it cannot work from a picked folder \[12]
* [ ] The machine or user account exists only for the agent \[3]

**Turn it off if:**

* [ ] It is a terminal or IDE you run agents in \[2]\[8]
* [ ] It is an agent app that asked for it during setup \[3]
* [ ] You cannot say what it needs it for \[1]

**If you ship a desktop agent:**

* [ ] Ask for a project folder through the standard open panel \[12]
* [ ] Keep that choice with a security-scoped bookmark \[12]
* [ ] Ask for Full Disk Access only after a real failure, and say why \[11]

## What would I do differently next time?

1. Start with the mechanism, not the drama. I began with the Muse dispute; the finding that changed my own setup advice was a 2024 forum answer about responsible code \[2].
2. Treat "the agent" as a process tree. An agent is never one app. It is whatever the terminal, the CLI and its tools add up to \[2]\[8].
3. Read the dissent before writing the conclusion. MacStories and Gruber moved me from "Apple is right" to "Apple is right about agents and vague about everything else" \[9]\[10].

## Sources

1. Apple Developer News, "Updates to Full Disk Access in macOS," October 2, 2026, [developer.apple.com](https://developer.apple.com/news/?id=p6zjojqw)
2. Quinn "The Eskimo!" (Apple DTS), "How to grant command line tools full disk access," Apple Developer Forums thread 756510, June 2024, [developer.apple.com](https://developer.apple.com/forums/thread/756510)
3. Karissa Bell (Engadget), "Apple sounds the alarm on AI agents and 'Full Disk Access'," October 2, 2026, [engadget.com](https://www.engadget.com/2276186/apple-sounds-the-alarm-on-ai-agents-and-full-disk-access/)
4. ghostty-org/ghostty, "macOS Ghostty loses folder access during Claude sessions despite Full Disk Access," Discussion 12947, June 7, 2026, [github.com](https://github.com/ghostty-org/ghostty/discussions/12947)
5. Sarah Perez (TechCrunch), "Apple says it's tightening macOS 'Full Disk Access' controls due to new risks from AI agents," October 2, 2026, [techcrunch.com](https://techcrunch.com/2026/10/02/apple-says-its-tightening-macos-full-disk-access-controls-due-to-new-risks-from-ai-agents/)
6. Ana Maria Constantin (The Next Web), "Meta denies its Muse AI agent read a journalist's private messages," September 30, 2026, [thenextweb.com](https://thenextweb.com/news/meta-muse-private-messages-denial-jason-aten)
7. Microsoft, "Microsoft Digital Defense Report 2026," October 2, 2026, [microsoft.com](https://www.microsoft.com/en-us/corporate-responsibility/topics/cybersecurity/reports/microsoft-digital-defense-report/)
8. microsoft/vscode, "macOS: Child processes cannot access TCC-protected resources," Issue 307364, 2026, [github.com](https://github.com/microsoft/vscode/issues/307364)
9. John Voorhees (MacStories), "Apple Announces Plan to Impose New Full Disk Access Controls on Mac Developers," October 2, 2026, [macstories.net](https://www.macstories.net/linked/apple-announces-plan-to-impose-new-full-disk-access-controls-on-mac-developers/)
10. John Gruber (Daring Fireball), "Apple Is Going to Further Tighten the Screws on Full Disk Access on MacOS, in Response to Agentic AI Apps Running Amok," October 2, 2026, [daringfireball.net](https://daringfireball.net/2026/10/apple_full_disk_access)
11. Quinn "The Eskimo!" (Apple DTS), "Query related to privacy protection changes in Catalina," Apple Developer Forums thread 121352, 2019, [developer.apple.com](https://developer.apple.com/forums/thread/121352)
12. Apple Developer Documentation, "Accessing files from the macOS App Sandbox," accessed October 4, 2026, [developer.apple.com](https://developer.apple.com/documentation/security/accessing-files-from-the-macos-app-sandbox)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on October 4, 2026

---
title: "The Fix Shipped 27 Days Early: What I Learned Researching the keyv Shai-Hulud npm Worm"
description: "npm 12 turned dependency install scripts off on July 8. On August 4 a hijacked keyv release used a preinstall hook to spread to hundreds of packages. Here is the 10-minute check, the cleanup order, and the two lines of .npmrc that close the gap."
last_updated: "October 2, 2026"
source: "https://syedmoinuddin.com/blog/keyv-shai-hulud-npm-worm-check"
---

# The Fix Shipped 27 Days Early: What I Learned Researching the keyv Shai-Hulud npm Worm

npm 12 turned dependency install scripts off on July 8. On August 4 a hijacked keyv release used a preinstall hook to spread to hundreds of packages. Here is the 10-minute check, the cleanup order, and the two lines of .npmrc that close the gap.

Here is the whole argument up front. On July 8, 2026, npm 12 shipped with dependency install scripts turned off by default \[1]\[2]. Twenty-seven days later, on August 4, a hijacked keyv release used exactly that feature, a `preinstall` hook, to steal credentials and republish itself into hundreds of other packages \[3]. The fix existed before the attack. It did not help anyone on a bundled npm, because the Node.js Release WG decided not to land npm 12 on Node 22, 24 or 26 \[4]. If you run Node today, install scripts from your dependencies still run unless you turn them off yourself. This post is the 10-minute check worth running now, plus the two lines of config that close most of the gap.

I started this expecting to write a "here is the latest worm" recap. What changed my mind was the npm 12 timeline. The new defaults shipped in July, so I expected the advice to be "update and you are covered". Then I read the Node.js Release WG thread and found that no current Node line bundles npm 12. That gap, between a security default being released and being the thing on your machine, is the useful part of this story.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/timeline-light-62cca5aa.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/timeline-dark-4751467c.svg" alt="Timeline from June to November 2026: npm v12 changes announced June 9, npm 12.0.0 ships with install scripts off July 8, keyv 6.0.0 published with a preinstall hook August 4 at 09:35 UTC, 27 days later, Morphisec counts 1,280+ packages August 20, Node 22, 24 and 26 still ship without npm 12 on October 2, and Node 27 alpha opens October 28." />

*FIG. 01 · The fix shipped 27 days before the worm · npm 12 on Jul 8, keyv\@6.0.0 on Aug 4, Node 27 alpha on Oct 28 \[2]\[3]\[4]*

## What actually happened on August 4?

Phoenix Security's timeline is the most precise one I found \[3]. Between 09:02 and 09:04 UTC, the attacker planted IDE hooks on keyv's `main` branch through a hijacked maintainer account. At 09:35, `keyv@6.0.0` was published with a new `setup.mjs` file and `"preinstall": "node setup.mjs"` in `package.json` \[3]\[5]. Four minutes later the payload had been copied into 19 `@keyv/*` workspace packages. At 12:10, the `latest` tags were partly rolled back to clean releases \[3].

The dropper does not carry the malware itself. It downloads the legitimate Bun runtime (v1.3.13) and uses it to run a 728 KB obfuscated file called `Math_Symbol.js` \[3]\[5]. That file collects secrets, uploads them encrypted to public GitHub repositories whose description contains "Shai-Hulud: Here We Go Again" (Aikido counted about 1,300 of them), and then uses any npm token it found to inject itself into other packages, bump their versions and publish them \[5]\[3]. That last step is why this is a worm and not a single bad release.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/attack-chain-light-cef10b0b.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/attack-chain-dark-1aaf372a.svg" alt="Five-step attack chain on August 4, 2026: IDE hooks planted on keyv main at 09:02 UTC, keyv 6.0.0 published with a preinstall hook at 09:35, setup.mjs downloads Bun 1.3.13 and runs a 728 KB payload, credentials are harvested to public GitHub repos, and stolen npm tokens republish other packages, looping back to step two." />

*FIG. 02 · Five steps, and the fifth restarts the first · every stolen publish token becomes another 09:35 \[3]*

Sygnia notes this is a return of the Shai-Hulud family, whose first wave hit npm in September 2025 \[6]. Morphisec's Brad LaPorte calls it the fourth wave, and makes the point that stuck with me most: the release was properly signed. In his words, "the signature was honest. The code was not." \[7]

## Why would I have keyv if I never installed it?

Because you rarely install it directly. The compromised list includes `flat-cache@6.1.24` and `file-entry-cache@11.1.6`, and Phoenix Security says those reached projects transitively through ESLint \[3]. If that is your path, the hook runs wherever you install dev dependencies, including CI, which is also where publish tokens and cloud credentials tend to live.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/dependency-chain-light-34f9ae19.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/dependency-chain-dark-2cb64a25.svg" alt="Dependency chain from your app to eslint, then a dashed link to file-entry-cache (11.1.6 compromised, 11.1.5 safe) and flat-cache (6.1.24 compromised, 6.1.23 safe). keyv alone has about 127 million weekly downloads." />

*FIG. 03 · You never typed keyv · the bad versions sit two hops below a devDependency \[3]\[5]*

I could not confirm which ESLint versions resolve to the bad versions, so treat the chain as a possibility to check, not a fact about your repo. Here is the check, using the full package list from Kodem Security's runbook \[8]:

```bash
# Run in every repo and in every CI image you build from
npm ls keyv flat-cache file-entry-cache cacheable-request cacheable \
  @cacheable/utils cache-manager @cacheable/net @cacheable/node-cache \
  @cacheable/memory ecto --all
```

The bad versions to look for, per Singapore's CSA and Aikido: `keyv` 6.0.0, `flat-cache` 6.1.24, `file-entry-cache` 11.1.6, `cacheable-request` 13.0.20, `cacheable` 2.5.1, `cache-manager` 7.2.10, `@cacheable/memory` 2.2.1, `@cacheable/node-cache` 3.1.2, `@cacheable/utils` 2.5.1, `@cacheable/net` 2.1.1 and `ecto` 5.0.1 \[9]\[5]. Kodem lists the safe pins as `keyv` 5.6.0, `flat-cache` 6.1.23, `file-entry-cache` 11.1.5, `cacheable-request` 13.0.19, `cache-manager` 7.2.9 and `ecto` 5.0.0 \[8].

## How big was it, really?

It depends who you ask, and when. Sygnia says 400+ packages, Aikido 444 packages across 1,381 versions, Phoenix 868 packages across the same 1,381 versions, and Morphisec more than 1,280 packages by August 20 \[6]\[5]\[3]\[7]. Sonatype tracks 2,225 affected versions, and CSA says over 1,300 \[10]\[9]. The number most of them agree on is reach: over 2 billion monthly installs \[5]\[9].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/blast-radius-light-20221f41.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/blast-radius-dark-33b3f662.svg" alt="Bar chart of reported counts by source. Packages: Sygnia 400+, Aikido 444, Phoenix 868, Morphisec 1,280+. Versions: CSA Singapore 1,300+, Aikido 1,381, Phoenix 1,381, Sonatype 2,225. Most sources agree on over 2 billion monthly installs." />

*FIG. 04 · Every source counts it differently · packages and versions reported between Aug 4 and Aug 20 \[3]\[5]\[6]\[7]\[10]\[9]*

I am not going to pick a winner. The counts measure different things at different times, and Kodem's advice is the right frame: treat the blast radius as "several hundred packages and rising rather than a settled number" \[8]. Your own lockfile is the only count that matters to you.

## What does it take, and what does it leave behind?

The payload goes after npm tokens, every kind of GitHub token (classic PATs, OAuth, App and OIDC), AWS credentials from files, environment variables, instance metadata and Secrets Manager, plus GCP, Azure, Kubernetes service account tokens, Vault, Stripe and Slack \[5]\[3]. It also scans about 200 file patterns for SSH keys, `.env` files, Terraform state and Docker configs \[5]\[7].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/what-it-takes-light-5a0efd9b.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/what-it-takes-dark-ade28c86.svg" alt="Two panels. It takes: npm tokens, GitHub tokens (classic PAT, OAuth, App, OIDC), AWS credentials, GCP and Azure credentials, Kubernetes service account tokens, Vault tokens, Stripe and Slack API tokens, and about 200 file patterns such as SSH keys and .env files. It leaves behind: a .claude/settings.json SessionStart hook, a .vscode/tasks.json folder-open task, a gh-token-monitor service, and bun-dl folders." />

*FIG. 05 · It takes the keys, then moves into your editor · removing the package does not remove the persistence \[5]\[8]*

The part most recaps skip is persistence. The worm commits to up to 50 branches per repository and adds hooks to `.claude/settings.json` (a SessionStart hook) and `.vscode/tasks.json` (a task that runs on folder open) \[5]\[8]. It also installs a token watcher called `gh-token-monitor` as a shell script, systemd service or macOS plist \[8]. So a clean lockfile is not a clean machine. Hunt for the leftovers:

```bash
# Payload files and the downloaded runtime
find . -name setup.mjs -path '*node_modules*' 2>/dev/null
find . -name 'Math_Symbol.js' 2>/dev/null
find ~ -maxdepth 4 -type d -name 'bun-dl-*' 2>/dev/null

# Editor and agent hooks added on or after the attack
find . -path '*/.vscode/tasks.json' -newermt '2026-08-04'
find . -path '*/.claude/settings.json' -newermt '2026-08-04'

# The token watcher, on Linux or macOS
find ~ -maxdepth 6 -name 'gh-token-monitor*' 2>/dev/null
find ~ -maxdepth 6 -name 'com.user.gh-token-monitor.plist' 2>/dev/null
```

Phoenix also suggests checking proxy or build logs for Bun downloads and the `Bun/1.3.13` user agent, and for traffic to `npm-cache[.]com` \[3].

## Why didn't npm 12 stop it?

It would have, for anyone running it. npm 12 stopped dependency `preinstall`, `install` and `postinstall` scripts from running unless you allow them, and also blocks Git and remote tarball dependencies by default \[1]\[2]. But npm usually arrives bundled with Node, and the Release WG decided not to land npm 12 on Node 26, 24 or 22 \[4]. The earliest bundled path is Node 27, whose alpha opens October 28, 2026, and even that depends on an npm 12 pull request landing in Node's `main` branch, which was still being worked out at the time I checked \[11].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/node-matrix-light-32a9454f.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/node-matrix-dark-c05877ce.svg" alt="Table of Node.js versions. Node 22, 24 and 26 bundle npm older than 12, so dependency install scripts run by default and you must check npm --version and opt in. Node 27 plans to bundle npm 12 with scripts off unless allowed, alpha from October 28, 2026 and release April 22, 2027." />

*FIG. 06 · No Node release you run today turns this on for you · npm 12 is opt-in until Node 27 \[4]\[11]*

So you opt in. You do not need npm 12 for the most important line. `ignore-scripts` works on older npm too, and npm added `min-release-age` (in days) in 11.10.0 and a granular `allowScripts` list in 11.16.0 \[12]. Craig Harmon's write-up has the equivalent setting for every package manager \[12]:

| Package manager | Release cooldown                | Unit    | Turn off dependency scripts                        |
| --------------- | ------------------------------- | ------- | -------------------------------------------------- |
| npm 11.10+      | `min-release-age=1` in `.npmrc` | days    | `ignore-scripts=true`, or `allowScripts` on 11.16+ |
| pnpm 10.16+     | `minimumReleaseAge: 1440`       | minutes | `allowBuilds` mapping                              |
| Yarn 4.10+      | `npmMinimalAgeGate: 1440`       | minutes | `enableScripts: false`                             |
| Bun 1.3+        | `minimumReleaseAge = 86400`     | seconds | `ignoreScripts = true`                             |

For npm, the whole change is this:

```ini
# .npmrc, committed to the repo
ignore-scripts=true
min-release-age=1
```

Why a one-day cooldown helps here: the `latest` tags were rolled back about two and a half hours after the bad publish \[3], and Harmon notes compromised releases "are usually flagged and removed from the registry within hours of publication" \[12]. Two caveats. Packages that need a native build (an `esbuild` or `sharp`, say) will break under `ignore-scripts`, and older npm versions ignore `min-release-age` silently, so check `npm --version` on every machine that installs \[13]. And the strongest control was already available: `npm ci` installs exactly what your lockfile pins, so a lockfile committed before August 4 never resolved `keyv@6.0.0` at all \[13]\[6].

## In what order should I clean up?

This is where the sources disagree, and it matters. Sygnia, Sonatype and Phoenix all say to remove persistence before revoking or rotating credentials, because some variants watch token validity and act destructively when a token is revoked \[6]\[10]\[3]. Kodem says the opposite for npm tokens: freeze publishing and revoke every npm automation token first, and calls the watcher's threat string, `IfYouBlockThisAPIKeyItWillCrashTheLiveProductionServersOfAllThirdPartyClients`, an extortion message "with no technical merit" \[8].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/response-order-light-4178edc9.svg" srcDark="https://images.syedmoinuddin.com/blogs/keyv-shai-hulud-npm-worm-check/response-order-dark-d36507b9.svg" alt="Five-step response: find with npm ls, contain by isolating the host and freezing publishing, hunt hooks and the monitor service, rotate npm, GitHub, cloud, Kubernetes, Vault and SSH credentials, then rebuild. Sygnia, Sonatype and Phoenix say remove persistence before revoking; Kodem says revoke npm tokens first." />

*FIG. 07 · Hunt first, then rotate · the sources split on npm tokens, not on rebuilding infected hosts \[3]\[6]\[10]\[8]*

My read: these are compatible if you separate the token from the host. Revoke npm publish tokens from a clean machine immediately, because that is what stops the spread. On any host that actually installed a bad version, hunt the watcher and hooks first, then rotate GitHub, cloud, Kubernetes, Vault and SSH credentials. Then do what CSA and Sonatype both recommend: treat that host as compromised and rebuild it rather than clean it \[9]\[10].

## What should I do this afternoon?

**If you have not checked yet:**

* [ ] Run the `npm ls` check on every repo and CI image \[8]
* [ ] Search for `setup.mjs`, `bun-dl-*` and new `.claude` or `.vscode` hooks \[3]\[8]

**Whether or not you were hit:**

* [ ] Commit an `.npmrc` with `ignore-scripts=true` and `min-release-age=1` \[12]
* [ ] Use `npm ci` in CI so the lockfile decides, not the registry \[6]\[13]
* [ ] Check `npm --version` everywhere; your Node version decides your defaults \[4]\[13]
* [ ] Rotate on the assumption of exposure, not proof of it, as Morphisec puts it \[7]

## Sources

1. GitHub Changelog, "Upcoming breaking changes for npm v12," June 9, 2026, [github.blog](https://github.blog/changelog/2026-06-09-upcoming-breaking-changes-for-npm-v12/)
2. Socket, "npm v12 Ships With Install Scripts Off by Default, Begins Deprecating 2FA-Bypass Tokens," July 8, 2026, [socket.dev](https://socket.dev/blog/npm-12)
3. Phoenix Security, "Mini Shai-Hulud keyv/cacheable npm Compromise: Self-Propagating Worm Steals CI, Cloud, and Developer Credentials," August 4, 2026, [phoenix.security](https://phoenix.security/mini-shai-hulud-keyv-cacheable-npm-supply-chain-worm/)
4. Node.js Release WG, "npm 12 request for Node.js 27 Alpha phase," GitHub issue 1183, 2026, [github.com](https://github.com/nodejs/Release/issues/1183)
5. Aikido Security, "Keyv and friends compromised in npm supply chain attack," August 4, 2026, [aikido.dev](https://www.aikido.dev/blog/keyv-and-friends-compromised-in-npm-supply-chain-attack)
6. Sygnia, "Shai-Hulud Returns: When Software Trust Becomes the Attack Surface," August 5, 2026, [sygnia.co](https://www.sygnia.co/threat-reports-and-advisories/shai-hulud-returns-software-supply-chain-attack-npm-keyv/)
7. Brad LaPorte (Morphisec), "Inside the fourth wave of the Shai-Hulud npm worm," SC Media, August 20, 2026, [scworld.com](https://www.scworld.com/perspective/inside-the-fourth-wave-of-the-shai-hulud-npm-worm)
8. Kodem Security, "keyv supply chain attack: Shai-Hulud npm worm affected versions, IOCs and first-hour response runbook," August 4, 2026, [kodemsecurity.com](https://www.kodemsecurity.com/resources/keyv-supply-chain-attack-shai-hulud-npm-worm-affected-versions-iocs-and-first-hour-response-runbook)
9. Cyber Security Agency of Singapore, "Ongoing npm Supply Chain Attack Affecting Keyv and Related Packages (Shai-Hulud Worm)," August 6, 2026, [csa.gov.sg](https://www.csa.gov.sg/alerts-and-advisories/advisories/ad-2026-009/)
10. Sonatype, "Mini Shai-Hulud npm Attack: Over 2,200 Components Compromised," August 5, 2026, [sonatype.com](https://www.sonatype.com/blog/mini-shai-hulud-npm-attack-more-than-2200-components-impacted)
11. npm/cli, "Request for npm 12 (re-)submission to Node.js main branch," GitHub issue 9997, 2026, [github.com](https://github.com/npm/cli/issues/9997)
12. Craig Harmon, "Locking down dependency installs across npm, pnpm, yarn, and bun," May 29, 2026, [craigory.dev](https://craigory.dev/blog/2026-05-29/package-manager-release-cooldown/)
13. Belchamber, "npm 12 install scripts: allowScripts and min-release-age," September 26, 2026, [tools.belchamber.us](https://tools.belchamber.us/articles/node/npm-12-install-scripts-and-release-age-cooldowns/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on October 2, 2026

---
title: "One Million Tokens Out: What Gemini 4 Argon's Output Cap Changes for the People Who Have to Run It"
description: "Argon raises the single-response ceiling from 64K to 1M tokens. The number is a trajectory, not an answer. What it does to the clock, the bill, the retry and the review, with 24 sources."
last_updated: "October 1, 2026"
source: "https://syedmoinuddin.com/blog/one-million-tokens-out"
---

# One Million Tokens Out: What Gemini 4 Argon's Output Cap Changes for the People Who Have to Run It

Argon raises the single-response ceiling from 64K to 1M tokens. The number is a trajectory, not an answer. What it does to the clock, the bill, the retry and the review, with 24 sources.

Here is the whole argument up front. Gemini 4 Argon's one-million-token output limit is the first spec in a year that changes engineering rather than pricing, and almost nobody is treating it that way. It is not a longer answer. Google's own sentence says what it is: headroom for the model to think deeply and generate hundreds of thousands of tokens in a single trajectory, up from 64K on earlier Gemini models \[1]. A trajectory that long is a job, not a request. It can run for hours at the generation speeds practitioners have measured on this generation of models, it can cost $10 at introductory pricing and $20 after, it cannot be retried as a unit without paying for everything that came before the failure, and it cannot be reviewed by a human who reads tokens. Every one of those is a problem you already solve for batch jobs, and none of them is a problem a chat-shaped integration solves for you. The output cap is a new primitive. Treat it like one.

I started this as a benchmark post. Argon leads DeepSWE v1.1 at 77.9% and loses Terminal-Bench 4.0 to Opus 5.5 by nine points, and the pattern of where it wins and loses is interesting \[1]\[2]. Then I wrote down the output cap next to the other caps, 128K on Opus 5.5, Fable 5.1, Sonnet 5.5 and GPT-6.1 Sol, and 64K on Gemini 3.8 Flash \[3]\[4]\[5], and realised the benchmark table was the less interesting half of the announcement. This is the other half, including the number I misread first.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-output-caps-light.png" srcDark="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-output-caps-dark.png" alt="Horizontal bar chart of maximum output tokens per response on a log scale: Gemini 3.8 Flash 64 thousand, Claude Sonnet 5.5 128 thousand, Claude Opus 5.5 128 thousand, GPT-6.1 Sol 128 thousand, GPT-6 Astra 128 thousand, Gemini 4 Argon 1 million." />

*FIG. 01 · Maximum output per response, September 2026 · Argon's cap against every model it was benchmarked against \[1]\[3]\[4]\[5]*

## What is the number, exactly?

The first thing I wrote down was "Argon can write a million tokens." That is not what Google wrote. Google's announcement says the output limit is being expanded to support longer, more complex use cases, and that when the model has the headroom to think deeply and generate hundreds of thousands of tokens in a single trajectory, it adds depth of reasoning to solve tough problems in one go \[1]. Three words in that sentence do the work: think, trajectory, hundreds.

Think, because the cap includes the model's reasoning. On every reasoning model in this comparison, thinking tokens count against the output limit and bill at the output rate: that is how the GPT-6.1 Sol model page describes its 128K cap, and how Anthropic bills thinking on Sonnet 5.5 and Opus 5.5 \[4]\[6]. Google's announcement says nothing about whether Argon's reasoning tokens bill at the output rate, which two day-one write-ups flagged as the open question \[7]. Until Google publishes the model page, the safe assumption is the industry one: the million is a thinking-plus-text budget, and most of it is thinking you never see.

Trajectory, because the examples Google gives are not documents. For libgav1, its open-source video decoder, Argon agents took an existing Rust port and replaced 32,000 lines of SIMD code by running many rounds of profile-guided experiments, studying the compiler's output and producing safe Rust the compiler would vectorise, ending at 2.7 times the Rust port's speed with identical video output \[1]. Many rounds of experiments is an agent loop. The output cap is what lets that loop live inside one response instead of being chopped into re-prompted turns \[7]\[8].

Hundreds, because Google's own description of the realistic case is hundreds of thousands of tokens, not a million. The million is the ceiling. A Hacker News commenter made the same point from the other side: the practical change is that a run no longer errors at 64K \[9].

So the number is a ceiling on a single trajectory of reasoning, tool use and text, and the realistic size of the thing it enables is a few hundred thousand tokens. Everything below follows from that reading, not from the headline.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-trajectory-anatomy-light.png" srcDark="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-trajectory-anatomy-dark.png" alt="Diagram of the anatomy of one long trajectory: a horizontal band of alternating thinking, tool call and text segments running from zero to one million tokens, with dashed markers at 64 thousand (the old Gemini cap) and 128 thousand (Opus 5.5, Sonnet 5.5, GPT-6.1 Sol and Astra), and a shaded region from 200 thousand to 500 thousand labelled hundreds of thousands, Google's stated realistic case." />

*FIG. 02 · What fills a long trajectory · thinking, tool calls and text against the old caps and Google's realistic range \[1]\[4]*

## How long does a million tokens take?

This is the question none of the launch coverage asked, and it is the one that decides whether a 1M-token response is a request or a job.

Models generate tokens one at a time, as the same Hacker News thread was quick to note, so a long trajectory is a long wait \[9]. Google has not published Argon's throughput, and Argon is not available to measure, so the honest move is to use the speeds this generation's models actually run at and see what a million tokens costs in wall-clock time.

Anthropic's SDK encodes an assumption. Its non-streaming timeout scales as sixty minutes multiplied by `max_tokens` over 128,000, which is to say the SDK budgets an hour for a full 128K response, or about 36 tokens per second \[10]. At that rate a million tokens is 7.8 hours. OpenRouter measures GPT-6.1 Sol at about 63 tokens per second, which makes a million tokens 4.4 hours \[11]. Simon Willison's Sonnet 5.5 run at xhigh produced its answer in 41 seconds for 5.74 cents of output, roughly 140 tokens per second, which makes a million tokens two hours \[12]. OpenAI's forthcoming Ultrafast tier claims 300 tokens per second, which would make it 55 minutes \[13].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-clock-light.png" srcDark="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-clock-dark.png" alt="Bar chart of hours to generate one million output tokens at four measured or claimed speeds: 36 tokens per second from the Anthropic SDK timeout formula gives 7.8 hours, 63 tokens per second from OpenRouter's GPT-6.1 Sol measurement gives 4.4 hours, 140 tokens per second from Simon Willison's Sonnet 5.5 run gives 2.0 hours, 300 tokens per second from OpenAI's Ultrafast claim gives 0.9 hours." />

*FIG. 03 · Wall-clock time for one million output tokens at speeds this generation actually runs at · Argon's own throughput is unpublished \[10]\[11]\[12]\[13]*

Pick any bar. None of them fits in an HTTP request. Google's own background-execution page says standard HTTP requests typically close after 60 seconds \[14]. Anthropic's SDK refuses a non-streaming request whose `max_tokens` implies more than ten minutes, which works out to about 21,000 tokens, and its errors page tells you to use streaming or the Batches API for anything longer \[10]\[15]. OpenAI's background mode exists because, in its words, reasoning models can take several minutes to solve complex problems \[16]. All three vendors built machinery for requests that outlive a connection, and the machinery is different on each.

* **Anthropic: stream it, or batch it.** The SDK's rule is a ten-minute ceiling for non-streaming calls, scaled by `max_tokens`; above that you stream and handle reconnects yourself, or you submit to the Batches API and collect later \[10]\[15]. There is no server-side resume cursor on a dropped stream.
* **OpenAI: background mode on Responses.** Set `background` to true, poll the response by id, cancel it, or stream it with a `starting_after` cursor so a dropped connection resumes where it left off. Background responses are stored for roughly ten minutes to enable polling, which makes the mode incompatible with zero data retention \[16].
* **Google: background execution on Interactions.** Set `background` to true, get an interaction id immediately, poll, stream, cancel, or reconnect to a stream from the last event id you processed. Google lists long reasoning, where thinking steps exceed HTTP connection limits, as a primary use \[14]. Gemini Enterprise adds a deferred tier that queues long agent workflows for off-peak capacity and targets completing 95% of them within 24 hours \[17].

The design that fits a million-token trajectory is the third one, and specifically the resume-from-event-id part. A stream that cannot be resumed is a stream you re-run from zero when the network blinks at token 700,000. Google shipped the resumable stream with 3.5 Flash and the output cap with Argon, and the order makes sense: you need the first before the second is usable.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-long-request-machinery-light.png" srcDark="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-long-request-machinery-dark.png" alt="Three-lane diagram of long-request machinery per vendor: Anthropic shows a ten-minute non-streaming limit, a streaming path with client-side reconnect and a Batches path, resume no; OpenAI shows Responses background mode with poll, cancel, a starting_after resume cursor and ten-minute storage, resume yes; Google shows Interactions background execution with poll, cancel, resume from last event id and a deferred tier targeting 95 percent within 24 hours, resume yes." />

*FIG. 04 · How each vendor handles a response that outlives the connection · only two of the three can resume a dropped stream server-side \[10]\[14]\[15]\[16]\[17]*

## What does a full response cost?

The second question the coverage mostly skipped. At $10 per million output tokens, a response that uses the whole cap costs $10 during the introductory period and $20 after it ends, on a date Google has not published \[1]. Two outlets did the multiplication \[7]\[8]; fewer put it next to the other models' caps, which is the comparison that matters for a router.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-cost-ceiling-light.png" srcDark="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-cost-ceiling-dark.png" alt="Bar chart of the cost of one maximum-length response at list price: Gemini 3.8 Flash 64 thousand tokens at 3.75 dollars per million is 24 cents, Sonnet 5.5 and GPT-6.1 Sol 128 thousand at 10 dollars per million is 1.28 dollars, Claude Opus 5.5 128 thousand at 20 dollars per million is 2.56 dollars, GPT-6 Astra 128 thousand at 50 dollars per million is 6.40 dollars, Gemini 4 Argon introductory 1 million at 10 dollars per million is 10 dollars, Gemini 4 Argon standard 1 million at 20 dollars per million is 20 dollars." />

*FIG. 05 · The most one response can cost, cap times list output price · Argon's ceiling is eight times Opus 5.5's and three times Astra's \[1]\[3]\[4]\[5]\[18]*

| Model             | Output cap | Output price per 1M                | Cost of a full response |
| ----------------- | ---------- | ---------------------------------- | ----------------------- |
| Gemini 3.8 Flash  | 64K        | $3.75 intro, $7.50 from Jan 1 \[5] | $0.24, then $0.48       |
| Claude Sonnet 5.5 | 128K       | $10 \[3]                           | $1.28                   |
| GPT-6.1 Sol       | 128K       | $10 \[4]                           | $1.28                   |
| Claude Opus 5.5   | 128K       | $20 \[18]                          | $2.56                   |
| GPT-6 Astra       | 128K       | $50 \[18]                          | $6.40                   |
| Gemini 4 Argon    | 1M         | $10 intro, $20 standard \[1]       | $10, then $20           |

Three things about that table.

First, the per-token price is a distraction. Argon is half the price of Opus 5.5 per output token and can cost eight times as much per response, because the cap is eight times larger. "Half the price" was already a half-truth for Sonnet 5.5, where cheaper tokens turned into more tokens per task \[19]. Argon is the same lesson with the ceiling moved. A cost model that prices requests by tokens times rate needs a third term, the cap you set, because that is now the only thing between a $0.50 call and a $20 one.

Second, the variance is the cost. A $10 ceiling is fine. A P99 of $10 on an endpoint whose median is $0.40 is a budgeting problem, and the one-million cap turns every call where the model decides a problem is hard into a potential P99. One of the Japanese write-ups put it plainly: the practical gain is delegating a long migration in one call, and the price is that cost per call starts to fluctuate \[20]. Set `max_output_tokens` per task class, not per model.

Third, on this metric Argon still beats the model it is positioned against. One early estimate puts Argon at $1.99 per Artificial Analysis task at introductory pricing against $3.26 for GPT-6 Astra, rising to $3.98 at standard pricing \[21]. I could not open the underlying page and am treating that as secondhand. But the direction matches the list prices: Astra's $50 per million output buys a 128K cap that costs $6.40 to fill; Argon's $10 buys a cap that costs $10 to fill and that you can set lower.

## What happens when it fails at token 700,000?

This is the engineering question, and it is the one the vendors' own machinery answers least well.

A chat-shaped integration treats a response as atomic: it succeeds or it fails, and you retry. A million-token response breaks that model twice. It breaks it on cost, because a failure at 70% of the way through has already billed 700,000 output tokens, and no vendor refunds a partial generation. And it breaks it on state, because the model's reasoning up to the failure is the valuable part, and on Anthropic and OpenAI that reasoning is bound to the conversation it was produced in, replayable only inside the same model's history \[6]\[16].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-retry-unit-light.png" srcDark="https://images.syedmoinuddin.com/blogs/one-million-tokens-out/argon1m-retry-unit-dark.png" alt="Diagram contrasting two retry units: a single one-million-token trajectory that fails at 700 thousand tokens and must restart from zero, billing 700 thousand output tokens and losing everything, versus a checkpointed loop of ten rounds where round seven fails and the run resumes from the round six checkpoint, losing only one round." />

*FIG. 06 · The retry unit · one trajectory versus a checkpointed loop when the failure lands late \[14]\[16]*

The two mitigations the vendors give you are resume and cancel. Google's background execution resumes a dropped stream from the last event id, and OpenAI's background mode resumes from a `starting_after` cursor; both let you cancel a run that has gone wrong rather than wait for it to finish spending \[14]\[16]. Anthropic's answer is streaming plus your own reconnect logic, or the Batches API, which trades the connection problem for a wait of up to 24 hours \[15]. None of the three resumes a trajectory after a server-side failure of the generation itself. The event log survives a dropped connection; it does not survive a dead run.

The mitigation you give yourself is a checkpoint, and Google's own examples show where to put it. The libgav1 rewrite ran many rounds of profile-guided experiments, each round being an edit, a compile, a benchmark and a read of the compiler's output \[1]. Each of those rounds is a tool call, and each tool call is a point where the state of the work exists outside the model: in the working tree, in the benchmark log, in the compiler output. If the trajectory dies at round 40, the state at round 39 is on disk. The trajectory was long; the unit of loss was one round. That is the design: let the model run a million tokens if it wants, but make sure every few thousand of them end in a side effect you can resume from, because the side effect is the checkpoint and the trajectory is not.

The same design answers the cancel question. A monitor that watches the stream can kill a run when the trajectory starts doing something it should not, and Google says it runs exactly that: misalignment mitigations that monitor Argon's chain of thought and actions and stop execution when necessary \[1]. You can only stop what you can see. If your integration waits for the whole response and reads it at the end, you have a million-token run with nobody watching it.

## Who reviews a million tokens?

The last question is a human one, and Google answers it in the same paragraph it uses to announce the capability. The Rust migrations, which scale from tens of thousands of lines in re2 and libgav1 to more than 800,000 lines for the Fuchsia Zircon kernel, are undergoing rigorous automated and manual auditing, emulation testing and review before rolling out to production \[1]. The capability is the trajectory. The product is the audit.

That reframes what the output cap is for. A million tokens of reasoning is not something a reviewer reads. The 32,000 lines of SIMD code that Argon replaced were reviewed by running the decoder and checking the video output was identical and the speed was 2.7 times better \[1]. The check was a test, not a read. Every one of Google's internal examples has the same shape: a fleet-wide memory optimisation measured in tebibytes freed, a quantum subroutine measured against a published baseline, a kernel rewrite measured by emulation \[1]. The trajectory produced an artifact, and the artifact had a verifier.

This is the same argument as the last three posts in this series, from the other end. The Opus and Fable post said the escalation rung is useless without a verify function; the Sonnet post said the cheaper lane is only cheaper when the task has a check \[18]\[19]. The output cap makes the point unavoidable. A model that can run for hours and spend $20 on one response is only safe to run against a task whose result can be checked without reading the run. If you cannot name the test, you cannot name the task.

## What are engineers saying after day one?

Argon is a day old and nobody outside the Fairwind cohort can call it, so the practitioner reports are reports about the announcement, not the model. I have weighted the ones that engage with the output cap rather than the benchmark table.

The Hacker News thread split the way Google's launches now split. One commenter read the phased release as Google not beating the allegation that it cannot ship a model; another quoted the price and said only "Wow" \[9]. On the cap itself, the thread's most upvoted technical point was deflationary: models generate one token at a time from everything before it, so a bigger output limit mostly means a run no longer errors at 64K, and the input limit has been a million on Gemini for a long time \[9]. That is correct and it is the right starting point. The interesting part is what you do once the run does not error.

The engineering outlets did the arithmetic the thread skipped. MarkTechPost's comparison table lists Argon at a million against 128K for Opus 5.5, Fable 5.1 and GPT-6 Astra, and prices a full response at $10 introductory and $20 standard \[8]. The DEV Community write-up gives a worked example, a million input tokens and 200,000 output tokens, at $4 on Argon against $8 on Opus 5.5 and $20 on Astra, which is the realistic shape Google describes rather than the ceiling \[7]. DataCamp was the first to flag that Google has not said whether reasoning tokens bill at the output rate, which, if the million is mostly thinking, is the single most important unpublished number \[22].

The benchmark reads add one thing the cap cannot fix. Argon trails Opus 5.5 on Terminal-Bench 4.0, 57.4% against 66.4%, and MarkTechPost notes it also trails on FrontierSWE v2 and OSWorld \[2]\[8]. Those are the benchmarks closest to the kind of tool-heavy loop the output cap is built for. Where Argon leads is long context, 84.2% at 256K to 1M against 71.8% for Astra and 66.8% for Opus 5.5 \[23], DeepSWE, the Vals Index, and the knowledge-work agents \[1]. Reading more and writing more are the same strength. Operating a terminal for a long time is a different one, and on day one the model with the biggest output cap is not the model that does that best.

Two caveats travel with everything in this section. All benchmark figures are vendor-reported and unverified by outside labs, as several outlets note \[24]. And Argon ships to the Fairwind cohort without cyber guardrails, which means the model the first testers are using is not the model developers will get \[1].

## How would I run a long trajectory?

No code in this post. Here is the operating checklist I would hand to a colleague before the first Argon call, and every line comes from a vendor document or from one of Google's own examples.

| Decision           | What I would do                                                                                  | Why                                                                        |
| ------------------ | ------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------- |
| Cap per task class | Set `max_output_tokens` per task class, not per model; keep the million for jobs with a verifier | The cap is the only thing between a $0.50 call and a $20 one \[1]          |
| Transport          | Background execution with a stored interaction id, never a held connection                       | HTTP closes at about 60 seconds; the run can take hours \[14]              |
| Resume             | Persist the last event id on every event; reconnect from it                                      | A dropped stream resumes; a restarted one bills from zero \[14]            |
| Checkpoint         | Make every few thousand tokens end in a side effect on disk: a commit, a test log, a benchmark   | Google's rewrites recovered from rounds, not from trajectories \[1]        |
| Watch              | Stream the thinking and actions to a monitor that can cancel                                     | You can only stop what you can see \[1]\[14]                               |
| Verify             | Name the test before the run; reject tasks that have no test                                     | The artifact has a verifier; the trajectory does not \[1]                  |
| Budget             | Alert on cost per call, not cost per token; track P99 per task class                             | Variance is the cost once the ceiling is $20 \[20]                         |
| Thinking rate      | Assume reasoning bills at the output rate until Google says otherwise                            | Unpublished; the industry default on every other reasoning model \[4]\[22] |
| Older models       | Keep 3.8 Flash at 64K for everyday work; its cap is a feature there                              | Google keeps 3.7 Flash alive for the same reason \[5]                      |

One row in that table is the one I would argue about with myself. "Keep the million for jobs with a verifier" sounds like a restriction. It is the opposite. The verifier is what lets you stop supervising. A job with a test can run for four hours while you do something else; a job without one has to be read, and nobody reads a million tokens.

## What does the side-by-side look like?

|                                 | Gemini 4 Argon                          | Claude Opus 5.5                | GPT-6.1 Sol                        | Gemini 3.8 Flash                        |
| ------------------------------- | --------------------------------------- | ------------------------------ | ---------------------------------- | --------------------------------------- |
| Announced                       | September 30, 2026 \[1]                 | September 22, 2026 \[18]       | September 29, 2026 \[4]            | September 2, 2026 \[5]                  |
| Available to developers         | Not yet; Fairwind cohort first \[1]     | Yes                            | Yes                                | Yes                                     |
| Max output per response         | 1M \[1]                                 | 128K \[18]                     | 128K \[4]                          | 64K \[5]                                |
| Output price per 1M             | $10 intro, $20 standard \[1]            | $20 \[18]                      | $10 \[4]                           | $3.75 intro, $7.50 from Jan 1 \[5]      |
| Cost of a full response         | $10, then $20                           | $2.56                          | $1.28                              | $0.24, then $0.48                       |
| Thinking counts against the cap | Not published \[22]                     | Yes \[6]                       | Yes \[4]                           | Yes \[5]                                |
| Long-request mechanism          | Interactions background execution \[14] | Streaming or Batches API \[15] | Responses background mode \[16]    | Interactions background execution \[14] |
| Resume a dropped stream         | From last event id \[14]                | Client-side only \[10]         | From `starting_after` cursor \[16] | From last event id \[14]                |
| Cancel a running response       | Yes \[14]                               | Close the stream               | Yes \[16]                          | Yes \[14]                               |
| Terminal-Bench 4.0              | 57.4% \[2]                              | 66.4% \[18]                    | Not in Google's table              | Not in Google's table                   |
| DeepSWE v1.1                    | 77.9% \[1]                              | 74.2% \[2]                     | Not in Google's table              | Not in Google's table                   |
| Long context, 256K to 1M        | 84.2% \[23]                             | 66.8% \[23]                    | Not in Google's table              | Not in Google's table                   |

## When should you reach for the million?

**A long trajectory is the right tool if:**

* [ ] The task is a loop of experiments with a measurable result, the libgav1 shape: edit, compile, benchmark, read the output, repeat \[1].
* [ ] The result can be verified without reading the run: a test suite, an emulator, a benchmark, an identical-output check \[1].
* [ ] You run it as a background interaction with a persisted event id and a monitor that can cancel \[14].
* [ ] The job's value clears $20 and a multi-hour wait with room to spare, so the P99 is a line item, not a surprise \[1]\[20].

**A 128K-class model is the right tool if:**

* [ ] The work is tool-heavy terminal operation, where Opus 5.5 leads Argon by nine points on Terminal-Bench 4.0 today \[2]\[18].
* [ ] You need the model now; Argon is not available to developers and Google gives no date \[1].
* [ ] The task fits in 128K with a comfortable margin, which is most tasks; Sonnet 5.5 and GPT-6.1 Sol fill that cap for $1.28 \[3]\[4].

**Nobody should reach for the million if:**

* [ ] The response will be read by a person. A million tokens is not a document; it is a log \[1].
* [ ] The integration holds a connection open and reads the result at the end. The connection will not survive the run, and nobody will be watching it \[14].
* [ ] There is no test. Google's own rewrites go through automated and manual auditing before production, and that audit is a verifier, not a reader \[1].
* [ ] You price by tokens times rate with no cap per task class. The cap is now the budget \[1].

## What would I do differently next time?

Three things, in the order I would do them.

First, I would read the sentence around the number before the number. "One million output tokens" sent me to a spreadsheet; "think deeply and generate hundreds of thousands of tokens in a single trajectory" would have sent me to the background-execution docs, which is where this post ended up anyway \[1]\[14].

Second, I would look up every vendor's long-request page before writing a word about caps. The output cap is useless without the machinery that lets a response outlive a connection, and the three vendors' machinery is different enough that the cap means different things on each. Anthropic's ten-minute rule, OpenAI's ten-minute storage window and Google's resume-from-event-id are three answers to the same question, and the question was the point \[10]\[14]\[16].

Third, I would wait for the model page. The two numbers this post could not pin down, Argon's generation speed and whether its reasoning bills at the output rate, both live on a page Google has not published, and both change the arithmetic in FIG. 03 and FIG. 05. When the page lands I will update both figures and the table, and say so at the top.

## Sources

1. Koray Kavukcuoglu, "Gemini 4 Argon: our next era of frontier intelligence," Google, September 30, 2026, [blog.google](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-4-argon/)
2. Fello AI, "Gemini 4 Argon Is Here: Benchmarks, Price, and Why You Cannot Use It Yet," October 1, 2026 (Terminal-Bench 4.0 and DeepSWE figures from Google's launch table), [felloai.com](https://felloai.com/gemini-4-argon/)
3. Claude Platform Docs, "Claude Sonnet 5.5" model overview (1M context, 128K max output, $10 per million output), [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/overview)
4. OpenAI Developers, "GPT-6.1 Sol" model page (128,000 max output tokens, Responses API for tools), [developers.openai.com](https://developers.openai.com/api/docs/models/gpt-6.1-sol)
5. Google AI for Developers, "What's new in Gemini 3.8 Flash" and "Gemini Developer API pricing" (64K output, $3.75 introductory, $7.50 from January 1, 2027), [ai.google.dev](https://ai.google.dev/gemini-api/docs/latest-model)
6. Claude Platform Docs, "What's new in Claude Sonnet 5.5" (thinking blocks bound to model and conversation; thinking billed as output), [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5)
7. DEV Community, "Gemini 4 Argon: Price, Access and Benchmarks," September 30, 2026, [dev.to](https://dev.to/projedefteri/gemini-4-argon-price-access-and-benchmarks-1g43)
8. MarkTechPost, "Google DeepMind Unveils Gemini 4 Argon with 1M Output Tokens for Coding, Knowledge Work and Cyber Defense," September 30, 2026, [marktechpost.com](https://www.marktechpost.com/2026/09/30/google-deepmind-unveils-gemini-4-argon-with-1m-output-tokens-for-coding-knowledge-work-and-cyber-defense/)
9. Hacker News, discussion thread on the Gemini 4 Argon announcement, September 30 to October 1, 2026, [news.ycombinator.com](https://news.ycombinator.com/item?id=49913571)
10. Anthropic, TypeScript SDK README, "Long Requests" and timeout formula (sixty minutes scaled by max_tokens over 128,000; ten-minute non-streaming limit), [npmjs.com](https://www.npmjs.com/package/@anthropic-ai/sdk)
11. OpenRouter, "OpenAI: GPT-6.1 Sol" model page (measured throughput and latency), accessed October 1, 2026, [openrouter.ai](https://openrouter.ai/openai/gpt-6.1-sol)
12. Simon Willison, "Claude Sonnet 5.5," September 28, 2026 (xhigh run: 41 seconds, 5.74 cents), [simonwillison.net](https://simonwillison.net/2026/Sep/28/claude-sonnet-5-5/)
13. OpenAI, "Introducing GPT-6.1 Sol," September 29, 2026 (Ultrafast tier, up to 300 tokens per second), [openai.com](https://openai.com/index/introducing-gpt-6-1-sol/)
14. Google AI for Developers, "Background execution," Gemini API (Interactions API: background, poll, cancel, resume from last event id; HTTP requests typically close after 60 seconds), [ai.google.dev](https://ai.google.dev/gemini-api/docs/background-execution)
15. Claude Platform Docs, "Errors," section "Long requests" (streaming or Message Batches API for requests over ten minutes), [platform.claude.com](https://platform.claude.com/docs/en/api/errors.md)
16. OpenAI Developers, "Background mode" (Responses API: background, polling, cancel, streaming with starting_after; ten-minute storage, not ZDR compatible), [developers.openai.com](https://developers.openai.com/api/docs/guides/background)
17. Google Cloud, Gemini Enterprise Agent Platform, "Autonomous agent scheduling" (deferred tier, 95% of tasks within 24 hours), [docs.cloud.google.com](https://docs.cloud.google.com/gemini-enterprise-agent-platform/scale/efficiency/autonomous-scheduling)
18. Syed Moinuddin, "Not a Winner, a Routing Rule: What I Learned Researching Claude Opus 5.5 vs Fable 5.1," September 27, 2026 (Opus 5.5 and Astra prices, 128K caps, Terminal-Bench 66.4%), [syedmoinuddin.com](https://syedmoinuddin.com/blog/claude-opus-5-5-vs-fable-5-1)
19. Syed Moinuddin, "Not a Ladder, a Fork: What I Learned Researching Claude Sonnet 5.5 vs Opus 5.5," September 29, 2026, [syedmoinuddin.com](https://syedmoinuddin.com/blog/claude-sonnet-5-5-vs-opus-5-5)
20. DenDen, "Gemini 4 Argon Announced: 1 Million Token Output, Pricing, and Availability," note.com, October 1, 2026, [note.com](https://note.com/dende2023/n/nffb533be6e02)
21. Fello AI, Artificial Analysis cost-per-task comparison quoted in the Argon write-up ($1.99 introductory, $3.98 standard, $3.26 for GPT-6 Astra), secondhand and unverified, [felloai.com](https://felloai.com/gemini-4-argon/)
22. DataCamp, "Gemini 4 Argon: Features, Benchmarks, Pricing, and Access," September 30, 2026, [datacamp.com](https://www.datacamp.com/blog/gemini-4-argon)
23. OfficeChai, "Google Introduces Gemini 4 Argon, Beats GPT 6 Astra And Opus 5.5 On Many Benchmarks" (long-context row from Google's table), September 30, 2026, [officechai.com](https://officechai.com/ai/gemini-4-argon-benchmarks)
24. Forkast, "Google's Gemini 4 Argon Closes the Pricing Triangle. The Benchmark Lead Is the Real Story," September 30, 2026, [forkast.news](https://forkast.news/googles-gemini-4-argon-closes-the-pricing-triangle-the-benchmark-lead-is-the-real-story/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on October 1, 2026

---
title: "Everyone Removed the Off Switch: What I Learned Reading the GPT-6.1 Sol, Sonnet 5.5 and Gemini 3.8 Flash Migration Guides"
description: "Three vendors deleted the same three knobs in one month: thinking off, sampling parameters, and forcing the model's hand. What 27 sources say about building one request for all of them, and what the cache line costs on each."
last_updated: "September 30, 2026"
source: "https://syedmoinuddin.com/blog/everyone-removed-the-off-switch"
---

# Everyone Removed the Off Switch: What I Learned Reading the GPT-6.1 Sol, Sonnet 5.5 and Gemini 3.8 Flash Migration Guides

Three vendors deleted the same three knobs in one month: thinking off, sampling parameters, and forcing the model's hand. What 27 sources say about building one request for all of them, and what the cache line costs on each.

Here is the whole argument up front. Between September 2 and September 29, 2026, Google, Anthropic and OpenAI each shipped a mid-tier model, and each one removed the same three things from its API. You can no longer turn thinking off: Gemini 3.8 Flash rejects `minimal`, Sonnet 5.5 rejects `disabled`, and GPT-6.1 Sol rejects `none` \[6]\[10]\[2]. You can no longer set `temperature`, `top_p` or `top_k` without an error or a silent strip \[7]\[2]\[10]. And you can no longer force the model's hand: Anthropic rejects forced tool choice and prefill, Google removes prefilled model turns, and OpenAI will not run tools at all on Chat Completions \[6]\[10]\[3]. What the three vendors left behind is the same shape, an effort enum with a cache that survives effort changes only if you ask nicely, and that shape is what a request builder should be written against. The prices happen to line up too, at $2 and $10 for two of the three, so the line that decides the bill is the one none of the launch posts lead with: what a cached token costs, and on Gemini, what it costs per hour to keep it cached.

I started this as the third post in a series. The first built an escalation ladder between Opus 5.5 and Fable 5.1 \[25]; the second showed the ladder cannot reach down to Sonnet 5.5 \[24]. The obvious next step was a router across three vendors, and I assumed the hard part would be the benchmarks. It was not. The hard part was that a request that worked on all three mid-tier models in August fails on all three in October, for three different reasons that turn out to be the same reason. This is that research, including the cache number I got wrong first.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-timeline-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-timeline-dark.png" alt="Timeline of four model launches in September 2026 with what each removed from its API: Gemini 3.8 Flash on September 2 removed the minimal thinking level, thinking budgets and sampling parameters; Opus 5.5 and GPT-6 Sol on September 22, with Opus removing thinking off and forced tool use; Sonnet 5.5 on September 28 removing disabled, forced tool use, sampling and prefill; GPT-6.1 Sol on September 29 removing none and minimal effort and tools on Chat Completions" />

*FIG. 01 · One month, four launches, three vendors · what each release removed from a working request \[2]\[6]\[10]\[14]*

## What did each vendor take away, and in what order?

Google went first, and quietly. Gemini 3.8 Flash shipped on September 2, the third Flash release in six weeks, at the same $0.75 and $3.75 introductory prices as 3.7 Flash \[12]\[21]. Its migration checklist reads like a list of things you used to be allowed to do: strip `temperature`, `top_p` and `top_k`; replace the numeric `thinking_budget` with the `thinking_level` string enum, where `minimal` is no longer supported and returns an error; remove `candidate_count`; standardise multi-turn conversations on a server-side `previous_interaction_id`; and remove prefilled model turns \[10]. The page also says the quiet part out loud: 3.8 Flash can use more tokens on longer tasks, by design, because it takes smaller reasoning steps, calls tools iteratively and verifies its work along the way \[10].

Anthropic went next, twice. Opus 5.5 on September 22 made thinking impossible to disable and turned forced tool use into an error \[14]. Sonnet 5.5 on September 28 followed with five breaking changes of its own: `disabled` returns a 400 and the lowest setting is now `between_tools`, forced tool choice returns a 400, thinking blocks are bound to the model and the conversation, the old computer use tool is rejected, and the advisor tool rejects three older advisors \[6]. Code coming from Sonnet 4.6 or earlier also loses thinking budgets, sampling parameters and assistant prefill, all with 400 errors rather than warnings \[7].

OpenAI closed the month. GPT-6.1 Sol arrived at DevDay on September 29, one week after GPT-6 Sol, at the same $2 and $10 prices but with cached input cut in half to $0.10 \[1]\[19]. It arrived alone: the GPT-6.1 Astra that had been expected alongside it did not ship, which The Next Web attributes to failed safety tests \[19]\[27]. The model page is short and firm: `none` and `minimal` reasoning efforts are not supported, tool calling requires the Responses API, and Chat Completions is supported only without tools \[3]. That matters because GPT-6 Sol, seven days older, still supports `none`, and still allows function calling on Chat Completions if and only if effort is `none` \[4]. One week separated a model you could use as a cheap non-reasoning function caller from one you cannot \[18]. The migration guide adds the sampling line: when effort is not `none`, and on 6.1 Sol it never is, remove `temperature`, `top_p` and `top_logprobs`, and on Chat Completions remove `logprobs` too \[2].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-knob-matrix-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-knob-matrix-dark.png" alt="Matrix of six request settings against three models, Sonnet 5.5, GPT-6.1 Sol and Gemini 3.8 Flash: thinking fully off is an error on all three; sampling parameters are an error on Sonnet and Sol and stripped on Gemini; prefilled assistant turns are an error on Sonnet and removed on Gemini and unsupported on Sol; forced tool choice is an error on Sonnet and unavailable on Sol's Chat Completions; tools on the legacy endpoint are blocked on OpenAI only; thinking budgets are errors on Sonnet and Gemini" />

*FIG. 02 · The same three knobs, removed three ways · error, strip, or endpoint change, per vendor \[2]\[3]\[6]\[7]\[10]*

## Why is "thinking off" gone everywhere at once?

The three vendors give three different reasons, and they add up to one.

Anthropic's is architectural. Every Sonnet 5.5 thinking block is signed over the conversation before it, bound to the model that produced it and to the account that produced it, and the API checks that binding on every replay \[6]. A model that sometimes does not think is a model whose conversation history sometimes has no signature to check. `between_tools` is the compromise: no up-front thinking, but the short progress notes the model writes between tool calls still come back as signed thinking blocks, and the setting only works at low, medium and high effort, never at xhigh or max, and never with a per-message effort change \[6]\[7].

OpenAI's is about the endpoint. The Responses API is where persisted reasoning, `configuration_update` items, async tool calling and mid-turn steering live; Chat Completions has none of them \[2]. GPT-6 Sol kept a back door open, function calling on Chat Completions with effort `none`, and GPT-6.1 Sol closed it by removing `none` \[3]\[4]. This is not a new direction so much as the end of one: developers hit the same wall on GPT-5.6 Sol, where the API started rejecting function tools with any non-`none` effort on Chat Completions, and one of them wrote on OpenAI's own forum that developers should not need to be babysat with denials and that Chat Completions should stay a mainline API \[17]. Seven months later it is a text-only endpoint for the newest mid-tier model.

Google's is about quality. Its 3.8 Flash page says the model works harder on purpose, and the earlier 3.5 Flash notes explain why `minimal` was always a soft promise: it matched the no-thinking setting for most queries but did not guarantee thinking was off, and the model could still reason on complex tasks \[10]\[13]. Removing `minimal` on 3.8 Flash turns a setting that sometimes thought into a floor, `low`, that always does.

Put the three together and the reason is the same. Every one of these models now carries reasoning state between turns, signed or persisted or preserved, and the vendors want that state present on every request so the model can be steered, cached and audited. A request with thinking off is a request with no state to carry. The off switch did not get removed because it was unpopular. It got removed because the thing it switched off became the thing everything else depends on.

## What does the effort ladder look like when you line all three up?

This is the figure I wish I had drawn before I tried to write a single effort parameter for three vendors.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-effort-ladders-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-effort-ladders-dark.png" alt="Three vertical effort ladders side by side: Sonnet 5.5 with between_tools at the bottom then low, medium, high, xhigh, max, with high marked as the API default and medium as the Claude Code default; GPT-6.1 Sol with none and minimal crossed out below low, medium, high, xhigh, max, with medium as default; Gemini 3.8 Flash with minimal crossed out below low, medium, high, with medium as default" />

*FIG. 03 · Effort levels, defaults and the rungs that now return errors · Sonnet 5.5, GPT-6.1 Sol, Gemini 3.8 Flash \[2]\[8]\[9]\[10]*

Read it bottom to top. Sonnet 5.5 has six rungs if you count `between_tools`, which is not an effort level but a thinking mode that caps effort at high; its API default is high and its Claude Code default is medium \[8]\[9]. GPT-6.1 Sol has five rungs, low through max, with `none` and `minimal` gone and medium as the default \[2]\[3]. Gemini 3.8 Flash has three, low, medium and high, with `minimal` gone and medium as the default \[10].

Two things follow. First, the word `medium` means three different amounts of thinking. Anthropic says its levels are recalibrated from Sonnet 5 and tells you to re-run your sweep rather than carry a setting over \[6]. OpenAI says to preserve your current effective effort and to start `none` users at `low` and compare \[2]. Google recommends `medium` for complex code and agentic use and `low` for latency-critical work \[10]. A builder that maps `medium` to `medium` across vendors is not mapping anything.

Second, the only rung that exists on all three is the range low to high. Xhigh and max exist on two. `between_tools` exists on one. If the lowest common denominator is the target, the router's effort type has three values, and everything above high is a vendor-specific escape hatch. That is more honest than it sounds: on Sonnet 5.5, max is the setting where cost per task overtakes Opus 5.5 while scoring lower \[24], and OpenAI's own factuality numbers show GPT-6.1 Sol's biggest gain over GPT-6 Sol at low effort, where factual errors dropped from 11.4% to 7.7% \[1]. The interesting rungs are the cheap ones.

## Why is the cache line the one that decides the bill?

List prices first, because two of the three are identical.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-pricing-grid-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-pricing-grid-dark.png" alt="Pricing grid per million tokens for four columns, Sonnet 5.5, GPT-6.1 Sol, Gemini 3.8 Flash introductory and Gemini 3.8 Flash from January 1 2027: input 2, 2, 0.75, 1.50; output 10, 10, 3.75, 7.50; cache read 0.20, 0.10, 0.075, 0.15; cache write 2.50, 2.50, storage 0.50 per hour, storage 1.00 per hour; cache read as share of input 10 percent, 5 percent, 10 percent, 10 percent" />

*FIG. 04 · List prices per million tokens, September 2026, with Gemini's January 1, 2027 column · cache read as a share of input in the last row \[3]\[8]\[11]*

Sonnet 5.5 and GPT-6.1 Sol both cost $2 per million input tokens and $10 per million output tokens \[8]\[3]. Gemini 3.8 Flash costs $0.75 and $3.75 through December 31, 2026, then $1.50 and $7.50 from January 1, 2027 \[11]. On input and output alone, Gemini is the cheapest by a wide margin and the other two are a coin flip.

The cache line breaks the tie. A Sonnet 5.5 cache read is $0.20, 10% of input, with a five-minute cache write at $2.50 \[8]. A GPT-6.1 Sol cache read is $0.10, 5% of input, with cache writes billed at 1.25 times the uncached rate, so also $2.50 \[1]\[3]. A Gemini 3.8 Flash context-cache read is $0.075, 10% of its input price, and there is no write price \[11]. There is a storage price instead: $0.50 per million tokens per hour through December 31, and $1.00 per million tokens per hour after that \[11].

That storage line is the number I got wrong first. I put $0.075 in the spreadsheet, called it the cheapest cache on the market, and moved on. It is the cheapest cache read on the market. It is also the only one of the three with a meter running while the cache exists, and the only one that requires you to create and expire the cache yourself; Anthropic and OpenAI charge you to write the cache and then let it sit for five or thirty minutes with no storage line \[8]\[2]\[11]. For a short agentic session that reuses a 150-thousand-token prefix for an hour, the storage comes to about seven cents at introductory pricing and about fifteen after January 1, small next to the read savings. For a fleet of long-lived caches that nobody expires, it is a bill that arrives with no tokens attached. The read price is the headline; the storage price is the footnote you find in December.

Here is the arithmetic on the session shape Anthropic prices in its own cost guide, 2 million cache-read tokens, 200 thousand fresh input tokens and 60 thousand output tokens \[15], with Gemini's storage estimated for a 150-thousand-token prefix held for one hour.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-session-cost-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-session-cost-dark.png" alt="Horizontal bar chart of cost for one illustrative agent session on four price lists: Sonnet 5.5 at 1.40 dollars, GPT-6.1 Sol at 1.20, Gemini 3.8 Flash introductory at 0.60 with a small hatched storage segment, Gemini 3.8 Flash from January 2027 at 1.20 with a hatched storage segment, each bar split into cache read, fresh input and output" />

*FIG. 05 · One illustrative Claude Code session shape priced on four lists · 2M cache reads, 200K fresh input, 60K output, plus Gemini storage for a 150K prefix held one hour \[3]\[8]\[11]\[15]*

| Session line                   | Sonnet 5.5 | GPT-6.1 Sol | Gemini 3.8 Flash, intro | Gemini 3.8 Flash, from Jan 1 |
| ------------------------------ | ---------- | ----------- | ----------------------- | ---------------------------- |
| 2M cache-read tokens           | $0.40      | $0.20       | $0.15                   | $0.30                        |
| 200K fresh input tokens        | $0.40      | $0.40       | $0.15                   | $0.30                        |
| 60K output tokens              | $0.60      | $0.60       | $0.225                  | $0.45                        |
| Cache storage, 150K for 1 hour | none       | none        | $0.075                  | $0.15                        |
| **Session total**              | **$1.40**  | **$1.20**   | **$0.60**               | **$1.20**                    |

Two things in that table surprised me. First, GPT-6.1 Sol undercuts Sonnet 5.5 by 14% on an identical session even though every list price except cache read is identical, and the whole gap is the $0.10 cache read; the Hacker News launch thread saw the same thing and called the cache price the actual big announcement \[16]. Second, on January 1, Gemini 3.8 Flash at standard pricing lands on exactly $1.20, the same as GPT-6.1 Sol. The cheapest model on the chart becomes a tie in fourteen weeks, and Google publishes the date.

Two caveats travel with the table. The models do not use the same tokens: Google says 3.8 Flash uses more by design \[10], and Sonnet 5.5 at max effort used more output tokens per task than any model Artificial Analysis had measured \[24]. And OpenAI has a surcharge the other two do not: prompts over 272 thousand input tokens are billed at twice the input and cache rates and 1.5 times the output rate for the full request \[3]. A session that grows past that line stops being $1.20.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-gemini-cliff-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-gemini-cliff-dark.png" alt="Bar chart of Gemini 3.8 Flash prices per million tokens doubling on January 1, 2027: input 0.75 to 1.50, output 3.75 to 7.50, cache read 0.075 to 0.15, and cache storage per hour 0.50 to 1.00" />

*FIG. 06 · Gemini 3.8 Flash, introductory versus standard pricing · every line doubles on January 1, 2027, including storage \[11]*

## Where do tool calls live now?

The third removed knob is the one that costs the most engineering time, because it is not a parameter. It is an endpoint.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-tool-surface-light.png" srcDark="https://images.syedmoinuddin.com/blogs/everyone-removed-the-off-switch/offswitch-tool-surface-dark.png" alt="Diagram of three vendor paths from old to new: Anthropic Messages API keeps the endpoint but forced tool choice becomes auto plus strict tools; OpenAI moves tool calls from Chat Completions, now text only, to the Responses API; Google moves from generateContent with prefilled turns to the Interactions API with a server-side previous interaction id" />

*FIG. 07 · Where a tool call has to go on each vendor after September 2026 · one endpoint kept, two endpoints changed \[2]\[3]\[6]\[10]*

Anthropic kept the endpoint and removed the lever. `tool_choice` of type `any` or `tool` returns a 400 on Sonnet 5.5, including on the token-counting endpoint; the replacement is `auto` with `strict: true` on the tool so its input matches the schema, plus a sentence in the prompt saying when the tool applies \[6]\[7]. Strict tools need `additionalProperties: false` on every object, a request can carry at most 20 of them, and on Amazon Bedrock strict tools are not available at all, so there you send `auto` alone and validate the input yourself \[7].

OpenAI kept the lever and moved the endpoint. Tool calling on GPT-6.1 Sol requires the Responses API; Chat Completions still works, but only for requests without tools \[3]. Anyone who used GPT-6 Sol as a cheap function caller on Chat Completions at effort `none` has a migration to do, and it is not a URL swap: the tool schema, the reasoning items you replay, and the way you change effort mid-conversation all live in different fields on Responses \[2]\[18]. A migration guide for Astra warns against moving a Chat Completions tool schema to Responses by changing only the URL, and that warning now applies to the mid-tier too \[2].

Google moved the endpoint and the state. The 3.8 Flash checklist standardises multi-turn conversations on a server-side `previous_interaction_id` through the Interactions API, removes prefilled model turns, and, for anyone still on `generateContent`, requires every function response to carry a `call_id` and a `name` \[10]. Its notes on pre-tool text warn of `Malformed_Function_Call` errors when the model writes prose before a call, with a workaround page \[10].

The pattern is the same one as the effort ladder. Each vendor is pushing tool calls onto the surface where its reasoning state lives, and off the surfaces where that state cannot be carried. A tool call is no longer a stateless request. It is a turn in a stateful conversation, and the vendors want it on the endpoint that knows the conversation.

## What are engineers reporting after day one?

GPT-6.1 Sol is a day old and Sonnet 5.5 is two, so the reports are launch-week reports, and I have weighted the ones that name a breaking change.

The loudest reaction on the OpenAI side was about the cache, not the model. One commenter on the launch thread called the $0.10 cached input the actual big announcement, since a 50% cheaper cache than GPT-6 Sol gets far more mileage in Codex; another reaction, quoted in the same roundup, was relief that GPT-6 Sol is going away, given that its best DeepSWE and OSWorld scores had come in below GPT-5.6 Sol's \[16]. A third pointed out that ChatGPT plan allowances were cut at the same time, so the best case for Codex subscribers is about 2.5 times cheaper rather than five \[26]. The speed story is still pending: OpenAI says an Ultrafast tier for 6.1 Sol is coming, at up to 8x its standard generation speed in Codex, and VentureBeat worked the announced multiplier out to roughly $12 and $60 per million tokens if it follows Astra's 6x pricing \[1]\[20].

The quieter reaction is the one that matters for this post. Open-source clients have started filing the migration as a feature request: LibreChat's issue for GPT-6.1 Sol asks to offer low through max, exclude `none` and `minimal`, normalise incompatible saved settings when a user switches models, route agent and tool calls through Responses, and strip the sampling parameters that now return errors \[22]. That is the request builder from this post written as a ticket, and it is a good ticket.

Then there is the gateway problem, which is my second misread. Several gateways document Anthropic's models with the line that reasoning remains opt-in via a `reasoning.enabled` flag, a claim OpenRouter's Sonnet 5 guide makes and that Sonnet 5.5's own docs now contradict: on the native API, `disabled` returns a 400, and the only way down is `between_tools` \[23]\[6]. Whether a gateway silently translates `enabled: false` into `between_tools`, or silently drops it, or errors, is something each gateway will document on its own schedule. If your requests go through one, the vendor's migration guide is not the only one you have to read.

On the Anthropic side, the day-one reports from my last post still stand: CodeRabbit measured fewer tokens and more issues found per review, GitHub's Copilot team saw fewer steps and tool calls, and the Hacker News thread split between subscribers who no longer see a reason to leave Opus 5.5 and developers who read the cost chart and concluded Sonnet is worse at every point on the curve \[24]. Nothing in that thread was about `between_tools`, which tells you how few people run Sonnet with thinking off on purpose. The people who do are the ones running it as a classifier or a formatter at volume, and they are the ones this migration hits.

On the Google side there is a month of use to draw on, and the pattern is the token appetite Google announced up front. The 3.8 Flash page recommends lowering effort for everyday tasks and notes that 3.7 Flash remains fully supported for workflows that prioritise compute efficiency \[10]. The fact that a vendor keeps the previous Flash alive as the efficient option, three weeks after replacing it, is its own data point.

## How would I write one request builder for all three?

No code in this post, so here is the builder as a table. It is the parameter map I would hand to a colleague, and every cell comes from the migration guides.

| Builder field            | Claude Sonnet 5.5 (Messages API)                        | GPT-6.1 Sol (Responses API)                              | Gemini 3.8 Flash (Interactions API)                         |
| ------------------------ | ------------------------------------------------------- | -------------------------------------------------------- | ----------------------------------------------------------- |
| Model ID                 | `claude-sonnet-5-5` \[8]                                | `gpt-6.1-sol` \[3]                                       | `gemini-3.8-flash` \[10]                                    |
| Effort: quick            | `low`, or `between_tools` if tools drive the work \[6]  | `low` \[2]                                               | `low` \[10]                                                 |
| Effort: default          | `medium` for scoped agentic work, `high` otherwise \[6] | `medium` \[2]                                            | `medium` \[10]                                              |
| Effort: hard             | `high`, then `xhigh` only with a measured gain \[9]     | `high`, then `xhigh` or `max` \[2]                       | `high`, the top rung \[10]                                  |
| Thinking off             | Not available; `disabled` is a 400 \[6]                 | Not available; `none` and `minimal` unsupported \[3]     | Not available; `minimal` returns an error \[10]             |
| Sampling parameters      | Non-default values return a 400 \[8]                    | Remove `temperature`, `top_p`, `top_logprobs` \[2]       | Strip `temperature`, `top_p`, `top_k` \[10]                 |
| Tool choice              | `auto` plus `strict: true` \[7]                         | Tools only on Responses \[3]                             | Function calling via Interactions \[10]                     |
| Prefilled assistant turn | 400 error \[7]                                          | Not a Responses concept                                  | Removed \[10]                                               |
| Change effort mid-run    | Per-message effort, beta, keeps cache \[9]              | `configuration_update` item, keeps prefix \[2]           | Not documented in the pages I read                          |
| Reasoning across turns   | Signed thinking blocks, append-only history \[6]        | Persisted reasoning items, replay if `store: false` \[2] | Thought signatures via `previous_interaction_id` \[10]\[13] |
| Cache: read / write      | $0.20 / $2.50 for 5 min, 512-token minimum \[8]         | $0.10 / 1.25x input, 30-minute TTL option \[3]\[2]       | $0.075 read, $0.50 per M per hour storage, intro \[11]      |
| Long-context surcharge   | None stated for 1M \[8]                                 | 2x input and cache, 1.5x output over 272K \[3]           | None stated for Flash \[11]                                 |

Three decisions in that table are deliberate.

* **The effort type has three values.** Quick, default, hard. Each maps to a vendor level, and the map is the thing you re-run when a vendor recalibrates, which all three did this month \[2]\[6]\[10]. Xhigh and max are not in the type; they are a per-vendor override you reach for by hand, for the reasons in the Sonnet post \[24].
* **Thinking off is not a field.** It was a field in August. Keeping it in the builder now means keeping a field that errors on every vendor. `between_tools` is the closest thing left and it belongs to one vendor, so it lives under the quick effort for Anthropic only.
* **Effort changes go through the vendor's cache-preserving path or not at all.** On Anthropic, changing the top-level effort between requests invalidates the cache, and per-message effort is the way to keep it \[9]. On OpenAI, the guide says to keep the request-level effort unchanged and use `configuration_update` items to preserve the prompt prefix \[2]. On Gemini I could not find the equivalent, so the builder never changes effort mid-run there. A cache write at 1.25 times input, paid because a router bumped effort, is the most avoidable line on the bill.

One thing the table cannot express is the order of operations for a switch between vendors. Reasoning state does not travel between any of these three; it barely travels between two models from the same vendor \[24]. A vendor switch is a fresh start with a written summary, not a continuation, and the builder should refuse to append a new vendor's turn to another vendor's history.

## What does the side-by-side look like?

|                         | Claude Sonnet 5.5                           | GPT-6.1 Sol                                           | Gemini 3.8 Flash                                              |
| ----------------------- | ------------------------------------------- | ----------------------------------------------------- | ------------------------------------------------------------- |
| Released                | September 28, 2026 \[8]                     | September 29, 2026 \[1]                               | September 2, 2026 \[12]                                       |
| Replaces                | Sonnet 5, June 30 \[5]                      | GPT-6 Sol, September 22 \[1]                          | 3.7 Flash, three weeks earlier \[21]                          |
| Input / output per 1M   | $2 / $10 \[8]                               | $2 / $10 \[3]                                         | $0.75 / $3.75 to Dec 31, then $1.50 / $7.50 \[11]             |
| Cache read per 1M       | $0.20 \[8]                                  | $0.10 \[1]                                            | $0.075, then $0.15 \[11]                                      |
| Cache write or storage  | $2.50 per 1M, 5 min \[8]                    | 1.25x input per write \[3]                            | $0.50 per 1M per hour, then $1.00 \[11]                       |
| Context / max output    | 1M / 128K \[8]                              | Tiered above 272K input \[3]                          | 1M / 64K \[10]                                                |
| Effort levels           | low, medium, high, xhigh, max \[6]          | low, medium, high, xhigh, max \[2]                    | low, medium, high \[10]                                       |
| Default effort          | high on API, medium in Claude Code \[8]\[9] | medium \[2]                                           | medium \[10]                                                  |
| Lowest thinking setting | `between_tools` \[6]                        | `low` \[3]                                            | `low` \[10]                                                   |
| Sampling parameters     | 400 error \[8]                              | Remove \[2]                                           | Strip \[10]                                                   |
| Tool-calling surface    | Messages API, `auto` + strict \[7]          | Responses API only \[3]                               | Interactions API \[10]                                        |
| Legacy endpoint status  | Not applicable                              | Chat Completions, text only \[3]                      | `generateContent`, needs `call_id` and `name` \[10]           |
| Vendor's positioning    | Well-scoped everyday tasks \[5]             | Near-Astra intelligence for a fifth of the price \[1] | Most intelligent workhorse, works harder by design \[12]\[10] |

## Which one should you reach for?

**Sonnet 5.5 is the right lane if:**

* [ ] You already run Claude Code or the Messages API and the task has a spec and a check; the migration from Sonnet 5 is six items long \[6].
* [ ] You need tool-heavy, latency-sensitive runs with up-front thinking off and can live at high effort or below, which is exactly what `between_tools` is for \[6].
* [ ] Your prompts are short: the minimum cacheable prompt dropped to 512 tokens, so system prompts and tool definitions that never cached on Sonnet 5 now do \[6]\[9].

**GPT-6.1 Sol is the right lane if:**

* [ ] Your sessions are cache-heavy: at $0.10 per million cached tokens the same session costs 14% less than on Sonnet 5.5 with every other price identical \[1]\[8].
* [ ] You are already on the Responses API. If you are on Chat Completions with tools, budget the migration before the model, not after \[3]\[2].
* [ ] You can keep prompts under 272 thousand input tokens, where the surcharge doubles the input and cache rates \[3].

**Gemini 3.8 Flash is the right lane if:**

* [ ] You are pricing for the next fourteen weeks, at $0.75 and $3.75, and have a plan for January 1, when every line doubles \[11].
* [ ] You can manage explicit context caches with a storage meter, creating and expiring them yourself \[11].
* [ ] Three effort levels are enough, and you have set the lower one for everyday work, because the model spends more tokens by design at the default \[10].

**None of the three is the fix if:**

* [ ] Your product depends on thinking being off. That setting no longer exists on any of these models; the older siblings that still allow it, GPT-6 Sol, GPT-6 Luna and Gemini 3.7 Flash, are the honest choice until you re-baseline \[2]\[10].
* [ ] Your router changes effort between requests to save money. On two vendors that invalidates the cache unless you use the vendor's specific mechanism, and on the third I could not confirm one \[9]\[2].
* [ ] You compare them at defaults. High, medium and medium are three different amounts of thinking, and a comparison at defaults is a comparison of effort levels, not models \[8]\[2]\[10].

## What would I do differently next time?

Three things, in the order I would do them.

First, I would read the pricing page for the storage line before the read line. I found Gemini's $0.075 cache read in a launch article and its $0.50 per million per hour storage price two hours later in the pricing table \[11]. The read price is what a comparison post prints. The storage price is what a finance team prints.

Second, I would diff the model pages, not the announcements. The single most consequential sentence in this research is on OpenAI's GPT-6 Sol model page, not its GPT-6.1 Sol announcement: Chat Completions supports function calling only with reasoning effort set to `none` \[4]. Read next to the 6.1 Sol page, which drops `none`, that sentence is the migration. The announcement never mentions it.

Third, I would treat a gateway's parameter docs as a second migration guide with its own release schedule. My builder assumed a `reasoning.enabled` flag existed on Anthropic models because a gateway said so, and the native API disagrees \[23]\[6]. When three vendors change their request shape in one month, every abstraction layer between you and them is a place where an August request can still look valid in October.

## Sources

1. OpenAI, "Introducing GPT-6.1 Sol," September 29, 2026, [openai.com](https://openai.com/index/introducing-gpt-6-1-sol/)
2. OpenAI Developers, "Using GPT-6" (GPT-6 family guide and migration quickstart), [developers.openai.com](https://developers.openai.com/api/docs/guides/latest-model)
3. OpenAI Developers, "GPT-6.1 Sol" model page, [developers.openai.com](https://developers.openai.com/api/docs/models/gpt-6.1-sol)
4. OpenAI Developers, "GPT-6 Sol" model page, [developers.openai.com](https://developers.openai.com/api/docs/models/gpt-6-sol)
5. Anthropic, "Introducing Claude Sonnet 5.5," September 28, 2026, [anthropic.com](https://www.anthropic.com/claude-sonnet-5-5)
6. Claude Platform Docs, "What's new in Claude Sonnet 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5)
7. Claude Platform Docs, "Migrating to Claude Sonnet 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide)
8. Claude Platform Docs, "Claude Sonnet 5.5" model overview, [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/overview)
9. Addy Osmani, "Building with Claude Sonnet 5.5," claude.dev, September 28, 2026, [claude.dev](https://claude.dev/blog/building-with-claude-sonnet-5-5/)
10. Google AI for Developers, "What's new in Gemini 3.8 Flash," updated September 23, 2026, [ai.google.dev](https://ai.google.dev/gemini-api/docs/latest-model)
11. Google AI for Developers, "Gemini Developer API pricing," accessed September 30, 2026, [ai.google.dev](https://ai.google.dev/gemini-api/docs/pricing)
12. Google, "Introducing Gemini 3.8 Flash and 3.8 Flash Cyber," The Keyword, September 2, 2026, [blog.google](https://blog.google/innovation-and-ai/models-and-research/gemini-models/3-8-flash-and-3-8-flash-cyber/)
13. Google AI for Developers, "What's new in Gemini 3.5 Flash" (thinking levels and thought preservation), [ai.google.dev](https://ai.google.dev/gemini-api/docs/generate-content/whats-new-gemini-3.5)
14. Claude Platform Docs, "What's new in Claude Opus 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5)
15. Addy Osmani, "What a task costs on Opus 5.5," claude.dev, September 25, 2026, [claude.dev](https://claude.dev/blog/what-a-task-costs-on-opus-5-5/)
16. Jake Handy, "Model Drop: GPT-6.1 Sol," Handy AI, September 29, 2026, [handyai.substack.com](https://handyai.substack.com/p/model-drop-gpt-61-sol)
17. OpenAI Developer Community, "Gpt-5.6 chat completion reasoning effort \[bug / behavior change]," 2026, [community.openai.com](https://community.openai.com/t/gpt-5-6-chat-completion-reasoning-effort-bug-behavior-change/1386454)
18. DataCamp, "GPT-6.1 Sol: Features, Benchmarks, Pricing, and Access," September 29, 2026, [datacamp.com](https://www.datacamp.com/blog/gpt-6-1-sol)
19. TechCrunch, "OpenAI launches GPT-6.1 Sol, says it nearly matches GPT-6 Astra and costs less," September 29, 2026, [techcrunch.com](https://techcrunch.com/2026/09/29/openai-launches-gpt-6-1-sol-says-it-nearly-matches-gpt-6-astra-and-costs-less/)
20. VentureBeat, "OpenAI's GPT-6.1 Sol offers Astra-like performance at 1/5th price. A new Ultrafast tier clocks at 300 tokens per second," September 29, 2026, [venturebeat.com](https://venturebeat.com/technology/openais-gpt-6-1-sol-offers-astra-like-performance-at-1-5th-price-a-new-ultrafast-tier-clocks-at-300-tokens-per-second)
21. Thurrott, "Google Releases Gemini 3.8 Flash and Cyber Variant," September 2, 2026, [thurrott.com](https://www.thurrott.com/a-i/340992/google-releases-gemini-3-8-flash-and-cyber-variant)
22. LibreChat, issue #16527, "Add GPT-6.1 Sol (gpt-6.1-sol) support," September 29, 2026, [github.com](https://github.com/LibreChat-AI/LibreChat/issues/16527)
23. OpenRouter, "Claude 5 Sonnet Migration Guide" (gateway parameter mapping), [openrouter.ai](https://openrouter.ai/docs/cookbook/evaluate-and-optimize/model-migrations/claude-5-sonnet)
24. Syed Moinuddin, "Not a Ladder, a Fork: What I Learned Researching Claude Sonnet 5.5 vs Opus 5.5," September 29, 2026, [syedmoinuddin.com](https://syedmoinuddin.com/blog/claude-sonnet-5-5-vs-opus-5-5)
25. Syed Moinuddin, "Not a Winner, a Routing Rule: What I Learned Researching Claude Opus 5.5 vs Fable 5.1," September 27, 2026, [syedmoinuddin.com](https://syedmoinuddin.com/blog/claude-opus-5-5-vs-fable-5-1)
26. eesel AI, "GPT-6.1 Sol: what's new, pricing, and when it beats Astra," September 30, 2026, [eesel.ai](https://www.eesel.ai/blog/gpt-6-1-sol)
27. The Next Web, "OpenAI releases GPT-6.1 Sol at a fifth of GPT-6 Astra's token prices," September 29, 2026, [thenextweb.com](https://thenextweb.com/news/openai-gpt-6-1-sol-price-astra-devday)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on September 30, 2026

---
title: "Not a Ladder, a Fork: What I Learned Researching Claude Sonnet 5.5 vs Opus 5.5"
description: "Sonnet 5.5 is half the price per token, not half the price per task, and neither model can read the other's reasoning. What 27 sources and a day of engineer reports show."
last_updated: "September 29, 2026"
source: "https://syedmoinuddin.com/blog/claude-sonnet-5-5-vs-opus-5-5"
---

# Not a Ladder, a Fork: What I Learned Researching Claude Sonnet 5.5 vs Opus 5.5

Sonnet 5.5 is half the price per token, not half the price per task, and neither model can read the other's reasoning. What 27 sources and a day of engineer reports show.

Here is the whole argument up front. Claude Sonnet 5.5 is not a cheaper Opus 5.5. It is a cheaper model at low, medium and high effort, an equally expensive one at max, and a different model in the one way that matters for routing: no other model can read a Sonnet 5.5 thinking block, and Sonnet 5.5 cannot read an Opus 5.5 block \[3]\[4]. So the ladder I built last week, where a conversation climbs from Opus 5.5 to Fable 5.1 and keeps its reasoning \[26], cannot be extended downward. Between Sonnet 5.5 and Opus 5.5 there is no climb. There is a fork, and you take it before the first token, per task, based on whether the task has a spec and a check.

I started this as the obvious sequel: a routing rule with one more rung. Sonnet 5.5 landed on September 28, six days after Opus 5.5 \[1]\[2], at exactly half of Opus's input and output prices \[5]\[21], with a launch table that shows it beating Opus on one benchmark and sitting within two or three points on most of the rest \[1]. Every source I read after that took a piece out of that plan, starting with the benchmark I misread first.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-terminal-bench-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-terminal-bench-dark.png" alt="Bar chart of Terminal-Bench 4.0 scores from the Sonnet 5.5 system card: Sonnet 5.5 at max effort 70.6 percent with 1.5 percent of trials served by a fallback model, Opus 5.5 at xhigh 66.4 percent with 10 percent of trials served by a fallback model, Opus 5.5 at max 64.8 percent, each with error bars of about 2.5 points" />

*FIG. 01 · Terminal-Bench 4.0 as the system card reports it · scores, effort levels, fallback share and standard error \[7]*

## Why did the one benchmark Sonnet wins almost fool me?

The first number I wrote down was 70.6. That is Sonnet 5.5's Terminal-Bench 4.0 score in Anthropic's launch table, against 66.4 for Opus 5.5 \[1]. Read as a headline, the cheaper model beats the flagship on the benchmark closest to what Claude Code actually does. Half of the day-one comparison posts led with it, and so did my first draft.

Then I opened section 8.5 of the system card, and the win shrank three separate times. First, effort: the 70.6 is Sonnet 5.5 at max, while the 66.4 is Opus 5.5 at xhigh, because that is Opus's highest score on this benchmark; at max, Opus 5.5 scores 64.8, which Anthropic calls within noise of xhigh \[7]. Second, safeguards: both runs had cyber safeguards on, and requests the classifiers flagged were answered by a fallback model. For Sonnet 5.5 that touched 1.5% of trials. For Opus 5.5 it touched 10% \[7]. Third, noise: with 330 trials per model, the standard error is ±2.5 points for Sonnet 5.5 and ±2.6 for Opus 5.5 \[7]. A 4.2-point gap with a tenth of one side's trials answered by an older model is not a result I would put in a routing rule.

A Hacker News commenter got there before me, pointing to the same section and concluding that the fallback gap alone could explain the difference \[14]. Two independent write-ups also report a Vals run in which the order reverses, with Opus 5.5 ahead of Sonnet 5.5 on Terminal-Bench 4.0; I could not open the Vals page myself, so I am flagging that as secondhand rather than building on it \[23]\[24].

The rest of the table points one way. Opus 5.5 leads on FrontierCode (54.4% against 46.2% at max, or 52.1% at Sonnet's best setting, xhigh), CursorBench (57.8% against 55.5%), Humanity's Last Exam with tools (67.7% against 64.5%), OSWorld 2.1 (81.8% against 80.1%) and Chartography (64.4% against 61.6%) \[1]. The system card adds SWE-Bench Pro at 89.9% against 81.3% \[7]. The two knowledge-work rows are within a rounding error: 1846 against 1844 on GDPval-AA and 1822 against 1811 on AA-Briefcase \[1]. And the footnote on FrontierCode is the most instructive line on the page: at max effort Sonnet 5.5 scores lower than at xhigh, because it more often ran Claude Code's code-review skill across many subagents, which in two cases produced a timeout or out-of-scope edits \[1]. More thinking, worse score, higher bill.

Anthropic's own caption says it plainly: on several evaluations Sonnet 5.5 at max performs comparably to Opus 5.5, but in its own and external testers' hands, Opus 5.5 remains clearly stronger at complex, open-ended work requiring sustained judgment \[1]. The lesson I am keeping from last week still holds and now has a fourth item. Before reading any benchmark number, pin the version, the harness, the effort level, and the fallback rate.

## Why is "half the price" true per token and false per task?

List prices first, because they are the only numbers nobody disputes.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-pricing-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-pricing-dark.png" alt="Horizontal bar chart comparing Sonnet 5.5 and Opus 5.5 list prices per million tokens: input 2 vs 4 dollars, output 10 vs 20, five minute cache write 2.50 vs 5, cache read 0.20 vs 0.20, with ratios 2x, 2x, 2x and 1x" />

*FIG. 02 · List price per million tokens on the Claude API · Sonnet 5.5 vs Opus 5.5, September 2026 \[5]\[8]*

Sonnet 5.5 costs $2 per million input tokens and $10 per million output tokens, with five-minute cache writes at $2.50, one-hour cache writes at $4, and cache reads at $0.20 \[5]. Opus 5.5 costs $4 and $20, with five-minute cache writes at $5, one-hour writes at $8, and cache reads at $0.20 \[8]. Every line is exactly double except the last one, which is identical. The reason is a pricing choice I covered last week: Opus 5.5's cache read sits at 5% of its input price, while Sonnet 5.5 keeps the usual 10% multiplier, and the two land on the same $0.20 \[26]. Sonnet 5.5's prices are unchanged from Sonnet 5 \[1].

In an agentic session, that shared line is most of your input. Here is the arithmetic on the illustrative session shape Anthropic prices in its Opus 5.5 cost guide: 2 million cache-read tokens, 200 thousand fresh input tokens, 60 thousand output tokens \[9].

```ts
// Claude API list prices, USD per million tokens.
const PRICES = {
  "claude-sonnet-5-5": { input: 2, output: 10, cacheRead: 0.2 },
  "claude-opus-5-5":   { input: 4, output: 20, cacheRead: 0.2 },
} as const;

type Usage = { cacheRead: number; freshInput: number; output: number };

function sessionCost(model: keyof typeof PRICES, u: Usage): number {
  const p = PRICES[model];
  return (u.cacheRead * p.cacheRead + u.freshInput * p.input + u.output * p.output) / 1_000_000;
}

// Illustrative Claude Code session shape from Anthropic's cost guide.
const session: Usage = { cacheRead: 2_000_000, freshInput: 200_000, output: 60_000 };

sessionCost("claude-sonnet-5-5", session); // 1.40
sessionCost("claude-opus-5-5", session);   // 2.40, so Sonnet is 42% cheaper, not 50%

// Push the cache share up, the way long sessions do.
const longSession: Usage = { cacheRead: 5_000_000, freshInput: 100_000, output: 60_000 };

sessionCost("claude-sonnet-5-5", longSession); // 1.80
sessionCost("claude-opus-5-5", longSession);   // 2.60, now only 31% cheaper
```

Same tokens, 42% cheaper on the standard shape and 31% cheaper on a cache-heavy one. A Hacker News reader spotted the same line in the launch table within minutes: with cache reads priced the same as Opus, there will not be that much price difference in agentic coding \[14].

Then the two models stop using the same tokens, and this is where the "up to 30% less" claim needs its footnote. Anthropic's 30% compares Sonnet 5.5 with Sonnet 5, not with Opus, and it comes from needing fewer tokens and fewer tool calls for the same work rather than from any price cut \[1]\[20]. Against Opus 5.5 the token story runs the other way at the top of the range. Artificial Analysis measured about 193 thousand output tokens per Intelligence Index task for Sonnet 5.5 at max, the highest it has ever recorded, roughly 60% more than Opus 5.5 at max \[10]. The result is a cost per task of $7.60 for Sonnet 5.5 at max against $5.98 for Opus 5.5 at max \[10]\[12]. Half the price per token, 27% more per task.

Lower down the curve the picture flips back. Sonnet 5.5 at low costs $0.41 per index task, at medium $0.59, at high $1.08 \[11]. Opus 5.5 at its own default, medium, costs $1.34 \[12]. So "cheaper" is a true statement about three of Sonnet's five effort levels and a false one about the top of the curve. Artificial Analysis's summary is blunter than Anthropic's: at its $2 and $10 pricing, Sonnet 5.5 sits off the intelligence-versus-cost frontier, behind Opus 5.5 at the high effort levels, with the high setting its most competitive \[10].

## What happens when you put both models on one chart?

This is the chart I wish I had drawn before writing the first draft. Every point comes from Artificial Analysis Intelligence Index v4.3.2, run with Anthropic's default fallback on, and the Opus points are from the snapshot I took for last week's post \[10]\[11]\[12].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-aa-index-cost-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-aa-index-cost-dark.png" alt="Scatter plot of Artificial Analysis Intelligence Index v4.3.2 against cost per task on a log scale: Opus 5.5 at low 42 for 0.55 dollars, medium 51 for 1.34, high 54 for 1.82, xhigh 56 for 3.46, max 58 for 5.98, and Sonnet 5.5 at low 36 for 0.41, medium 41 for 0.59, high 47 for 1.08, max 56 for 7.60, with a bracket marking that Sonnet at max ties Opus at xhigh for 2.2 times the cost" />

*FIG. 03 · Artificial Analysis Intelligence Index v4.3.2 vs cost per task · Opus 5.5 snapshot 27 September, Sonnet 5.5 snapshot 29 September 2026 \[10]\[11]\[12]*

Read it left to right. Sonnet 5.5 at low scores 36 for $0.41 and at medium 41 for $0.59 \[11]. Opus 5.5 at low scores 42 for $0.55 \[12]. So the cheapest Opus setting outscores the two cheapest Sonnet settings for about the price of Sonnet's medium. At high, Sonnet 5.5 scores 47 for $1.08 \[11]; Opus 5.5 at medium scores 51 for $1.34 \[12]. Then the right edge: Sonnet 5.5 at max scores 56 for $7.60, which is exactly the score of Opus 5.5 at xhigh, for $3.46 \[10]\[12]. Same index score, 2.2 times the cost. A Hacker News commenter asked the question the chart asks: why run Sonnet 5.5 at xhigh when Opus 5.5 at high scores higher for less \[14]? On this index, I do not have a good answer.

I left one point off. Artificial Analysis publishes a Sonnet 5.5 page for each of the five effort levels, and the xhigh page would not load for me on two attempts, so the chart has four Sonnet points, not five \[11]. I would rather show the gap than guess the number.

Two caveats travel with the chart. Artificial Analysis ran a pre-release deployment of Sonnet 5.5 that Anthropic says had a bug affecting structured-output requests, since fixed; both parties expect the effect to be small and to understate Sonnet's scores \[1]\[10]. And the index rewards breadth: on its AA-Omniscience knowledge test Sonnet 5.5 scores 54% accuracy against 66% for Opus 5.5, with a lower hallucination rate (47% against 59%), and it sits about six points lower on Humanity's Last Exam and SciCode \[10]. A smaller model knows less and makes things up less. Both halves of that sentence matter for routing, and Anthropic said as much on launch day: Sonnet 5.5 does not advance the frontier of its models' capabilities \[1]\[21].

The right side of the chart also has last week's failure mode. Simon Willison ran his pelican-on-a-bicycle prompt on Sonnet 5.5 at max, and the model thought for 128,000 tokens, at $1.28, before running out of output room and producing no SVG, the same bug he hit on Opus 5.5 \[13]. At xhigh the same prompt cost 5.74 cents, took 41 seconds, and drew a correct bicycle \[13]. Max is where over-thinking shows up first on both models, and on Sonnet it costs more than on Opus.

## What are engineers reporting after day one?

Benchmarks tell you where to look. Practitioners tell you what breaks. Sonnet 5.5 is a day old as I write this, so the reports are launch-day reports, from engineers in the US and Europe, and I have weighted the ones that come with numbers.

The efficiency story is real and consistent. GitHub's Copilot team found Sonnet 5.5 matched Sonnet 5 on coding tasks while using significantly fewer steps, tokens and tool calls, and finishing noticeably faster \[18]. CodeRabbit measured it at 6 of 13 known issues found in code review against 4 for Sonnet 5, at a slightly higher precision, and plans to move simple and moderate reviews over now \[19]. Lovable's evals showed a third fewer tool calls and roughly half the shell runs per task \[1]. Base44 ran 118 real app builds and found Sonnet 5.5 reached Opus 5-level app quality in 3.6 iterations per build where Opus 5 took 7.7, with the fewest failed tool calls of any model they compared \[1]. Balyasny's finance suite used about 121 thousand tokens per answer against 497 thousand for Sonnet 5 \[1]. Those are all vendor-supplied quotes in a launch post, but the direction is the same in every independent test I found.

The most useful head-to-head came from a small shop that ran the same coding task three times each on Sonnet 5.5, Sonnet 5, Opus 5.5 and GPT-6 Sol. The two Anthropic models behaved almost identically, about six steps each, every hidden test passed, but Opus 5.5 took 68 seconds and $0.33 per run against 48 seconds and $0.19 for Sonnet 5.5. Their conclusion: on a task that size, Opus bought nothing extra \[23]. That is the fork in one sentence. When the task is scoped and checkable, the extra judgment has nothing to do.

Writing is the surprise. Dan Shipper at Every reported that Sonnet 5.5 dramatically improved on writing even against Opus 5.5 in his tests, that GPT-6 Astra remains his favourite for drafting, and that Sonnet 5.5 beats it at revision, which is why Every's engineers reach for it for quick iterative coding \[16]. Every's own headline verdict is more careful: a more capable partner than Sonnet 5, so long as you keep a hand on the wheel and know when to call in Opus \[15]. Simon Willison's read is similar: almost as good as Opus 5.5 on some coding tasks, and now the model behind claude.ai's free tier, replacing Sonnet 5 as the default for Free and Pro users, which he thinks gives Anthropic a much more capable free offering than ChatGPT's \[13]\[22].

The dissent clusters in two places. The first is the Opus 5.5 subscriber who does not see a reason to switch. One Hacker News developer on the 5x plan wrote that Opus 5.5's efficiency makes the limits sufficient for everyday work, even running two or three sessions at once, and wondered when Sonnet 5.5 would ever come up \[14]. Another said the only advantage he could anticipate was that he still hits session limits with Opus 5.5, and Sonnet 5.5 is a better fallback for those than Sonnet 5 \[14]. The second is the cost-per-task crowd, who read the same chart I drew above and concluded Sonnet is, in one commenter's words, a far worse version of Opus at every point on the cost and speed curve, and that what Anthropic needs is something competitive with GPT-6 Luna or Gemini Flash \[14]. Another summed up Sonnet 5 as bad, Sonnet 5.5 as a lot better, and neither as close to Fable \[14].

Then there is the safeguard noise, which is louder than for any Sonnet before it. The system card says users should expect increased refusals with Sonnet 5.5, even on benign cybersecurity-related tasks, and that blocked requests fall back to Sonnet 5 automatically in Anthropic's apps but only if you opt in on the API \[7]\[17]. Launch-day reports from developers include a write-ahead-log durability review flagged and rerouted, a parser task flagged for using the word fuzz, an ESP32 Bluetooth presence-detection project bounced to an older model, and a paying member of the Cyber Verification Program who still cannot use either 5.5 model for authorized bounty work \[14]. Anthropic says the expanded program will cover Sonnet 5.5 soon \[1]. Until it does, the fallback is a cost and latency event you should expect to see in logs.

## Why can't you bolt Sonnet onto the bottom of the ladder?

This is the part of the research that turned a sequel into a correction.

Last week's post ended with an escalation ladder: run Opus 5.5, raise its effort, and move to Fable 5.1 only after xhigh fails the same check twice, because Fable can read Opus 5.5's thinking blocks and the climb keeps its reasoning \[26]. The obvious sequel adds Sonnet 5.5 as rung zero. Start cheap, climb when the check fails.

The docs close that door in both directions. Sonnet 5.5 reads thinking blocks from Sonnet 5, Opus 4.8, Haiku 4.5 and earlier models. It does not read blocks from Opus 5, Opus 5.5, or any Fable or Mythos model. And no other model reads Sonnet 5.5's blocks \[3]. Opus 5.5's blocks, in turn, are readable only by Fable 5.1 and Mythos 5.1 \[6]. When a request carries a block the target model cannot read, the API drops it before the model sees it; the request still succeeds, and dropped blocks are not billed, which means a router that switches models mid-conversation loses the reasoning silently \[3]\[4].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-thinking-wall-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-5-vs-opus-5-5/sonnet55-opus55-thinking-wall-dark.png" alt="Diagram of thinking-block compatibility between four models: a solid arrow from Opus 5.5 to Fable 5.1 labelled reasoning carries forward, a crossed-out dashed arrow from Fable 5.1 back to Opus 5.5, and a wall between Sonnet 5.5 and Opus 5.5 with crossed-out arrows in both directions, plus a small note that Sonnet 5.5 reads Sonnet 5, Opus 4.8 and Haiku 4.5 blocks" />

*FIG. 04 · Who can read whose thinking blocks · the Opus to Fable climb keeps reasoning, the Sonnet to Opus switch drops it both ways \[3]\[6]*

I nearly got this wrong from a secondary source. One comparison post published within hours of launch states that Opus 5.5 can read thinking blocks from Sonnet models, so a Sonnet-to-Opus escalation keeps its reasoning \[25]. The platform docs say the opposite in one sentence: no other model reads Claude Sonnet 5.5 thinking blocks \[3]. Addy Osmani's day-one guide repeats it word for word \[8]. I checked because the claim was load-bearing for the ladder, and the ladder fell over.

Four more constraints shape the fork.

* **Switching models costs a cache write.** The cache belongs to the previous model, so the first turn on the new one pays the write price on the whole conversation \[9]. On a Sonnet-to-Opus switch that write is at Opus prices.
* **The defaults are not equal.** Sonnet 5.5 defaults to high effort on the Claude API and medium in Claude Code and the apps; Opus 5.5 defaults to medium \[1]\[5]\[8]. An A/B test that never sets `output_config.effort` compares Sonnet at high against Opus at medium.
* **Changing effort at the top level invalidates the cache.** To run one turn at a different level, use per-message effort, which is in beta and keeps the cache, and which Sonnet 5.5 supports and Sonnet 5 does not \[3]\[8].
* **Keep the conversation append-only.** For accounts created on or after August 31, 2026, a request that replays a Sonnet 5.5 thinking block after an edit to earlier history returns a 400 error, on the Claude API, Bedrock and Google Cloud \[3]\[4]. Same rule as Opus 5.5, same fix: mid-conversation system messages instead of edits.

One breaking change is Sonnet-only and worth knowing before you migrate. Sonnet 5 turned thinking off with `disabled`; on Sonnet 5.5 that returns a 400, and the lowest setting is `between_tools`, which skips up-front thinking, still emits short progress-update thinking blocks between tool calls, only works at low, medium and high, and does not allow effort to change mid-conversation \[3]\[4]. The other breaking changes line up with Opus 5.5: forced tool use returns an error, the old `computer_20251124` tool is rejected on the Claude API and Google Cloud, and the advisor tool rejects Opus 4.8, Opus 4.7 and Sonnet 5 as advisors \[3]. One request builder still serves both models, as long as it never sends `disabled`.

## How would I encode the fork?

Here is the rule as code. It uses plain fetch against the Messages API so every field is visible, and it only uses parameters the docs confirm for both models: adaptive thinking, effort under `output_config`, and the default tool choice \[3]\[6]. The one Sonnet-only field, `between_tools`, is used where the docs say it belongs: low-latency, tool-heavy runs at high effort or below \[3].

```ts
type Effort = "low" | "medium" | "high" | "xhigh" | "max";
type Model = "claude-sonnet-5-5" | "claude-opus-5-5";
type Rung = { model: Model; effort: Effort; upFrontThinking: boolean };
type Message = { role: "user" | "assistant"; content: unknown };
type Verdict = { ok: true } | { ok: false; feedback: string };

// The fork happens here, before the first token, from what the task looks like.
// scoped: a spec exists and a check (test, build, script) can grade the result.
// judgment: open-ended, no pattern in the codebase, or the deliverable must be right first time.
type TaskShape = { scoped: boolean; latencySensitive: boolean; usesTools: boolean };

function pickLane(t: TaskShape): Rung[] {
  if (t.scoped) {
    // Sonnet lane. between_tools only where tools drive the work and speed matters.
    const quick = t.latencySensitive && t.usesTools;
    return [
      { model: "claude-sonnet-5-5", effort: "medium", upFrontThinking: !quick },
      { model: "claude-sonnet-5-5", effort: "high",   upFrontThinking: true },
    ];
  }
  // Opus lane. No Sonnet rung below it: the reasoning would not carry up anyway.
  return [
    { model: "claude-opus-5-5", effort: "medium", upFrontThinking: true },
    { model: "claude-opus-5-5", effort: "high",   upFrontThinking: true },
    { model: "claude-opus-5-5", effort: "xhigh",  upFrontThinking: true },
  ];
}

async function callClaude(rung: Rung, messages: Message[]) {
  const res = await fetch("https://api.anthropic.com/v1/messages", {
    method: "POST",
    headers: {
      "x-api-key": process.env.ANTHROPIC_API_KEY ?? "",
      "anthropic-version": "2023-06-01",
      "content-type": "application/json",
    },
    body: JSON.stringify({
      model: rung.model,
      max_tokens: 64000,                       // thinking is billed as output; leave room
      thinking: rung.upFrontThinking
        ? { type: "adaptive" }                 // the only mode on Opus 5.5
        : { type: "between_tools" },           // Sonnet 5.5 only, high effort or below
      output_config: { effort: rung.effort },
      messages,
    }),
  });
  if (!res.ok) throw new Error(`Claude API ${res.status}: ${await res.text()}`);
  return res.json();
}

export async function runForked(
  task: string,
  shape: TaskShape,
  verify: (reply: any) => Promise<Verdict>,
) {
  const lane = pickLane(shape);
  // Append-only history. Editing earlier turns invalidates bound thinking blocks.
  const messages: Message[] = [{ role: "user", content: task }];

  for (const rung of lane) {
    const reply = await callClaude(rung, messages);

    // Refusals exit. Escalating a refusal to Opus buys a refusal at Opus prices.
    if (reply.stop_reason === "refusal") return { status: "refused", rung, reply };
    if (reply.stop_reason === "max_tokens") continue;

    // Same model within a lane, so thinking blocks stay readable. Pass them back untouched.
    messages.push({ role: "assistant", content: reply.content });

    const verdict = await verify(reply);
    if (verdict.ok) return { status: "done", rung, reply };

    messages.push({
      role: "user",
      content: `The check failed:\n${verdict.feedback}\nFind the root cause and fix it.`,
    });
  }

  // The Sonnet lane ran out. Do not append Opus to this history: its reasoning is gone
  // the moment the model changes. Hand Opus the task, the diff and the failed checks, fresh.
  return { status: "reroute-fresh", messages };
}
```

A few decisions in there are deliberate.

* **The fork is a function of the task, not of the previous failure.** Anthropic's own guide draws the line the same way: Sonnet 5.5 for well-scoped everyday coding, high-volume development, polished documents and repeatable agent tasks; Opus 5.5 for complex work requiring careful judgment, long-horizon agentic coding, and the hardest problems \[8]. The AWS launch post puts it in one line: Opus 5.5 takes the judgment calls, Sonnet 5.5 takes the work where the approach is already clear \[27].
* **No max rung on either lane, and no xhigh on Sonnet.** Max over-thinks on both models \[13], and Sonnet at max costs more per task than Opus at max while scoring lower \[10]\[12]. Sonnet at xhigh exists, but on the index Opus at high beats it on cost and score, so the lane stops at high \[11]\[12].
* **A reroute is a fresh start, not an append.** When the Sonnet lane fails, the code returns the history for a human or an orchestrator to summarise into a new Opus request. That is uglier than a ladder, and it is honest about what the API does.
* **The verify function is still the real work.** Anthropic's cost guide argues the cheapest fix is giving the model a way to check its own work before paying for more effort \[9], and its Sonnet 5.5 guide adds that at low effort the model sometimes skips a check that exercises the change, with a system-prompt paragraph to fix it \[8]. The fork is only as good as the check that decides which lane a task belongs in.

In Claude Code the fork already exists as a keystroke. The `default` model stays Opus 5.5 on every plan, `/model sonnet` switches to Sonnet 5.5 at medium effort, and Sonnet 5.5 has no fast mode there \[8]. Nothing in the docs suggests the two share reasoning when you switch mid-session, so I now treat that command the way I treat a new terminal: fine at the start of a task, not in the middle of one.

## What does the side-by-side look like?

|                                         | Claude Sonnet 5.5                                          | Claude Opus 5.5                              |
| --------------------------------------- | ---------------------------------------------------------- | -------------------------------------------- |
| Released                                | September 28, 2026 \[5]                                    | September 22, 2026 \[2]                      |
| API model ID                            | `claude-sonnet-5-5` \[5]                                   | `claude-opus-5-5` \[6]                       |
| Input / output per 1M tokens            | $2 / $10 \[5]                                              | $4 / $20 \[8]                                |
| Cache read per 1M tokens                | $0.20 \[5]                                                 | $0.20 \[8]                                   |
| Five-minute cache write per 1M tokens   | $2.50 \[5]                                                 | $5 \[8]                                      |
| Context window / max output             | 1M / 128K \[5]                                             | 1M / 128K \[5]                               |
| Default effort, Claude API              | high \[5]                                                  | medium \[5]                                  |
| Default effort, Claude Code             | medium \[8]                                                | medium \[26]                                 |
| Relative latency in Anthropic's docs    | Fast \[5]                                                  | Moderate \[5]                                |
| Lowest thinking setting                 | `between_tools` \[3]                                       | Adaptive, always on \[6]                     |
| Forced tool use                         | Returns an error \[3]                                      | Returns an error \[6]                        |
| Reads the other model's thinking blocks | No \[3]                                                    | No \[3]                                      |
| Minimum cacheable prompt                | 512 tokens \[3]                                            | Not stated in the pages I read               |
| Terminal-Bench 4.0, system card         | 70.6% at max, 1.5% fallback trials \[7]                    | 66.4% at xhigh, 10% fallback trials \[7]     |
| AA Intelligence Index v4.3.2 at max     | 56, $7.60 per task \[10]                                   | 58, $5.98 per task \[12]                     |
| Cyber safeguard fallback                | Sonnet 5 \[7]                                              | Opus 4.8 \[2]                                |
| Anthropic's positioning                 | Well-scoped everyday tasks, documents, slides, design \[1] | Complex work requiring careful judgment \[1] |

## Which one should you reach for?

**Sonnet 5.5 is the right lane if:**

* [ ] The task has a spec and a check: a bug fix with a failing test, a feature with acceptance criteria, a review against a rubric \[8].
* [ ] You run the same agent task repeatedly and the win is throughput: review bots, investigation, drafting, high-volume development \[8]\[19].
* [ ] The deliverable is a document, deck, spreadsheet or interface, where testers rate its eye for design and its prose above Sonnet 5 and, for revision, above Opus 5.5 \[1]\[16].
* [ ] Latency matters more than the last two index points, and you can run at medium or high \[8]\[11].
* [ ] You keep hitting Opus session limits on a subscription and need a second lane that is not Sonnet 5 \[14].

**Opus 5.5 is the right lane if:**

* [ ] The problem has no existing pattern in the codebase, or the run is long and unsupervised \[9].
* [ ] The deliverable has to be right the first time, or the task is graded on breadth of knowledge, where Opus leads by 12 points on AA-Omniscience \[10].
* [ ] You would otherwise reach for Sonnet at xhigh or max. On the index, Opus at high scores higher for less, and Opus at max is cheaper per task than Sonnet at max \[10]\[12].
* [ ] The work is repository-scale coding, where Opus leads SWE-Bench Pro by nine points and FrontierCode by two to eight depending on effort \[1]\[7].

**Neither lane is the fix if:**

* [ ] You planned to start on Sonnet and escalate mid-conversation. The reasoning does not travel in either direction; reroute fresh instead \[3].
* [ ] You keep hitting cyber refusals on legitimate security work. Both models fall back to older models, and the answer is the verification program, not the model picker \[7]\[17].
* [ ] You have not set `output_config.effort`. The API defaults differ, so any comparison at defaults is a comparison of two effort levels, not two models \[5].
* [ ] The job needs a Luna-class price. Haiku 5.5 is the model Anthropic says is coming for that, in the coming weeks \[1].

## What would I do differently next time?

Three things, in the order I would do them.

First, I would read the system card before the launch table. The launch table gave me a 4.2-point Sonnet win; the system card gave me the effort mismatch, the 10% fallback share and the standard error that put the win inside the noise \[1]\[7]. Every headline number needs its footnote, and the footnotes live in the card.

Second, I would verify any claim about thinking-block compatibility against the model's own "what's new" page, and only there. A secondary source told me the ladder worked; the docs told me no other model reads Sonnet 5.5's blocks \[3]\[25]. That one sentence changed the structure of the post, and it would have changed the structure of a router.

Third, I would set effort explicitly in every request I compare, and I would start the sweep at the surface default rather than the API default. Sonnet 5.5's docs say to re-run the effort sweep because the levels are recalibrated and a setting from Sonnet 5 will not carry over \[3]\[8]. Anthropic's advice for measuring on your own tasks has not changed since last week: run the same backlog task on each model, read turns, output tokens and cost from `/usage`, and repeat for three or four tasks before drawing a conclusion \[9]. I would add one column to that spreadsheet now: how many of those turns were served by a fallback model.

## Sources

1. Anthropic, "Introducing Claude Sonnet 5.5," September 28, 2026, [anthropic.com](https://www.anthropic.com/claude-sonnet-5-5)
2. Anthropic, "Introducing Claude Opus 5.5," September 22, 2026, [anthropic.com](https://www.anthropic.com/claude-opus-5-5)
3. Claude Platform Docs, "What's new in Claude Sonnet 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5)
4. Claude Platform Docs, "Migrating to Claude Sonnet 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide)
5. Claude Platform Docs, "Claude Sonnet 5.5" (model overview, with the four-model comparison table), [platform.claude.com](https://platform.claude.com/docs/en/models/sonnet-5-5/overview)
6. Claude Platform Docs, "What's new in Claude Opus 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5)
7. Anthropic, "System Card: Claude Sonnet 5.5," September 28, 2026, sections 3.3, 8.1 and 8.5, [anthropic.com](https://www.anthropic.com/claude-sonnet-5-5-system-card)
8. Addy Osmani, "Building with Claude Sonnet 5.5," claude.dev, September 28, 2026, [claude.dev](https://claude.dev/blog/building-with-claude-sonnet-5-5/)
9. Addy Osmani, "What a task costs on Opus 5.5," claude.dev, September 25, 2026, [claude.dev](https://claude.dev/blog/what-a-task-costs-on-opus-5-5/)
10. Artificial Analysis, "Claude Sonnet 5.5 reaches #2 on the Artificial Analysis Intelligence Index," September 28, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/articles/claude-sonnet-5-5)
11. Artificial Analysis, Claude Sonnet 5.5 model pages at low, medium, high and max effort (Intelligence Index v4.3.2, default fallback), accessed September 29, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/models/claude-sonnet-5-5)
12. Artificial Analysis, Claude Opus 5.5 release page (all five effort levels, Intelligence Index v4.3.2), accessed September 27, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/models/releases/claude-opus-5-5)
13. Simon Willison, "Claude Sonnet 5.5," September 28, 2026, [simonwillison.net](https://simonwillison.net/2026/Sep/28/claude-sonnet-5-5/)
14. Hacker News, discussion thread on the Claude Sonnet 5.5 launch, September 28 to 29, 2026, [news.ycombinator.com](https://news.ycombinator.com/item?id=49881850)
15. Katie Parrott, "Vibe Check: Sonnet 5.5 Finds Its Place in Claude's Crowded Family," Every, September 28, 2026, [every.to](https://every.to/vibe-check/sonnet-5-5-vibe-check)
16. Dan Shipper on X, launch-day notes on Sonnet 5.5 writing and revision, September 28, 2026, [x.com](https://x.com/danshipper/status/2104636728992776510)
17. Steven J. Vaughan-Nichols, "You picked Claude Sonnet 5.5, but Anthropic may send your request to Sonnet 5 in higher-risk situations," The New Stack, September 28, 2026, [thenewstack.io](https://thenewstack.io/claude-sonnet-cyber-safeguards/)
18. GitHub Changelog, "Claude Sonnet 5.5 in GitHub Copilot," September 28, 2026, [github.blog](https://github.blog/changelog/2026-09-28-claude-sonnet-5-5-in-github-copilot/)
19. CodeRabbit, "Sonnet 5.5 vs Opus 5.5 Code Review Benchmarks," September 2026, [coderabbit.ai](https://www.coderabbit.ai/blog/sonnet-5-5-model-review)
20. VentureBeat, "Anthropic launches Claude Sonnet 5.5 with 30% cost reduction per-task due to faster speeds and fewer tool calls," September 28, 2026, [venturebeat.com](https://venturebeat.com/technology/anthropic-launches-claude-sonnet-5-5-with-30-cost-reduction-per-task-due-to-faster-speeds-and-fewer-tool-calls)
21. CNBC, "Anthropic Sonnet 5.5 launch: Price, features and safety," September 28, 2026, [cnbc.com](https://www.cnbc.com/2026/09/28/anthropic-sonnet-5-5-launch.html)
22. Tom's Guide, "Claude Sonnet 5.5 just launched, here's why it's about to become your daily driver," September 29, 2026, [tomsguide.com](https://www.tomsguide.com/ai/claude/claude-sonnet-5-5-just-launched-heres-why-its-about-to-become-your-daily-driver)
23. Atomic Agent, "Claude Sonnet 5.5 vs Opus 5.5: Benchmarks & Pricing," September 29, 2026, [atomicagent.io](https://atomicagent.io/blog/claude-sonnet-5-5/)
24. Kingy AI, "Claude Sonnet 5.5 vs Opus 5.5: Cost, Benchmarks & Tokens," September 29, 2026, [kingy.ai](https://kingy.ai/blog/claude-sonnet-5-5-vs-opus-5-5/)
25. Myclaw, "Sonnet 5.5 vs Opus 5.5," September 29, 2026, the comparison whose thinking-block claim the platform docs contradict, [myclaw.ai](https://myclaw.ai/blog/sonnet-5-5-vs-opus-5-5)
26. Syed Moinuddin, "Not a Winner, a Routing Rule: What I Learned Researching Claude Opus 5.5 vs Fable 5.1," September 27, 2026, [syedmoinuddin.com](https://syedmoinuddin.com/blog/claude-opus-5-5-vs-fable-5-1)
27. AWS Machine Learning Blog, "Introducing Claude Sonnet 5.5 on AWS," September 28, 2026, [aws.amazon.com](https://aws.amazon.com/blogs/machine-learning/introducing-claude-sonnet-5-5-on-aws/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on September 29, 2026

---
title: "Not a Winner, a Routing Rule: What I Learned Researching Claude Opus 5.5 vs Fable 5.1"
description: "Opus 5.5 is the default, Fable 5.1 is the escalation, and the API only lets reasoning travel one way. What 23 sources and a week of engineer reports show."
last_updated: "September 27, 2026"
source: "https://syedmoinuddin.com/blog/claude-opus-5-5-vs-fable-5-1"
---

# Not a Winner, a Routing Rule: What I Learned Researching Claude Opus 5.5 vs Fable 5.1

Opus 5.5 is the default, Fable 5.1 is the escalation, and the API only lets reasoning travel one way. What 23 sources and a week of engineer reports show.

Here is the whole argument up front. Stop asking which of the two models wins. Run Claude Opus 5.5 as your default, raise its effort before you touch the model picker, and move a task to Claude Fable 5.1 only when Opus 5.5 at xhigh fails the same check twice. That is Anthropic's own guidance \[5]\[7], it is what the independent numbers show once you compare them on a single index version \[9]\[10], and it is where the engineers who have run both for a week are landing \[13]\[15]\[16]. The detail I did not expect: the escalation only works in one direction. Fable 5.1 can read Opus 5.5's reasoning. Opus 5.5 cannot read Fable's \[3]. The routing rule is not a matter of taste. It is the shape of the API.

I started this as a normal comparison post. I wanted a table, a winner, and a recommendation. I ended up with a routing rule instead, because every source I checked kept pulling me back to three questions: which numbers are actually comparable, what a task costs rather than a token, and what happens to the conversation when you switch models. This is that research, including the number I misread first.

## Why did the first scoreboard I read point the wrong way?

The first number I wrote down was 66. That is what Artificial Analysis gave Fable 5.1 at max effort on launch day, the highest score it had measured at the time \[11]. Three weeks later, the same firm said Opus 5.5 had taken the top spot with 58 \[8]. Read side by side, that looks like Fable ahead by eight points.

It is not. Since that first article, Artificial Analysis has revised its index. The current version, 4.3.2, is a ten-evaluation mix that now includes AA-Briefcase v1.1, GDPval-AA v2.1 and Terminal-Bench 4.0 \[10]. On that version, Fable 5.1 at max scores 53 \[10] and Opus 5.5 at max scores 58 \[9]. The gap flipped direction because the ruler changed, not because either model did.

Anthropic's own launch posts have the same trap built in. The Fable 5.1 post reported 1853 on GDPval-AA v2 and 73.4% on CursorBench 3.2.0 \[2]. The Opus 5.5 post reports Fable 5.1 at 1735 on GDPval-AA v2.1 and 51.8% on CursorBench 4.0 \[1]. Even a row with the same name moved: OSWorld 2.0 with partial credit went from 77.9% for Fable 5.1 \[2] to 80.7% \[1], and I could not find a note explaining the re-run.

Two more details change what those tables mean. Anthropic ran Opus 5.5 at max effort for most rows and at xhigh for Terminal-Bench 4.0 \[1], which is not the medium default you get out of the box \[3]. And Anthropic itself says the gap between the two models in its own use is "narrower than these scores suggest" \[1].

The lesson I am keeping: before reading any benchmark number, pin three things. The benchmark version, the harness, and the effort level. If any of the three differ, the comparison is decoration.

## What does each model cost, and why is price per token the wrong number?

List prices first, because they are the only numbers nobody disputes.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-opus-5-5-vs-fable-5-1/opus55-fable51-pricing-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-opus-5-5-vs-fable-5-1/opus55-fable51-pricing-dark.png" alt="Horizontal bar chart comparing Opus 5.5 and Fable 5.1 list prices per million tokens: input 4 vs 10 dollars, output 20 vs 50, five minute cache write 5 vs 12.50, cache read 0.20 vs 0.25, with ratios 2.5x, 2.5x, 2.5x and 1.25x" />

*FIG. 01 · List price per million tokens on the Claude API · Opus 5.5 vs Fable 5.1, September 2026 \[1]\[4]*

Opus 5.5 costs $4 per million input tokens and $20 per million output tokens, with cache reads at $0.20 and five-minute cache writes at $5 \[1]. Fable 5.1 costs $10 and $50, with cache reads at $0.25 and five-minute cache writes at $12.50 \[4]. So Fable is 2.5 times the price on input, output and cache writes, but only 1.25 times the price on cache reads \[7]. The reason is a deliberate pricing choice: Fable 5.1's cache read sits at 2.5% of its input price, well under the 10% multiplier most Claude models used \[21], while Opus 5.5's moved to 5% \[3].

Why does that one line matter so much? Because in long agentic sessions, cache reads are most of your input. Engineers in the Hacker News launch thread reported 95 to 99 percent of their input coming from cache, and one noted that at those ratios Fable 5.1 was already costing about the same as Opus 5 \[14]. Anthropic's own cost guide makes the same point: in a long Claude Code session, cache reads are the biggest line by token count, while output is the biggest line by dollars \[7].

Here is the arithmetic, using the illustrative session shape Anthropic prices in that guide: 2 million cache-read tokens, 200 thousand fresh input tokens, and 60 thousand output tokens \[7].

```ts
// Claude API list prices, USD per million tokens.
const PRICES = {
  "claude-opus-5-5": { input: 4, output: 20, cacheRead: 0.2 },
  "claude-fable-5-1": { input: 10, output: 50, cacheRead: 0.25 },
} as const;

type Usage = { cacheRead: number; freshInput: number; output: number };

function sessionCost(model: keyof typeof PRICES, u: Usage): number {
  const p = PRICES[model];
  return (u.cacheRead * p.cacheRead + u.freshInput * p.input + u.output * p.output) / 1_000_000;
}

// Illustrative Claude Code session shape (cache writes left out, as in the source).
const session: Usage = { cacheRead: 2_000_000, freshInput: 200_000, output: 60_000 };

sessionCost("claude-opus-5-5", session);  // 2.40
sessionCost("claude-fable-5-1", session); // 5.50, about 2.3x
```

Same tokens, 2.3 times the bill, not 2.5. The cheap cache narrows the gap on long, context-heavy runs, and the output price widens it on runs that think or write a lot \[7].

But the two models do not use the same tokens, and this is where headline claims get slippery. Anthropic's 40% figure compares Opus 5.5 with Opus 5, not with Fable, and it is an estimate for typical workloads at default settings rather than a cut to the token price \[7]. Anthropic's Lydia Hallie summed up the pitch as "Feels like Fable" with faster output and a lower per-task cost than Opus 5 \[22]. Independent measurement adds a wrinkle: at max effort, Artificial Analysis counted about 119 thousand output tokens per index task for Opus 5.5 against about 78 thousand for Fable 5.1 \[8].

Artificial Analysis also published the cleanest decomposition I found, for Opus 5.5 against Opus 5 at max. The extra tokens alone would have raised cost per task by about 80%, to $10.51. The 20% price cut brought that to $8.41, and the cheaper cache reads brought it to $5.98, within a few cents of Opus 5's $5.86 \[12]. One commenter in the launch thread put it more simply than any chart: it is only a price drop if price times tokens goes down \[14]. Another went back to the same data and worked out a median saving of about 38% across medium to max, once you treat max as the outlier it is \[14].

## What happens when you hold the index version fixed?

This is the chart I wish I had started with. Every point comes from Artificial Analysis Intelligence Index v4.3.2: same harness, same fallback setting, same day \[9]\[10].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-opus-5-5-vs-fable-5-1/opus55-fable51-aa-index-cost-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-opus-5-5-vs-fable-5-1/opus55-fable51-aa-index-cost-dark.png" alt="Scatter plot of Artificial Analysis Intelligence Index v4.3.2 against cost per task on a log scale: Opus 5.5 at low 42 for 0.55 dollars, medium 51 for 1.34, high 54 for 1.82, xhigh 56 for 3.46, max 58 for 5.98, and Fable 5.1 at max 53 for 7.63, with a bracket marking 4.2 times the cost for one point lower" />

*FIG. 02 · Artificial Analysis Intelligence Index v4.3.2 vs cost per task · snapshot 27 September 2026 \[9]\[10]*

Read it left to right. Opus 5.5 at medium, its default, scores 51 for $1.34 per task. At high it scores 54 for $1.82. Fable 5.1 at max scores 53 for $7.63 \[9]\[10]. Opus 5.5 at high is one point better for about a quarter of the cost. Artificial Analysis reports that four of Opus 5.5's five effort levels sit on its intelligence versus cost frontier, costing less than or outscoring Fable 5.1, GPT-6 Astra and Opus 5 \[8].

I only plotted Fable 5.1 at max. When I checked its lower-effort pages, some still showed numbers from the earlier index version, and mixing them in would have repeated the exact mistake from the previous section.

The right side of the chart holds the surprise. Opus 5.5 at max is by far its most expensive setting, and Simon Willison showed why in the most memorable test of launch week. His pelican-on-a-bicycle SVG prompt at max effort failed twice, both times hitting the 128,000-token output cap while the model was still reasoning, at $2.56 and nearly twenty minutes per attempt \[13]. He now suspects max is "effectively useless" \[13]. Fable 5.1 at max did not over-think the same prompt \[13]. Anthropic's docs describe the mechanism: at the same effort level, Opus 5.5 thinks more per turn than Opus 5, most of all at xhigh and max, so you should leave headroom in `max_tokens` \[3].

One honest caveat. Artificial Analysis runs its own reference harness with Anthropic's default server-side fallback switched on \[8]\[11]. It is not your repository. It is the fairest public comparison available, and it is still a benchmark.

## What are AI engineers reporting after a week with both?

Benchmarks tell you where to look. Practitioners tell you what breaks. I read the launch-week write-ups from engineers in the US and Europe, and a pattern shows up quickly.

The strongest endorsement came from Every's seven-day review \[15]. Kieran Klaassen moved his daily driver from Fable 5.1 to Opus 5.5 and puts it at roughly 90% of Fable's coding ability; on a shared Ruby task, Fable at high wrote 26 lines while Opus at extra high wrote 14 \[15]. Dan Shipper called it a "smaller Fable", faster and cheaper and therefore easier to use every day \[15]. Mike Taylor still reaches for Fable on the biggest problems, and in two of his timed tasks Opus 5.5 ran out the clock without producing the actual deliverable \[15]. Every disclosed that it had pre-launch access \[15].

The most useful single data point came from a Hacker News commenter who happened to be testing a patch-review harness. Across 12 patches containing 14 known issues, Opus 5.5 found 8 for $15.40, Fable 5.1 found 7 for $66.34, Opus 5 found 6 for $58.19, and Sonnet 5 found 2 for $19.15, measured as equivalent API cost from a subscription \[14]. He called Opus 5.5 "both the best and the cheapest" in that run and flagged the small sample himself \[14]. The same thread held the clearest counterexample: a developer whose first Opus 5.5 code review cited line numbers that did not exist in the file, who then noticed the session was running at medium effort rather than the high he thought he had set \[14]. That is the default-effort change from the docs showing up in real life \[3].

Simon Willison made Opus 5.5 his default in Claude Code \[13]. Zvi Mowshowitz, whose roundup pulls reactions from dozens of engineers, called it the most consistently positive set of reactions he has collected \[16]. Box CEO Aaron Levie reported 63% fewer tokens, 42% less verbosity and 30% faster runs than Opus 5 on enterprise knowledge work \[16].

The dissent is worth reading closely, because it clusters. Yuchen Jin said GPT-6 Astra still felt better for coding and for a tricky research question \[16]. Jef Allbright described a writing task with several nested layers of meaning where Opus 5.5 worked faster but shallower, while Fable 5.1 understood it immediately \[16]. One user reported that roughly 1% of the time Opus 5.5 does something drastic, like crashing a staging server or killing running apps, even in auto mode \[16]. That sits awkwardly next to Anthropic's claims that Opus 5.5 is less likely than recent models to take hard-to-reverse actions and more resistant to prompt injection than Opus 5 \[1]\[20]. Anthropic also notes that Opus 5.5 often suspects it is being evaluated, which limits how far its own safety numbers generalize \[1]. And there is precedent for caution: Opus 5 also beat Fable 5 on many benchmarks, yet proved more limited on complex real-world problems \[18].

Much of the enthusiasm is about communication, which sounds soft until you remember why people left Opus 5. Reviewers described Opus 5 as a chatterbox that ended tasks with a trail of loose ends \[19]. Every measured Opus 5.5's prose at a Flesch-Kincaid grade of 6.95 against 7.43 for Fable 5.1, the most readable model they had tested, while noting that it still tends to bury the point \[15].

## Where does Fable 5.1 still earn its price?

Anthropic's selection guide still lists Fable 5.1 as the pick for the highest available capability: agent sessions that run for hours, multistep deep research, and analysis carried through to a finished document, spreadsheet or deck \[5]. Its cost guide is more concrete: move up for long runs you will not supervise, for problems with no existing pattern in the codebase, and for large changes that coordinate many subagents \[7].

The independent evidence points to the same corners. Zvi noted that Fable 5.1 takes all seven Vals professional rows along with MedCode, SAGE and both MLCR evaluations, a cluster he reads as expert-domain work graded purely on correctness \[16]. Every's advice lands in the same place: stay on Fable when the problem is too big to eyeball or the deliverable has to be right the first time \[15].

Three cautions keep me from making this a clean split. First, Anthropic's internal HAProxy test cuts the other way on a long-horizon job: translating it from C to Rust, both models passed nearly all of its regression tests, but Opus 5.5 finished in 9.5 hours against 12 and cost 51% less \[1]. Long-horizon alone is not a reason to escalate. Second, in Anthropic's internal research-report test, where any invented figure or quote counted as a failure, 16 of 18 Opus 5.5 reports cleared the bar and none of Fable 5.1's did \[1]. That is a vendor-run test, but it complicates the idea that Fable is automatically the safer pick for correctness. Third, Fable 5.1 is not the permissive option for security or biology work. Opus 5.5 ships with the same class of safeguards as Fable 5.1, most cybersecurity tasks are routed to Opus 4.8 \[1], and flagged biology requests go to Opus 5 \[17]. The looser sibling is Claude Mythos 5.1, the same model as Fable 5.1 with different safeguards, available only through trusted access programs \[2]\[23].

## Why is the escalation a one-way door?

This is the part of the research that turned a comparison into a rule.

Every thinking block records which model produced it. On the Claude API, Fable 5.1 and Mythos 5.1 can read thinking blocks from Opus 5.5, so a conversation that moves up keeps its reasoning. Opus 5.5 cannot read Fable blocks, so a conversation that steps back down continues without the previous model's reasoning. The API drops those blocks silently, the request still succeeds, and the dropped blocks are not billed \[3].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-opus-5-5-vs-fable-5-1/opus55-fable51-escalation-ladder-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-opus-5-5-vs-fable-5-1/opus55-fable51-escalation-ladder-dark.png" alt="Diagram of a five-rung escalation ladder: Opus 5.5 at medium, high, xhigh, xhigh retry, then Fable 5.1 at high, with a solid forward arrow for thinking blocks carrying over and a crossed-out dashed backward arrow for thinking blocks being dropped" />

*FIG. 03 · The escalation rule as a ladder · raise effort first, escalate once, reasoning only travels forward \[3]\[5]\[7]*

Three more constraints shape the rule.

* **Keep the conversation append-only.** For accounts created on or after August 31, 2026, the API rejects a request that replays a thinking block after anything before it has changed, including the system prompt, the tools or an earlier message. Anthropic recommends mid-conversation system messages instead of edits \[3].
* **Switching models costs a cache write.** The cache belongs to the previous model, so the first turn on the new one pays the write price on the whole conversation. Compact first, or start fresh with a short written plan \[7].
* **The defaults are not equal.** Opus 5.5 defaults to medium effort and Fable 5.1 to high \[4]\[5]. Comparing them at defaults compares two different amounts of thinking.

The good news for integration work is that the breaking changes line up. On Opus 5.5, thinking cannot be disabled and forced tool use returns an error, and both changes also apply to Fable 5.1 \[3]. One request builder can serve both models.

## How would I encode this as an actual routing rule?

Here is the rule as code. It uses plain fetch against the Messages API so every field is visible, and it only uses parameters the docs confirm for both models: adaptive thinking, effort under `output_config`, and the default tool choice \[3]\[4].

```ts
type Effort = "low" | "medium" | "high" | "xhigh" | "max";
type Model = "claude-opus-5-5" | "claude-fable-5-1";
type Rung = { model: Model; effort: Effort };
type Message = { role: "user" | "assistant"; content: unknown };
type Verdict = { ok: true } | { ok: false; feedback: string };

// Raise effort before switching models. Escalate once, after xhigh fails twice.
// No "max" rung: that is where over-thinking shows up first.
const LADDER: Rung[] = [
  { model: "claude-opus-5-5", effort: "medium" },
  { model: "claude-opus-5-5", effort: "high" },
  { model: "claude-opus-5-5", effort: "xhigh" },
  { model: "claude-opus-5-5", effort: "xhigh" },
  { model: "claude-fable-5-1", effort: "high" },
];

async function callClaude(rung: Rung, messages: Message[]) {
  const res = await fetch("https://api.anthropic.com/v1/messages", {
    method: "POST",
    headers: {
      "x-api-key": process.env.ANTHROPIC_API_KEY ?? "",
      "anthropic-version": "2023-06-01",
      "content-type": "application/json",
    },
    body: JSON.stringify({
      model: rung.model,
      max_tokens: 64000,              // headroom: thinking is billed as output
      thinking: { type: "adaptive" }, // the only mode on both models
      output_config: { effort: rung.effort },
      messages,
    }),
  });
  if (!res.ok) throw new Error(`Claude API ${res.status}: ${await res.text()}`);
  return res.json();
}

export async function runWithEscalation(
  task: string,
  verify: (reply: any) => Promise<Verdict>,
) {
  // Append-only history. Editing earlier turns invalidates bound thinking blocks.
  const messages: Message[] = [{ role: "user", content: task }];

  for (const rung of LADDER) {
    const reply = await callClaude(rung, messages);

    // Same safeguard class on both models: escalating a refusal buys nothing.
    if (reply.stop_reason === "refusal") return { status: "refused", rung, reply };

    // Ran out of room mid-thought: try the next rung from the same history.
    if (reply.stop_reason === "max_tokens") continue;

    // Pass content back untouched, thinking blocks included.
    // Fable 5.1 can read Opus 5.5 blocks, so the climb keeps the reasoning.
    messages.push({ role: "assistant", content: reply.content });

    const verdict = await verify(reply);
    if (verdict.ok) return { status: "done", rung, reply };

    messages.push({
      role: "user",
      content: `The check failed:\n${verdict.feedback}\nFind the root cause and fix it.`,
    });
  }
  return { status: "needs-human", messages };
}
```

A few decisions in there are deliberate.

* **No max rung.** Max is where over-thinking shows up first \[8]\[13]. I would reach for it by hand on a single hard problem, not bake it into an automated ladder.
* **Refusals exit instead of escalating.** Both models run the same class of safeguards \[1], so sending a refusal up the ladder just pays Fable prices to get refused again. Handle it with Anthropic's fallback options instead \[3].
* **The verify function is the real work.** Anthropic's cost guide argues that the cheapest fix is giving the model a way to check its own work, like a test, a build, or a script that calls the endpoint, before paying for more effort \[7]. The ladder is only as good as the check that decides when to climb it.

## What does the side-by-side look like?

|                                         | Claude Opus 5.5                    | Claude Fable 5.1                                  |
| --------------------------------------- | ---------------------------------- | ------------------------------------------------- |
| Released                                | September 22, 2026 \[1]            | September 1, 2026 \[4]                            |
| API model ID                            | `claude-opus-5-5` \[3]             | `claude-fable-5-1` \[4]                           |
| Input / output per 1M tokens            | $4 / $20 \[1]                      | $10 / $50 \[4]                                    |
| Cache read per 1M tokens                | $0.20 \[1]                         | $0.25 \[4]                                        |
| Five-minute cache write per 1M tokens   | $5 \[1]                            | $12.50 \[4]                                       |
| Context window / max output             | 1M / 128K \[4]                     | 1M / 128K \[4]                                    |
| Default effort                          | medium \[3]                        | high \[4]                                         |
| Relative latency in Anthropic's docs    | Moderate \[4]                      | Slower \[4]                                       |
| Thinking                                | Adaptive, always on \[3]           | Adaptive, always on \[4]                          |
| Forced tool use                         | Returns an error \[3]              | Returns an error \[3]                             |
| Reads the other model's thinking blocks | No \[3]                            | Yes \[3]                                          |
| AA Intelligence Index v4.3.2 at max     | 58, $5.98 per task \[9]            | 53, $7.63 per task \[10]                          |
| Anthropic's positioning                 | Start here for most workloads \[5] | Move here when xhigh or max evals fall short \[5] |

## Which one should you reach for?

**Opus 5.5 is the right default if:**

* [ ] You supervise the work closely: feature work across a few files, debugging, code review with follow-up edits \[7].
* [ ] Cost per task matters and you can set effort per job, medium for scoped work and high when medium stalls \[7].
* [ ] You build things you look at, like interfaces, prototypes and visual tools \[15].
* [ ] Humans have to read the output, like summaries, pull request descriptions and specs \[1]\[15].

**Escalate to Fable 5.1 if:**

* [ ] Opus 5.5 at xhigh has failed the same check twice \[7].
* [ ] The run is long and unsupervised, or the problem has no existing pattern in your codebase \[7].
* [ ] The result is graded on expert-domain correctness more than on presentation \[16].
* [ ] The deliverable has to be right the first time \[15].

**Neither model is the fix if:**

* [ ] You keep hitting safeguard refusals on security or biology work. That is an access program question, not a model tier question \[1]\[2].
* [ ] The job is a lookup, a log read or a file search. Anthropic suggests a smaller model for those subagents \[7].
* [ ] You have not defined done or set a budget. Every found Opus 5.5 will happily take the whole afternoon if you let it \[15].

## What would I do differently next time?

Three things, in the order I would do them.

First, I would pin the index version, the harness and the effort level before writing down a single number. The 66 versus 58 misread almost made it into the first draft of this post, and a reader acting on it would have paid 2.5 times the token price for a model that scores lower on the current index.

Second, I would measure on my own tasks before quoting anyone else's percentages. Anthropic's advice here is refreshingly specific: run the same backlog task on each model, read turns, output tokens and cost from `/usage`, and repeat for three or four tasks before drawing a conclusion \[7].

Third, I would set a stopping rule before any long run. Anthropic's playbook suggests saying what done looks like and when to stop and ask, in the prompt or in `CLAUDE.md`, and deleting old "think carefully" lines because the model already thinks before every reply \[6]. After reading about Every's timed-task failures \[15], I treat that as mandatory, not optional.

## Sources

1. Anthropic, "Introducing Claude Opus 5.5," September 22, 2026, [anthropic.com](https://www.anthropic.com/claude-opus-5-5)
2. Anthropic, "Introducing Claude Fable 5.1 and Claude Mythos 5.1," September 1, 2026, [anthropic.com](https://www.anthropic.com/claude-fable-and-mythos-5-1)
3. Claude Platform Docs, "What's new in Claude Opus 5.5," [platform.claude.com](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5)
4. Claude Platform Docs, "Claude Fable 5.1" (model overview), [platform.claude.com](https://platform.claude.com/docs/en/models/fable-5-1/overview)
5. Claude Platform Docs, "Choosing the right model," [platform.claude.com](https://platform.claude.com/docs/en/about-claude/models/choosing-a-model)
6. Addy Osmani, "Getting the most out of Opus 5.5 in Claude and Claude Code," claude.dev, September 22, 2026, [claude.dev](https://claude.dev/blog/getting-the-most-out-of-opus-5-5/)
7. Addy Osmani, "What a task costs on Opus 5.5," claude.dev, September 25, 2026, [claude.dev](https://claude.dev/blog/what-a-task-costs-on-opus-5-5/)
8. Artificial Analysis, "Claude Opus 5.5 takes the top spot on the Artificial Analysis Intelligence Index," September 22, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/articles/claude-opus-5-5)
9. Artificial Analysis, Claude Opus 5.5 release page (all five effort levels, Intelligence Index v4.3.2), accessed September 27, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/models/releases/claude-opus-5-5)
10. Artificial Analysis, Claude Fable 5.1 model page (max, default fallback, Intelligence Index v4.3.2), accessed September 27, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/models/claude-fable-5-1)
11. Artificial Analysis, "Claude Fable 5.1 tops the Artificial Analysis Intelligence Index," September 1, 2026, [artificialanalysis.ai](https://artificialanalysis.ai/articles/claude-fable-5-1)
12. Artificial Analysis on X, cost per task decomposition for Claude Opus 5.5 (max), September 2026, [x.com](https://x.com/ArtificialAnlys/status/2102541956014657615)
13. Simon Willison, "Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war," September 22, 2026, [simonwillison.net](https://simonwillison.net/2026/Sep/22/opus-and-sol-and-luna/)
14. Hacker News, discussion thread on Claude Opus 5.5 pricing and token use, September 2026, [news.ycombinator.com](https://news.ycombinator.com/item?id=49804160)
15. Katie Parrott, "Vibe Check: Opus 5.5 Is Pulling Our Codex Converts Back to Claude," Every, September 22, 2026, [every.to](https://every.to/vibe-check/vibe-check-opus-5-5-is-pulling-our-codex-converts-back-to-claude)
16. Zvi Mowshowitz, "Claude Opus 5.5 Should Raise Your Ambitions," LessWrong, September 26, 2026, [lesswrong.com](https://www.lesswrong.com/posts/rtPiip9igy3QvxYdM/claude-opus-5-5-should-raise-your-ambitions)
17. The Decoder, "Claude Opus 5.5 matches Fable 5.1 performance at lower cost and promises less Claudish writing," September 2026, [the-decoder.com](https://the-decoder.com/claude-opus-5-5-matches-fable-5-1-at-40-percent-lower-cost-as-anthropic-promises-to-fix-claudish-writing/)
18. Techzine Global, "Claude Opus 5.5 beats Fable 5.1 at a much lower cost," September 2026, [techzine.eu](https://www.techzine.eu/news/applications/144462/claude-opus-5-5-beats-fable-5-1-at-a-much-lower-cost/)
19. PCWorld, "Claude Opus 5.5 promises to cut the chatter," September 2026, [pcworld.com](https://www.pcworld.com/article/3241475/claude-opus-5-5-promises-to-cut-the-chatter.html)
20. Digital Trends, "Anthropic launches Claude Opus 5.5 with Fable 5.1 level performance at a 40% lower price," September 2026, [digitaltrends.com](https://www.digitaltrends.com/computing/anthropic-launches-claude-opus-5-5-with-fable-5-1-level-performance-at-a-40-lower-price/)
21. VentureBeat, "Anthropic's Claude Fable 5.1 and Mythos 5.1 arrive with a 75% cost reduction for Fable cache reads," September 1, 2026, [venturebeat.com](https://venturebeat.com/technology/anthropics-claude-fable-5-1-and-mythos-5-1-arrive-with-a-75-cost-reduction-for-fable-cache-reads)
22. 9to5Mac, "Anthropic upgrades Claude with new Opus 5.5 model, details here," September 22, 2026, [9to5mac.com](https://9to5mac.com/2026/09/22/anthropic-upgrades-claude-with-new-opus-5-5-model-details-here/)
23. MacRumors, "Anthropic Launches Claude Fable 5.1 With Lower Costs and Fewer False Positives," September 1, 2026, [macrumors.com](https://www.macrumors.com/2026/09/01/anthropic-claude-fable-5-1/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on September 27, 2026

---
title: "Polydact: A Wearable Robotic Sixth Finger That Coils Like a Tentacle, and the One Spiral Behind Its Grasp"
description: "I fell down a rabbit hole into Polydact, a 3D-printed supernumerary finger controlled by a hand-sewn flex-sensor glove, and one piece of octopus-inspired math explains almost everything clever about it."
last_updated: "July 19, 2026"
source: "https://syedmoinuddin.com/blog/polydact-wearable-robotic-sixth-finger"
---

# Polydact: A Wearable Robotic Sixth Finger That Coils Like a Tentacle, and the One Spiral Behind Its Grasp

I fell down a rabbit hole into Polydact, a 3D-printed supernumerary finger controlled by a hand-sewn flex-sensor glove, and one piece of octopus-inspired math explains almost everything clever about it.

Here is the one-line lesson I took from Polydact, and it is the kind of thing that makes me love robotics: the clever part is not the motors, the Raspberry Pi, or the ROS graph. It is that a single equation, a logarithmic spiral, decides almost everything the finger can physically do \[1]\[3]. Choose the spiral, and the smallest object it can grab, the number of printed bones, and how tightly it coils all fall out of the math instead of trial and error. Polydact is a wearable robotic sixth finger built by T. Miguel Pegues as a Master of Science in Robotics (MSR '26) project, and it grasps by wrapping a soft tentacle around objects rather than pinching them \[1]. It is on display at Open Sauce this weekend in San Mateo \[8]. I did not build it. I just could not stop reading about it, so I broke it down the way I wish more project write-ups broke themselves down.

## What exactly is Polydact, and why a tentacle instead of a finger?

Polydact is a wearable robotic sixth finger: a soft, printed digit you mount near your wrist that gives your hand more reach and grip than it has on its own \[1]. The twist that hooked me is the morphology. Instead of a rigid jointed thumb that pinches, Polydact is a tentacle that coils, so it grasps by wrapping around an object the way an octopus arm or an elephant trunk does \[1]\[3].

That choice puts it in interesting company. The best-known extra digit right now is the Third Thumb from Dani Clode and Tamar Makin's lab at Cambridge, a rigid 3D-printed thumb mounted opposite your biological thumb and driven by pressure sensors under your toes \[4]\[5]. Siena's Soft-SixthFinger took a different route, a wearable extra finger controlled by an EMG cap that reads eyebrow movement, aimed at helping stroke patients grasp again \[6]. Polydact sits apart from both: it is a wrap-grasp tentacle, and it is controlled by the wearer's own free fingers through a flex-sensor glove \[1].

Is an extra finger even a real advantage, or just a gimmick? The most convincing evidence I found is not robotic at all. A Nature Communications study of two people born with a functional sixth finger showed they could perform one-handed tasks that the rest of us need two hands for, backed by dedicated muscles, nerves, and cortical wiring for the extra digit \[7]. Polydact is essentially the engineering question that biology already answered: if a sixth finger genuinely helps, can you bolt a good one on? Pegues frames the project a little more playfully, calling it a proof of concept on the way to something bigger, a nod to a many-armed surgeon he read about once \[1]\[8].

## How does one logarithmic spiral decide what the finger can grab?

This is the part that made me sit up. The tentacle geometry is lifted directly from SpiRobs, a 2024 paper by Wang, Freris, and Wei that reports a class of soft robots shaped like a logarithmic spiral \[1]\[3]. Their headline claim is wild on its own: one spiral morphology, 3D printed in TPU and pulled by cables, grasping objects that range from 5.6 mm to 115 mm across, and lifting up to 260 times its own weight \[3].

The insight that reframed soft robotics for me is what the SpiRobs authors call model-first design. In most soft robotics you build the hardware, then fight to model it afterward with heavy simulation and trial and error. Here the order flips: you pick the logarithmic spiral first, and the shape, the fabrication, and the grasping range are direct outcomes of that model \[3]. The geometry is the design.

You can watch that principle drive real decisions in Pegues' build notes. He set the spiral scaling factors to a of 1.0 and b of 0.1 with a split angle of 30 degrees. He wanted the tentacle to coil around itself twice in one direction, which required at least 24 bones, so he used 30. Those exact parameters produce a tightest coil of about 2.3 cm, which is therefore the smallest diameter object the finger can pick up \[1]. He deliberately did not set a target for the largest diameter, because a wrap-grasp scales up gracefully on its own.

```python
# Polydact tentacle: the spiral IS the design.
# Values from Pegues' build notes.
spiral = {
    "a": 1.0,                 # base scaling factor
    "b": 0.1,                 # growth rate of the log spiral
    "split_angle_deg": 30,
    "bones": 30,              # >= 24 needed for two full self-coils
    "tightest_coil_cm": 2.3,  # smallest graspable diameter
}
# Change a and b, and the whole grasping window moves with them.
```

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/polydact-wearable-robotic-sixth-finger/polydact-spiral-light.png" srcDark="https://images.syedmoinuddin.com/blogs/polydact-wearable-robotic-sixth-finger/polydact-spiral-dark.png" alt="The logarithmic spiral spec behind Polydact: scaling factors a and b, a 30 degree split angle, and 30 bones producing a 2.3 cm tightest coil" />

*FIG. 01 · The spiral parameters (a, b, and split angle) are the design surface. The tightest coil, about 2.3 cm, is not tuned by hand: it falls out of the geometry.*

## How is the tentacle actually built to survive real use?

The fabrication is where you can tell an engineer sweated the failure modes, and I loved reading it. The whole tentacle is printed in one piece: rigid PLA bones threaded onto a flexible TPU spine \[1]. That mix is deliberate, stiff segments for shape and cable anchoring, a soft backbone so the whole thing can curl.

Two details are the kind of thing you only add after imagining what breaks. First, the spine has interior barbs so the bones physically cannot slide off even if the PLA and TPU stop adhering during printing \[1]. He did not trust the layer bond, so he designed a mechanical backstop for when it fails. Second, a strip of 3M GM640 gripping tape runs along the inner surface, which does double duty: it adds grip for holding objects, and it visually marks the main coiling direction so the wearer can orient the finger at a glance \[1]. Small touches, but they are exactly the difference between a render and a thing that works on a person.

## How do you control a tentacle with three fingers?

Here is the second design choice I admire: the control is deliberately low-tech and human-legible. No machine learning, no EMG decoding. The wearer puts on a hand-sewn glove with flex sensors over the middle three fingers, and each sensor's bend reading is mapped straight to a motor velocity \[1]. The motors spool or unspool three cables that run the full length of the tentacle and tie off in a knot at the tip, so pulling a cable coils the tentacle in one direction \[1].

The genuinely thoughtful bit is that the whole device is color coded red, green, and blue, so the wearer always knows which finger drives which coil direction \[1]. Ring finger bends the tentacle toward the wrist on the back of the hand (red), middle finger coils it toward the elbow in the plane of the palm (green), and index finger coils it toward the wrist on the front of the hand (blue) \[1]. That last one, the blue direction, is the one you reach for to actually grab things \[1].

```python
# Three flex sensors, three coil directions, three colors.
# The color coding tells the wearer which finger does what.
control_map = {
    "ring":   {"color": "red",   "coil": "toward wrist, back of hand"},
    "middle": {"color": "green", "coil": "toward elbow, plane of palm"},
    "index":  {"color": "blue",  "coil": "toward wrist, front of hand"},
}
# The index (blue) direction is the one you reach for to grasp.
```

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/polydact-wearable-robotic-sixth-finger/polydact-control-light.png" srcDark="https://images.syedmoinuddin.com/blogs/polydact-wearable-robotic-sixth-finger/polydact-control-dark.png" alt="Polydact three-finger control mapping: flex glove to motor velocity to cable spool, with red, green, and blue color coding per coil direction" />

*FIG. 02 · Flex glove to motor velocity to cable spool. Color coding maps each free finger to a coil direction so the mapping stays legible on the hand.*

## What does the software and signal path look like?

Under the glove it is a small, clean ROS graph, and reading it is a nice reminder that good robotics software is mostly about drawing the right boundary between two nodes. Polydact runs a sensor node and a motor coordinator node \[1]. The sensor node reads the flex values and publishes a `MotorGoal` message that commands motor velocity. The motor coordinator node subscribes to those messages and uses the Dynamixel SDK to write the actual commands to the motors over a Robotis U2D2 \[1]\[9].

I like that the signal path visibly evolved. Early on, flex values were read from a Raspberry Pi Pico 2's onboard ADC and shipped over USB serial to a laptop that ran both nodes. The current setup reads flex through an MCP3008 ADC wired to a Raspberry Pi that runs its own sensor node, while the motor coordinator can run on either the Pi or a laptop on the same network \[1]. That is the un-glamorous, honest middle of a real hardware project: the first ADC worked, the second one scaled better, and the ROS boundary meant swapping it did not touch the motor code.

```python
# Conceptual sketch of the two-node ROS graph Pegues describes.
# (Illustrative, not his exact source.)

# Node A: read flex, publish a motor goal.
def sensor_node(adc, pub):
    while running:
        flex = adc.read_all()                 # MCP3008, or Pico 2 ADC over serial
        goal = MotorGoal(velocity=flex_to_velocity(flex))
        pub.publish(goal)                     # topic: /motor_goal

# Node B: subscribe, spool cable through the motors.
def on_motor_goal(goal):
    for motor, v in zip(motors, goal.velocity):
        dxl.write_velocity(motor, v)          # Dynamixel SDK -> U2D2 -> motors
```

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/polydact-wearable-robotic-sixth-finger/polydact-signalpath-light.png" srcDark="https://images.syedmoinuddin.com/blogs/polydact-wearable-robotic-sixth-finger/polydact-signalpath-dark.png" alt="Polydact signal path: flex sensor to ADC to ROS sensor node to motor coordinator to Dynamixel motors to cable spools to tentacle" />

*FIG. 03 · Flex sensor to ADC to sensor node to motor coordinator to Dynamixel motors to cable spools to tentacle. The pub/sub boundary is what let the ADC swap out cleanly.*

## How does Polydact compare to the other extra fingers out there?

I found it clarifying to line the projects up side by side. They are chasing the same dream from very different directions.

| Project               | Form                                          | Actuation                      | Control input                     | Grasp style                      |
| --------------------- | --------------------------------------------- | ------------------------------ | --------------------------------- | -------------------------------- |
| Polydact \[1]\[3]     | Soft printed tentacle, PLA bones on TPU spine | Cable-driven, Dynamixel motors | Flex-sensor glove on your fingers | Wraps and coils around objects   |
| Third Thumb \[4]\[5]  | Rigid printed extra thumb                     | Motor-tendon                   | Pressure sensors under the toes   | Opposes your natural thumb       |
| Soft-SixthFinger \[6] | Soft single extra finger                      | Tendon-driven                  | EMG cap reading eyebrow motion    | Wraps for grasp compensation     |
| SpiRobs \[3]          | Logarithmic spiral soft robot                 | Cable-driven                   | Current-based contact detection   | Octopus-style wrap across scales |

The pattern that jumps out: everyone agrees a wrap-grasp is the versatile move, and the real design fights are over how the human tells the device what to do. Toes, eyebrows, or, in Polydact's case, the free fingers you already have.

## When does a soft tentacle finger make sense, and when does it not?

A quick fit and not-fit read for anyone thinking about wrap-grasp augmentation.

**Good fit:**

* [ ] You need to grab objects of wildly different sizes without swapping end effectors, which is exactly the range a logarithmic spiral buys you \[3].
* [ ] You want cheap, fast fabrication, since the whole tentacle is a single 3D print in common filaments \[1]\[3].
* [ ] You want the control to stay legible to a human, where a bend maps to a motion you can see and predict \[1].
* [ ] You are building a proof of concept or a portfolio piece and want the design decisions to be explainable rather than tuned by hand \[1].

**Not a great fit:**

* [ ] You need precise, repeatable pinch grips on tiny rigid parts, where a stiff jointed gripper still wins.
* [ ] You need high, calibrated grip force, since cable-pulled soft coils trade force for adaptability.
* [ ] You need it to disappear onto the body, because the motors, Pi, and chest band are visible hardware, not a slim wearable \[1].
* [ ] You want fingertip force or slip sensing today, which this build does not yet include \[1].

## What I actually learned from studying Polydact

Three things stuck with me, and they are why I wanted to write this up.

First, model-first design is a mindset I want to steal for software. Pegues did not sculpt a tentacle until it felt right, he picked a spiral and let the grasp range be a consequence \[1]\[3]. The equivalent in my world is choosing a data model or an interface so clean that behavior falls out of it instead of being patched on later.

Second, legible control is a feature, not a limitation. He could have reached for EMG or a learned policy. Instead a flex glove, three cables, and three colors give you a device a first-time user can reason about \[1]. That restraint is the same instinct behind good API design.

Third, the honesty of the constraints is the whole story. Barbs for when the print delamination happens, an ADC swap that scaled, a smallest graspable object that is simply what the math allows \[1]. This is what I love about robotics as an outsider looking in: the physical world does not let you hand-wave. Reading Polydact made me want to go build something that touches the real world, and honestly, that is the best thing a project write-up can do to you.

## Sources

1. T. Miguel Pegues, "Polydact, A Flexible New Finger" (project page), [tmpegues.github.io](https://tmpegues.github.io/projects/polydact)
2. T. Miguel Pegues, Polydact source code repository, [github.com](https://github.com/tmpegues/polydact)
3. Z. Wang, N. M. Freris, and X. Wei, "SpiRobs: Logarithmic spiral-shaped robots for versatile grasping across scales," Device, 2024, [cell.com](https://www.cell.com/device/fulltext/S2666-9986\(24\)00603-3)
4. D. Clode, L. Dowdall, E. da Silva, K. Selen, D. Cowie, G. Dominijanni, and T. R. Makin, "Evaluating initial usability of a hand augmentation device across a large and diverse sample," Science Robotics, 2024, [science.org](https://www.science.org/doi/10.1126/scirobotics.adk5183)
5. University of Cambridge, "Getting to grips with an extra thumb," [cam.ac.uk](https://www.cam.ac.uk/stories/third-thumb)
6. I. Hussain, G. Salvietti, G. Spagnoletti, and D. Prattichizzo, "The Soft-SixthFinger: A Wearable EMG Controlled Robotic Extra-Finger for Grasp Compensation in Chronic Stroke Patients," IEEE Robotics and Automation Letters, 2016
7. "Augmented manipulation ability in humans with six-fingered hands," Nature Communications, 2019, [nature.com](https://www.nature.com/articles/s41467-019-10306-w)
8. Open Sauce 2026, "Exhibits," [opensauce.com](https://www.opensauce.com/exhibits)
9. ROBOTIS, DynamixelSDK, [github.com](https://github.com/ROBOTIS-GIT/DynamixelSDK)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on robotics, hardware, and building things that survive contact with the physical world.


Last updated on July 19, 2026

---
title: "Claude Sonnet 5 in Production: What I Liked, What Bit Me, and the Token Tax Behind the Matching Price"
description: "A first-person migration log from swapping a real agentic stack (crawler, MCP servers, Claude Code) from Sonnet 4.6 to Sonnet 5, including the operational gotchas no benchmark chart warns you about."
last_updated: "July 5, 2026"
source: "https://syedmoinuddin.com/blog/claude-sonnet-5-in-production"
---

# Claude Sonnet 5 in Production: What I Liked, What Bit Me, and the Token Tax Behind the Matching Price

A first-person migration log from swapping a real agentic stack (crawler, MCP servers, Claude Code) from Sonnet 4.6 to Sonnet 5, including the operational gotchas no benchmark chart warns you about.

The one-line lesson from moving my stack to Claude Sonnet 5: the benchmarks are the least interesting part of the story. On agentic coding and long-context work it is a real step up from Sonnet 4.6 \[1]\[5], and the 1M-token context window at mid-tier pricing genuinely changed how I structure crawler and agent prompts \[1]. But whether the migration felt smooth or painful came down to three operating-surface changes, not capability: a new tokenizer that inflates token counts, adaptive thinking that is now always on, and request-compatibility constraints that throw errors on code that ran fine yesterday \[1]\[7]. The "same $3/$15 price as 4.6" is technically true and practically misleading \[1]\[8]. Here is what I liked, what bit me, and what I would check before you migrate anything at scale.

## What actually changed from Sonnet 4.6?

Sonnet 5 (codename Fennec, model ID `claude-sonnet-5`) shipped June 30, 2026 as Anthropic's most agentic Sonnet-class model \[3]\[6]. Strip the marketing and the deltas that matter to a builder are these:

* **1M-token context window**, now the default and the only variant. That is roughly 555k words in a single request, enough to hold a large codebase or a folder of long documents at once \[1]\[8]. On Sonnet 4.6 that capacity used to sit a tier up.
* **Adaptive thinking is on by default.** A request with no thinking field ran without thinking on 4.6; the same request now runs with adaptive thinking on 5 \[1].
* **A new tokenizer** (the one introduced with Opus 4.7). The same text now produces roughly 1.0x to 1.35x as many tokens, about 30% more on typical content \[1]\[8].
* **Three hard behavior changes on migration** \[1]\[7]:
  1. Thinking is on unless you disable it.
  2. Setting `temperature`, `top_p`, or `top_k` to a non-default value returns a 400 error. You remove them.
  3. `max_tokens` is a hard cap on total output, thinking plus response. Budgets tuned for 4.6's no-thinking output can now truncate.
* **Real-time cyber safeguards**, a first for the Sonnet tier. Refusals return as a successful HTTP 200 with `stop_reason` set to `refusal`, not as an error \[1].
* **Priority Tier is gone** on this model \[1].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-in-production/sonnet5-token-tax-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-in-production/sonnet5-token-tax-dark.png" alt="Sonnet 5 operating-surface changes and the token tax: the three changes that decide a migration, and why the same list price costs more per task" />

*FIG. 01 · The three operating-surface changes that actually decide your migration, and why the same list price costs more per task.*

## What did I like?

The wins were real, and most of them were about follow-through rather than raw IQ.

**Agentic coding follow-through.** On multi-file work it plans, executes, and then actually verifies. It tends to write tests first, build the feature on top, and run the suite before it calls the job done \[5]. On a big feature that reads like good engineering: it caught its own breakage before I did.

**1M context at mid-tier pricing.** I stopped chunking as aggressively. For crawler output analysis and agent-log review, passing the whole thing in one request and letting the model hold it changed the shape of my prompts \[1].

**Lower hallucination and sycophancy.** Anthropic's own evaluations report lower rates of hallucination, sycophancy, and misaligned behavior than 4.6, plus better prompt-injection resistance \[1]\[6]. For an agent touching live systems, the injection-resistance delta is the one I care about most.

**Benchmarks, for what they are worth.** SWE-bench Verified 85.2%, Terminal-Bench 2.1 80.4%, OSWorld-Verified 81.2%, and it edges Opus 4.8 on knowledge work (GDPval-AA v2 Elo 1618 vs 1615) \[6]\[8].

## What bit me?

This is the half nobody puts in the launch post.

**The token tax.** Same list price, about 30% more tokens for the same text, so cost per task goes up even though the rate card did not move \[1]\[8]. On token-heavy workloads (large contexts, long outputs) that is exactly where the "savings" quietly erode \[8].

**Verbosity.** Ask for something small and you get a lot back: extra helpers, a test file longer than the feature \[5]. On a one-line change that is not diligence, it is a model that cannot help itself. Independent testing clocked it as very verbose and slower than 4.6, both downstream of the extra thinking \[5]\[6].

**Existing calls throw.** The `temperature` / `top_p` / `top_k` 400 error is the one that broke my code on the first run. Anything that set those (most of my sampling-tuned calls did) has to have them stripped \[1]\[7].

**max_tokens truncation.** Because thinking now counts against `max_tokens`, a limit sized for 4.6's response-only output started clipping outputs mid-answer until I raised it \[1].

**Refusals as 200s.** The cyber safeguards mean a refusal comes back as a normal 200 with `stop_reason: refusal`. If your agent loop only checks for HTTP errors, it treats a refusal as a valid empty completion \[1]. I had to add explicit handling.

**The max-effort trap.** Cranking effort to the top is often the worst deal on the menu: independent review found it roughly doubled cost without finding meaningfully more bugs, and at max effort Sonnet 5 can cost more than Opus 4.8 at a comparable reasoning setting \[5]\[6]. More effort is not free and frequently not worth it.

## What has to change in your calling code?

Three fixes cover almost every break I hit. They are illustrative; match them to your SDK.

Turn thinking off where you do not want it:

```python
# Sonnet 5: thinking is on by default. To run without it:
message = client.messages.create(
    model="claude-sonnet-5",
    max_tokens=4096,
    thinking={"type": "disabled"},
    messages=[{"role": "user", "content": prompt}],
)
```

Strip non-default sampling parameters (the 400 fix):

```python
# Sonnet 4.6 (worked): non-default sampling
client.messages.create(
    model="claude-sonnet-4-6",
    temperature=0.2, top_p=0.9,
    max_tokens=4096, messages=messages,
)

# Sonnet 5 (returns 400 if these are non-default): remove them
client.messages.create(
    model="claude-sonnet-5",
    max_tokens=4096, messages=messages,
)
```

Handle a refusal as a real outcome, not an empty success:

```python
resp = client.messages.create(
    model="claude-sonnet-5",
    max_tokens=4096, messages=messages,
)

# Cyber safeguards can refuse; this arrives as a 200, not an error.
if resp.stop_reason == "refusal":
    handle_refusal(resp)   # do not treat as a valid empty completion
```

## Is the "matching price" actually matching?

No, and this is the part worth internalizing before you budget. The per-token list price is unchanged from 4.6 at $3/$15, with an introductory $2/$10 running through August 31, 2026 \[1]\[8]. But list price per token is not cost per task. The new tokenizer means the same request turns into more tokens, so an equivalent job can cost more even at the same rate, and the intro discount is a two-month coupon that expires on September 1 \[1]\[8]. Prompt caching softens it (cache reads bill at 0.1x input) and the Batch API gives 50% off, so hot-path repeated context is where you claw cost back \[8].

The rule I landed on: never trust the rate card. Run a representative sample of your real prompts through both models and compare actual token counts and dollar totals, not the per-token price \[1]\[8].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-in-production/sonnet5-migration-map-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-sonnet-5-in-production/sonnet5-migration-map-dark.png" alt="Like versus bit-me, and the migrate-or-hold decision: what you gain, what breaks, and the checks that gate a safe switch" />

*FIG. 02 · The migration decision at a glance: what you gain, what breaks, and the checks that gate a safe switch.*

## When should you crank the effort dial, and when shouldn't you?

Adaptive thinking exposes effort levels (low, medium, high, max, xhigh), defaulting to high on the API and in Claude Code \[1]\[8]. The instinct is to reach for max on hard problems. Resist it as a default. Max effort roughly doubled cost for no meaningful accuracy gain in independent bug-finding tests, and its latency (time to first token climbs sharply with effort) makes it a poor fit for anything interactive \[5]\[8]. Reserve the top of the dial for genuinely hard, offline, one-shot reasoning where a better answer is worth the spend, and turn thinking down (or off) for structured, low-ambiguity tasks where 4.6 already did fine \[1].

## What would I do differently before migrating?

Three things I wish I had done before flipping the model string, not after:

1. **Measured token cost first**, on real prompts, not the rate card. The tokenizer change is the whole economic story and I found it the expensive way \[1]\[8].
2. **Grepped for `temperature` / `top_p` / `top_k` and thinking-budget settings** across the codebase before the first call, instead of letting the 400s find them for me \[1]\[7].
3. **Added refusal-aware handling** to the agent loop up front, so a `stop_reason: refusal` never masquerades as an empty success \[1].

The upgrade was worth it for my agentic and long-context paths. But "drop-in" is doing a lot of work in the marketing, and the drop-in part is the capability, not the operating surface.

## Sonnet 4.6 vs Sonnet 5 vs Opus 4.8, at a glance

| Dimension                         | Sonnet 4.6           | Sonnet 5                                     | Opus 4.8                        |
| --------------------------------- | -------------------- | -------------------------------------------- | ------------------------------- |
| Context window                    | tier-limited         | 1M (default, only variant)                   | 1M                              |
| List price (in/out per Mtok)      | $3 / $15             | $3 / $15 ($2/$10 intro to Aug 31)            | roughly 2.5x Sonnet             |
| Tokenizer                         | prior                | new (about 30% more tokens)                  | new                             |
| Thinking                          | off unless requested | adaptive, on by default                      | adaptive                        |
| Agentic coding (SWE-bench Pro)    | 58.1%                | 63.2%                                        | 69.2%                           |
| Knowledge work (GDPval-AA v2 Elo) | lower                | 1618                                         | 1615                            |
| Cyber safeguards                  | none (Sonnet tier)   | real-time, on by default                     | stronger for cyber work         |
| Priority Tier                     | yes                  | no                                           | yes                             |
| Best for                          | prior default        | high-volume agentic and long-context default | hardest reasoning, long-horizon |

## Migrate now, or hold?

**Migrate to Sonnet 5 now if:**

* [ ] You are on 4.6 and your workload leans on coding, tool use, or long agentic follow-through.
* [ ] You can dry-run real prompts and confirm the token and cost delta before moving production traffic.
* [ ] You control the calling code and can strip `temperature` / `top_p` / `top_k` and resize `max_tokens`.
* [ ] Your agent loop can handle a `stop_reason: refusal` cleanly.
* [ ] Long context (large codebases, log folders, doc sets) is a real part of your work.

**Hold or route elsewhere if:**

* [ ] Your workload is token-heavy and margin-sensitive, and you have not measured the tokenizer impact yet.
* [ ] You depend on Priority Tier or on setting sampling parameters directly.
* [ ] Your tasks are simple or latency-critical: route those to Haiku instead.
* [ ] You need the hardest reasoning or reduced cyber guardrails: that is an Opus 4.8 job.

## Sources

1. Anthropic, "What's new in Claude Sonnet 5" (Claude Platform docs), [platform.claude.com](https://platform.claude.com/docs/en/about-claude/models/whats-new-sonnet-5)
2. Anthropic, "Claude Sonnet 5 System Card" (verify behavioral and safety claims here before publishing)
3. Anthropic, "Introducing Claude Sonnet 5" (launch announcement)
4. Anthropic, "Transparency Hub" (verify all benchmark figures here before publishing)
5. CodeRabbit, "Claude Sonnet 5 review," [coderabbit.ai](https://www.coderabbit.ai/blog/claude-sonnet-5-review)
6. DataCamp, "Claude Sonnet 5: Features, Benchmarks, and Pricing," [datacamp.com](https://www.datacamp.com/blog/claude-sonnet-5)
7. Caylent, "Claude Sonnet 5 Launch Analysis: What Changed, What Matters, and What to Validate," [caylent.com](https://caylent.com/blog/claude-sonnet-5-launch-analysis-what-changed-what-matters-and-what-to-validate)
8. Handy AI, "Model Drop: Claude Sonnet 5," [handyai.substack.com](https://handyai.substack.com/p/model-drop-claude-sonnet-5)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on July 5, 2026

---
title: "What a Turborepo Monorepo Taught Me About Code Quality: The File Tree Mattered More Than the Linter"
description: "A first-person account of what a real company monorepo taught me: that code quality came from the file structure and a single source of truth for our models, not from lint rules. Where the apps and packages go, where the backend models live, and what I would do differently."
last_updated: "July 5, 2026"
source: "https://syedmoinuddin.com/blog/turborepo-monorepo-code-quality"
---

# What a Turborepo Monorepo Taught Me About Code Quality: The File Tree Mattered More Than the Linter

A first-person account of what a real company monorepo taught me: that code quality came from the file structure and a single source of truth for our models, not from lint rules. Where the apps and packages go, where the backend models live, and what I would do differently.

Here is what a real Turborepo monorepo taught me at work: the thing that moved our code quality was not the linter, it was the file structure and a single source of truth for our models. A linter catches formatting and a few footguns; it does nothing about two services drifting out of sync, duplicated types, or a change in one app silently breaking another. The structure did. Splitting the repo into thin apps and thick shared packages, putting our database models in one package that every app imports, and letting the build graph fail when a contract broke: that is what made bad code expensive and good structure compounding. Here is the layout, where the models live, and what I would do differently.

## What does a Turborepo monorepo actually look like?

Two directories carry the whole idea. Turborepo's own guidance is to split packages into `apps/` for applications and services, and `packages/` for everything else, like libraries, tooling, and shared code \[1]. A widely used refinement adds a third layer: keep `apps/` thin (deployment entry points), keep `packages/` thick (shared business logic, UI, and models), and put centralized configuration in a `tooling` or `packages/config` directory that everything else extends \[6].

```
company-monorepo/
  apps/
    web/            # Next.js frontend
    api/            # backend service (Node or Nest; see note for FastAPI/Go)
  packages/
    db/             # @repo/db: schema, migrations, generated client + types
    ui/             # shared component library
    config/         # shared tsconfig, eslint, tailwind base configs
  turbo.json
  package.json
  pnpm-workspace.yaml
```

The important mental model: a monorepo is an architecture decision that organizes code, and Turborepo is the performance layer that orchestrates and caches tasks on top of it. They are not competitors, they complete each other \[8]. Workspaces (pnpm, npm, or yarn) resolve the local package graph so an app importing `@repo/ui` gets the local source directly, with no publish step in between; Turborepo sits above that and decides what to build in what order, what to cache, and what to skip \[5].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-structure-light.png" srcDark="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-structure-dark.png" alt="Turborepo apps and packages layout with the shared models package highlighted" />

*FIG. 01 · The apps and packages split, with the one package every app depends on: the models.*

## Why did the structure matter more than the linter?

Because a linter and the structure solve different problems, and only one of them was our actual problem. Shared lint and formatting configs are worth having, and most "code quality" writeups stop there. But formatting was never why our code broke. It broke when two services assumed different shapes for the same object, when a type got copy-pasted and then edited in one place only, or when a change in one app reached production before anyone noticed it broke another.

The structure is what closed those gaps. Because apps consume shared packages from source with no publish step, a change to a shared package is visible to every consumer in the same atomic commit \[5]. Because the dependency graph is explicit, a contract change that breaks a downstream app fails that app's build instead of shipping. The linter tells you a line is ugly; the structure tells you a change is wrong.

## Where do the models live, and why does that fix code quality?

In one package, and that single decision did more for backend code quality than any rule we added. We put the database models in a dedicated package (call it `@repo/db`) that owns the schema, the migrations, and the generated client and types, and every app imports from it \[3]. That is the single source of truth: schemas defined once, imported everywhere, so if a column changes, dependent apps flag build-time type errors immediately rather than failing at runtime \[11].

```prisma
// packages/db/prisma/schema.prisma
model User {
  id        String   @id @default(cuid())
  email     String   @unique
  name      String?
  createdAt DateTime @default(now())
}
```

```ts
// packages/db/src/index.ts
export { PrismaClient } from "../generated/prisma/client";
export const prisma = new PrismaClient();
```

```ts
// apps/web or apps/api: one import, the same types everywhere
import { prisma } from "@repo/db";

const user = await prisma.user.findFirst();
```

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-single-source-light.png" srcDark="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-single-source-dark.png" alt="One shared models package imported by every app, so a schema change type-checks across the whole repo" />

*FIG. 02 · One schema, defined once and imported everywhere: a column change becomes a build-time type error, not a runtime surprise.*

The gotcha that bites every new developer: the generated client has to exist before anything can build. If someone runs dev on an app without generating the client first, they get errors \[3]. The fix is to wire it into the task graph so it always runs first, keep migration commands uncached because the schema changes often, and list `DATABASE_URL` in `globalEnv` so task hashing stays correct \[3].

```json
// turbo.json
{
  "$schema": "https://turborepo.dev/schema.json",
  "globalEnv": ["DATABASE_URL"],
  "tasks": {
    "db:generate": { "cache": false },
    "build": {
      "dependsOn": ["^build", "^db:generate"],
      "outputs": ["dist/**", ".next/**", "!.next/cache/**"]
    },
    "dev": {
      "dependsOn": ["^db:generate"],
      "cache": false,
      "persistent": true
    },
    "lint": {},
    "typecheck": { "dependsOn": ["^build"] },
    "test": { "dependsOn": ["^build"] },
    "db:deploy": { "cache": false }
  }
}
```

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-task-graph-light.png" srcDark="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-task-graph-dark.png" alt="Turborepo task graph showing db:generate running before build so the generated client always exists first" />

*FIG. 03 · The task graph: db:generate runs before every build, so the generated client always exists first.*

One wrong turn worth naming: we reached for multiple databases with their own clients before understanding that multiple Prisma clients in one monorepo tend to overwrite each other. The sustainable pattern is one database with multiple schemas, not several separate databases wired together with workarounds \[10].

If your backend is not JavaScript or TypeScript, this section changes shape. Turborepo will still orchestrate and cache a FastAPI or Go service as a task, but the shared-package type safety is a JS/TS benefit. For a Python or Go backend, generate a typed client from the OpenAPI or schema and treat that generated package as the single source of truth, instead of hand-writing a TS models package.

## What file-structure conventions actually earned their place?

A few, and they are boring, which is the point. The root `package.json` stays private, keeps minimal devDependencies (basically just turbo and repo tooling), and its scripts only delegate to `turbo run`. No build logic lives at the root \[2].

```json
// package.json
{
  "name": "company-monorepo",
  "private": true,
  "packageManager": "pnpm@9.0.0",
  "scripts": {
    "build": "turbo run build",
    "dev": "turbo run dev",
    "lint": "turbo run lint",
    "test": "turbo run test",
    "typecheck": "turbo run typecheck"
  },
  "devDependencies": { "turbo": "latest" }
}
```

The conventions that held up: shared config packages for `tsconfig`, `eslint`, and Tailwind that every app extends, so the rules stay consistent across the repo rather than drifting per app \[6]\[5]. Package tasks over root tasks, always, reaching for root tasks only when a package task cannot do the job \[2]. Domain-driven isolation for packages rather than one junk-drawer `utils`, which is also why there is no hard package count; teams of 10 to 20 engineers commonly run somewhere around 10 to 25 packages covering UI, logic, database, and config \[6]. And the trap to avoid: broad barrel files and careless cross-imports that quietly create circular dependencies and slow builds \[6].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-three-layers-light.png" srcDark="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-three-layers-dark.png" alt="Three layers: thin apps on top, thick shared packages in the middle, shared config at the base" />

*FIG. 04 · Thin apps, thick packages, shared config: the three layers every app extends.*

## What did caching change about how we enforce quality?

It made the checks fast enough to actually enforce. A gate you cannot afford to run on every pull request is not a gate. Turborepo's remote cache stores task results so CI never has to do the same work twice \[7], and because it understands the dependency graph, changing only the models package rebuilds only the apps that depend on it \[11]. In practice that means lint, typecheck, and tests can each run as their own parallel CI job after a shared install, with each depending on upstream packages being built first \[5].

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-cache-ripple-light.png" srcDark="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-cache-ripple-dark.png" alt="Changing one package rebuilds only its dependents, with cached tasks skipped" />

*FIG. 05 · Change one package and only its dependents rebuild, cached and incremental.*

The honest caveat: build-speed numbers get quoted loosely, including a common "40 to 85 percent faster builds" figure \[9]. Treat that as a vendor-adjacent claim, not a promise. The real win is not a headline percentage, it is that fast, incremental checks turn code-quality rules from aspirational into enforced.

## When is a Turborepo monorepo the wrong call?

When the projects do not actually share much, or when the stack fights the tooling. If your projects evolve independently with minimal shared dependencies, separate repos are fine, and the upfront convention cost buys you little \[7]. And Turborepo's core strengths are aimed at JS/TS monorepos with interdependent tasks; if your projects span multiple languages with little to share as packages, the sharing benefit shrinks even though task orchestration still works \[9]. The failure mode of a polyrepo it does solve is real, though: twenty repos and twenty teams tend to grow twenty flavors of tooling and lose all visibility into cross-project breakage \[9].

## Polyrepo vs monorepo vs monorepo with Turborepo, at a glance

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-comparison-light.png" srcDark="https://images.syedmoinuddin.com/blogs/turborepo-monorepo-code-quality/turborepo-comparison-dark.png" alt="Comparison of polyrepo, workspaces-only monorepo, and monorepo with Turborepo across code sharing, source of truth, and build speed" />

*FIG. 06 · Polyrepo, workspaces alone, and workspaces plus Turborepo, at a glance.*

| Dimension                         | Polyrepo                       | Monorepo (workspaces only) | Monorepo + Turborepo                           |
| --------------------------------- | ------------------------------ | -------------------------- | ---------------------------------------------- |
| Code sharing                      | Copy or publish packages       | Local source, no publish   | Local source, orchestrated builds              |
| Single source of truth for models | Hard (duplicated or published) | Possible (shared package)  | Shared package, drift caught at build time     |
| Config consistency (ts, eslint)   | Diverges per repo              | Shared config packages     | Shared config, enforced across tasks           |
| Build and CI speed                | Isolated, no cross reuse       | Rebuilds everything        | Cached, parallel, only affected rebuild        |
| Breaking-change visibility        | Low (isolated)                 | Atomic commit shows impact | Atomic commit, graph fails affected build      |
| Onboarding "what goes where"      | Low upfront, drift later       | Upfront convention cost    | Upfront cost, pays off at scale                |
| Multi-language (Python, Go) fit   | Fine (separate)                | Loose orchestration        | Orchestrates tasks, type-sharing is JS/TS only |
| Best for                          | Independent projects           | Small shared codebase      | Many related apps sharing code and models      |

## Checklist: reach for it, or stay polyrepo?

**Reach for a Turborepo monorepo if:**

* [ ] Multiple apps share real code (UI, types, models, config) and tend to change together.
* [ ] You want one models package every app imports, with drift caught at build time.
* [ ] Your stack is mostly JS/TS, so shared packages buy you type safety across the boundary.
* [ ] CI speed matters and you can wire caching, local or remote.
* [ ] You can pay the upfront "what goes where" convention cost.

**Stay polyrepo (or rethink) if:**

* [ ] Your projects evolve independently with little shared code.
* [ ] Your services are in different languages and you would not share TS packages anyway.
* [ ] One team owns one app and the monorepo overhead buys nothing yet.
* [ ] You need per-repo access control or independent release cadences a monorepo complicates.

## Sources

1. Turborepo, "Structuring a repository" (Turborepo docs), [turborepo.dev](https://turborepo.dev/docs/crafting-your-repository/structuring-a-repository)
2. Vercel, "Turborepo structure best practices" (vercel/turborepo), [github.com](https://github.com/vercel/turborepo/blob/main/skills/turborepo/references/best-practices/structure.md)
3. Prisma, "How to use Prisma ORM with Turborepo" (Prisma docs), [prisma.io](https://www.prisma.io/docs/guides/deployment/turborepo)
4. Pliszko, "Shared database schema with DrizzleORM and Turborepo," [pliszko.com](https://pliszko.com/blog/post/2023-08-31-shared-database-schema-with-drizzleorm-and-turborepo)
5. Ajeet Chaulagain, "Inside a 3-app Turborepo monorepo: parallelism, caching, and CI that stays fast," [ajeetchaulagain.com](https://ajeetchaulagain.com/blog/turborepo-monorepo-ci/)
6. Daily Dev Post, "The scalable Turborepo folder structure (2026)," [dailydevpost.com](https://dailydevpost.com/blog/turborepo-folder-structure-scalability-guide)
7. Strapi, "Turborepo guide (v2.x, tasks, remote caching)," [strapi.io](https://strapi.io/blog/turborepo-guide)
8. Rohit Arya, "Monorepo vs TurboRepo: what is the real difference?" [rohitarya18.medium.com](https://rohitarya18.medium.com/monorepo-vs-turborepo-whats-the-real-difference-2b3e04cf022b)
9. Earthly, "Using Turborepo to build your first monorepo," [earthly.dev](https://earthly.dev/blog/build-monorepo-with-turporepo/)
10. Vercel, "Multiple Prisma clients and databases" (turborepo discussion #3493), [github.com](https://github.com/vercel/turborepo/discussions/3493)
11. DoHost, "Scaling Next.js with Drizzle and PostgreSQL in a Turborepo," [dohost.us](https://dohost.us/index.php/2026/06/10/micro-frontends-and-monorepos-scaling-next-js-with-drizzle-and-postgresql/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on monorepos, developer tooling, and building things that survive contact with production.


Last updated on July 5, 2026

---
title: "Scaling React in 2026: 7 Decisions That Mattered, and Why None of Them Were useMemo"
description: "Scaling a React app in 2026 had almost nothing to do with re-renders. The React Compiler deleted the hand-memoization busywork; the decisions that actually scaled were about where state lives, how data is fetched, and how much JavaScript you ship."
last_updated: "June 29, 2026"
source: "https://syedmoinuddin.com/blog/scaling-react-2026"
---

# Scaling React in 2026: 7 Decisions That Mattered, and Why None of Them Were useMemo

Scaling a React app in 2026 had almost nothing to do with re-renders. The React Compiler deleted the hand-memoization busywork; the decisions that actually scaled were about where state lives, how data is fetched, and how much JavaScript you ship.

The biggest thing scaling a React app in 2026 taught me: the decisions that made it scale had almost nothing to do with re-renders. I spent my early years sprinkling `useMemo`, `useCallback`, and `React.memo` like seasoning, chasing render counts in the Profiler. Then the React Compiler shipped stable \[1]\[2], started auto-memoizing at build time, and quietly deleted most of that work: one report measured 20–60% fewer re-renders for zero code changes \[3]. What the compiler *doesn't* touch is the stuff that actually decides whether an app scales: where state lives, how data is fetched, and how much JavaScript you ship. It explicitly won't fix your data-fetching waterfalls or your architecture \[2]. So here are the 7 decisions that mattered, and why none of them were `useMemo`.

## Step 1: Did you turn the compiler on and stop hand-memoizing?

The first decision is to delete the busywork. React Compiler 1.0 reached stable status in late 2025 \[2], and it inserts memoization per reactive scope at build time, often more precisely than you'd write by hand \[1].

If you're on Next.js, switching it on is a one-line config change \[4]:

```js
// next.config.js
const nextConfig = {
  reactCompiler: true,
}
module.exports = nextConfig
```

Once it's on, the code you used to write disappears:

```jsx
// Before: manual memoization everywhere
const filtered = useMemo(() => items.filter((i) => i.active), [items])
const onPick = useCallback((id) => setSelected(id), [])

// After: the compiler handles it
const filtered = items.filter((i) => i.active)
const onPick = (id) => setSelected(id)
```

The default that didn't work was wrapping everything by hand. It was constant cognitive overhead, and almost nobody actually profiled whether it helped \[2]. `useMemo` and `useCallback` aren't dead. They're escape hatches now, for precise control like a value that feeds a `useEffect` dependency, not a daily reflex \[1]\[2].

One caution: the compiler bails out silently on components that break the Rules of React, and you won't notice unless the lint rule is on \[2]. Keep it on.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/scaling-react-2026/react-scaling-decision-stack-light.png" srcDark="https://images.syedmoinuddin.com/blogs/scaling-react-2026/react-scaling-decision-stack-dark.png" alt="The 2026 React scaling stack: a layered diagram showing where the work moved, colocated UI state on the client, a server-cache layer, server components for data-heavy work, and route-split bundles, with the discarded 'chase re-renders' loop crossed out" />

## Step 2: Is your state colocated, or living at the top of the tree?

Here's what the compiler can't do for you: it can't decide *which* components subscribe to a piece of state. That's an architecture choice, and it's where the real re-render cost lives.

Global, rapidly-changing state is one of the leading causes of slow React apps \[6]. Every update to a top-level store or provider re-renders everything wired into it.

The fix is colocation: keep state as close as possible to where it's used \[6].

```jsx
// State lives in the field that owns it, not in the parent form
function NameField() {
  const [value, setValue] = useState("")
  return <input value={value} onChange={(e) => setValue(e.target.value)} />
}
```

The default that didn't work was lifting all state to a top-level provider "just in case." Colocation is a performance optimization *and* a maintenance one \[6]; reach for context or a store only for state that's genuinely shared across the tree.

## Step 3: Are you treating server data as state?

This was the single most expensive mental model I had to unlearn. Server data is not state. It's a *cache* of state, and conflating the two is a mistake \[7].

UI state (is the modal open?) and server-cache state (the user's data) have completely different problems: server data goes stale, needs refetching, deduping, and background updates \[7]. Managing it with `useState` and a hand-rolled `useEffect` means reimplementing a cache badly.

```jsx
// Don't hand-roll server state
useEffect(() => {
  fetch(url)
    .then((r) => r.json())
    .then(setData)
}, [url])

// Let a cache layer own it: staleness, dedup, refetch handled
const { data } = useQuery({ queryKey: ["user", id], queryFn: fetchUser })
```

Keep `useState` for UI state; put server data in a dedicated layer (TanStack Query, or the framework's server cache). The two buckets need different tools \[7].

## Step 4: Did you kill the data-fetching waterfall?

This is the one the compiler will never save you from \[2], and it's usually the biggest scaling bottleneck in the whole app.

A waterfall happens when components each fetch their own data and render sequentially: every nested component waits for its parent's request before starting its own \[8]. The network tab shows a staircase instead of a stack.

There are two fixes, and both come down to decoupling data fetching from components \[11]. Fetch in parallel, or hoist the fetch above the components that need it and read from a shared cache:

```jsx
// Waterfall: each await blocks the next
const user = await getUser()
const orders = await getOrders() // waits for user, for no reason

// Parallel: both start at once
const [user, orders] = await Promise.all([getUser(), getOrders()])
```

If you already use TanStack Query, you can run the fetches high in the tree and let each component read the result from the `QueryClient` cache instead of triggering its own request \[8]. The default that didn't work was a `useEffect` fetch in every component, a guaranteed staircase.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/scaling-react-2026/react-fetch-waterfall-vs-parallel-light.png" srcDark="https://images.syedmoinuddin.com/blogs/scaling-react-2026/react-fetch-waterfall-vs-parallel-dark.png" alt="Waterfall versus parallel data fetching shown as two timing diagrams: sequential requests staggered like a staircase on top, the same requests aligned and starting together on the bottom, with total time collapsing" />

## Step 5: Did you move work to the server?

Server Components changed where the work happens. A server component can read your data layer directly without you building an API for it, and any heavy libraries it uses cost *zero* client bundle \[10].

There's a subtler win too: a server-side waterfall is often better than a client-side one, because on the server you control the network \[11]. The link between your render server and your database is faster, closer, and more reliable than a user's phone on hotel Wi-Fi \[11].

The default that didn't work was shipping data-fetching code, parsing libraries, and the fetch round-trip itself down to the client. Push static and data-heavy, non-interactive work to the server; keep client components for the parts that are actually interactive.

One honest caveat: RSC isn't a magic wand. If you `await` each query sequentially on the server, you've just moved the waterfall, not removed it \[11].

## Step 6: Are you shipping the whole app on the first load?

Bundle size is a scaling tax everyone pays and few measure. As the app grows, especially with large third-party libraries, the single bundle balloons and first load slows.

Code-split at route boundaries first; it's the biggest win for the least effort \[12]\[13]. Then lazy-load heavy components that only render on a specific interaction \[13]:

```jsx
import { lazy, Suspense } from "react"

const Dashboard = lazy(() => import("./routes/Dashboard"))

;<Suspense fallback={<Spinner />}>
  <Dashboard />
</Suspense>
```

The default that didn't work came in two flavors: one giant bundle, or (once people discover `lazy`) over-splitting every tiny component, which just trades load time for flicker and new waterfalls \[13]. Split by route and by heavy, offscreen features. Don't split your buttons.

## Step 7: Are you measuring, or guessing?

The compiler removes a whole class of problems, but the biggest mistake teams make after enabling it is assuming performance is now "solved" \[2]. It isn't.

Profile before you optimize \[5]. Use the React DevTools Profiler for re-renders and the network and INP numbers for what the user actually feels \[2]. Your machine is faster than your users', so measure on a production build and a real device \[5].

And remember what "scalable" actually means: it's as much about the codebase as the runtime. Feature-based module boundaries and typed API contracts are what let the *team* keep shipping as the app grows, the part no Profiler will show you. The default that didn't work was optimizing on vibes.

## What I reached for vs. what actually scaled

| The instinct                 | What it cost                   | The decision that scaled         | Where the leverage was         |
| ---------------------------- | ------------------------------ | -------------------------------- | ------------------------------ |
| `useMemo` on everything      | Cognitive overhead, unmeasured | Turn the compiler on \[1]\[2]    | Build-time auto-memoization    |
| State at the top of the tree | Whole-tree re-renders          | Colocate state \[6]              | Smaller re-render blast radius |
| Server data in `useState`    | Stale data, manual refetch     | A cache layer \[7]               | Right tool for server cache    |
| Per-component fetching       | Sequential waterfalls          | Hoist / parallelize \[8]\[11]    | Network, not render            |
| Libraries on the client      | Bloated bundle                 | Server Components \[10]          | Zero-cost server work          |
| One big bundle               | Slow first load                | Route-level code-splitting \[13] | Ship less JS                   |
| Optimizing on vibes          | Wasted effort                  | Measure first \[5]               | Data-driven fixes              |

## When this playbook applies, and when it's overkill

Reach for these decisions when:

* The app is genuinely growing: more routes, more data, more people touching the code.
* You can feel the pain: slow first load, janky interactions, a network tab full of staircases.
* You're on React 19+ or a modern framework where the compiler and RSC are available.

Skip the ceremony when:

* It's a small static SPA, a prototype, or a three-screen landing page. Don't bolt on a cache layer, RSC, and aggressive splitting for an app that doesn't have the problems they solve.
* You haven't tried colocation yet, so don't reach for a global store first \[6].
* Your codebase breaks the Rules of React and you haven't enabled the compiler's lint rule: turning the compiler on blind will silently skip those components \[2].

## Sources

1. [React Compiler (React docs)](https://react.dev/learn/react-compiler/introduction)
2. [Stop Writing useMemo and useCallback: A Migration Guide to React Compiler 1.0](https://adeelhere.com/blog/2026-03-24-react-compiler-migration-guide)
3. [React Compiler Deep Dive: How Automatic Memoization Eliminates 90% of Performance Optimization Work](https://dev.to/pockit_tools/react-compiler-deep-dive-how-automatic-memoization-eliminates-90-of-performance-optimization-work-1351)
4. [React Compiler: Drop useMemo and useCallback, Let the Compiler Handle It](https://realcoding.blog/2026/03/23/react-compiler-automatic-memoization-en/)
5. [useMemo (React docs)](https://react.dev/reference/react/useMemo)
6. [State Colocation will make your React app faster, Kent C. Dodds](https://kentcdodds.com/blog/state-colocation-will-make-your-react-app-faster)
7. [Application State Management with React, Kent C. Dodds](https://kentcdodds.com/blog/application-state-management-with-react)
8. [Fetch Waterfall in React, Sentry](https://blog.sentry.io/fetch-waterfall-in-react/)
9. [Performance and Request Waterfalls, TanStack Query Docs](https://tanstack.com/query/latest/docs/framework/react/guides/request-waterfalls)
10. [Server Components (React docs)](https://react.dev/reference/rsc/server-components)
11. [The Big "Server Waterfall Problem" with RSCs, Kent C. Dodds](https://www.epicreact.dev/server-waterfall-problem-rscs)
12. [lazy (React docs)](https://react.dev/reference/react/lazy)
13. [Code splitting with React.lazy and Suspense, web.dev](https://web.dev/articles/code-splitting-suspense)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and the frontend/backend craft. Follow along for more deep dives on the tools changing how we ship software.


Last updated on June 29, 2026

---
title: "Chain of Thought"
description: "Collapsible reasoning steps for AI thinking interfaces."
last_updated: "June 28, 2026"
source: "https://syedmoinuddin.com/blog/chain-of-thought"
---

# Chain of Thought

Collapsible reasoning steps for AI thinking interfaces.

```tsx
import {
  ChainOfThought,
  ChainOfThoughtContent,
  ChainOfThoughtItem,
  ChainOfThoughtStep,
  ChainOfThoughtTrigger,
} from "@/components/chain-of-thought/chain-of-thought"

export default function ChainOfThoughtDemo() {
  return (
    <ChainOfThought className="max-w-lg">
      <ChainOfThoughtStep defaultOpen>
        <ChainOfThoughtTrigger>Understanding the request</ChainOfThoughtTrigger>
        <ChainOfThoughtContent>
          <ChainOfThoughtItem>
            The user wants a weekly summary of their sales, grouped by region
            and sorted by revenue.
          </ChainOfThoughtItem>
        </ChainOfThoughtContent>
      </ChainOfThoughtStep>

      <ChainOfThoughtStep>
        <ChainOfThoughtTrigger>Querying the database</ChainOfThoughtTrigger>
        <ChainOfThoughtContent>
          <ChainOfThoughtItem>
            Running an aggregate over the orders table for the last 7 days,
            joining on the regions lookup.
          </ChainOfThoughtItem>
        </ChainOfThoughtContent>
      </ChainOfThoughtStep>

      <ChainOfThoughtStep>
        <ChainOfThoughtTrigger>Composing the answer</ChainOfThoughtTrigger>
        <ChainOfThoughtContent>
          <ChainOfThoughtItem>
            Formatting the results into a table and highlighting the top region
            by revenue.
          </ChainOfThoughtItem>
        </ChainOfThoughtContent>
      </ChainOfThoughtStep>
    </ChainOfThought>
  )
}

```

## Features

* Collapsible steps for showing an agent's reasoning.
* Connecting line between steps that adapts to the active step.
* Optional left icon per step, with a chevron swap on hover.
* Composable parts: step, trigger, content, and item.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/chain-of-thought
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge lucide-react radix-ui
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Install the required components</Step>

      * [Collapsible](https://ui.shadcn.com/docs/components/collapsible)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/chain-of-thought.tsx" 
      "use client"

      import React from "react"
      import { ChevronDown, Circle } from "lucide-react"

      import { cn } from "@/lib/utils"
      import {
        Collapsible,
        CollapsibleContent,
        CollapsibleTrigger,
      } from "@/components/ui/collapsible"

      export type ChainOfThoughtItemProps = React.ComponentProps<"div">

      export const ChainOfThoughtItem = ({
        children,
        className,
        ...props
      }: ChainOfThoughtItemProps) => (
        <div className={cn("text-sm text-muted-foreground", className)} {...props}>
          {children}
        </div>
      )

      export type ChainOfThoughtTriggerProps = React.ComponentProps<
        typeof CollapsibleTrigger
      > & {
        leftIcon?: React.ReactNode
        swapIconOnHover?: boolean
      }

      export const ChainOfThoughtTrigger = ({
        children,
        className,
        leftIcon,
        swapIconOnHover = true,
        ...props
      }: ChainOfThoughtTriggerProps) => (
        <CollapsibleTrigger
          className={cn(
            "group flex cursor-pointer items-center justify-start gap-1 text-left text-sm text-muted-foreground transition-colors hover:text-foreground",
            className
          )}
          {...props}
        >
          <div className="flex items-center gap-2">
            {leftIcon ? (
              <span className="relative inline-flex size-4 items-center justify-center">
                <span
                  className={cn(
                    "transition-opacity",
                    swapIconOnHover && "group-hover:opacity-0"
                  )}
                >
                  {leftIcon}
                </span>
                {swapIconOnHover && (
                  <ChevronDown className="absolute size-4 opacity-0 transition-opacity group-hover:opacity-100 group-data-[state=open]:rotate-180" />
                )}
              </span>
            ) : (
              <span className="relative inline-flex size-4 items-center justify-center">
                <Circle className="size-2 fill-current" />
              </span>
            )}
            <span>{children}</span>
          </div>
          {!leftIcon && (
            <ChevronDown className="size-4 transition-transform group-data-[state=open]:rotate-180" />
          )}
        </CollapsibleTrigger>
      )

      export type ChainOfThoughtContentProps = React.ComponentProps<
        typeof CollapsibleContent
      >

      export const ChainOfThoughtContent = ({
        children,
        className,
        ...props
      }: ChainOfThoughtContentProps) => {
        return (
          <CollapsibleContent
            className={cn(
              "overflow-hidden text-popover-foreground data-[state=closed]:animate-collapsible-up data-[state=open]:animate-collapsible-down",
              className
            )}
            {...props}
          >
            <div className="grid grid-cols-[min-content_minmax(0,1fr)] gap-x-4">
              <div className="ml-1.75 h-full w-px bg-primary/20 group-data-[last=true]:hidden" />
              <div className="ml-1.75 h-full w-px bg-transparent group-data-[last=false]:hidden" />
              <div className="mt-2 space-y-2">{children}</div>
            </div>
          </CollapsibleContent>
        )
      }

      export type ChainOfThoughtProps = {
        children: React.ReactNode
        className?: string
      }

      export function ChainOfThought({ children, className }: ChainOfThoughtProps) {
        const childrenArray = React.Children.toArray(children)

        return (
          <div className={cn("space-y-0", className)}>
            {childrenArray.map((child, index) => (
              <React.Fragment key={index}>
                {React.isValidElement(child) &&
                  React.cloneElement(
                    child as React.ReactElement<ChainOfThoughtStepProps>,
                    {
                      isLast: index === childrenArray.length - 1,
                    }
                  )}
              </React.Fragment>
            ))}
          </div>
        )
      }

      export type ChainOfThoughtStepProps = {
        children: React.ReactNode
        className?: string
        isLast?: boolean
      }

      export const ChainOfThoughtStep = ({
        children,
        className,
        isLast = false,
        ...props
      }: ChainOfThoughtStepProps & React.ComponentProps<typeof Collapsible>) => {
        return (
          <Collapsible
            className={cn("group", className)}
            data-last={isLast}
            {...props}
          >
            {children}
            <div className="flex justify-start group-data-[last=true]:hidden">
              <div className="ml-1.75 h-4 w-px bg-primary/20" />
            </div>
          </Collapsible>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import {
  ChainOfThought,
  ChainOfThoughtContent,
  ChainOfThoughtItem,
  ChainOfThoughtStep,
  ChainOfThoughtTrigger,
} from "@/components/chain-of-thought"
```

```tsx
<ChainOfThought>
  <ChainOfThoughtStep defaultOpen>
    <ChainOfThoughtTrigger>Understanding the request</ChainOfThoughtTrigger>
    <ChainOfThoughtContent>
      <ChainOfThoughtItem>Reasoning goes here.</ChainOfThoughtItem>
    </ChainOfThoughtContent>
  </ChainOfThoughtStep>
</ChainOfThought>
```


Last updated on June 28, 2026

---
title: "Timeline"
description: "A vertical or horizontal timeline with steps, dates, and indicators."
last_updated: "June 28, 2026"
source: "https://syedmoinuddin.com/blog/timeline"
---

# Timeline

A vertical or horizontal timeline with steps, dates, and indicators.

```tsx
import {
  Timeline,
  TimelineContent,
  TimelineDate,
  TimelineHeader,
  TimelineIndicator,
  TimelineItem,
  TimelineSeparator,
  TimelineTitle,
} from "@/components/timeline/timeline"

const items = [
  {
    id: 1,
    date: "March 2024",
    title: "Project Initialized",
    description: "Set up the repository and the initial architecture.",
  },
  {
    id: 2,
    date: "April 2024",
    title: "Design System",
    description: "Built the component library and design tokens.",
  },
  {
    id: 3,
    date: "May 2024",
    title: "Beta Release",
    description: "Shipped the first beta to a group of early adopters.",
  },
  {
    id: 4,
    date: "June 2024",
    title: "Public Launch",
    description: "Opened the product up to everyone.",
  },
]

export default function TimelineDemo() {
  return (
    <Timeline defaultValue={3} className="max-w-lg">
      {items.map((item) => (
        <TimelineItem key={item.id} step={item.id}>
          <TimelineHeader>
            <TimelineDate>{item.date}</TimelineDate>
            <TimelineTitle>{item.title}</TimelineTitle>
          </TimelineHeader>
          <TimelineIndicator />
          <TimelineSeparator />
          <TimelineContent>{item.description}</TimelineContent>
        </TimelineItem>
      ))}
    </Timeline>
  )
}

```

## Features

* Vertical and horizontal orientations.
* Controlled or uncontrolled active step.
* Composable parts: item, header, date, title, content, indicator, and separator.
* Completed steps are highlighted automatically up to the active step.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/timeline
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install @base-ui/react clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/timeline.tsx" 
      "use client"

      import { createContext, useCallback, useContext, useState } from "react"
      import { mergeProps } from "@base-ui/react/merge-props"
      import { useRender } from "@base-ui/react/use-render"

      import { cn } from "@/lib/utils"

      // Types
      type TimelineContextValue = {
        activeStep: number
        setActiveStep: (step: number) => void
      }

      // Context
      const TimelineContext = createContext<TimelineContextValue | undefined>(
        undefined
      )

      const useTimeline = () => {
        const context = useContext(TimelineContext)
        if (!context) {
          throw new Error("useTimeline must be used within a Timeline")
        }
        return context
      }

      // Components
      interface TimelineProps extends useRender.ComponentProps<"div"> {
        defaultValue?: number
        value?: number
        onValueChange?: (value: number) => void
        orientation?: "horizontal" | "vertical"
      }

      function Timeline({
        defaultValue = 1,
        value,
        onValueChange,
        orientation = "vertical",
        className,
        render,
        children,
        ...props
      }: TimelineProps) {
        const [activeStep, setInternalStep] = useState(defaultValue)

        const setActiveStep = useCallback(
          (step: number) => {
            if (value === undefined) {
              setInternalStep(step)
            }
            onValueChange?.(step)
          },
          [value, onValueChange]
        )

        const currentStep = value ?? activeStep

        const defaultProps = {
          className: cn(
            "group/timeline flex data-[orientation=horizontal]:w-full data-[orientation=horizontal]:flex-row data-[orientation=vertical]:flex-col",
            className
          ),
          "data-orientation": orientation,
          "data-slot": "timeline",
          children,
        }

        return (
          <TimelineContext.Provider
            value={{ activeStep: currentStep, setActiveStep }}
          >
            {useRender({
              defaultTagName: "div",
              render,
              props: mergeProps<"div">(defaultProps, props),
            })}
          </TimelineContext.Provider>
        )
      }

      // TimelineContent
      function TimelineContent({
        className,
        render,
        children,
        ...props
      }: useRender.ComponentProps<"div">) {
        const defaultProps = {
          className: cn("text-sm text-muted-foreground", className),
          "data-slot": "timeline-content",
          children,
        }

        return useRender({
          defaultTagName: "div",
          render,
          props: mergeProps<"div">(defaultProps, props),
        })
      }

      // TimelineDate
      type TimelineDateProps = useRender.ComponentProps<"time">

      function TimelineDate({
        className,
        render,
        children,
        ...props
      }: TimelineDateProps) {
        const defaultProps = {
          className: cn(
            "mb-1 block text-xs font-medium text-muted-foreground group-data-[orientation=vertical]/timeline:max-sm:h-4",
            className
          ),
          "data-slot": "timeline-date",
          children,
        }

        return useRender({
          defaultTagName: "time",
          render,
          props: mergeProps<"time">(defaultProps, props),
        })
      }

      // TimelineHeader
      function TimelineHeader({
        className,
        render,
        children,
        ...props
      }: useRender.ComponentProps<"div">) {
        const defaultProps = {
          className: cn(className),
          "data-slot": "timeline-header",
          children,
        }

        return useRender({
          defaultTagName: "div",
          render,
          props: mergeProps<"div">(defaultProps, props),
        })
      }

      // TimelineIndicator
      type TimelineIndicatorProps = useRender.ComponentProps<"div">

      function TimelineIndicator({
        className,
        children,
        render,
        ...props
      }: TimelineIndicatorProps) {
        const defaultProps = {
          "aria-hidden": true,
          className: cn(
            "absolute size-4 rounded-full border-2 border-primary/20 group-data-completed/timeline-item:border-primary group-data-[orientation=horizontal]/timeline:-top-6 group-data-[orientation=horizontal]/timeline:left-0 group-data-[orientation=horizontal]/timeline:-translate-y-1/2 group-data-[orientation=vertical]/timeline:top-0 group-data-[orientation=vertical]/timeline:-left-6 group-data-[orientation=vertical]/timeline:-translate-x-1/2",
            className
          ),
          "data-slot": "timeline-indicator",
          children,
        }

        return useRender({
          defaultTagName: "div",
          render,
          props: mergeProps<"div">(defaultProps, props),
        })
      }

      // TimelineItem
      interface TimelineItemProps extends useRender.ComponentProps<"div"> {
        step: number
      }

      function TimelineItem({
        step,
        className,
        render,
        children,
        ...props
      }: TimelineItemProps) {
        const { activeStep } = useTimeline()

        const defaultProps = {
          className: cn(
            "group/timeline-item relative flex flex-1 flex-col gap-0.5 group-data-[orientation=horizontal]/timeline:mt-8 group-data-[orientation=horizontal]/timeline:not-last:pe-8 group-data-[orientation=vertical]/timeline:ms-8 group-data-[orientation=vertical]/timeline:not-last:pb-6 has-[+[data-completed]]:**:data-[slot=timeline-separator]:bg-primary",
            className
          ),
          "data-completed": step <= activeStep || undefined,
          "data-slot": "timeline-item",
          children,
        }

        return useRender({
          defaultTagName: "div",
          render,
          props: mergeProps<"div">(defaultProps, props),
        })
      }

      // TimelineSeparator
      function TimelineSeparator({
        className,
        render,
        children,
        ...props
      }: useRender.ComponentProps<"div">) {
        const defaultProps = {
          "aria-hidden": true,
          className: cn(
            "absolute self-start bg-primary/10 group-last/timeline-item:hidden group-data-[orientation=horizontal]/timeline:-top-6 group-data-[orientation=horizontal]/timeline:h-0.5 group-data-[orientation=horizontal]/timeline:w-[calc(100%-1rem-0.25rem)] group-data-[orientation=horizontal]/timeline:translate-x-4.5 group-data-[orientation=horizontal]/timeline:-translate-y-1/2 group-data-[orientation=vertical]/timeline:-left-6 group-data-[orientation=vertical]/timeline:h-[calc(100%-1rem-0.25rem)] group-data-[orientation=vertical]/timeline:w-0.5 group-data-[orientation=vertical]/timeline:-translate-x-1/2 group-data-[orientation=vertical]/timeline:translate-y-4.5",
            className
          ),
          "data-slot": "timeline-separator",
          children,
        }

        return useRender({
          defaultTagName: "div",
          render,
          props: mergeProps<"div">(defaultProps, props),
        })
      }

      // TimelineTitle
      function TimelineTitle({
        className,
        render,
        children,
        ...props
      }: useRender.ComponentProps<"h3">) {
        const defaultProps = {
          className: cn("text-sm font-medium", className),
          "data-slot": "timeline-title",
          children,
        }

        return useRender({
          defaultTagName: "h3",
          render,
          props: mergeProps<"h3">(defaultProps, props),
        })
      }

      export {
        Timeline,
        TimelineContent,
        TimelineDate,
        TimelineHeader,
        TimelineIndicator,
        TimelineItem,
        TimelineSeparator,
        TimelineTitle,
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import {
  Timeline,
  TimelineContent,
  TimelineDate,
  TimelineHeader,
  TimelineIndicator,
  TimelineItem,
  TimelineSeparator,
  TimelineTitle,
} from "@/components/timeline"
```

```tsx
<Timeline defaultValue={3}>
  <TimelineItem step={1}>
    <TimelineHeader>
      <TimelineDate>March 2024</TimelineDate>
      <TimelineTitle>Project Initialized</TimelineTitle>
    </TimelineHeader>
    <TimelineIndicator />
    <TimelineSeparator />
    <TimelineContent>Set up the repository.</TimelineContent>
  </TimelineItem>
</Timeline>
```


Last updated on June 28, 2026

---
title: "Scaling RAG to 10M Documents: The Hallucination Fixes That Worked Were the Boring Ones"
description: "Hallucination is a retrieval problem wearing a generation costume. Scaling a RAG pipeline past 10M documents, the fixes that actually moved the fabrication rate were the unglamorous ones: dedup, an abstention gate, and post-hoc grounding checks."
last_updated: "June 27, 2026"
source: "https://syedmoinuddin.com/blog/scaling-rag-10m-documents"
---

# Scaling RAG to 10M Documents: The Hallucination Fixes That Worked Were the Boring Ones

Hallucination is a retrieval problem wearing a generation costume. Scaling a RAG pipeline past 10M documents, the fixes that actually moved the fabrication rate were the unglamorous ones: dedup, an abstention gate, and post-hoc grounding checks.

The biggest thing scaling a retrieval pipeline past 10M documents taught me: hallucination is a retrieval problem wearing a generation costume. I spent the first weeks tuning prompts and swapping in bigger models, and the fabrication rate barely moved. What actually moved it was unglamorous, killing duplicate and contradictory chunks before they reached the model, adding a confidence gate that let the system answer "I don't know," and verifying every claim against the retrieved text after generation. None of that is a model upgrade. RAG narrows hallucination but never erases it \[1], and at scale the leverage lives in retrieval precision and the licence to abstain, not in the LLM. Here's the order I learned that in.

## Why didn't a bigger model fix the hallucinations?

That was my first move, because it's the easy one. Swap the generator, rewrite the system prompt to "only use the retrieved passages," and wait for the numbers to improve.

They barely did.

The research lines up with what I saw on my own corpus: RAG reduces hallucination, but it does not eliminate it \[1]\[4]. Worse, a model will often hallucinate *rather than* abstain, and it does this **more** under RAG than in a closed-book setting when the retrieved context is insufficient \[5]. You hand it weak evidence, it fills the gap confidently.

The lesson landed hard. The smartest model you can afford is still capped by the evidence you put in front of it \[2]. If the retrieval layer feeds it noise, no amount of prompt scolding saves the answer. So I stopped tuning the generator and went upstream.

## What was actually poisoning the answers?

Duplicates and contradictions.

Most knowledge bases aren't truth-shaped, they're document-shaped. You end up with the 2022, 2023, and 2024 version of the same policy sitting in the index, all equally retrievable \[3].

So the retriever does its job and pulls back two chunks: "Refunds take 5 days" and "Refunds take 14 days." The model has no mechanism to know which one is current \[3]. It picks one, or splits the difference, and now you've shipped a confident wrong answer that *looks* grounded because it technically came from a real document.

This was boring fix number one, and it moved the needle more than anything else: drop near-duplicates at ingestion, before they ever touch retrieval.

```python
# At ingestion: drop near-duplicate chunks before they reach the index
seen = MinHashLSH(threshold=0.85)
for chunk in chunks:
    sig = minhash(chunk.text)
    if seen.query(sig):          # a near-identical chunk already indexed
        continue
    seen.insert(chunk.id, sig)
    index.add(chunk, metadata={"version": chunk.version, "source": chunk.source})
```

Pair that with metadata filtering so version and recency are first-class at query time, and a whole category of "contradiction hallucinations" disappears, not because the model got smarter, but because it stopped being handed a contradiction.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/scaling-rag-10m-documents/rag-hallucination-defense-layers-light.png" srcDark="https://images.syedmoinuddin.com/blogs/scaling-rag-10m-documents/rag-hallucination-defense-layers-dark.png" alt="Four-layer hallucination defense: deduplication, hybrid retrieve and rerank, confidence gate, and grounding verification, rendered as stacked hairline panels with FIG. numbering" />

## Why did raising top-k make things worse, not better?

My next instinct was the obvious one: if the right answer might not be retrieved, just retrieve more. Push `k` from 5 to 20 so the correct chunk is *somewhere* in the prompt.

That backfired.

Models prioritize information at the very start and end of a long context and quietly skip the middle, the "lost-in-the-middle" effect \[3]\[10]. If the critical chunk lands fifth out of twenty, the model may conclude the information isn't there at all, then fall back to its training data. A hallucination born from good intentions \[3].

The fix isn't fewer candidates or more candidates, it's a two-stage retrieve. Cast a wide net with cheap recall, then use an expensive, precise reranker to reorder and keep only the few that matter \[7]\[8].

The bi-encoder that fetched your top 30 might rank chunk #17 as most relevant. A cross-encoder reads the actual query against each chunk's actual text and realizes chunk #3 is the real match. That reordering is the difference between a good RAG and a great one, and it only ever runs on the top 15–30 candidates, never the full corpus \[7]\[8].

## How do you make the system admit it doesn't know?

This was boring fix number two, and it bought the most user trust per line of code.

Every retrieved chunk carries a relevance score by the time it reaches the prompt. So gate on it. If nothing clears the bar, don't generate, return an honest "I couldn't find this in the knowledge base."

```python
def answer(query, index, threshold=0.65):
    candidates = hybrid_retrieve(query, index, k=30)     # BM25 + dense
    ranked = cross_encoder_rerank(query, candidates)     # precise reorder
    top = ranked[:5]
    if max(c.score for c in top) < threshold:
        return Abstain("Insufficient evidence in the knowledge base.")
    return generate_grounded(query, top)
```

This felt wrong at first, I was deliberately making the system answer *fewer* questions. But a confident wrong answer is infinitely worse than an honest abstention \[5]\[6]\[13]. The literature converges on the same move under different names: selective RAG driven by a sufficient-context signal \[5], a calibrated "reject option" \[6], and uncertainty thresholding that decides whether to answer, hedge, or abstain \[12].

An abstention isn't the system failing. It's the system working correctly.

## How do you catch a hallucination after the model has already written it?

The gate stops the model from answering with no evidence. It doesn't stop the model from drifting away from evidence it *did* receive. So I added boring fix number three: a post-hoc grounding check.

Split the generated answer into individual claims. For each one, verify it's actually supported by the retrieved chunks, entailment via an off-the-shelf NLI model, or fuzzy matching, since the model paraphrases rather than quotes \[6]\[11].

```python
def verify(answer, context_chunks):
    claims = split_into_claims(answer)
    flagged = [c for c in claims if not entailed_by(c, context_chunks)]
    faithfulness = 1 - len(flagged) / max(len(claims), 1)
    return faithfulness, flagged     # surface flagged claims, don't silently drop them
```

I run this asynchronously: stream the answer to the user immediately, run verification in parallel, and surface a warning if a claim couldn't be traced to a source. Crucially, I don't auto-suppress the response, I show the user *which specific claim* failed verification \[6]\[11]. That's far more useful than a blanket "this might be wrong," and it turns the verifier into a debugging tool, not just a guardrail.

## What about retrieval quality itself, embeddings, hybrid, chunking?

This is the part everyone wants to optimize, and it matters, but it's table stakes, not the differentiator.

Hybrid retrieval beats either method alone. Dense embeddings capture meaning but miss exact identifiers, error codes, and rare terms; BM25 catches the literal string but misses paraphrase. Most production pipelines combine both \[9].

Chunking is a genuine tradeoff with no free answer: chunks too small lose their surrounding context, chunks too large smuggle in irrelevant noise or blow the context budget \[9]\[10]. Structure-aware splitting plus a one-line context prefix on each chunk was the best balance I found.

But here's the thing I'd tell my earlier self: I could have perfected chunking and embeddings for a month and still shipped hallucinations, because the failures weren't coming from there. They were coming from contradictions, missing abstention, and unverified claims. Get retrieval *good enough*, then spend your real effort on the three boring fixes above.

## How did you know any of this was working?

You can't improve what you don't measure, and you can't measure it once and walk away.

I track two families of metric continuously in production, not just in an offline test set \[8]: **faithfulness** (is the answer grounded in the retrieved context?) and **context relevance** (did retrieval even fetch the right material?). Tools like RAGAS and DeepEval score these directly, and a well-tuned pipeline can hit faithfulness in the mid-90s \[8].

The split is what makes it actionable. Low context relevance is a *retrieval* failure, fix chunking, embeddings, or reranking. Low faithfulness with good context is a *generation* failure, tighten the prompt or the grounding check \[8]\[12]. Same symptom on the surface, completely different repair underneath. Before I separated them, I was guessing.

## Where does hallucination actually come from, and what fixes it?

| Failure mode                    | What people reach for | What actually moved it                          | When it matters most              |
| ------------------------------- | --------------------- | ----------------------------------------------- | --------------------------------- |
| Stale / contradictory chunks    | A bigger model        | Dedup + version metadata at ingestion \[3]      | Any corpus with document versions |
| Lost-in-the-middle              | Raise top-k           | Retrieve wide, rerank, keep few \[3]\[7]\[10]   | Long contexts, many candidates    |
| Insufficient evidence           | Harder prompt         | Confidence gate that abstains \[5]\[6]          | Open-domain, sparse coverage      |
| Unsupported claims slip through | Trust the model       | Post-hoc grounding / entailment check \[6]\[11] | High-stakes, audited answers      |
| Exact term vs. paraphrase miss  | Better embeddings     | Hybrid BM25 + dense retrieval \[9]              | IDs, codes, names, rare terms     |

## Should you even build this?

Not every problem needs a 10M-document pipeline. A few honest disqualifiers I wish I'd checked first:

* **Skip RAG if your data fits a long-context window.** If the whole corpus is 200k–1M tokens, a long-context model reading it directly is simpler and often more accurate on a small, static set \[3]. RAG earns its complexity at scale, not below it.
* **Don't use vector search for structured queries.** "Which customers spent more than $5,000 in December?" is a SQL question. Vector search can't do aggregations or joins \[3].
* **Build this when** you have millions of documents, frequent updates, contradictory or versioned sources, a need for citations and provenance, and a domain where a confident wrong answer carries real cost \[1].

If you land in that last bucket, the order is: dedup first, gate second, verify third. Retrieval polish underneath all of it.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/scaling-rag-10m-documents/rag-fabrication-before-after-light.png" srcDark="https://images.syedmoinuddin.com/blogs/scaling-rag-10m-documents/rag-fabrication-before-after-dark.png" alt="Before and after across the pipeline: stacked monochrome bars showing where unsupported claims drop at each stage, raw generation, after dedup, after the confidence gate, after grounding verification" />

## Sources

1. [A Systematic Review of Key Retrieval-Augmented Generation Systems: Progress, Gaps, and Future Directions](https://arxiv.org/abs/2507.18910)
2. [Enhancing LLMs with Domain-specific RAG: Long-form Consumer Health QA in Ophthalmology](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12478434/)
3. [How to Stop AI Hallucinations in Enterprise RAG Systems (A Complete Guide), Redgate Simple Talk](https://www.red-gate.com/simple-talk/ai/how-to-stop-ai-hallucinations-in-enterprise-rag-systems-a-complete-guide/)
4. [Reducing Hallucination in Structured Outputs via Retrieval-Augmented Generation](https://arxiv.org/abs/2404.08189)
5. [Sufficient Context: A New Lens on Retrieval Augmented Generation Systems](https://arxiv.org/abs/2411.06037)
6. [HALT-RAG: A Task-Adaptable Framework for Hallucination Detection with Calibrated NLI Ensembles and Abstention](https://arxiv.org/abs/2509.07475)
7. [MEGA-RAG: Multi-Evidence Guided Answer Refinement for Mitigating Hallucinations](https://pmc.ncbi.nlm.nih.gov/articles/PMC12540348/)
8. [LLM-Assisted Question-Answering on Technical Documents Using Structured Data-Aware RAG](https://arxiv.org/abs/2506.23136)
9. [RAG Without the Lag: Interactive Debugging for Retrieval-Augmented Generation Pipelines](https://arxiv.org/abs/2504.13587)
10. [A Survey of Scaling in Large Language Model Reasoning](https://arxiv.org/abs/2504.02181)
11. [HalluSearch at SemEval-2025 Task 3: A Search-Enhanced RAG Pipeline for Hallucination Detection](https://arxiv.org/abs/2504.10168)
12. [Hallucination Mitigation: RAG, Decoding, and Training, Michael Brenndoerfer](https://mbrenndoerfer.com/writing/hallucination-mitigation)
13. [Enhancing RAG with Active Learning: Reject Incapables and Answer Capables](https://arxiv.org/abs/2502.09073)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and shipping things that survive production. Follow along for more deep dives on the tools changing how we ship software.


Last updated on June 27, 2026

---
title: "The Same Context, Billed on Every Turn: How to Cut Agentic AI Token Costs"
description: "An LLM is stateless, so every turn re-sends the entire context as fresh input tokens. Here are five stacking techniques (caching, lazy-loading, routing, and compaction) that cut agentic token bills by 60–90% with no quality loss."
last_updated: "June 5, 2026"
source: "https://syedmoinuddin.com/blog/cut-agentic-ai-token-costs"
---

# The Same Context, Billed on Every Turn: How to Cut Agentic AI Token Costs

An LLM is stateless, so every turn re-sends the entire context as fresh input tokens. Here are five stacking techniques (caching, lazy-loading, routing, and compaction) that cut agentic token bills by 60–90% with no quality loss.

If your agent feels cheap in the prototype and terrifying on the invoice, the cause is almost always the same: an LLM is stateless, so every turn re-sends the entire context (system prompt, tool schemas, files read, and the full transcript so far) as fresh input tokens. \[7] The fix is not a cheaper model. It's five techniques that stop you paying for the same tokens twice: **prompt caching**, **semantic caching**, **lazy-loading tools**, **routing and cascading**, and **compaction**. Stacked, published case studies and benchmarks put the savings at 60–90% with no measurable quality loss. \[8]\[26] An unoptimized agent running 100 messages a day at \~166K input tokens can run roughly $1,000–$2,500 a month depending on model; the same workload tuned lands closer to $50–$100. \[3]

This is a layered problem, so this is a layered playbook. Apply them in order, caching first, because it's the highest-ROI change you can make to an API bill. \[8]

## Why the bill grows when nothing seems to change

There is no session stored on the provider's servers. Each request is independent, so the runtime re-encodes your whole prompt every single time. \[1] Turn 1 might send 5,000 input tokens. By turn 30 the model is carrying 25,000–35,000 input tokens of accumulated context on *every* request, the system prompt, dozens of retrieved files, and the entire prior transcript. \[7] Multiply that by a loop that runs dozens of steps to finish one task, and the per-call "fraction of a cent" becomes a real number.

Two more things make it worse. Output tokens typically cost 3x to 10x more than input tokens, so a chatty agent is expensive on both ends. \[2] And retry loops compound fast, a tool that errors and gets re-called drags its bloated context along for the ride. \[7]

Everything below is about attacking one of three levers: stop reprocessing tokens you've already paid for, stop loading tokens you don't need, and stop sending tokens to a model that's overkill for the task.

## Layer 1, Prompt caching: stop paying to re-read your own prompt

Prompt caching is the single most impactful change for any app with a large, reused prefix. \[10] Under the hood it's K/V caching: the provider stores the key-value tensors computed from a stable prompt prefix, then skips that computation on the next request that starts with the identical bytes. \[5]

<div className="not-prose my-8 flex justify-center">
  <img src="https://images.syedmoinuddin.com/blogs/cut-agentic-ai-token-costs/kv-caching.png" alt="How prompt caching works under the hood: the text becomes tokens, then vectors, then the K/V tensors a provider stores and reuses when the next request starts with an identical prefix" width={359} height={140} className="h-auto w-full max-w-[359px] rounded-lg ring-1 ring-black/10 dark:ring-white/10" />
</div>

The mechanics differ by provider. **Anthropic** uses explicit, developer-controlled breakpoints, you tag a content block with `cache_control` and everything up to and including it gets cached. \[12] **OpenAI** caches automatically once a stable prefix exceeds \~1,024 tokens, billing the cached portion at 50% of the normal input rate with no code changes. \[13] **Google** offers both implicit caching (automatic, no guaranteed savings) and explicit context caching with guaranteed discounts. \[5]

Anthropic's pricing is the one worth memorizing because it's the most controllable:

* Cache **write**: 1.25× base input for a 5-minute TTL, or 2.0× for a 1-hour TTL. \[12]
* Cache **read**: 0.10× base input, a 90% discount. \[12]

That read discount breaks even after roughly two reads on the 5-minute tier, or three reads on the 1-hour tier. \[15] Output tokens are unaffected; caching only changes the input side. \[15]

Here's the minimal Anthropic setup, note that order matters, because the cache is strictly prefix-based:

```json
{
  "system": [
    {
      "type": "text",
      "text": "You are a code reviewer for a strict TypeScript monorepo...",
      "cache_control": { "type": "ephemeral", "ttl": "1h" }
    }
  ],
  "messages": [{ "role": "user", "content": "Review this diff." }]
}
```

Three rules decide whether you actually get the hit:

1. **Put stable content first.** System instructions, tool schemas, retrieval context, and few-shot examples go at the front; the dynamic user turn goes last. \[8] Anything that changes mid-prefix invalidates everything after it. \[14]
2. **Mind the TTL default.** As of March 6, 2026, Anthropic's *default* TTL dropped from 1 hour to 5 minutes. \[11] If your traffic is bursty (say, a request every 7 minutes) you'll pay the write cost every time and never read. Set `"ttl": "1h"` explicitly for shared static content like a system prompt that needs to stay warm across users. \[13]\[14]
3. **Watch the breakpoint limit.** You get up to four breakpoints per request, and if you modify content earlier than the 20 blocks before a breakpoint, you lose the hit. Teams running long agent loops add intermediate breakpoints every \~18 blocks to keep more of the prefix cached. \[14]\[15]

The numbers justify the fuss. ProjectDiscovery's Neo agent documented a 59% cost drop from prompt caching alone, climbing past 90% on fully optimized paths. \[8]\[14] Track your `cache_read_input_tokens` to `input_tokens` ratio in the console, aim for a hit rate above 70% on stable-prompt workloads. \[2]\[11]

## Layer 2, Semantic caching: skip the model entirely on near-duplicate queries

Prompt caching and semantic caching sound similar and do completely different things. \[4] Prompt caching requires a 100% exact prefix match and discounts the input you reprocess. \[12] Semantic caching skips the LLM call altogether when a *new* query is close enough in meaning to one you've already answered.

The pattern: embed the incoming query, run a vector similarity search against recent queries, and if cosine similarity clears a threshold, typically 0.92–0.95, return the cached response instead of hitting the model. \[33]

```python
q_vec = embed(user_query)
hit = vector_store.search(q_vec, k=1)

if hit and hit.score >= 0.93:
    return hit.cached_response          # zero LLM tokens spent
else:
    answer = call_llm(user_query)
    vector_store.upsert(q_vec, answer)
    return answer
```

Realistic hit rates run 25–40% for customer-facing apps and 50–60% for internal tools with repetitive queries, and your API cost drops roughly in proportion to the hit rate. \[33] Common implementations use GPTCache, Redis with vector search, or pgvector. \[33] For fully deterministic outputs (status checks, periodic reports, FAQ responses) plain application-layer response caching eliminates the call before you even reach the semantic layer. \[32]

The one caveat: set the threshold carefully. Too low and you'll return confidently wrong answers to questions you never actually answered.

## Layer 3, Lazy-load tools: don't pay for a toolbox you never open

This is the silent killer in MCP-heavy setups. The more tools a model knows about, the more schema it has to carry in context on every interaction, and all of it loads *before* your first prompt does any work. \[19] A typical enterprise MCP server with 400 tools consumes over 400,000 tokens just loading schemas, which doesn't even fit inside a 200K context window. \[21]

Progressive disclosure fixes this by revealing tool complexity gradually. Instead of front-loading every definition, the agent discovers tools on demand and fetches the full schema only when it's about to use one. \[21] Anthropic's MCP Tool Search is the retrofit version: 50 MCP tools that previously cost \~77K tokens drop to \~8.7K with tool search active, about an 85% reduction, preserving 95% of the context window for actual work. \[24]

<div className="not-prose my-8 flex justify-center">
  <img src="https://images.syedmoinuddin.com/blogs/cut-agentic-ai-token-costs/tool-search-costs.png" alt="Token cost of MCP tool loading compared: eager loading with no cache ($17,280) versus tool search plus caching ($2,588), with the eager-and-caching and tool-search-no-cache options in between" width={294} height={172} className="h-auto w-full max-w-[294px] rounded-lg ring-1 ring-black/10 dark:ring-white/10" />
</div>

There's a quality dividend too, not just a cost one. Model accuracy degrades when it has to choose from too many tools; research puts the threshold around 20–25 tools before selection accuracy measurably declines. \[21] Anthropic's internal testing found that lazy tool loading improved Opus 4's tool-selection accuracy from 49% to 74%, fewer irrelevant options means more reasoning spent on the actual task. \[21]

Agent Skills are the same idea at the knowledge layer. In Claude Code, only a \~1,024-character description loads per skill at startup; the full `SKILL.md` body loads only when the skill is relevant, and supporting files load only when referenced. \[23]\[24] The pattern generalizes: always load high-frequency tools, and defer rare ones behind a search interface or on-demand fetch. \[23]

A practical host-layer rule you can implement today without waiting for protocol changes:

```text
- Tools used > 60% of sessions   →  load eagerly
- Tools used < 10% of sessions   →  expose name + 1-line description only;
                                     hydrate full schema on first call
```

You'll almost always find a Pareto pattern, a handful of verbose tools that rarely get used are eating a disproportionate slice of context. \[23] That's where the cheapest wins live.

## Layer 4, Routing and cascading: stop sending easy work to expensive models

Most organizations use their most expensive model for every request, and that single habit drives the bulk of avoidable spend. \[33] Not every task needs a frontier model. Routing dispatches each query to the cheapest model that can handle it adequately; cascading starts cheap and escalates only when the cheap model isn't confident. \[29]\[32]

A lightweight classifier, a small model or even a rules-based check, sorts requests by complexity, then routes. \[33] In practice, 50–70% of enterprise requests can be handled by the cheapest tier, \[33] and a well-built cascade lands around 87% cost reduction by ensuring the expensive model only sees the \~10% of queries that genuinely need it. \[32]

```python
tier = classify_complexity(query)   # tiny/fast classifier

if tier == "simple":
    model = "haiku"     # lookups, formatting, extraction
elif tier == "standard":
    model = "sonnet"    # most code and analysis
else:
    model = "opus"      # architectural reasoning, hard debugging

answer = call(model, query)
```

You don't have to hand-roll the gateway. LiteLLM, Portkey, OpenRouter, and Bifrost all support multi-model routing and fallback out of the box, \[32] and a production-grade gateway can cut costs up to 85% while holding \~95% of top-tier performance. \[29] If you live in Claude Code, the built-in version is `/model opusplan` at session start, Opus for planning, a cheaper model for execution. \[8]

A related lever: don't make the model reason when it doesn't need to. Selective reasoning, only enabling chain-of-thought or higher "thinking effort" on hard queries, has been shown to cut token consumption by \~48% while *improving* accuracy on a reasoning benchmark, because indiscriminate reasoning wastes tokens on straightforward questions. \[31]

## Layer 5, Compaction and clean context: pay for signal, not history

The last lever attacks accumulated history. Long sessions don't just get expensive, they get *confused*. As context fills, performance degrades in a way Anthropic calls "context rot": the agent starts re-reading files it already read, restating decisions, and drifting from your original constraints. \[1]\[37] Context drift kills agents before context limits do. \[9]

There are three complementary moves here.

**Compaction.** Anthropic shipped a server-side Compaction API in beta (January 2026, for Opus 4.6 and Sonnet 4.6 and carried into Opus 4.8) that automates the summarize-and-replace loop. When input tokens cross a configurable threshold, the API summarizes the conversation so far, drops the older message blocks, and continues from the compressed summary, no client-side history juggling. \[39]\[40] Crucially for your bill, only the new summary needs to be written as a fresh cache entry. \[39]

```python
import anthropic

client = anthropic.Anthropic()

response = client.beta.messages.create(
    betas=["compact-2026-01-12"],
    model="claude-opus-4-8",
    max_tokens=4096,
    messages=messages,
    context_management={"edits": [{"type": "compact_20260112"}]},
)
```

**Sub-agents.** Instead of one agent dragging the entire context through every step, spin up separate agent instances for isolated parts of a task, so no single agent has to carry the whole thing. \[1] It's a cleaner solution for complex, long-running work, and it keeps each context window focused.

**Trim at ingestion, not at compression.** Tool output verbosity is the primary token-budget killer. \[9] Filter and truncate tool responses *as they come in*, keep only what the agent needs to reason about next, rather than letting junk accumulate and paying to summarize it later. \[9] Removing that noise typically clears 30–70% of a context window, saving roughly the same in dollars. \[4]

The payoff isn't only financial. On SWE-bench Verified, a 6x context-compression approach delivered a 51.8–71.3% token-budget reduction *and* a 5.0–9.2% improvement in issue-resolution rates, cleaner context is both cheaper and better. \[4] Guideline-based compaction methods (ACON) report 26–54% reductions in peak token usage on agentic benchmarks. \[9]

Watch for the drift signals as your trigger: re-reads of already-processed content, restated decisions, or the goal wording quietly changing mid-task. \[9]

## One more free win: cap your outputs and batch your offline work

Two quick ones that don't fit a layer but pay for themselves. First, set `max_tokens` deliberately, output tokens are your 3x–10x cost multiplier, so an unbounded ceiling is an open tab. \[2] Second, anything that doesn't need a real-time answer (overnight document processing, bulk classification, evals) belongs on a Batch API, which runs at a 50% discount. \[32]

And put a guardrail on the whole thing: soft budget alerts at 50% and 80% of your monthly cap, plus a hard limit that pauses processing at 100%. A single runaway loop from a coding bug can drain a budget overnight. \[2]

## Decision checklist: which layer to reach for

**Reach for prompt caching if…**

* You have a large, stable system prompt, tool schema, or document context reused across calls.
* Your cache-read-to-input ratio is low and your prompts haven't changed, you may be silently on the 5-minute TTL. \[11]
* You're running multi-turn agent loops (the prefix barely changes between steps).

**Reach for semantic caching if…**

* Your traffic has meaningful query repetition (support bots, internal FAQ tools).
* Near-duplicate questions are common and exact-match caching keeps missing them.

**Reach for lazy-loading if…**

* You've connected more than \~20–25 tools and notice the agent picking wrong tools. \[21]
* A huge chunk of your context is consumed before the first user message. \[19]

**Reach for routing/cascading if…**

* You're sending every request to your most expensive model.
* Your traffic has a clear easy/hard split (most of it is easy).

**Reach for compaction if…**

* Sessions are long-running and hit the context window.
* The agent is showing drift, re-reading files, forgetting constraints. \[1]

**Don't bother (yet) if…**

* You're pre-product-market-fit at trivial volume, instrument first, optimize when the bill is real.
* Your prompts are unique every time with no reuse (caching won't help; focus on routing and output limits).
* Every query genuinely needs frontier-model reasoning (routing buys you little; compaction and caching still do).

<div className="not-prose my-8 flex justify-center">
  <img src="https://images.syedmoinuddin.com/blogs/cut-agentic-ai-token-costs/savings-stack.png" alt="The savings stack: prompt and semantic caching, lazy-loading context, routing and cascading, and context compaction layered together into one cost-reduction strategy" width={335} height={150} className="h-auto w-full max-w-[335px] rounded-lg ring-1 ring-black/10 dark:ring-white/10" />
</div>

*Pricing, TTL defaults, and beta feature availability in this space change quickly, verify the current details in each provider's pricing page and docs before publishing.*

## Sources

1. Muhammad Attaullah Bhatti, "Why Long AI Sessions Get Expensive and Confused." Medium. [https://muhammadattaullahbhatti.medium.com/why-long-ai-sessions-get-expensive-and-confused-token-burning-prompt-caching-context-windows-and-5b2258b2454d](https://muhammadattaullahbhatti.medium.com/why-long-ai-sessions-get-expensive-and-confused-token-burning-prompt-caching-context-windows-and-5b2258b2454d)
2. Fastio, "AI Agent Token Cost Optimization: Complete Guide for 2026." [https://fast.io/resources/ai-agent-token-cost-optimization/](https://fast.io/resources/ai-agent-token-cost-optimization/)
3. Ida Silfverskiöld, "Agentic AI: How to Save on Tokens." Data Science Collective, Medium. [https://medium.com/data-science-collective/agentic-ai-how-to-save-on-tokens-9a1571ac6c85](https://medium.com/data-science-collective/agentic-ai-how-to-save-on-tokens-9a1571ac6c85)
4. "Agentic AI: How to Save on Tokens." Towards Data Science. [https://towardsdatascience.com/agentic-ai-how-to-save-on-tokens/](https://towardsdatascience.com/agentic-ai-how-to-save-on-tokens/)
5. "Don't Break the Cache: An Evaluation of Prompt Caching for Long-Horizon Agentic Tasks." arXiv. [https://arxiv.org/pdf/2601.06007](https://arxiv.org/pdf/2601.06007)
6. NVIDIA Technical Blog, "Building for the Rising Complexity of Agentic Systems with Extreme Co-Design." [https://developer.nvidia.com/blog/building-for-the-rising-complexity-of-agentic-systems-with-extreme-co-design/](https://developer.nvidia.com/blog/building-for-the-rising-complexity-of-agentic-systems-with-extreme-co-design/)
7. Vantage, "The Hidden Cost Driver in Agentic Coding Sessions in 2026." [https://www.vantage.sh/blog/agentic-coding-costs](https://www.vantage.sh/blog/agentic-coding-costs)
8. ProgramStrategyHQ, "Techniques to Reduce AI Token Usage: The 2026 Playbook." [https://www.programstrategyhq.com/post/techniques-to-reduce-ai-token-usage-the-2026-playbook-for-cutting-costs-without-losing-quality](https://www.programstrategyhq.com/post/techniques-to-reduce-ai-token-usage-the-2026-playbook-for-cutting-costs-without-losing-quality)
9. Zylos Research, "AI Agent Context Compression: Strategies for Long-Running Sessions." [https://zylos.ai/research/2026-02-28-ai-agent-context-compression-strategies/](https://zylos.ai/research/2026-02-28-ai-agent-context-compression-strategies/)
10. Finout, "Anthropic API Pricing in 2026: Complete Guide." [https://www.finout.io/blog/anthropic-api-pricing](https://www.finout.io/blog/anthropic-api-pricing)
11. DEV Community, "Anthropic Silently Dropped Prompt Cache TTL from 1 Hour to 5 Minutes." [https://dev.to/whoffagents/anthropic-silently-dropped-prompt-cache-ttl-from-1-hour-to-5-minutes-16ao](https://dev.to/whoffagents/anthropic-silently-dropped-prompt-cache-ttl-from-1-hour-to-5-minutes-16ao)
12. Claude API Docs, "Prompt caching." [https://platform.claude.com/docs/en/build-with-claude/prompt-caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching)
13. Technspire, "Prompt Caching in 2026: Anthropic, OpenAI, Azure Compared." [https://technspire.com/en/blog/prompt-caching-2026-real-cost-wins](https://technspire.com/en/blog/prompt-caching-2026-real-cost-wins)
14. ProjectDiscovery, "How We Cut LLM Costs by 59% With Prompt Caching." [https://projectdiscovery.io/blog/how-we-cut-llm-cost-with-prompt-caching](https://projectdiscovery.io/blog/how-we-cut-llm-cost-with-prompt-caching)
15. DEV Community, "Prompt Caching With the Claude API: A Practical Guide." [https://dev.to/thegdsks/prompt-caching-with-the-claude-api-a-practical-guide-14ce](https://dev.to/thegdsks/prompt-caching-with-the-claude-api-a-practical-guide-14ce)
16. Solo.io, "Reduce MCP Token Usage with Agentgateway Progressive Disclosure." [https://www.solo.io/blog/keeping-context-and-tokens-low-with-progressive-disclosure-in-agentgateway](https://www.solo.io/blog/keeping-context-and-tokens-low-with-progressive-disclosure-in-agentgateway)
17. Matthew Kruczek, "Progressive Disclosure MCP: 85x Token Savings Benchmark." [https://matthewkruczek.ai/blog/progressive-disclosure-mcp-servers.html](https://matthewkruczek.ai/blog/progressive-disclosure-mcp-servers.html)
18. Layered System, "MCP Tool Schema Bloat: The Hidden Token Tax (and How to Fix It)." [https://layered.dev/mcp-tool-schema-bloat-the-hidden-token-tax-and-how-to-fix-it/](https://layered.dev/mcp-tool-schema-bloat-the-hidden-token-tax-and-how-to-fix-it/)
19. Software Thug, "Claude Code MCP Tool Search: How Lazy Loading Cut Token Usage by 85%." [https://www.softwarethug.com/posts/claude-code-mcp-tool-search-lazy-loading/](https://www.softwarethug.com/posts/claude-code-mcp-tool-search-lazy-loading/)
20. PremAI, "LLM Cost Optimization: 8 Strategies That Cut API Spend by 80% (2026 Guide)." [https://blog.premai.io/llm-cost-optimization-8-strategies-that-cut-api-spend-by-80-2026-guide/](https://blog.premai.io/llm-cost-optimization-8-strategies-that-cut-api-spend-by-80-2026-guide/)
21. Maxim, "Top 5 LLM Routing Techniques." [https://www.getmaxim.ai/articles/top-5-llm-routing-techniques/](https://www.getmaxim.ai/articles/top-5-llm-routing-techniques/)
22. "When to Reason: Semantic Router for vLLM." arXiv. [https://arxiv.org/pdf/2510.08731](https://arxiv.org/pdf/2510.08731)
23. Zylos Research, "AI Agent Cost Optimization: Token Economics and FinOps in Production." [https://zylos.ai/research/2026-02-19-ai-agent-cost-optimization-token-economics](https://zylos.ai/research/2026-02-19-ai-agent-cost-optimization-token-economics)
24. TechCloudPro, "How to Cut Enterprise LLM Costs by 50%: Caching, Routing, and Infrastructure Strategies." [https://techcloudpro.com/blog/enterprise-llm-cost-optimization/](https://techcloudpro.com/blog/enterprise-llm-cost-optimization/)
25. InfoQ, "Claude Opus 4.6 Introduces Adaptive Reasoning and Context Compaction for Long-Running Agents." [https://www.infoq.com/news/2026/03/opus-4-6-context-compaction/](https://www.infoq.com/news/2026/03/opus-4-6-context-compaction/)
26. Claude API Docs, "Compaction." [https://platform.claude.com/docs/en/build-with-claude/compaction](https://platform.claude.com/docs/en/build-with-claude/compaction)
27. Claude Lab, "Context Compaction API Complete Guide." [https://claudelab.net/en/articles/api-sdk/compaction-api-context-management](https://claudelab.net/en/articles/api-sdk/compaction-api-context-management)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and the frontend/backend craft. June 2026.


Last updated on June 5, 2026

---
title: "You Don't Import It, You Own It: Why shadcn/ui Beats Every Other Component Library"
description: "Most UI libraries hand you a black box and hope you never look inside. shadcn/ui hands you the source, and that one decision changes everything downstream."
last_updated: "June 5, 2026"
source: "https://syedmoinuddin.com/blog/shadcn-ui-you-own-it"
---

# You Don't Import It, You Own It: Why shadcn/ui Beats Every Other Component Library

Most UI libraries hand you a black box and hope you never look inside. shadcn/ui hands you the source, and that one decision changes everything downstream.

*Most UI libraries hand you a black box and hope you never look inside. shadcn/ui hands you the source, and that one decision changes everything downstream.*

Here's the whole argument before I defend it: every other component library is something you *rent*. You import a `<Button>`, it arrives as a sealed dependency, and customizing it means fighting someone else's CSS from the outside. shadcn/ui drops the actual component code into your repo, styled with Tailwind you can read and edit. You own it. That single difference is why it's the best UI approach we have right now.

Let me show you why.

## The rented-button problem

If you've shipped real frontend, you know the tax. You install a component library, drop in a button, and it looks great, until the design spec calls for a 2px-tighter radius and a different focus ring. Now you're three `!important` overrides deep, fighting a stylesheet you can't see.

The reason is structural, not a bug. Traditional libraries ship as a compiled package, so the component internals live behind an abstraction layer you're not meant to touch. You customize *around* the author's decisions, never *through* them.

shadcn/ui removes the layer entirely. The fix isn't a better override API, it's no override needed at all.

## Layer 1, The components land in your codebase

You run one command and the source code arrives in your folder:

```bash
npx shadcn@latest add button
```

That `button.tsx` is now yours. Change the hover state by editing the file. Add a variant the maintainers never imagined. There's no theme-provider gymnastics and no waiting on a merged PR. The code does exactly what you can see it doing.

This sounds like a small philosophical difference. In practice it's the line between a library that fights you and one that disappears into your codebase.

## Layer 2, Accessibility you didn't have to build

The usual catch with "just copy the code" is that you inherit the hard parts: keyboard nav, focus traps, ARIA wiring, screen-reader behavior. A truly accessible dropdown is genuinely difficult work.

shadcn/ui sidesteps the tradeoff. Components sit on battle-tested headless primitives, and as of 2026 you choose the engine: Radix UI for the exhaustive accessibility feature set, or Base UI for leaner bundles, both behind the identical component API. \[1]\[2] The primitive handles the brutal a11y logic; the shadcn layer gives you styling you fully control. You get correctness *and* ownership, which used to be an either/or.

## Layer 3, Tailwind keeps the styling honest

Every component is styled with Tailwind utility classes right there in the file. No hidden stylesheet, no CSS-in-JS runtime, no specificity war. A dev who's never seen the repo can open `button.tsx` and understand exactly why it looks the way it does in ten seconds.

Theming runs through CSS variables and design tokens, so one change to your color or radius cascades cleanly everywhere. With Tailwind v4 underneath, that token system is faster than the config-file era ever was. \[1] Change one thing, everything updates, nothing breaks invisibly.

## Layer 4, The registry turned it into an ecosystem

shadcn/ui stopped being "a set of components" a while ago. The registry model lets anyone publish components that install the same frictionless way, and the community ran with it, an enormous catalog of blocks, dashboard shells, data tables, multi-step forms, and full design systems, all installable through the same CLI and all inheriting your project's tokens automatically. \[3]

These aren't sealed templates. They land as editable code, exactly like the core components. Start from a production-grade dashboard and reshape it instead of starting from an empty `<div>`. Namespaced registries even let teams run their own internal "store" per product. \[3]

![shadcn/ui, a CLI and registry that copies component source straight into your project](https://images.syedmoinuddin.com/blogs/shadcn-ui-you-own-it/wordmark.png)

## Layer 5, Built for the agent-assisted workflow

This is where it pulled genuinely ahead. The 2026 CLI v4 release leaned into the reality that a lot of UI now gets built with coding agents in the loop. \[4]

You can preview what a registry will add before anything touches your files:

```bash
npx shadcn@latest add button --dry-run
npx shadcn@latest add button --diff
npx shadcn@latest add button --view
```

`init` scaffolds full templates for Next.js, Vite, Astro, Laravel, React Router, and TanStack Start. \[4] And `shadcn/skills` feeds coding agents the project-specific context (which primitives are in use, the registry layout, the current APIs) so the agent building your UI stops hallucinating a different library's syntax. \[4]\[5] Most libraries treat AI assistance as an afterthought. shadcn/ui built the rails for it.

## Who's actually running this

You don't have to take the philosophy on faith. The approach is trusted in production by teams at OpenAI, Sonos, and Adobe, among others. \[2] When the orgs with the most demanding design and accessibility bars converge on the same pattern, that's signal, not hype.

## Is shadcn/ui a fit for you?

**It's a fit if you:**

* Work in React and are comfortable with Tailwind
* Want full control over component markup and styles
* Care about accessibility but don't want to build it from scratch
* Build with coding agents and want them to understand your setup
* Maintain a design system across multiple products

**It's probably not a fit if you:**

* Want a fully managed library where upgrades are automatic and you never touch internals (MUI or Mantine may suit you better)
* Aren't using React or Tailwind and don't want to adopt them
* Need a no-code or drag-and-drop UI builder
* Have zero appetite for owning and maintaining component code in your repo

## The bottom line

The best UI library is the one that gives you the correctness of a serious framework and the control of writing it yourself, without forcing the choice. shadcn/ui is the only popular option that delivers both: accessible primitives you didn't have to build, styled with code you fully own, installable in seconds, extensible through a thriving registry, and tuned for the agent-assisted workflow that defines frontend work today.

You don't import shadcn/ui. You absorb it. And once you've built with a library that works *with* you instead of around you, renting your buttons feels unthinkable.

## Sources

1. shadcn/ui, *shadcn/cli v4* changelog (March 2026): [https://ui.shadcn.com/docs/changelog/2026-03-cli-v4](https://ui.shadcn.com/docs/changelog/2026-03-cli-v4)
2. shadcn/ui, *Package Imports and Target Aliases* changelog (May 2026): [https://ui.shadcn.com/docs/changelog/2026-05-package-imports-target-aliases](https://ui.shadcn.com/docs/changelog/2026-05-package-imports-target-aliases)
3. shadcn/ui, Changelog index (Blocks, Unified Radix Package, Registry Directory): [https://ui.shadcn.com/docs/changelog](https://ui.shadcn.com/docs/changelog)
4. shadcn/ui, CLI v4, project templates, and `shadcn/skills` (March 2026): [https://ui.shadcn.com/docs/changelog/2026-03-cli-v4](https://ui.shadcn.com/docs/changelog/2026-03-cli-v4)
5. shadcn/ui March 2026 Update: CLI v4, AI Agent Skills and Design System Presets (Medium): [https://medium.com/@nakranirakesh/shadcn-ui-march-2026-update-cli-v4-ai-agent-skills-and-design-system-presets-d30cf200b0e9](https://medium.com/@nakranirakesh/shadcn-ui-march-2026-update-cli-v4-ai-agent-skills-and-design-system-presets-d30cf200b0e9)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and the frontend/backend craft. Follow along for more deep dives on the tools changing how we ship software.


Last updated on June 5, 2026

---
title: "The 12 AI Books That Actually Make You Better at Building (2026)"
description: "A pillar-by-pillar reading guide for engineers shipping agents, LLM systems, RAG, evals, and reliable production AI, organized by what you build, not by hype."
last_updated: "June 2, 2026"
source: "https://syedmoinuddin.com/blog/12-ai-books-that-make-you-better-at-building-2026"
---

# The 12 AI Books That Actually Make You Better at Building (2026)

A pillar-by-pillar reading guide for engineers shipping agents, LLM systems, RAG, evals, and reliable production AI, organized by what you build, not by hype.

*A pillar-by-pillar reading guide for engineers shipping agents, LLM systems, RAG, evals, and reliable production AI.*

Most "best AI books" lists are written for curiosity. This one is written for people who have to make it work in production on Monday.

If you only have time for three, read **AI Engineering** by Chip Huyen, the **LLM Engineer's Handbook** by Iusztin and Labonne, and **Designing Machine Learning Systems**, also Huyen. Those three alone give you the full arc: how to think about an LLM product, how to build it, and how to keep it alive under real traffic.

The other nine are here because at some point you'll hit a specific wall (a flaky agent loop, a RAG pipeline that retrieves garbage, an eval suite you don't trust) and you'll want the book that was written by someone who already hit that exact wall. That's how I've organized this: by the five things engineers actually build, not by hype.

We're past the era of writing a clever prompt and calling it a product. So let's read like builders.

***

![The five things engineers actually build, Backend, Agents, and RAG mapping to concrete outputs](https://images.syedmoinuddin.com/blogs/12-ai-books-that-make-you-better-at-building-2026/ai-books-pillars.png)

## Pillar 1, LLM Systems: understand the thing you're calling

You can build a lot on top of an API you don't understand. You just can't *debug* it. These three move you from "API user" to "engineer who knows why the output looks like that."

**1. Build a Large Language Model (From Scratch), Sebastian Raschka**
The one that ends the black-box era for you. You build a working LLM in PyTorch step by step: tokenization, attention, the transformer block, pretraining, fine-tuning. Raschka explains hard ideas with unusual clarity, and once you've implemented attention yourself, every weird model behavior afterward makes more sense.
*Best for:* engineers who want intuition, not just incantations.
*Skip if:* you genuinely never need to reason about model internals, but you probably do.

**2. Hands-On Large Language Models, Jay Alammar & Maarten Grootendorst**
Alammar is the person behind "The Illustrated Transformer," and the same visual instinct runs through the whole book. It's the fastest path from concept to running code across tokenization, embeddings, fine-tuning, and evaluation using the Hugging Face ecosystem.
*Best for:* people who learn by building and want the visuals to stick.
*Skip if:* you want pure from-scratch theory, pair it with Raschka instead.

**3. Prompt Engineering for LLMs, John Berryman & Albert Ziegler**
Prompting got dismissed as a fad and then quietly became context engineering, the highest-leverage skill in the stack. This is the rigorous treatment: how models read your input, why structure beats cleverness, and how to design prompts that hold up in a system instead of a demo.
*Best for:* anyone whose "it works in the playground" keeps breaking in production.
*Skip if:* you've already internalized context engineering deeply.

***

## Pillar 2, Agents: systems that don't just respond, they act

A year ago most teams were wiring up basic retrieval. Now multi-agent orchestration, tool-calling, and autonomous task loops are shipping into production. These three teach the patterns that keep agents from turning brittle.

![An agent orchestrating tools and tasks, fanning out to a toolset, documents, and long-running work, then looping the results back](https://images.syedmoinuddin.com/blogs/12-ai-books-that-make-you-better-at-building-2026/ai-books-agent-orchestration.png)

**4. AI Agents and Applications, Roberto Infante (Manning)**
The most design-pattern-focused of the bunch. It moves from prompt and context engineering to advanced RAG to multi-agent systems with `LangGraph` and `MCP`, with a deliberate focus on concepts and architectures that stay stable even as models and APIs churn. That "won't go stale next quarter" framing is exactly what you want from an agents book.
*Best for:* backend engineers building real, multi-step agent systems.
*Skip if:* you only need a single-shot tool-calling helper.

**5. Building LLM-Powered Applications, Valentina Alto**
The fastest zero-to-prototype book. `LangChain`, memory, chains, and agents from chapter one, with current code. Its strongest section is the practical one: structuring agent loops, handling failures gracefully, and chaining tools without the whole thing becoming fragile, plus multi-agent collaboration patterns.
*Best for:* getting a working agent prototype standing up quickly.
*Skip if:* you want framework-agnostic theory over hands-on LangChain.

**6. Multi-Agent Systems with AutoGen, Victor Dibia**
When one agent isn't enough and you need several specialized agents collaborating, this is the focused deep-dive. Dibia covers designing and implementing multi-agent systems with the `AutoGen` framework, conversation patterns, roles, and orchestration.
*Best for:* teams committing to a multi-agent architecture.
*Skip if:* a single agent with good tools still solves your problem (it often does).

***

## Pillar 3, RAG: retrieval that doesn't hand back garbage

RAG is "easy to demo, hard to make good." The gap is chunking, reranking, evaluation, and knowing when plain retrieval isn't enough. These two close it.

**7. Unlocking Data with Generative AI and RAG, Keith Bourne (Packt)**
A dedicated, end-to-end RAG book: pipelines, RAG-powered memory, graph-based RAG, and reliable recall. If retrieval is the core of what you build, this is the focused text rather than a chapter inside a broader book.
*Best for:* engineers whose product *is* the retrieval layer.
*Skip if:* you only need light RAG inside a larger app, Huyen's chapter may be enough.

**8. Generative AI with LangChain (2nd ed.), Ben Auffarth & Leonid Kuligin**
The "connect LLMs to the real world" book. It covers wiring models to tools, databases, and APIs, with RAG and multi-agent workflows built on `LangChain` and `LangGraph`. The second edition is current, which matters in a framework that moves this fast.
*Best for:* building domain assistants that pull from your own data.
*Skip if:* you're avoiding the LangChain ecosystem entirely.

***

## Pillar 4, Evals & the full-stack picture: know if it's actually working

Building the system is half the job. Knowing whether it's good, and proving it didn't regress after a model swap, is the other half. This is where most teams are weakest.

![A desk buried in changelog scraps and dated notes under a lamp, a compass at the center, finding direction in the mess is exactly what evals are for](https://images.syedmoinuddin.com/blogs/12-ai-books-that-make-you-better-at-building-2026/ai-books-reading-desk.webp)

**9. AI Engineering, Chip Huyen (O'Reilly, 2025)**
If you read one book on this list, make it this one. It covers the full stack of production LLM applications: evaluation frameworks, prompt design, RAG, agent architectures, and the real deployment tradeoffs, latency vs. accuracy, cost vs. capability, automation vs. human oversight. The evals material alone is worth the cover price, because almost nobody else treats it this seriously.
*Best for:* literally every AI engineer in 2026.
*Skip if:* there is no good reason to skip this one.

**10. LLM Engineer's Handbook, Paul Iusztin & Maxime Labonne**
Reads like it was written by engineers who already hit the walls you're about to hit. End-to-end: data, fine-tuning, evaluation, deployment, and the operational glue. It's the practical companion to Huyen's more conceptual full-stack view.
*Best for:* turning a prototype into a maintainable LLM application.
*Skip if:* you're still at the "what even is fine-tuning" stage, start with Pillar 1.

***

## Pillar 5, Production reliability: shipping is when the hard part starts

A script that works on your laptop and a system that runs for months are different animals. These two are about the second animal.

**11. Designing Machine Learning Systems, Chip Huyen**
The system-level classic. Data pipelines, deployment, monitoring, scaling, and the failure modes that only show up in production. It predates the LLM gold rush, which is exactly why it's durable, these fundamentals don't expire when the model names change.
*Best for:* tech leads and architects responsible for the whole system.
*Skip if:* you want LLM-specific tactics first, read it second, after AI Engineering.

**12. Building LLMs for Production, Louis-François Bouchard & Louie Peters**
The bridge from prototype to production specifically for LLM apps: reliability, scaling, fine-tuning, and the deployment patterns that bite teams shipping real products rather than running experiments.
*Best for:* the messy gap between "the demo works" and "it survives launch."
*Skip if:* you're not shipping to real users yet.

***

## The 12 at a glance

| #  | Book                                        | Pillar             | Level                 | Best for                               |
| -- | ------------------------------------------- | ------------------ | --------------------- | -------------------------------------- |
| 1  | Build a Large Language Model (From Scratch) | LLM Systems        | Intermediate          | Model intuition from first principles  |
| 2  | Hands-On Large Language Models              | LLM Systems        | Beginner–Intermediate | Learning by building, visually         |
| 3  | Prompt Engineering for LLMs                 | LLM Systems        | Beginner–Intermediate | Context engineering that survives prod |
| 4  | AI Agents and Applications                  | Agents             | Intermediate          | Durable agent design patterns          |
| 5  | Building LLM-Powered Applications           | Agents             | Beginner–Intermediate | Fast agent prototypes                  |
| 6  | Multi-Agent Systems with AutoGen            | Agents             | Intermediate–Advanced | Multi-agent orchestration              |
| 7  | Unlocking Data with Generative AI and RAG   | RAG                | Intermediate          | Retrieval-first products               |
| 8  | Generative AI with LangChain (2nd ed.)      | RAG                | Intermediate          | Domain assistants over your data       |
| 9  | AI Engineering                              | Evals / Full stack | Intermediate          | Everyone, the anchor read              |
| 10 | LLM Engineer's Handbook                     | Evals / Full stack | Intermediate          | Prototype → maintainable app           |
| 11 | Designing Machine Learning Systems          | Production         | Intermediate–Advanced | System-level reliability               |
| 12 | Building LLMs for Production                | Production         | Intermediate          | Surviving launch                       |

***

## Where to actually start (don't read all 12 at once)

You don't need twelve books. You need the three that match what you're building right now. Pick your track:

* **Building agents?** → AI Engineering (9) → AI Agents and Applications (4) → LLM Engineer's Handbook (10)
* **Building RAG / search?** → AI Engineering (9) → Unlocking Data with GenAI and RAG (7) → Generative AI with LangChain (8)
* **Going deep on fundamentals?** → Build an LLM From Scratch (1) → Hands-On LLMs (2) → AI Engineering (9)
* **Responsible for reliability / scale?** → Designing ML Systems (11) → AI Engineering (9) → Building LLMs for Production (12)

One book a month. In a quarter you'll have depth most people in this space simply don't have.

**A reading list is a fit if you:** ship AI features, own reliability, or keep getting stuck past the demo stage.
**It's probably not a fit if you:** just want a high-level "what is AI" overview, these are builder's books, and they assume you write code.

***

## Sources

1. Chip Huyen, *AI Engineering*, O'Reilly, 2025.
2. Chip Huyen, *Designing Machine Learning Systems*, O'Reilly.
3. Sebastian Raschka, *Build a Large Language Model (From Scratch)*.
4. Jay Alammar & Maarten Grootendorst, *Hands-On Large Language Models*, O'Reilly.
5. John Berryman & Albert Ziegler, *Prompt Engineering for LLMs*, O'Reilly.
6. Paul Iusztin & Maxime Labonne, *LLM Engineer's Handbook*, Packt.
7. Valentina Alto, *Building LLM-Powered Applications*.
8. Roberto Infante, *AI Agents and Applications: With LangChain, LangGraph, and MCP*, Manning.
9. Victor Dibia, *Multi-Agent Systems with AutoGen*, Manning.
10. Ben Auffarth & Leonid Kuligin, *Generative AI with LangChain*, 2nd ed.
11. Keith Bourne, *Unlocking Data with Generative AI and RAG*, Packt.
12. Louis-François Bouchard & Louie Peters, *Building LLMs for Production*.

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and shipping things that survive production. Follow along for more deep dives on the tools changing how we ship software.


Last updated on June 2, 2026

---
title: "The Claude Workflow That Replaced 200 Words of Context With Two Sentences"
description: "How stacking four Claude features lets you stop re-explaining yourself at the start of every chat, and just ask for the thing. Preferences, Styles, Projects, and Memory do the carrying."
last_updated: "June 2, 2026"
source: "https://syedmoinuddin.com/blog/claude-workflow-replaced-200-words-with-two-sentences"
---

# The Claude Workflow That Replaced 200 Words of Context With Two Sentences

How stacking four Claude features lets you stop re-explaining yourself at the start of every chat, and just ask for the thing. Preferences, Styles, Projects, and Memory do the carrying.

*How stacking four Claude features lets you stop re-explaining yourself at the start of every single chat, and just ask for the thing.*

Here's the whole trick before the explanation. My prompts used to open with a 200-word wall: who I am, my stack, my conventions, my tone, the project background. Now they open like this:

> Add rate limiting to the `/api/upload` route using our existing Redis setup.
> Match the error-handling pattern we already use elsewhere.

Two sentences. No preamble. And the output is *more* on-target than the 200-word version ever was, because the context didn't disappear, it moved. It now lives in four Claude features that load automatically, instead of in a paragraph I retype every time. This post shows you exactly how to set that up.

***

## The 200-word problem

If you use Claude for real work, you know the tax. Every new chat starts cold, so you paste the same block: "I'm a full-stack engineer, we use TypeScript and Postgres, keep it concise, here's the architecture…" You're not prompting, you're re-onboarding the model from scratch, every time.

The reason this happens is structural, not a bug. Each conversation opens in a fresh context window with nothing pre-loaded from yesterday's chat. So unless something carries that context for you, *you* are the carrier. The fix is to make the platform hold it instead.

There are four places to put context so it loads on its own. Stack them, and the 200 words evaporate.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-workflow-replaced-200-words-with-two-sentences/claude-context-stack-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-workflow-replaced-200-words-with-two-sentences/claude-context-stack-dark.png" alt="Four Claude features (Profile Preferences, Custom Style, Projects, and Memory) stacking into a context layer that absorbs the manual 200-word prompt preamble and outputs a two-sentence prompt" />

***

## Layer 1, Profile Preferences: who you are, set once

This is the global base layer. In `Settings`, the personal preferences field lets you tell Claude standing facts about you and how you want responses, your role, your defaults, your hard "do nots." It applies across every chat you have, automatically.

This is where "I'm a full-stack engineer" and "keep answers concise, no fluff" live permanently. Write it once; never type it again.

## Layer 2, Custom Style: how you write, locked in

Tone is the other half of most people's preamble, "make it punchy," "match my voice." Claude's Style feature handles that. You pick a built-in style or create a custom one from samples of your own writing, and Claude applies it to outputs.

So the entire "write it in a tight, no-nonsense tone" instruction collapses into a style you select once. That's another chunk of preamble gone.

## Layer 3, Projects: the context for *this* work

This is the heavy lifter. A Project is a self-contained workspace with its own instructions and knowledge base \[1]. Two parts matter:

* **Project instructions**, a global prompt that every chat inside the project inherits automatically, so you define behavior once instead of repeating it \[1]\[2].
* **Project knowledge**, documents you upload once (specs, style guides, API docs, architecture notes) that Claude references across every chat in that project \[2].

On paid plans, when your project knowledge approaches the context limit, Claude automatically switches to RAG mode to expand capacity rather than dropping content \[1]. One important detail to internalize: context is *not* shared between chats in a project unless it's in the knowledge base \[2], so durable facts belong in knowledge, not buried in one old chat.

This is where your stack, conventions, and architecture background go. That's the bulk of your 200 words, handled.

## Layer 4, Memory: what Claude learned about you

The last layer is the one that fills itself in. With memory enabled, Claude summarizes your conversations and synthesizes key facts (your role, preferences, recurring tools) into context that loads into every new standalone chat, refreshed about every 24 hours \[3]. You can also just tell it "remember that I…" and it updates immediately \[3].

One nuance worth knowing: memory and projects are separate spaces. The cross-chat synthesis covers your standalone conversations, and each project keeps its own dedicated memory, so contexts stay isolated and relevant rather than bleeding together \[3].

***

## The developer variant: CLAUDE.md

If your "workflow" is Claude Code rather than chat, the same principle has a cleaner home. Each Claude Code session starts with a fresh context window, and a `CLAUDE.md` file gives Claude persistent instructions that load at the start of every session \[4]. Pair it with auto memory, notes Claude writes for itself based on your corrections, and the repo effectively remembers its own rules \[4].

Keep it tight: the docs recommend targeting under \~200 lines per `CLAUDE.md`, and treating it as context rather than hard enforcement \[4]. Put your build commands, conventions, and "always/never" rules there, and you stop re-explaining the codebase entirely.

***

## The two-sentence template

Once the four layers hold your context, a good prompt only needs two things:

1. **The task**, what you want done, specifically.
2. **The constraint**, the one rule or output shape that this particular ask needs.

That's it. Everything else is already loaded.

```
[Task]  Add rate limiting to the /api/upload route using our existing Redis setup.
[Constraint]  Match the error-handling pattern we already use elsewhere.
```

Notice what's *not* there: no "I'm an engineer," no stack description, no tone instruction, no architecture recap. Preferences cover who you are, Style covers the voice, the Project covers the stack and patterns, Memory covers your habits.

<ThemedImage srcLight="https://images.syedmoinuddin.com/blogs/claude-workflow-replaced-200-words-with-two-sentences/two-sentence-prompt-before-after-light.png" srcDark="https://images.syedmoinuddin.com/blogs/claude-workflow-replaced-200-words-with-two-sentences/two-sentence-prompt-before-after-dark.png" alt="Before and after comparison: a 200-word context-heavy prompt on the left versus a two-sentence task-plus-constraint prompt on the right, with the context relocated into Preferences, Style, Projects, and Memory" />

***

## Setting it up (about 20 minutes, once)

1. **Fill in Profile Preferences.** `Settings` → personal preferences. Add your role, defaults, and 2–3 "do not" rules. Keep it to facts that are true in *every* chat.
2. **Create or pick a Style.** Generate a custom style from a few samples of your own writing so outputs match your voice by default.
3. **Build a Project per context.** One project per client, product, or codebase. Write the project instructions (behavior + standards) and upload your reference docs to project knowledge \[1]\[2]. Don't duplicate what's already in your preferences, let them stack.
4. **Turn on Memory.** `Settings` → Capabilities → enable memory, then seed it: tell Claude the few durable facts you want it to hold \[3].
5. **(Devs) Add a `CLAUDE.md`.** Drop build commands, conventions, and rules into the repo root; keep it under \~200 lines \[4]. Use the `#` shortcut to promote a one-off instruction into it when it proves useful.

After that, every new chat starts with Claude already knowing the setup. You just ask for the thing.

***

## Is this workflow a fit for you?

**It's a fit if you:**

* Start most chats by pasting the same background block
* Work on the same projects or codebases repeatedly
* Care about consistent tone and standards across outputs
* Are on a paid plan (project knowledge with RAG scaling needs one) \[1]

**It's probably not a fit if you:**

* Mostly ask one-off, unrelated questions with no shared context
* Need strict, *enforced* guardrails, these features are context, not hard rules, so for non-negotiable blocks a tool-level hook is the right call \[4]
* Handle sensitive data you can't put into project knowledge (redact first, or keep it out)

***

## Sources

1. Anthropic, "What are projects?" Claude Help Center. [https://support.claude.com/en/articles/9517075-what-are-projects](https://support.claude.com/en/articles/9517075-what-are-projects)
2. Anthropic, "How can I create and manage projects?" Claude Help Center. [https://support.claude.com/en/articles/9519177-how-can-i-create-and-manage-projects](https://support.claude.com/en/articles/9519177-how-can-i-create-and-manage-projects)
3. Anthropic, "Use Claude's chat search and memory to build on previous context." Claude Help Center. [https://support.claude.com/en/articles/11817273-use-claude-s-chat-search-and-memory-to-build-on-previous-context](https://support.claude.com/en/articles/11817273-use-claude-s-chat-search-and-memory-to-build-on-previous-context)
4. Anthropic, "How Claude remembers your project" (CLAUDE.md & auto memory), Claude Code Docs. [https://code.claude.com/docs/en/memory](https://code.claude.com/docs/en/memory)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and shipping things that survive production. Follow along for more deep dives on the tools changing how we ship software.


Last updated on June 2, 2026

---
title: "The Scanner That Refuses to Run Your Code: Inside Perplexity's Bumblebee"
description: "Most supply-chain scanners run your package manager to check for poison, which is exactly how poison spreads. Perplexity's open-source Bumblebee takes the opposite bet: it never runs anything."
last_updated: "June 1, 2026"
source: "https://syedmoinuddin.com/blog/perplexity-bumblebee-read-only-scanner"
---

# The Scanner That Refuses to Run Your Code: Inside Perplexity's Bumblebee

Most supply-chain scanners run your package manager to check for poison, which is exactly how poison spreads. Perplexity's open-source Bumblebee takes the opposite bet: it never runs anything.

Most supply-chain scanners have a dirty secret: to check whether you've installed a poisoned package, they run your package manager, which is exactly how the poison spreads. Perplexity's new open-source scanner takes the opposite bet. It never runs anything.

On May 22, 2026, Perplexity open-sourced **Bumblebee**, a read-only scanner it already uses internally to protect the developer machines behind Perplexity Search, the Comet browser, and its Computer agent. \[1]\[2] It's on GitHub under Apache 2.0, written entirely in Go, with **zero non-standard-library dependencies** and a single static binary. \[1]

The pitch is narrow on purpose. Bumblebee answers one question, fast: *when an advisory names a compromised package, version, or extension, which of my developer machines have it on disk right now?* \[1]

That sounds simple. In practice, it's the question most security tooling can't answer in the minutes that matter.

## The gap nobody else fills

When a supply-chain advisory drops at 2 a.m., your existing tools each tell you something *adjacent* to what you need:

* **SBOMs** tell you what shipped in a build artifact.
* **EDR** tells you what ran or touched the network.
* **Endpoint inventory** tools track installed *applications*.

None of them look at the messy local state where the risk actually lives, lockfiles, package-manager install metadata, editor extensions, browser add-ons, and AI agent configs scattered across hundreds of laptops. \[1]\[3] That's the layer attackers increasingly target, because a developer's machine is a soft entry point into everything they can push, deploy, or sign. \[3]

Bumblebee turns that scattered on-disk state into structured records, then flags exact matches against a catalog of known-bad packages. \[1]

![Bumblebee mapping scattered developer-machine state (lockfiles, extensions, MCP configs) into a single exposure view](https://images.syedmoinuddin.com/blogs/perplexity-bumblebee-read-only-scanner/bumblebee-supply-chain-scan.webp)

## Why "read-only" is the whole point

Here's the part every dev should internalize.

`npm install` doesn't just copy files. Packages can carry **postinstall scripts** that execute automatically the moment the package manager touches them. \[4] That's how most modern supply-chain worms propagate, Shai-Hulud-style self-replication, credential theft on install, the works.

So a scanner that "checks" your exposure by invoking `npm ls`, `pip show`, or `go list` has a fatal flaw: **it can trigger the very attack it was sent to find.** \[4]

Bumblebee refuses to play that game. It:

* **Never executes** install scripts or lifecycle hooks.
* **Never invokes** a package manager (`npm`, `pnpm`, `bun`, `pip`, …).
* **Never reads** your source files.

It only parses metadata that's already sitting on disk, `package-lock.json`, `pnpm-lock.yaml`, `go.sum`, `*.dist-info/METADATA`, extension manifests, MCP JSON configs, and so on. \[1] The scan can't become the breach. There's even a quiet privacy detail: MCP host configs often stash credentials in their `env` blocks, and Bumblebee parses those configs for the server inventory it needs **without emitting the secret values** in its records. \[1]

## What it actually covers

One binary, eleven surfaces, the kind of coverage that normally takes three or four separate tools. \[3]

| Surface                 | Emitted `ecosystem` | Reads (examples)                                                 |
| ----------------------- | ------------------- | ---------------------------------------------------------------- |
| npm / pnpm / Yarn / Bun | `npm`               | `package-lock.json`, `pnpm-lock.yaml`, `yarn.lock`, `bun.lock`   |
| PyPI                    | `pypi`              | `*.dist-info/METADATA`, `*.egg-info/PKG-INFO`                    |
| Go modules              | `go`                | `go.sum`, `go.mod`                                               |
| RubyGems                | `rubygems`          | `Gemfile.lock`, installed `*.gemspec`                            |
| Composer                | `packagist`         | `composer.lock`, `vendor/composer/installed.json`                |
| MCP configs             | `mcp`               | `mcp.json`, `claude_desktop_config.json`, Gemini CLI settings, … |
| Editor extensions       | `editor-extension`  | VS Code, Cursor, Windsurf, VSCodium manifests                    |
| Browser extensions      | `browser-extension` | Chromium `manifest.json`, Firefox `extensions.json`              |

(All four JS package managers normalize to the `npm` ecosystem, since that's where the registry risk lives.) \[1]

## Three profiles, one job

Bumblebee is a **one-shot** scanner, each run scans once and exits. Cadence is your runner's job (cron, launchd, systemd, MDM). \[1] You pick a profile based on how wide you need to look:

* **`baseline`**, standard global/user package roots, toolchains, editor + browser extensions, MCP configs. For routine, lightweight fleet inventory. \[1]\[5]
* **`project`**, targeted dev directories like `~/code` or `~/work`. For known workspaces. \[1]\[5]
* **`deep`**, explicit `--root` paths, up to and including `$HOME`. For active incident sweeps. \[1]\[5]

A safety rail worth noting: `baseline` and `project` *refuse* bare-home roots, only `deep` is allowed to walk your entire home directory. \[1]

```bash
# Install (Go 1.25+, into $GOBIN)
go install github.com/perplexityai/bumblebee/cmd/bumblebee@v0.1.1

# Routine global inventory
bumblebee scan --profile baseline > inventory.ndjson

# On-demand exposure scan against a published advisory
bumblebee scan --profile deep \
  --root "$HOME" \
  --exposure-catalog ./catalog.json \
  --findings-only \
  --max-duration 10m
```

Output is **NDJSON**, one component record per line, with a `scan_summary` record at the end so receivers know whether to trust the run. \[1] Each match carries a `confidence` of `high`, `medium`, or `low`, so you can tell "exact name+version from canonical metadata" apart from "a path reference that *might* mean it's installed." \[1]

## The AI-assisted feedback loop

The detection logic isn't magic, it's an **exposure catalog**: minimal JSON doing exact `(ecosystem, name, version)` matching. \[1] Where it gets interesting is how Perplexity keeps that catalog fresh.

Their internal loop runs five steps: a threat signal comes in → **Perplexity Computer drafts a structured catalog entry** (ecosystem, name, affected versions, source links) → it opens a GitHub PR → a human reviews and merges → Bumblebee re-scans every endpoint against the updated catalog and routes findings to the security team. \[5]\[3] The repo ships maintained catalogs in `threat_intel/`, assembled with Computer and updated via PRs as new campaigns surface. \[1]

It's a clean example of the pattern your audience keeps running into: **let the agent draft, keep the human on the merge button.** The AI never ships a detection rule on its own.

## Should you run it? A quick checklist

Bumblebee is sharp, not universal. It's a fit if:

* ✅ You run a **fleet** of developer machines and need fast "who's exposed?" answers during incidents.
* ✅ You're on **macOS or Linux** (no Windows support today). \[6]
* ✅ You already have MDM/fleet tooling to schedule and collect runs.
* ✅ You want detection logic you can **read, fork, and tune** to your own stack.

It's *not* the right tool if:

* ❌ You want **remediation**, Bumblebee finds, it doesn't fix or quarantine. \[6]
* ❌ You need **deep SCA / transitive vuln analysis**, that's still Snyk/Socket/Phylum territory. \[6]
* ❌ You expect **fuzzy matching**, it's exact-match only by design, which means a catalog gap is a blind spot.

One honest caveat the analysts flagged: because the detection logic is public, a motivated attacker can study it to engineer evasion. \[6] Open detection is a tradeoff, not a free lunch.

## The takeaway

Bumblebee won't replace your SBOM, your EDR, or your SCA scanner, and it isn't trying to. It does one unglamorous thing exceptionally well: it answers *"which machines have package X\@Y right now?"* in seconds, without ever becoming the attack it's hunting. \[1]\[3]

For a v0.1.1 release that's a single dependency-free binary, that's a remarkably clean idea, and one worth keeping in your incident-response toolbox.

## Sources

1. Perplexity, *Bumblebee* GitHub repository (README, coverage, profiles, usage), `github.com/perplexityai/bumblebee` (v0.1.1, May 22, 2026)
2. TestingCatalog, "Perplexity open-sources Bumblebee security scanner"
3. MarkTechPost, "Perplexity Open-Sources Bumblebee: A Read-Only Supply-Chain Scanner for Developer Endpoints"
4. Perplexity Hub, "Perplexity Is Open-Sourcing Bumblebee" (read-only rationale, postinstall scripts)
5. OpenTools, "Perplexity Open-Sources Bumblebee to Scan Developer Machines for Supply-Chain Threats" (scan profiles, workflow)
6. AI Weekly, "Perplexity open-sources Bumblebee supply-chain scanner" (limitations, evasion tradeoff, vendor landscape)
7. explainX, "Bumblebee: Perplexity's Open-Source Supply Chain Security Scanner for Developer Endpoints (2026)"

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer writing about AI tooling, agentic systems, and the frontend/backend craft. Follow along for more deep dives on the tools changing how we ship software.


Last updated on June 1, 2026

---
title: "The Invisible Box Around Your Text, and How to Finally Trim It"
description: "Remove the empty space CSS bakes around text. A one-line, optical fix using text-box-trim and text-box-edge, with progressive enhancement for browser support."
last_updated: "June 1, 2026"
source: "https://syedmoinuddin.com/blog/text-box-trim-css"
---

# The Invisible Box Around Your Text, and How to Finally Trim It

Remove the empty space CSS bakes around text. A one-line, optical fix using text-box-trim and text-box-edge, with progressive enhancement for browser support.

Every font ships with empty vertical space baked in above and below the letters. For years the only way to remove it was magic-number margins and prayer. `text-box-trim` makes it a one-line, optical-not-metric fix.

Type some text in a heading and inspect it. The glyphs don't fill the line box, there's a sliver of empty space above the capitals and below the baseline that you never asked for. It's not padding. It's not margin. It's the font itself, and every font has a different amount of it.

That invisible space is why a button's label never looks *quite* centered, why the gap above your `<h1>` is always a few pixels off from the gap below it, and why you've shipped more than one `margin-top: -0.15em` with a comment that just says `// don't ask`. There's finally a real fix: the `text-box-trim` and `text-box-edge` properties. Let me walk through what the space actually is and how to cut it cleanly.

## What is the invisible space?

It's called **leading**, specifically *half-leading*. Every font file defines its own default line height, larger than the letters themselves, and the browser splits the extra space into two halves: one above the text, one below. \[4] Different fonts bake in different amounts, which is exactly why consistent vertical typesetting has always been a pain on the web: the same `font-size` produces different-height line boxes across fonts. \[3]

So when you set `line-height: 1.5`, that breathing room isn't centered on the letters in any way you control, it's distributed by metrics buried in the font. The letters sit inside an invisible box that's taller than they are, and that box is what throws your alignment off.

## The old way (magic numbers and shame)

Before this existed, there was no clean way to remove that half-leading. \[9] You reached for one of:

* Negative margins tuned by eyeball (`margin-top: -0.18em`) that broke the moment you changed the font.
* Padding hacks to fake the offset back.
* `::before`/`::after` pseudo-elements with negative margins to claw back the leading.

All of them are font-specific magic numbers. Swap the typeface and every value is wrong again. It was guesswork dressed up as CSS.

## The new way: two properties that do one job

The fix is split across two properties, and the split is the whole mental model:

* **`text-box-trim`** decides *which* edges to cut: `none`, `trim-start` (top only), `trim-end` (bottom only), or `trim-both`. \[3]
* **`text-box-edge`** decides *how much* to cut, i.e. *where* the new edge lands. It takes one or two keywords: the first is the over (top) edge, the second is the under (bottom) edge. \[6]

`text-box-edge` does nothing on its own, it only takes effect once `text-box-trim` is set to something other than `none`. \[6] And there's a shorthand that sets both at once, which is the form you showed and the one I reach for:

```css
h1 {
  text-box: trim-both cap alphabetic;
}
```

That reads as: trim both edges; cut the top flush with the top of the **cap**ital letters, and cut the bottom flush with the **alphabetic** baseline. \[3] No magic numbers, and it adapts to whatever font is actually rendering.

## The edge values, in plain terms

The `text-box-edge` keywords are just named lines in the font's anatomy. Valid **over (top)** values are `text`, `cap`, and `ex`; valid **under (bottom)** values are `text` and `alphabetic`: \[6]

* `cap`, trim the top down to the top of capital letters. The usual choice for headings.
* `ex`, trim the top down to the x-height (the top of lowercase letters like *x*). Tighter, good for all-lowercase type.
* `alphabetic`, trim the bottom up to the baseline, ignoring descenders. The usual choice for the under edge.
* `text`, trim to the font's full text edge (the em box, including ascender/descender room). The loosest cut; the only value valid as a single keyword. \[6]

So `cap alphabetic` (cap on top, baseline on bottom) is the sensible default for most UI text, which is why it's the value most examples land on. \[3]

## Where this actually earns its keep

This isn't a cosmetic toy, it removes a category of alignment bugs:

* **Buttons and badges.** Text inside a button often looks vertically off because the half-leading above and below isn't equal. Trim it and the label sits where it should, no padding fudging. \[9]
* **Headings against other elements.** When an `<h1>` sits next to an icon or in a flex row, the leading throws the optical alignment off. `trim-both` lets you center on the actual letters. \[9]
* **Tight, deliberate spacing.** Want the gap above a heading to exactly match the gap below it? Trim the font's contribution to zero and your `margin` is now the *only* thing creating space, which means it's finally predictable.

The principle: trimming turns vertical spacing from *metric* (whatever the font baked in) into *optical* (what you actually set). That's the win.

## The gotchas, read these before you ship it

* **It only trims the first and last line.** `text-box-trim` cuts the half-leading at the very top and very bottom of a block, not the leading *between* lines in a wrapped paragraph. \[9] For multi-line body text, your `line-height` still does its normal job in the middle.
* **The default is no trimming.** Despite what some demos imply, the properties don't kick in until you opt in (`text-box: normal` is the same as `none auto`). \[5] Nothing changes on your existing pages by accident.
* **Browser support is good but not universal.** As of early 2026 it works in Chrome and Edge 133 (February 2025) and Safari 18.2 (December 2024), but Firefox does not support it yet. \[1] So treat it as progressive enhancement, not a load-bearing layout tool.

Because of that last point, gate it behind `@supports` and let unsupported browsers fall back to your normal spacing:

```css
h1 {
  /* normal spacing everyone gets */
  margin-block: 0.5rem;
}

@supports (text-box-trim: trim-both) {
  h1 {
    text-box: trim-both cap alphabetic;
    margin-block: 0.75rem; /* now that the leading is gone, set real spacing */
  }
}
```

## The takeaway

For years, the empty space around text was a thing you fought with negative margins and hoped nobody resized the font. `text-box-trim` and `text-box-edge` turn it into a property you declare: pick which edges to cut and where the cut lands, and the browser does the font math for you. Use the shorthand, default to `trim-both cap alphabetic`, remember it only touches the first and last line, and wrap it in `@supports` until Firefox catches up.

It's a small property. It quietly deletes a whole genre of "why is this off by three pixels" bugs.

## Sources

1. ICS Media, "Using CSS text-box-trim and text-box-edge for vertical text spacing," March 2026 (browser support as of January 2026), [ics.media](https://ics.media/en/entry/250319/)
2. MDN Web Docs, "text-box (shorthand), CSS", [developer.mozilla.org](https://developer.mozilla.org/en-US/docs/Web/CSS/text-box)
3. MDN Web Docs, "text-box-trim, CSS", [developer.mozilla.org](https://developer.mozilla.org/en-US/docs/Web/CSS/text-box-trim)
4. (see \[3]) Font metrics and leading explanation, MDN.
5. MDN Web Docs, "text-box (the normal keyword equals none auto)", [developer.mozilla.org](https://developer.mozilla.org/en-US/docs/Web/CSS/text-box)
6. MDN Web Docs, "text-box-edge, CSS" (valid over/under keywords), [developer.mozilla.org](https://developer.mozilla.org/en-US/docs/Web/CSS/text-box-edge)
7. Can I Use, "CSS text-box-trim support table", [caniuse.com](https://caniuse.com/css-text-box-trim)
8. CSS-Tricks Almanac, "text-box-trim" (old workarounds, button centering, defined in CSS Inline Layout Module Level 3), [css-tricks.com](https://css-tricks.com/almanac/properties/t/text-box-trim/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on June 1, 2026

---
title: "The Scraper That Doesn't Get Banned: Building a Scalable Web Scraping Pipeline in Go"
description: "A Go web scraping pipeline that survives at scale: rate limits per domain, rotating proxies, retries, and the layered architecture that keeps you from getting banned."
last_updated: "May 31, 2026"
source: "https://syedmoinuddin.com/blog/scalable-web-scraping-pipeline-go"
---

# The Scraper That Doesn't Get Banned: Building a Scalable Web Scraping Pipeline in Go

A Go web scraping pipeline that survives at scale: rate limits per domain, rotating proxies, retries, and the layered architecture that keeps you from getting banned.

A scraping script that works on your laptop and a pipeline that runs for months at scale are two completely different things. The gap between them is proxies, rate limiting, retries, and architecture, and Go is unusually good at all four.

On localhost, scraping feels deterministic. You request a URL, the HTML loads, your selectors resolve, you get data. It works almost every time. Then you point the same code at ten thousand URLs across real targets, and the illusion collapses: IPs get banned within the hour, requests time out, a parser error kills the whole run, and the site starts feeding you CAPTCHAs.

I build crawlers in Go for a living, and the lesson that took the longest to sink in is that a scraper isn't a script, it's a pipeline. Once you treat it like a system with decoupled stages, the hard problems (blocking, scale, reliability) become layers you can solve one at a time. This is how I build them.

Go earns its place here for a concrete reason: goroutines and channels give you high-throughput concurrency with almost no overhead, it compiles to a single static binary you can drop on any box, and on parsing-heavy work Go scrapers typically run several times faster than the Python equivalent. \[1] For a pipeline whose whole job is doing thousands of things at once, that matters.

## The mental model: four decoupled stages

Every scalable scraper is the same four stages, and the trick is to keep them *separate* so a failure in one doesn't take down the others:

1. **Frontier**, the queue of URLs waiting to be fetched, deduplicated so you never crawl the same page twice.
2. **Fetch**, workers that pull URLs, send HTTP requests through proxies and rate limits, and return raw responses.
3. **Parse**, extract structured data from raw HTML, *after* fetching, never inside it.
4. **Store**, write results somewhere durable.

The single most important architectural rule, learned the hard way: **fetch raw first, parse later.** Don't let a regex error on one weird page kill a network request that cost you a proxy rotation and three seconds. \[7] Pull the bytes, store or queue them, and parse in a stage that's allowed to fail independently.

## Layer 1, Fetch: pick the right tool, don't over-reach

The fetch layer is where most people reach for a headless browser by reflex. Don't. Headless Chrome is slow, memory-hungry, and usually unnecessary. Match the tool to the target: \[1]\[2]

* **`net/http` + `goquery`**, for static HTML. Fastest, lightest, most control. goquery gives you jQuery-style CSS selectors over the response body.
* **Colly**, when you need crawling: link-following, cookie handling, request queues, and built-in concurrency, all out of the box.
* **chromedp or Rod**, *only* when the data is rendered by JavaScript and there's no underlying API to hit. Rod adds stealth features; chromedp is the common choice. Reserve these for pages that genuinely need a browser. \[1]\[2]

Most "I need a headless browser" situations are actually "I didn't check the network tab for the JSON endpoint the page is already calling." Check first.

## Layer 2, Rate limiting: rotate at human speed

The fastest way to get banned is to behave like a machine. A real visitor doesn't fire fifty requests per second from one address. \[5] Your scraper shouldn't either, and the clean way to enforce that in Go is the official `golang.org/x/time/rate` package, a token-bucket limiter maintained alongside the standard library. \[3]

You create a limiter with a rate `r` and a burst size `b`, and you call `Wait` before each request. The key refinement for a real crawler: **one limiter per domain**, so you're polite to each target independently instead of throttling your whole pipeline to the slowest site.

```go
type DomainLimiter struct {
    mu       sync.Mutex
    limiters map[string]*rate.Limiter
    r        rate.Limit
    burst    int
}

func NewDomainLimiter(perSecond float64, burst int) *DomainLimiter {
    return &DomainLimiter{
        limiters: make(map[string]*rate.Limiter),
        r:        rate.Limit(perSecond),
        burst:    burst,
    }
}

// Wait blocks until this domain is allowed another request.
func (d *DomainLimiter) Wait(ctx context.Context, host string) error {
    d.mu.Lock()
    lim, ok := d.limiters[host]
    if !ok {
        lim = rate.NewLimiter(d.r, d.burst)
        d.limiters[host] = lim
    }
    d.mu.Unlock()
    return lim.Wait(ctx) // sleeps until a token frees up
}
```

`Wait` is the method to reach for in a scraper, it blocks until a token is available rather than rejecting the request, which is exactly the smoothing behavior you want. \[3] And watch the responses: the moment you start seeing `429 Too Many Requests`, back off immediately. The server is telling you the limit. \[7]

## Layer 3, Proxies: the part that actually decides whether you get blocked

A single IP burns out fast against a serious target. After enough requests it gets flagged and your scraper stops working until you swap. \[5] Proxies are how you spread load across many addresses, and choosing the right *type* matters more than the pool size on the marketing page: \[4]

* **Datacenter**, fast and cheap, best for unprotected sites. Easiest to detect and block.
* **Residential**, routed through real home ISP addresses, so requests look like they came from an apartment, not a server rack. Expensive (priced per GB), but they get through advanced bot management and geo-blocks.
* **ISP**, static IPs with residential trust signals; ideal for sticky sessions like logged-in flows where rapid rotation triggers lockouts.
* **Mobile**, extreme trust because blocking one risks blocking many real users behind carrier NAT. Reserve for hard edge cases.

The rotation decision is just as important as the type. **Per-request rotation** (a fresh IP every call) is right when each request is independent. **Sticky sessions** (one IP held for a few-minute window) are right when you need continuity (a cart, a login, a multi-step flow) because switching IPs mid-session breaks cookies and gets you bounced to a CAPTCHA. Most failed residential setups are using per-request rotation where they needed sticky sessions. \[5]

In Go, the clean pattern is one reusable `http.Client` per proxy, picked round-robin, so you're not rebuilding transports on every request:

```go
type ProxyPool struct {
    clients []*http.Client
    n       uint64
}

func NewProxyPool(proxyURLs []string) (*ProxyPool, error) {
    clients := make([]*http.Client, 0, len(proxyURLs))
    for _, p := range proxyURLs {
        pu, err := url.Parse(p)
        if err != nil {
            return nil, err
        }
        clients = append(clients, &http.Client{
            Timeout:   30 * time.Second,
            Transport: &http.Transport{Proxy: http.ProxyURL(pu)},
        })
    }
    return &ProxyPool{clients: clients}, nil
}

func (p *ProxyPool) Next() *http.Client {
    i := atomic.AddUint64(&p.n, 1)
    return p.clients[i%uint64(len(p.clients))]
}
```

One 2026 caveat worth knowing: proxy *sourcing* is now a real security and compliance question. Google Cloud's takedown of the IPIDEA network in January 2026 showed that where your residential IPs come from matters, and Cloudflare's "Pay Per Crawl" (HTTP 402) model is starting to shift parts of the web from hard blocking toward metered, paid access. \[4] Vet your provider, and don't assume free or grey-market pools are safe.

## Layer 4, Looking human: headers, user agents, and TLS

Proxies hide your IP, but the request itself still carries fingerprints. Rotate your `User-Agent` and send a realistic, consistent set of headers, a real browser doesn't send a bare request with no `Accept-Language`. \[8] For aggressively protected targets, the next layer down is TLS fingerprint spoofing (libraries like CycleTLS), because anti-bot systems increasingly fingerprint the TLS handshake itself, not just the headers. \[1] Layer these defenses based on how hard the target pushes back, don't pay the cost of browser automation and TLS spoofing on a site that a plain `net/http` request walks straight into.

## Layer 5, Resilience: failures are the normal case

Once you leave localhost, failure stops being an edge case and becomes an operating condition. Networks flake, proxies time out, targets get overloaded. \[7] Build for it from the start:

* **Retry with exponential backoff and jitter.** Don't retry instantly, that just hammers a struggling endpoint. Increase the delay each attempt, and add randomness so a thousand workers don't all retry in lockstep.
* **Know what's retryable.** A `429` or `503` or a timeout deserves a retry. A `404` or `401` does not, retrying it wastes a proxy and a token.
* **Cap attempts, then dead-letter.** After a few failures, stop and route the URL to a dead-letter queue for manual review instead of looping forever. \[6]

```go
func DoWithRetry(ctx context.Context, attempt func() error) error {
    const maxAttempts = 4
    base := 500 * time.Millisecond
    for i := 0; i < maxAttempts; i++ {
        err := attempt()
        if err == nil {
            return nil
        }
        if !isRetryable(err) {
            return err // don't retry 4xx (except 429)
        }
        // exponential backoff with full jitter
        window := base * (1 << i)
        sleep := time.Duration(rand.Int63n(int64(window)))
        select {
        case <-time.After(sleep):
        case <-ctx.Done():
            return ctx.Err()
        }
    }
    return errors.New("max retries exceeded")
}
```

The mindset shift is accepting an **error budget**: at scale, 1–3% of requests will fail no matter what you do. Build the pipeline to retry and move on, not to demand perfection. \[7]

## Layer 6, Scaling out: workers, a shared frontier, and a queue

The in-process version of scale is the worker pool, a fixed set of goroutines all reading from one channel of URLs. This alone takes you a long way:

```go
func Crawl(ctx context.Context, urls <-chan string, results chan<- Result, workers int) {
    var wg sync.WaitGroup
    for i := 0; i < workers; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for u := range urls {        // ranges until the channel closes
                results <- fetch(ctx, u)
            }
        }()
    }
    wg.Wait()
    close(results)
}
```

When one machine isn't enough, you go distributed, and the components are well-established: a **scheduler/queue** holds the URL frontier, **stateless workers** pull from it across many nodes, and a **store** collects results. \[6] The pieces that make it survive production:

* **Deduplicate the frontier.** A shared store like Redis tracks seen URLs so workers across nodes never crawl the same page twice. \[8]
* **Use a real message queue** (NATS, RabbitMQ, Kafka) for the URL frontier so work isn't lost when a worker crashes. \[6]
* **Separate retry queues** with increasing delays, feeding a dead-letter queue after repeated failure, never push failed URLs straight back into the main queue, or you build an infinite loop that hammers broken endpoints. \[6]
* **Keep workers stateless** so a crash loses no data, and **restart them periodically**, long-lived workers parsing malformed HTML accumulate memory leaks. \[6]\[7]
* **Score your workers.** They won't all have the same proxy quality and network speed; route the hard jobs to your best performers. \[6]

## Storage and observability

Store raw responses first (object storage or a `raw_pages` table), then run parsing as its own stage writing structured rows to Postgres or MongoDB. That separation means a parser bug is a re-run over saved bytes, not a re-crawl.

Then watch the system, because a scraper that can't see itself is a scraper that's quietly failing. The metrics that matter aren't vanity numbers, they're **success rate**, **latency** (if a target slows down, slow your scraper down to avoid a ban), and **cost per successful request**, which is the number that actually tells you whether a proxy provider is worth it. \[4]\[7] When you trial proxies, compare on cost-per-success on *your* targets, not on headline pool size. \[4]

## The line you don't cross: legal and ethical

This isn't legal advice (I'm an engineer, not a lawyer, and this area is actively being shaped in courtrooms) but every scraper builder needs the lay of the land. \[9]

The simplest test anyone has produced: open an incognito window, don't log in, and try to view the page. If you can see it without authenticating, it's public data, and under current US case law scraping it is likely defensible. If it's behind a login, you're in dangerous territory. Courts have effectively drawn the line at authentication. \[9] The landmark *hiQ Labs v. LinkedIn* ruling held that accessing publicly visible pages doesn't violate the Computer Fraud and Abuse Act, the Ninth Circuit ruled this way in 2019 and reaffirmed it in 2022. \[9]

But "not a CFAA violation" isn't the whole story:

* **Terms of Service can still bite.** *Meta v. Bright Data* showed that scraping data subject to a site's terms may be a breach-of-contract issue even when the data looks public. \[9]
* **Anti-circumvention is its own risk.** *Reddit v. Perplexity* (filed late 2025, pending in early 2026) invokes the DMCA over allegedly circumventing rate limits and anti-bot measures, a different legal theory from the CFAA. \[9]
* **robots.txt is voluntary but meaningful.** Ignoring it isn't automatically illegal, but respecting it reads as good faith, and disregarding it can be used as evidence of bad faith in a lawsuit. Read it. \[9]
* **Personal data triggers privacy law.** GDPR and CCPA apply the moment you collect data about identifiable people, regardless of whether the page was public. Minimize and avoid PII unless you have a real basis to handle it. \[9]

The honest summary: scrape public, non-personal data, respect robots.txt and rate limits, read the terms, and get real legal advice before any high-stakes commercial scraping.

## The takeaway

A scraper that survives isn't the one with the cleverest selectors, it's the one built as a pipeline of independent layers. Fetch with the lightest tool that works. Meter yourself per domain and rotate at human speed. Pick proxy types and rotation modes to match the target. Assume failure and retry with backoff and jitter. Decouple fetch from parse so one bad page can't sink a run. Scale out with a deduplicated frontier, a durable queue, and stateless workers. And stay on the right side of the line while you do it.

Go gives you the concurrency and the single-binary simplicity to make all of this boringly reliable. The rest is discipline: build the layers, watch the metrics, and respect the sites you're pulling from.

## Sources

1. Roundproxies, "Web scraping in Golang: 2026 step-by-step guide," updated December 2025, [roundproxies.com](https://roundproxies.com/blog/web-scraping-golang/)
2. Olostep, "Web Scraping in Golang: Libraries, Anti-Blocking, and Scale," 2026, [olostep.com](https://www.olostep.com/blog/web-scraping-golang)
3. The Go Programming Language, "Go Wiki: Rate Limiting" and golang.org/x/time/rate package docs, [go.dev/wiki](https://go.dev/wiki/RateLimiting) · [pkg.go.dev](https://pkg.go.dev/golang.org/x/time/rate)
4. Olostep, "Best Proxies for Web Scraping: What Actually Scales," 2026, [olostep.com](https://www.olostep.com/blog/best-proxies-web-scraping)
5. Technology.org, "Rotating Residential Proxies for Web Scraping: When They Beat Datacenter Proxies," May 2026, [technology.org](https://www.technology.org/2026/05/14/rotating-residential-proxies-for-web-scraping-when-they-beat-datacenter-proxies/)
6. Bright Data, "Guide to Distributed Web Crawling: Scale Your Scraping," 2025, [brightdata.com](https://brightdata.com/blog/web-data/distributed-web-crawling)
7. OnlineProxy, "How to Scale Web Scraping: Architecture for 1 Million Requests per Day," April 2026, [medium.com](https://medium.com/@onlineproxypmm/how-to-scale-web-scraping-architecture-for-1-million-requests-per-day-b8c43088412f)
8. DEV Community, "Building a High-Concurrency Web Crawler in Go: A Practical Guide," January 2026, [dev.to](https://dev.to/jones_charles_ad50858dbc0/building-a-high-concurrency-web-crawler-in-go-a-practical-guide-i3a)
9. Legal landscape, PromptCloud, Tendem, and SociaVault compliance overviews (hiQ v. LinkedIn, Meta v. Bright Data, Reddit v. Perplexity, CFAA, robots.txt, GDPR/CCPA), 2026, [promptcloud.com](https://www.promptcloud.com/blog/is-web-scraping-legal/) · [tendem.ai](https://tendem.ai/blog/is-web-scraping-legal-compliance-overview) · [sociavault.com](https://sociavault.com/blog/web-scraping-legality-court-cases-public-vs-private-data)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on May 31, 2026

---
title: "Boring on Purpose: Go Basics for People Who Want to Ship"
description: "Go's whole pitch is that the basics are enough. A pragmatic tour of the small toolset (structs, slices, errors, goroutines, interfaces) that ships real systems."
last_updated: "May 30, 2026"
source: "https://syedmoinuddin.com/blog/boring-on-purpose-go-basics"
---

# Boring on Purpose: Go Basics for People Who Want to Ship

Go's whole pitch is that the basics are enough. A pragmatic tour of the small toolset (structs, slices, errors, goroutines, interfaces) that ships real systems.

Go was designed to be small. Fewer features, fewer ways to do things, fewer footguns. That's not a limitation, it's the whole point, and it's why you can learn the basics in an afternoon and be productive the same week.

Most languages grow by adding things. Go grew by refusing to. No inheritance, no exceptions, no generics for its first decade, no clever metaprogramming. What's left is a language with a tiny surface area that compiles to a single fast binary and is genuinely hard to misuse.

I write Go for backend services and crawlers every day, and the thing I'd tell anyone starting out is this: the basics *are* most of the language. There's no deep second layer you're missing. Learn these few things well and you can build real systems.

Let's go.

## Hello, world (and the toolchain)

A Go program is made of packages. The entry point is `main`:

```go
package main

import "fmt"

func main() {
    fmt.Println("Hello, world")
}
```

Run it with `go run main.go`. When you're ready to ship, `go build` compiles it to a single static binary, no runtime to install on the server, no dependency hell. That one fact is why Go deployments are so boring (in the good way): copy one file, run it.

A real project starts with `go mod init yourname/project`, which creates a module and tracks dependencies in `go.mod`. That's the entire setup ceremony.

## Variables, types, and zero values

Two ways to declare. Inside a function, `:=` infers the type and is what you'll use 90% of the time:

```go
var name string = "explicit"   // full form
age := 30                       // inferred, function scope only
count := 0                      // int
ratio := 3.14                   // float64
ok := true                      // bool
```

The basic types are what you'd expect: `int`, `float64`, `string`, `bool`, plus sized variants like `int64` and `byte`.

The one idea that surprises newcomers: **every type has a zero value**, and Go uses it automatically. No uninitialized garbage. Numbers start at `0`, strings at `""`, booleans at `false`, and pointers, slices, maps, and interfaces at `nil`. You can lean on this, a freshly declared `var total int` is already `0`, ready to use.

## Functions, and the thing that makes Go *Go*

Functions are ordinary, but Go has one trick that shapes the entire language: **multiple return values**.

```go
func divide(a, b int) (int, error) {
    if b == 0 {
        return 0, fmt.Errorf("cannot divide %d by zero", a)
    }
    return a / b, nil
}
```

That second return value is how Go does error handling, which deserves its own section, because it's the thing people either love or fight.

## Error handling: explicit on purpose

Go has no exceptions. A function that can fail returns an `error` as its last value, and you check it. Immediately. Every time.

```go
result, err := divide(10, 0)
if err != nil {
    log.Printf("division failed: %v", err)
    return
}
fmt.Println(result)
```

Yes, you'll write `if err != nil` a lot. That's the trade: there's no hidden control flow, no invisible stack-unwinding, no surprise about where a failure goes. You can read a Go function top to bottom and see every path it can take. After a week it stops feeling verbose and starts feeling like the code is just honest with you.

## Structs and methods, no classes required

Go doesn't have classes. It has structs (data) and methods (behavior attached to a type):

```go
type User struct {
    ID    int
    Name  string
    Email string
}

// a method with a receiver, this is how behavior attaches to a type
func (u User) Greeting() string {
    return "Hi, " + u.Name
}

func main() {
    u := User{ID: 1, Name: "Ada", Email: "ada@example.com"}
    fmt.Println(u.Greeting())
}
```

Use a pointer receiver (`func (u *User)`) when the method needs to modify the struct or when the struct is large and you want to avoid copying it. That's most of the design decision right there.

## Slices and maps: the two workhorses

You'll reach for these constantly. A **slice** is a growable list:

```go
nums := []int{1, 2, 3}
nums = append(nums, 4)        // append returns a new slice, reassign it
fmt.Println(len(nums))        // 4

for i, n := range nums {      // index and value
    fmt.Println(i, n)
}
```

A **map** is a key-value store, with the "comma ok" idiom for checking presence:

```go
ages := make(map[string]int)
ages["ada"] = 36

age, ok := ages["ada"]        // ok is false if the key is missing
if ok {
    fmt.Println(age)
}
```

The one gotcha to internalize: `append` may return a *new* underlying array, so always assign its result back. And map iteration order is random by design, never depend on it.

## defer: cleanup that can't be forgotten

`defer` schedules a call to run when the surrounding function returns, no matter how it returns. It's how Go handles cleanup without `try/finally`:

```go
f, err := os.Open("data.txt")
if err != nil {
    return err
}
defer f.Close()   // runs when the function exits, guaranteed
// ... use f freely; you've already handled closing it
```

Open a thing, defer closing it on the next line, and forget about it. Files, locks, database rows, same pattern every time.

## Goroutines and channels: concurrency that's actually approachable

This is Go's headline feature, and it's simpler than its reputation suggests. Put `go` in front of a function call and it runs concurrently, a **goroutine**, which is far lighter than an OS thread. You can run thousands.

```go
go doWork()   // runs concurrently; main keeps going
```

The problem with concurrency is always communication, and Go's answer is **channels**, typed pipes that goroutines use to pass values safely:

```go
ch := make(chan string)

go func() {
    ch <- "done"          // send into the channel
}()

msg := <-ch               // receive (blocks until a value arrives)
fmt.Println(msg)
```

The Go proverb is *don't communicate by sharing memory; share memory by communicating.* Instead of locking shared state, you pass ownership of data through channels. It takes one project to click, and then concurrent code stops being scary.

## Interfaces: satisfied without saying so

Go interfaces are structural. A type satisfies an interface just by having the right methods, you never write `implements`. This is quietly one of the best things about the language.

```go
type Stringer interface {
    String() string
}

// User automatically satisfies Stringer just by having this method
func (u User) String() string {
    return fmt.Sprintf("User(%d, %s)", u.ID, u.Name)
}
```

Because satisfaction is implicit, you can define small interfaces *where you consume them*, and any type with the right shape fits. The community wisdom ("accept interfaces, return structs") falls right out of this. Keep interfaces tiny; the standard library's `io.Reader` and `io.Writer` are each a single method, and they're everywhere.

## The handful of gotchas worth knowing early

* **`append` returns a new slice.** Always reassign: `s = append(s, x)`.
* **Map order is random.** If you need order, sort the keys yourself.
* **Loop variables** were historically reused across iterations, capturing one in a goroutine could bite you. Modern Go fixed this, but if you see old advice about copying the loop variable, that's why.
* **A `nil` slice is fine to use.** You can `append` to it and `range` over it. A `nil` map, however, panics if you write to it, `make` it first.
* **Unused variables and imports are compile errors.** The compiler refuses to let you be sloppy. Annoying on day one, a gift by month two.

## The takeaway

Go's whole pitch is that the basics are enough. There's no expert dialect you graduate into, the same small set of tools (structs, slices, maps, errors, goroutines, interfaces) builds everything from a CLI to a high-throughput service. The language stays out of your way so you spend your thinking on the problem, not the syntax.

So write the verbose `if err != nil`. Lean on zero values. Pass data through channels. Keep your interfaces small. It feels almost too plain at first, and then you ship something, and you realize plain was the feature all along.

## Sources

1. The Go Programming Language, official site and docs, [go.dev/doc](https://go.dev/doc/)
2. A Tour of Go (interactive intro), [go.dev/tour](https://go.dev/tour/)
3. Effective Go (idioms and style), [go.dev/doc/effective_go](https://go.dev/doc/effective_go)
4. Go by Example (annotated runnable examples), [gobyexample.com](https://gobyexample.com/)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on May 30, 2026

---
title: "I Spent 6 Months Tuning Claude Code. Here's the Exact Setup That Finally Worked."
description: "The exact Claude Code setup after six months: a lean CLAUDE.md, lazy-loaded skills, subagents, hooks, git worktrees, and the five MCP servers that earn their place."
last_updated: "May 29, 2026"
source: "https://syedmoinuddin.com/blog/claude-code-setup-6-months"
---

# I Spent 6 Months Tuning Claude Code. Here's the Exact Setup That Finally Worked.

The exact Claude Code setup after six months: a lean CLAUDE.md, lazy-loaded skills, subagents, hooks, git worktrees, and the five MCP servers that earn their place.

CLAUDE.md, subagents, hooks, skills, worktrees, and the five MCP servers that earn their place.

For the first month, I used Claude Code the way most people do: a chat box in my terminal that happened to be able to edit files. It was fast and impressive and produced a steady stream of code I didn't fully trust. Six months later it runs a real chunk of my workflow across a Go crawler backend, a pile of Next.js frontends, and a fleet of FastAPI services, and it does it without me babysitting every diff.

The difference wasn't a better model. It was finally understanding that Claude Code is not a chatbot. It's an agent loop with a handful of extension points, and each one has a different *context cost*. Once that clicked, the whole thing got predictable.

This is the setup I landed on. Not a docs summary, the actual layout, the rules, the things I stopped doing.

## The one idea that fixed everything: context cost

Every extension point plugs into a different part of the loop, and the only question that matters is *when does this load into the context window.*

* `CLAUDE.md` is loaded every single session. It's always-on. Expensive by default.
* Skills load lazily, Claude sees only a name and a one-line description until a task actually matches, then it pulls the body in.
* Subagents run in their own separate context and hand back only the result.
* Hooks don't touch the context at all. They're shell commands that fire on events.
* MCP servers add tools, and tools have a token weight whether you call them or not.

Once you think in those terms, the placement decisions answer themselves. If a rule must be true on *every* turn, it goes in `CLAUDE.md`. If it's a procedure you need *sometimes*, it's a skill. If it's noisy research that would pollute your main thread, it's a subagent. If it's an automatic guardrail, it's a hook. Stop arguing with the model in chat, encode the decision once and move on.

That framing is straight from how the tool is built. Claude Code launched in early 2025 as a terminal tool that could edit files and run bash; the extension layers arrived over the following year, MCP, then subagents, hooks, skills, plugins, and most recently agent teams. \[1]\[2]

![A CONTEXT card loading into a CLAUDE.md file, surrounded by project folders](https://images.syedmoinuddin.com/blogs/claude-code-setup-6-months/6.jpg)

*Context cost in one picture: everything funnels through the context window, so where a rule loads is really a decision about what it costs.*

## Layer 1, CLAUDE.md: the rules I'm tired of repeating

`CLAUDE.md` is project memory. It's the thing Claude reads before it does anything, so the temptation is to dump your whole engineering handbook in there. Don't. Every token in this file is paid on every turn. Mine is deliberately short, stable, non-negotiable rules only.

The actual core of mine, trimmed:

```markdown
# Engineering rules (always apply)

## Frontend

- Tailwind only. No CSS modules, no styled-components, no inline style objects.
- pnpm. Never npm or yarn.
- Strict TypeScript. `any` is banned, if you reach for it, stop and ask.

## Backend (Python)

- Poetry for deps. No bare pip.
- FastAPI routes are async-only.
- Every request/response model is a Pydantic schema. No raw dicts crossing a boundary.

## Infra

- Every Dockerfile/compose service declares memory limits.
- Commits are atomic and conventional. One logical change per commit.

## Workflow

- When I describe a bug, feature, or task, draft a Jira ticket for it
  (title, description, acceptance criteria, priority, labels) before writing code.
```

That last rule is the one that quietly changed how I work. I describe what I'm about to do, and a structured ticket comes back before a single line is written. The work documents itself.

The discipline here is editing it like code. A recurring mistake or a review comment I keep leaving is a `CLAUDE.md` edit, not a one-off correction I'll have to repeat next week. If I find myself typing "no, use Tailwind" twice, that's a bug in this file.

![Core changes (rules, events, reasoning, types) flowing into a tracked pull request](https://images.syedmoinuddin.com/blogs/claude-code-setup-6-months/2.jpg)

*The mental model: each extension point loads into context at a different time, so where a rule lives is really a decision about what it costs.*

## Layer 2, Skills: the procedures I don't want to paste

Skills are the part that genuinely surprised me. A skill is a folder with a `SKILL.md`, YAML frontmatter (a name and a description) plus instructions, and optionally scripts and templates. \[5]\[8] At session start Claude only sees the name and description, roughly a hundred tokens. When a task matches, it reads the full body. If the body points at scripts, those run in bash and only their *output* comes back, the source never burns tokens. \[8]

That progressive-disclosure model means you can keep a big library of workflows around at almost no standing cost. I invoke them as slash commands or let Claude pull them in on its own.

The ones that earn their keep for me:

* `new-service`, scaffolds a FastAPI service the way I actually structure them: async routes, Pydantic schemas, Poetry, Dockerfile with memory limits, the lot.
* `pr-review`, runs my pre-PR checklist before I ever open the PR. Catches the `any` that slipped in, the missing test, the non-atomic commit.
* `webp-pipeline`, my S3 image-optimization routine, because I have run the "convert these to WebP and re-upload" dance enough times to never want to type it again.

Rule of thumb: if I've pasted the same 150-word prompt twice, it becomes a skill.

![A workflow that goes explore, then plan, then review, then build](https://images.syedmoinuddin.com/blogs/claude-code-setup-6-months/4.jpg)

*A skill captures a repeatable procedure (explore, plan, review, build) and loads only when a task actually matches.*

## Layer 3, Subagents: keeping the main thread clean

A subagent is a separate Claude instance with its own context window that does one job and returns only the result. \[4] You define it in `.claude/agents/` as Markdown with frontmatter, name, description, the tools it's allowed, and a system prompt.

```markdown
---
name: schema-auditor
description: Reviews DB queries and Pydantic models for N+1s, missing indexes, and unvalidated input
tools: Read, Grep, Glob
---

You are a database and schema reviewer. Inspect the changed files only.
Report: risky queries, missing indexes, any boundary taking a raw dict
instead of a validated schema. Be specific with file and line. Do not edit.
```

The reason subagents matter isn't delegation for its own sake, it's context hygiene. When I ask the main session to "go read these forty files and tell me where auth is enforced," all forty files end up in my main context and everything afterward is slower and dumber. Hand that to a subagent and I get back a two-paragraph answer while my main thread stays focused on the actual task.

One trap worth flagging, because it bit me: if you leave the `tools` field off a subagent, it implicitly inherits *every* tool, including your MCP tools. \[8] Scope them deliberately. A reviewer that can only read should not be able to write or hit your database.

## Layer 4, Hooks: automation that doesn't depend on me asking

Hooks are the layer I underused the longest. They're shell commands wired to lifecycle events, think git hooks, but for the agent. You configure them in `settings.json` (or interactively via `/hooks`), with an event, a matcher, and a command. \[3] They don't ask permission and they don't cost context; they just fire.

My two workhorses:

```json
{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "hooks": [
          {
            "type": "command",
            "command": "pnpm prettier --write $CLAUDE_FILE 2>/dev/null; true"
          }
        ]
      }
    ],
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [{ "type": "command", "command": "./.claude/guard-bash.sh" }]
      }
    ]
  }
}
```

The `PostToolUse` formatter means I stopped caring whether Claude's output is formatted, it always is, deterministically, without a single token spent telling it to. The `PreToolUse` gate is a small script that blocks the commands I never want run unattended (anything touching `rm -rf`, force-pushes, prod env files). The model proposing something dangerous and a script refusing to run it are two different safety layers, and I want both.

If a rule can be enforced by a program instead of a prompt, enforce it with a program. Prompts are probabilistic. Hooks are not.

## Layer 5, Worktrees: how I run three of these at once

This isn't a Claude Code feature, it's plain git, but it's the thing that took my throughput from "one task at a time" to genuinely parallel. `git worktree` lets you check out multiple branches into separate directories backed by the same repo. One Claude Code session per worktree, each on its own branch, each with its own clean context.

```bash
git worktree add ../helixcrawl-rate-control feature/rate-control
git worktree add ../helixcrawl-bugfix     fix/sitemap-parser
# now open a Claude Code session in each directory
```

While one session refactors the rate-control service, another chases a parser bug, and I review whichever finishes first. No stashing, no branch-switching mid-thought, no two agents fighting over the same working tree. For anything bigger than a quick edit, this is how I work now.

## The five MCP servers that earn their place

MCP is the highest-setup, highest-temptation layer. Every server you connect adds tools, and tools cost context whether or not you call them. I've installed and removed a lot of them. These five stayed, because each one removes a real copy-paste loop from my day. (Edit the config directly, `.mcp.json` for project scope, rather than fighting the CLI wizard. \[8])

![Several machines and tools (a database, a browser, a cloud) wired together into one loop](https://images.syedmoinuddin.com/blogs/claude-code-setup-6-months/5.jpg)

*MCP wires external tools (Jira, GitHub, Postgres, a browser, live docs) into the agent loop. Every server adds tools, and tools cost context.*

1. **Atlassian / Jira.** Non-negotiable for me. My `CLAUDE.md` drafts tickets; this server actually files them, links them to branches, and updates status. The loop from "I'm starting this" to a tracked ticket is now one sentence.
2. **GitHub.** PRs, issues, and review comments without leaving the session. It reads the diff, drafts the PR body against my checklist, and pulls review threads back in when I'm addressing feedback.
3. **Postgres.** Schema-aware. Instead of guessing at column names or pasting `\d+` output, Claude inspects the live schema before it writes a query or a migration. This alone killed a whole category of "that column doesn't exist" errors.
4. **Playwright.** Browser automation for E2E checks and for poking at the frontends I'm building. Given my crawler work, having the agent drive a real browser to verify a flow, instead of asserting it "should" work, is worth the tool weight.
5. **Context7 (live library docs).** The honest fix for hallucinated APIs. It pulls current documentation for whatever library is in play, so the agent writes against the version I'm actually on instead of whatever it half-remembers. For fast-moving packages this is the difference between working code and confident nonsense.

Everything else (the calendar servers, the chat servers, the dozen "cool demo" integrations) I turned off. If a server isn't removing a recurring loop, it's just tax on every prompt.

## The whole thing, on disk

```
.claude/
├── CLAUDE.md            # always-on rules (short on purpose)
├── settings.json        # hooks: formatter + bash guard
├── .mcp.json            # the five servers
├── guard-bash.sh        # pre-tool safety gate
├── agents/
│   ├── schema-auditor.md
│   ├── pr-reviewer.md
│   └── docs-researcher.md
└── skills/
    ├── new-service/SKILL.md
    ├── pr-review/SKILL.md
    └── webp-pipeline/SKILL.md
```

![A hand-drawn .claude folder tree: rules, agents, skills, settings, MCP](https://images.syedmoinuddin.com/blogs/claude-code-setup-6-months/1.jpg)

*The whole setup on disk: a lean `.claude` folder, rules, agents, skills, settings, MCP. Nothing in it is long.*

Nothing in here is long. `CLAUDE.md` is a few hundred tokens. Each subagent is maybe thirty lines. The hooks are one gate and one formatter. The power isn't in any single file, it's in not making the model re-derive my conventions every session.

## What I stopped doing

* **Stuffing CLAUDE.md.** My first version was a 2,000-token wall of preferences. Half of them were "sometimes" rules that belonged in skills. Cutting it made every response sharper.
* **Arguing in chat.** Correcting the same thing twice is a config smell. The fix lives in a file, not in my patience.
* **Trusting "done."** The model is much better than it was at flagging its own uncertainty, but I still let hooks and a review subagent be the thing that says done, not the chat message. A green test suite is a fact; "I've completed the task" is a claim.
* **Collecting MCP servers.** Fun to connect, expensive to keep. Five is plenty.

## The takeaway

Six months in, the setup that works isn't clever. It's boring and it's layered: stable rules that are always loaded, procedures that load on demand, research that happens off to the side, guardrails that run as code, and just enough external tools to close the loops I actually hit. The model got better over those six months too, but the thing that made it *trustworthy* was deciding, for every rule, where it should live and what it should cost.

Start with `CLAUDE.md`. Add the rest when a real trigger shows up. Don't try to wire up all six extension points on day one, you'll just build a slower agent.

## Sources

1. Claude Code, "Extend Claude Code" (features overview), 2026, [code.claude.com](https://code.claude.com/docs/en/features-overview)
2. Towards AI, "Claude Code Extensions Explained: Skills, MCP, Hooks, Subagents, Agent Teams & Plugins," April 2026, [pub.towardsai.net](https://pub.towardsai.net/claude-code-extensions-explained-skills-mcp-hooks-subagents-agent-teams-plugins-9294907e84ff)
3. Claude Code documentation, Hooks configuration, [docs.claude.com](https://docs.claude.com/en/docs/claude-code/overview)
4. Level Up Coding, "A Mental Model for Claude Code: Skills, Subagents, and Plugins," March 2026, [levelup.gitconnected.com](https://levelup.gitconnected.com/a-mental-model-for-claude-code-skills-subagents-and-plugins-3dea9924bf05)
5. Smith Horn Group, "Choosing between skills, subagents, and MCP servers in Claude Code," 2025, [smithhorngroup.substack.com](https://smithhorngroup.substack.com/p/choosing-between-skills-subagents)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on May 29, 2026

---
title: "The Bluffing Problem: What Claude Opus 4.8 Changes About Trusting AI Code"
description: "Claude Opus 4.8's real upgrade isn't raw capability, it's honesty. A model ~4x less likely to let its own code flaws slip by silently, and what that means for agentic AI."
last_updated: "May 28, 2026"
source: "https://syedmoinuddin.com/blog/claude-opus-4-8-bluffing-problem"
---

# The Bluffing Problem: What Claude Opus 4.8 Changes About Trusting AI Code

Claude Opus 4.8's real upgrade isn't raw capability, it's honesty. A model ~4x less likely to let its own code flaws slip by silently, and what that means for agentic AI.

AI models are getting faster and more autonomous, but the real bottleneck for production work isn't raw capability, it's whether the model tells you the truth about what it actually did. Claude Opus 4.8 makes that its headline bet.

A model that confidently says "done" is more dangerous than a model that says "I'm not sure this is right." That gap is exactly where most agentic coding workflows break.

Anthropic released Claude Opus 4.8 on May 28, 2026, roughly six weeks after Opus 4.7, and at the same price as its predecessor. \[1]\[2] The benchmark gains are real but modest. The interesting part is what the model was trained *not* to do: jump to conclusions and claim progress it can't back up.

For anyone wiring AI into long-running agents, CI pipelines, or autonomous engineering loops, that's the upgrade that actually matters.

## What is the bluffing problem?

The bluffing problem is the point where an AI model's confidence stops tracking its correctness. The code compiles, the agent reports success, the summary sounds plausible, and nobody notices that a flaw slipped through, because the model never flagged it.

It's a quiet failure mode. It rarely shows up in a demo. It shows up three weeks later in production, in the 20% of the system the model glossed over while sounding 100% certain.

## What developers should know before adopting 4.8

* The benchmark jump over 4.7 is incremental, not dramatic. The reliability and honesty improvements are the real story.
* The clearest win is calibration: the model is far less likely to let its own mistakes pass silently. \[1]
* Pricing is unchanged, so there's no cost penalty to upgrading. \[1]
* "Fast mode" is now meaningfully cheaper, which changes the math for high-volume, latency-sensitive workloads. \[1]
* New effort controls let you trade quality for speed and rate-limit headroom per task, useful for tuning agent fleets. \[1]
* It's already live in third-party tooling like GitHub Copilot, so you may be using it before you choose to. \[5]

## Why honesty is the headline feature

Every frontier model is trained to be honest. The hard part is calibration under uncertainty, knowing when the evidence is thin and saying so, instead of producing a confident-sounding answer that *looks* like a reasonable response.

Anthropic's framing is direct: a general problem with AI models is that they sometimes jump to conclusions and claim progress despite thin evidence. \[1] Opus 4.8 is trained to flag that uncertainty instead of papering over it. In their evaluations, the model is around four times less likely than its predecessor to let flaws in code it wrote pass unremarked. \[1]

That number is the one worth tattooing on the wall. In a single chat, a confident wrong answer is annoying. In an autonomous agent running unattended across hundreds of subtasks, a confident wrong answer compounds.

## The capability gains (the modest part)

The benchmark deltas over Opus 4.7 are steady improvements rather than a generational leap:

* Agentic coding: 64.3% → 69.2% \[2]
* Multidisciplinary reasoning with tools: 54.7% → 57.9% \[2]
* Computer/browser use (Online-Mind2Web): 84%, a clear jump over both Opus 4.7 and GPT-5.5 \[1]

Anthropic also claims Opus 4.8 tops OpenAI's GPT-5.5 and Google's Gemini 3.1 Pro across several agentic benchmarks, including coding, financial analysis, and computer use. \[4] As always with vendor-reported numbers, treat them as a starting point for your own evals, not gospel, which, fittingly, is exactly the kind of skepticism this release is built to support.

## What ships alongside the model

The model rarely arrives alone, and the surrounding features tell you where Anthropic thinks the work is heading.

* **Dynamic workflows.** A research-preview feature in Claude Code that lets the model plan a large task, run hundreds of parallel subagents in a single session, then verify its own outputs before reporting back. Anthropic says it can handle codebase-scale migrations across hundreds of thousands of lines of code, using the existing test suite as the bar. \[1] Available on Enterprise, Team, and Max plans.
* **Effort control.** A new setting next to the model picker in claude.ai and Cowork. Higher effort means deeper, more frequent reasoning; lower effort means faster responses that burn through rate limits more slowly. Available on all plans. \[1]
* **Messages API system entries.** Developers can now insert system instructions mid-conversation inside the messages array, updating permissions, token budgets, or environment context as an agent runs, without breaking the prompt cache. \[1]

## The pricing math

Pricing is identical to Opus 4.7 for regular usage: $5 per million input tokens and $25 per million output tokens. \[1] Fast mode runs at 2.5× the speed for $10 per million input and $50 per million output, and Anthropic notes fast mode is now roughly three times cheaper than it was on previous models. \[1]

For high-throughput agent workloads, that fast-mode price drop is the line item most likely to change your architecture decisions. Combined with effort controls, you now have two independent knobs, speed and reasoning depth, to tune cost against quality per task instead of per model.

The API string is `claude-opus-4-8`.

## The alignment side

Anthropic ran its standard pre-release alignment assessment. The team reported that Opus 4.8 reaches new highs on prosocial traits like supporting user autonomy and acting in the user's interest, and that rates of misaligned behavior, deception or cooperation with misuse, are substantially lower than Opus 4.7, landing close to their best-aligned model, Claude Mythos Preview. \[1]

For teams shipping AI into regulated or high-stakes domains (legal, healthcare, finance) lower deception rates aren't a feel-good metric. They're a diligence requirement.

## A practical adoption checklist

Upgrading a model isn't free even when the price tag is identical. Use these gates before you flip the default:

* **Before swapping in production agents:** re-run your own evals. The honesty gains mean you may see *more* flagged uncertainties, which is the point, but it can change downstream control flow.
* **Before relying on dynamic workflows:** confirm your test suite is genuinely the bar you want. The feature uses it as ground truth for large migrations.
* **Before scaling fast mode:** benchmark quality at the lower price point on your actual tasks, not on a toy example.
* **Before tuning effort down:** remember low effort burns rate limits more slowly but reasons less, fine for boilerplate, risky for anything touching trust boundaries.
* **Before assuming you're on it:** check your tooling. It's already generally available in GitHub Copilot for Pro+, Business, and Enterprise users, launching with a 15× premium request multiplier until usage-based billing begins June 1, 2026. \[5]

## What's next: Mythos

Anthropic also teased what comes after Opus. It plans to release a higher-intelligence class of model, Mythos-class, with Claude Mythos Preview already in the hands of a small number of organizations for cybersecurity work under Project Glasswing. The company says models at that capability level need stronger cyber safeguards before general release, and expects to bring Mythos-class models to all customers in the coming weeks. \[1]\[3]

If the honesty improvements in 4.8 are a preview of the safety posture those models will ship with, that's a reasonable trade for the wait.

## The takeaway

Opus 4.8 is a modest capability bump wrapped around a meaningful trust improvement. For chat, you'll notice it a little. For autonomous, agentic, long-running work, the direction the whole industry is sprinting toward, a model that knows when to say "I'm not sure" is worth more than a few benchmark points.

Treat AI output as scaffolding that still needs inspection. The good news with 4.8 is that the scaffolding is now more likely to tell you which parts it isn't sure about. Use that. Build your evals around it. And keep a human in the loop wherever the cost of being confidently wrong is high.

## Sources

1. Anthropic, "Introducing Claude Opus 4.8," May 28, 2026, [anthropic.com](https://www.anthropic.com/news/claude-opus-4-8)
2. 9to5Mac, "Anthropic upgrades Claude with new Opus 4.8 model, here's what's new," May 28, 2026, [9to5mac.com](https://9to5mac.com/2026/05/28/anthropic-upgrades-claude-with-new-opus-4-8-model-heres-whats-new/)
3. Axios, "Anthropic releases new model, Opus 4.8," May 28, 2026, [axios.com](https://www.axios.com/2026/05/28/anthropic-opus-release-mythos)
4. Yahoo Finance, "Anthropic debuts flagship Claude Opus 4.8 AI model as IPO race with OpenAI heats up," May 28, 2026, [finance.yahoo.com](https://finance.yahoo.com/news/anthropic-debuts-flagship-claude-opus-48-ai-model-as-ipo-race-with-openai-heats-up-170000527.html)
5. GitHub Changelog, "Claude Opus 4.8 is generally available for GitHub Copilot," May 28, 2026, [github.blog](https://github.blog/changelog/2026-05-28-claude-opus-4-8-is-generally-available-for-github-copilot/)
6. Anthropic, "Claude Opus 4.8 System Card," May 28, 2026, [anthropic.com](https://www.anthropic.com/claude-opus-4-8-system-card)

***

*Written by*

**Syed Moinuddin**

Full Stack Engineer.

Notes on AI tooling, agentic systems, and building things that survive contact with production.


Last updated on May 28, 2026

---
title: "Feature Bento"
description: "A bento-style feature grid with corner-decorator cards and a circular UI showcase."
last_updated: "May 23, 2026"
source: "https://syedmoinuddin.com/blog/feature-bento"
---

# Feature Bento

A bento-style feature grid with corner-decorator cards and a circular UI showcase.

```tsx
import {
  Calendar,
  ChevronDownIcon,
  ChevronLeftIcon,
  ChevronRightIcon,
  CircleIcon,
  type LucideIcon,
  MapIcon,
  MoreHorizontalIcon,
} from "lucide-react"
import type { ReactNode } from "react"

import { cn } from "@/lib/utils"
import { Card, CardContent, CardHeader } from "@/components/ui/card"

export default function FeatureBento() {
  return (
    <section className="bg-zinc-50 py-16 md:py-32 dark:bg-transparent">
      <div className="mx-auto max-w-2xl px-6 lg:max-w-5xl">
        <div className="mx-auto grid gap-4 lg:grid-cols-2">
          <FeatureCard>
            <CardHeader className="pb-3">
              <CardHeading
                icon={MapIcon}
                title="Real time location tracking"
                description="Advanced tracking system, Instantly locate all your assets."
              />
            </CardHeader>

            <div className="relative border-t border-dashed">
              <div
                aria-hidden
                className="absolute inset-0 [background:radial-gradient(125%_125%_at_50%_100%,transparent_40%,color-mix(in_oklab,var(--color-violet-600)_35%,transparent),transparent_100%)]"
              />
              <div className="relative px-6 pb-2 pt-6">
                <PaymentsTableMock />
              </div>
            </div>
          </FeatureCard>

          <FeatureCard>
            <CardHeader className="pb-3">
              <CardHeading
                icon={Calendar}
                title="Advanced Scheduling"
                description="Scheduling system, Instantly locate all your assets."
              />
            </CardHeader>

            <CardContent>
              <div className="mask-radial-at-right mask-radial-from-75% relative">
                <SchedulerMock />
              </div>
            </CardContent>
          </FeatureCard>

          <FeatureCard className="p-6 lg:col-span-2">
            <p className="mx-auto my-6 max-w-md text-balance text-center text-2xl font-semibold">
              Smart scheduling with automated reminders for maintenance.
            </p>

            <div className="flex justify-center gap-6 overflow-hidden">
              <CircularUI
                label="Inclusion"
                circles={[{ pattern: "border" }, { pattern: "border" }]}
              />
              <CircularUI
                label="Active"
                circles={[{ pattern: "none" }, { pattern: "primary" }]}
              />
              <CircularUI
                label="Join"
                circles={[{ pattern: "blue" }, { pattern: "none" }]}
              />
              <CircularUI
                label="Exclusion"
                circles={[{ pattern: "primary" }, { pattern: "none" }]}
                className="hidden sm:block"
              />
            </div>
          </FeatureCard>
        </div>
      </div>
    </section>
  )
}

interface FeatureCardProps {
  children: ReactNode
  className?: string
}

const FeatureCard = ({ children, className }: FeatureCardProps) => (
  <Card
    className={cn(
      "group relative rounded-none shadow-zinc-950/5",
      className
    )}
  >
    <CardDecorator />
    {children}
  </Card>
)

const CardDecorator = () => (
  <>
    <span className="absolute -left-px -top-px block size-2 border-l-2 border-t-2 border-foreground" />
    <span className="absolute -right-px -top-px block size-2 border-r-2 border-t-2 border-foreground" />
    <span className="absolute -bottom-px -left-px block size-2 border-b-2 border-l-2 border-foreground" />
    <span className="absolute -bottom-px -right-px block size-2 border-b-2 border-r-2 border-foreground" />
  </>
)

interface CardHeadingProps {
  icon: LucideIcon
  title: string
  description: string
}

const CardHeading = ({
  icon: Icon,
  title,
  description,
}: CardHeadingProps) => (
  <div className="p-6">
    <span className="flex items-center gap-2 text-sm text-muted-foreground">
      <Icon className="size-4" />
      {title}
    </span>
    <p className="mt-6 text-2xl font-semibold leading-snug">{description}</p>
  </div>
)

type PaymentRow = {
  status: string
  email: string
  amount: string
  done: boolean
  highlight?: boolean
}

const PAYMENTS: PaymentRow[] = [
  { status: "Success", email: "ken99@yahoo.com", amount: "$316.00", done: true },
  { status: "Success", email: "abe45@gmail.com", amount: "$242.00", done: true },
  {
    status: "Processing",
    email: "monserrat44@gmail.com",
    amount: "$837.00",
    done: true,
    highlight: true,
  },
  { status: "Failed", email: "carmella@hotmail.com", amount: "$721.00", done: false },
]

const PaymentsTableMock = () => (
  <div className="relative overflow-hidden rounded-md border border-line bg-background/80 text-xs backdrop-blur">
    <div className="border-b border-line p-3">
      <p className="text-sm font-semibold text-foreground">Payments</p>
      <p className="text-[11px] text-muted-foreground">Manage your payments.</p>
      <div className="mt-2 flex items-center gap-2">
        <div className="h-7 flex-1 rounded-md border border-line bg-background px-2 text-[11px] leading-7 text-muted-foreground">
          Filter emails…
        </div>
        <button
          type="button"
          className="flex h-7 items-center gap-1 rounded-md border border-line bg-background px-2 text-[11px] text-foreground"
        >
          Columns <ChevronDownIcon className="size-3" />
        </button>
      </div>
    </div>
    <div className="divide-y divide-line">
      <div className="grid grid-cols-[16px_72px_1fr_70px_16px] items-center gap-3 px-3 py-2 text-[10px] uppercase tracking-wide text-muted-foreground">
        <span />
        <span>Status</span>
        <span className="flex items-center gap-1">Email ↑↓</span>
        <span className="text-right">Amount</span>
        <span />
      </div>
      {PAYMENTS.map((row, i) => (
        <div
          key={i}
          className={cn(
            "grid grid-cols-[16px_72px_1fr_70px_16px] items-center gap-3 px-3 py-2",
            row.highlight && "bg-foreground/4"
          )}
        >
          <CircleIcon
            className={cn(
              "size-3",
              row.done ? "fill-foreground/80 text-foreground/80" : "text-foreground/40"
            )}
          />
          <span className="text-foreground">{row.status}</span>
          <span className="truncate text-muted-foreground">{row.email}</span>
          <span className="text-right font-medium text-foreground">{row.amount}</span>
          <MoreHorizontalIcon className="size-3 text-muted-foreground" />
        </div>
      ))}
    </div>
  </div>
)

type DayCell = { label: string; muted?: boolean; strong?: boolean }

const SchedulerMock = () => {
  const days: DayCell[] = [
    { label: "26", muted: true },
    { label: "27", muted: true },
    { label: "28", muted: true },
    { label: "1", muted: true },
    { label: "5" },
    { label: "6" },
    { label: "7" },
    { label: "8" },
    { label: "12" },
    { label: "13" },
    { label: "14" },
    { label: "15" },
    { label: "19", strong: true },
    { label: "20" },
    { label: "21" },
    { label: "22" },
    { label: "26", muted: true },
    { label: "27", muted: true },
    { label: "28", muted: true },
    { label: "29", muted: true },
  ]

  const slots = ["09:00", "09:30", "10:00", "10:30", "11:00", "11:30", "12:00"]

  return (
    <div className="flex h-64 overflow-hidden rounded-lg border border-line bg-background/60">
      <div className="flex-1 p-3">
        <div className="mb-2 flex items-center justify-between text-xs text-muted-foreground">
          <ChevronLeftIcon className="size-3" />
          <span className="text-foreground/70">May</span>
          <ChevronRightIcon className="size-3" />
        </div>
        <div className="grid grid-cols-4 gap-y-1 text-center text-[10px] text-muted-foreground">
          {["Th", "Fr", "Sa", "Su"].map((d) => (
            <span key={d}>{d}</span>
          ))}
        </div>
        <div className="mt-1 grid grid-cols-4 gap-y-1 text-center text-[11px]">
          {days.map((d, i) => (
            <span
              key={i}
              className={cn(
                "py-0.5",
                d.muted
                  ? "text-muted-foreground/40 line-through"
                  : "text-foreground",
                "strong" in d && d.strong && "font-semibold text-foreground"
              )}
            >
              {d.label}
            </span>
          ))}
        </div>
      </div>
      <div className="w-20 border-l border-line p-2">
        <p className="mb-1 text-[10px] font-medium text-foreground/80">Sunday, 16</p>
        <div className="space-y-1">
          {slots.map((t, i) => (
            <div
              key={t}
              className={cn(
                "rounded border border-line px-1.5 py-0.5 text-center text-[10px]",
                i === 2
                  ? "bg-foreground text-background"
                  : "bg-background text-foreground"
              )}
            >
              {t}
            </div>
          ))}
        </div>
      </div>
    </div>
  )
}

interface CircleConfig {
  pattern: "none" | "border" | "primary" | "blue"
}

interface CircularUIProps {
  label: string
  circles: CircleConfig[]
  className?: string
}

const CircularUI = ({ label, circles, className }: CircularUIProps) => (
  <div className={className}>
    <div className="size-fit rounded-2xl bg-linear-to-b from-border to-transparent p-px">
      <div className="relative flex aspect-square w-fit items-center -space-x-4 rounded-[15px] bg-linear-to-b from-background to-muted/25 p-4">
        {circles.map((circle, i) => (
          <div
            key={i}
            className={cn("size-7 rounded-full border sm:size-8", {
              "border-foreground": circle.pattern === "none",
              "border-foreground bg-[repeating-linear-gradient(-45deg,var(--color-border),var(--color-border)_1px,transparent_1px,transparent_4px)]":
                circle.pattern === "border",
              "border-foreground bg-background bg-[repeating-linear-gradient(-45deg,var(--foreground),var(--foreground)_1px,transparent_1px,transparent_4px)]":
                circle.pattern === "primary",
              "z-10 border-blue-500 bg-background bg-[repeating-linear-gradient(-45deg,var(--color-blue-500),var(--color-blue-500)_1px,transparent_1px,transparent_4px)]":
                circle.pattern === "blue",
            })}
          />
        ))}
      </div>
    </div>
    <span className="mt-1.5 block text-center text-sm text-muted-foreground">
      {label}
    </span>
  </div>
)

```

## Features

* 2 feature cards on top + 1 full-width card with circular UI below.
* Each card has corner-bracket decorators in the brand color.
* Striped circular UI elements in 4 visual variants.
* Soft radial gradient backgrounds inside each card.

## Usage

```tsx
import { FeatureBento } from "@/components/feature-bento"
```

```tsx
<FeatureBento />
```


Last updated on May 23, 2026

---
title: "Hero Pillars"
description: "A hero section with a headline, illustration, and four supporting feature pillars."
last_updated: "May 23, 2026"
source: "https://syedmoinuddin.com/blog/hero-pillars"
---

# Hero Pillars

A hero section with a headline, illustration, and four supporting feature pillars.

```tsx
import Image from "next/image"
import { BrainCircuit, Cpu, Gauge, Shield } from "lucide-react"

export default function HeroPillars() {
  return (
    <section className="py-16 md:py-32">
      <div className="mx-auto max-w-5xl space-y-12 px-6">
        <div className="relative z-10 grid items-center gap-4 md:grid-cols-2 md:gap-12">
          <h2 className="text-4xl font-semibold">
            The ecosystem that brings your product to life
          </h2>
          <p className="max-w-sm sm:ml-auto">
            Empower your team with workflows that adapt to your needs —
            whether you prefer git synchronization or an AI agent interface.
          </p>
        </div>

        <div className="px-3 pt-3 md:-mx-8">
          <div className="mask-b-from-75% mask-b-to-95% relative aspect-88/36 overflow-hidden rounded-2xl border border-line bg-zinc-50 dark:bg-zinc-950">
            <Image
              src="/audionugget.png"
              alt="Hero illustration"
              fill
              className="object-cover object-center"
              unoptimized
            />
          </div>
        </div>

        <div className="relative mx-auto grid grid-cols-2 gap-x-3 gap-y-6 sm:gap-8 lg:grid-cols-4">
          <div className="space-y-3">
            <div className="flex items-center gap-2">
              <Gauge className="size-4" />
              <h3 className="text-sm font-medium">Lightning Fast</h3>
            </div>
            <p className="text-sm text-muted-foreground">
              Built for speed, helping developers ship and innovate quickly.
            </p>
          </div>
          <div className="space-y-3">
            <div className="flex items-center gap-2">
              <Cpu className="size-4" />
              <h3 className="text-sm font-medium">Powerful</h3>
            </div>
            <p className="text-sm text-muted-foreground">
              Supports an entire stack helping teams scale with confidence.
            </p>
          </div>
          <div className="space-y-3">
            <div className="flex items-center gap-2">
              <Shield className="size-4" />
              <h3 className="text-sm font-medium">Secure by Default</h3>
            </div>
            <p className="text-sm text-muted-foreground">
              Industry-standard practices baked in so you can focus on the
              build.
            </p>
          </div>
          <div className="space-y-3">
            <div className="flex items-center gap-2">
              <BrainCircuit className="size-4" />
              <h3 className="text-sm font-medium">AI Powered</h3>
            </div>
            <p className="text-sm text-muted-foreground">
              Native AI integrations to help you and your team move faster.
            </p>
          </div>
        </div>
      </div>
    </section>
  )
}

```

## Features

* Two-column hero (heading + description) over a wide illustration block.
* 4-column responsive pillar grid below with icon + title + description.
* Soft mask fade at the bottom of the illustration.
* Dark/light gradient placeholder for the illustration.

## Usage

```tsx
import { HeroPillars } from "@/components/hero-pillars"
```

```tsx
<HeroPillars />
```


Last updated on May 23, 2026

---
title: "Spotlight Grid"
description: "A 3-card spotlight grid with radial-masked icon decorators."
last_updated: "May 23, 2026"
source: "https://syedmoinuddin.com/blog/spotlight-grid"
---

# Spotlight Grid

A 3-card spotlight grid with radial-masked icon decorators.

```tsx
import { Settings2, Sparkles, Zap } from "lucide-react"
import type { ReactNode } from "react"

import { Card, CardContent, CardHeader } from "@/components/ui/card"

export default function SpotlightGridDemo() {
  return (
    <div className="w-full p-3">
      <div className="grid grid-cols-3 gap-2 *:text-center">
        <Card className="group gap-0 py-3 shadow-zinc-950/5">
          <CardHeader className="px-2 pb-0">
            <CardDecorator>
              <Zap className="size-3.5" aria-hidden />
            </CardDecorator>
            <h3 className="mt-2 text-[11px] font-medium">Customizable</h3>
          </CardHeader>
          <CardContent className="px-2 pt-1">
            <p className="text-[10px] leading-tight text-muted-foreground">
              Tailor every aspect.
            </p>
          </CardContent>
        </Card>

        <Card className="group gap-0 py-3 shadow-zinc-950/5">
          <CardHeader className="px-2 pb-0">
            <CardDecorator>
              <Settings2 className="size-3.5" aria-hidden />
            </CardDecorator>
            <h3 className="mt-2 text-[11px] font-medium">Full control</h3>
          </CardHeader>
          <CardContent className="px-2 pt-1">
            <p className="text-[10px] leading-tight text-muted-foreground">
              Personalize freely.
            </p>
          </CardContent>
        </Card>

        <Card className="group gap-0 py-3 shadow-zinc-950/5">
          <CardHeader className="px-2 pb-0">
            <CardDecorator>
              <Sparkles className="size-3.5" aria-hidden />
            </CardDecorator>
            <h3 className="mt-2 text-[11px] font-medium">AI Powered</h3>
          </CardHeader>
          <CardContent className="px-2 pt-1">
            <p className="text-[10px] leading-tight text-muted-foreground">
              Smart from day one.
            </p>
          </CardContent>
        </Card>
      </div>
    </div>
  )
}

const CardDecorator = ({ children }: { children: ReactNode }) => (
  <div className="mask-radial-from-40% mask-radial-to-60% relative mx-auto size-14 duration-200 [--color-border:color-mix(in_oklab,var(--color-zinc-950)10%,transparent)] group-hover:[--color-border:color-mix(in_oklab,var(--color-zinc-950)20%,transparent)] dark:[--color-border:color-mix(in_oklab,var(--color-white)15%,transparent)] dark:group-hover:[--color-border:color-mix(in_oklab,var(--color-white)20%,transparent)]">
    <div
      aria-hidden
      className="absolute inset-0 bg-[linear-gradient(to_right,var(--color-border)_1px,transparent_1px),linear-gradient(to_bottom,var(--color-border)_1px,transparent_1px)] bg-size-[10px_10px] dark:opacity-50"
    />

    <div className="bg-background absolute inset-0 m-auto flex size-7 items-center justify-center border-l border-t">
      {children}
    </div>
  </div>
)

```

## Features

* 3-column responsive grid using `@container` queries.
* Radial-masked grid decorator behind each icon.
* Hover state lifts the decorator border opacity.
* Dark mode aware via `color-mix()` variables.

## Usage

```tsx
import { SpotlightGrid } from "@/components/spotlight-grid"
```

```tsx
<SpotlightGrid />
```


Last updated on May 23, 2026

---
title: "Sync Showcase"
description: "An accordion synced with an animated preview pane, perfect for product showcases."
last_updated: "May 23, 2026"
source: "https://syedmoinuddin.com/blog/sync-showcase"
---

# Sync Showcase

An accordion synced with an animated preview pane, perfect for product showcases.

```tsx
"use client"

import { useState } from "react"
import { AnimatePresence, motion } from "motion/react"
import {
  ChartBarIncreasingIcon,
  Database,
  Fingerprint,
  IdCard,
} from "lucide-react"

import {
  Accordion,
  AccordionContent,
  AccordionItem,
  AccordionTrigger,
} from "@/components/ui/accordion"

type ItemKey = "item-1" | "item-2" | "item-3" | "item-4"

const PREVIEWS: Record<ItemKey, { gradient: string; label: string }> = {
  "item-1": {
    gradient: "from-emerald-500/30 via-emerald-500/10 to-transparent",
    label: "Database Visualization",
  },
  "item-2": {
    gradient: "from-amber-500/30 via-amber-500/10 to-transparent",
    label: "Advanced Authentication",
  },
  "item-3": {
    gradient: "from-sky-500/30 via-sky-500/10 to-transparent",
    label: "Identity Management",
  },
  "item-4": {
    gradient: "from-rose-500/30 via-rose-500/10 to-transparent",
    label: "Analytics Dashboard",
  },
}

export default function SyncShowcase() {
  const [activeItem, setActiveItem] = useState<ItemKey>("item-1")
  const preview = PREVIEWS[activeItem]

  return (
    <section className="py-12 md:py-20 lg:py-32">
      <div className="absolute inset-0 -z-10 bg-linear-to-b sm:inset-6 sm:rounded-b-3xl dark:block dark:to-[color-mix(in_oklab,var(--color-zinc-900)_75%,var(--color-background))]" />

      <div className="mx-auto max-w-5xl space-y-8 px-6 md:space-y-16 lg:space-y-20">
        <div className="relative z-10 mx-auto max-w-2xl space-y-6 text-center">
          <h2 className="text-balance text-4xl font-semibold lg:text-6xl">
            The foundation for modern teams
          </h2>
          <p className="text-muted-foreground">
            More than just models — an entire stack of APIs and platforms
            helping developers and businesses innovate faster.
          </p>
        </div>

        <div className="grid gap-12 sm:px-12 md:grid-cols-2 lg:gap-20 lg:px-0">
          <Accordion
            type="single"
            value={activeItem}
            onValueChange={(value) =>
              value && setActiveItem(value as ItemKey)
            }
            className="w-full"
          >
            <AccordionItem value="item-1">
              <AccordionTrigger>
                <div className="flex items-center gap-2 text-base">
                  <Database className="size-4" />
                  Database Visualization
                </div>
              </AccordionTrigger>
              <AccordionContent>
                Visualize and explore your data with rich, interactive
                dashboards built for fast iteration.
              </AccordionContent>
            </AccordionItem>

            <AccordionItem value="item-2">
              <AccordionTrigger>
                <div className="flex items-center gap-2 text-base">
                  <Fingerprint className="size-4" />
                  Advanced Authentication
                </div>
              </AccordionTrigger>
              <AccordionContent>
                Multi-factor, passkeys, SSO — drop-in auth flows that match
                your product's identity.
              </AccordionContent>
            </AccordionItem>

            <AccordionItem value="item-3">
              <AccordionTrigger>
                <div className="flex items-center gap-2 text-base">
                  <IdCard className="size-4" />
                  Identity Management
                </div>
              </AccordionTrigger>
              <AccordionContent>
                Fine-grained roles and permissions for teams of any size,
                built on familiar standards.
              </AccordionContent>
            </AccordionItem>

            <AccordionItem value="item-4">
              <AccordionTrigger>
                <div className="flex items-center gap-2 text-base">
                  <ChartBarIncreasingIcon className="size-4" />
                  Analytics Dashboard
                </div>
              </AccordionTrigger>
              <AccordionContent>
                Track product metrics, user funnels, and revenue in one
                unified dashboard.
              </AccordionContent>
            </AccordionItem>
          </Accordion>

          <div className="relative flex overflow-hidden rounded-3xl border border-line bg-background p-2">
            <div className="absolute inset-0 right-0 ml-auto w-15 border-l border-line bg-[repeating-linear-gradient(-45deg,var(--color-border),var(--color-border)_1px,transparent_1px,transparent_8px)]" />
            <div className="relative aspect-[76/59] w-[calc(3/4*100%+3rem)] overflow-hidden rounded-2xl border border-line bg-background">
              <AnimatePresence mode="wait">
                <motion.div
                  key={activeItem}
                  initial={{ opacity: 0, y: 6, scale: 0.98 }}
                  animate={{ opacity: 1, y: 0, scale: 1 }}
                  exit={{ opacity: 0, y: 6, scale: 0.98 }}
                  transition={{ duration: 0.2 }}
                  className={`flex size-full items-center justify-center bg-linear-to-br ${preview.gradient}`}
                >
                  <span className="text-sm font-medium text-foreground/80">
                    {preview.label}
                  </span>
                </motion.div>
              </AnimatePresence>
            </div>
          </div>
        </div>
      </div>
    </section>
  )
}

```

## Features

* Accordion items linked to a synchronized preview pane.
* Smooth fade/slide transition via Motion when switching items.
* Each item has a unique color-tinted preview placeholder.
* Diagonal hatched sidebar suggests an in-app surface.

## Usage

```tsx
import { SyncShowcase } from "@/components/sync-showcase"
```

```tsx
<SyncShowcase />
```


Last updated on May 23, 2026

---
title: "Dot Grid Spotlight"
description: "Interactive dot grid with a cursor-tracking spotlight effect."
last_updated: "May 22, 2026"
source: "https://syedmoinuddin.com/blog/dot-grid-spotlight"
---

# Dot Grid Spotlight

Interactive dot grid with a cursor-tracking spotlight effect.

```tsx
"use client"

import { useTheme } from "next-themes"

import { DotGridSpotlight } from "@/components/dot-grid-spotlight"

const DOT_COLOR = {
  light: {
    default: "rgba(0, 0, 0, 0.08)",
    active: "rgba(0, 0, 0, 0.16)",
  },
  dark: {
    default: "rgba(255, 255, 255, 0.06)",
    active: "rgba(255, 255, 255, 0.12)",
  },
} as const

export default function DotGridSpotlightDemo() {
  const { resolvedTheme } = useTheme()
  const theme = resolvedTheme === "dark" ? "dark" : "light"

  return (
    <div className="relative aspect-square w-xs max-w-full overflow-hidden rounded-xl border bg-black/1 dark:bg-white/5">
      <DotGridSpotlight
        dotColor={DOT_COLOR[theme]?.default}
        activeDotColor={DOT_COLOR[theme]?.active}
      />
    </div>
  )
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/dot-grid-spotlight
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/dot-grid-spotlight.tsx" 
      "use client"

      import React, { useEffect, useRef } from "react"

      import { cn } from "@/lib/utils"

      export type DotGridSpotlightProps = {
        /**
         * The base color of the default/inactive dots.
         * @default "rgba(255, 255, 255, 0.05)"
         */
        dotColor?: string

        /**
         * The color of the active dots when illuminated by the cursor's spotlight.
         * @default "rgba(255, 255, 255, 0.1)"
         */
        activeDotColor?: string

        /**
         * The distance (in pixels) between each dot in the grid.
         * @default 10
         */
        spacing?: number

        /**
         * The default radius of the dots when they are outside the interaction area.
         * @default 1
         */
        baseRadius?: number

        /**
         * The maximum radius of a dot when it is at the exact center of the cursor.
         * @default 2
         */
        activeRadius?: number

        /**
         * The radius (in pixels) of the interaction area (spotlight) around the cursor.
         * @default 128
         */
        interactionRadius?: number

        /**
         * The maximum opacity (alpha) at the exact center of the spotlight.
         * Accepts a value between `0` and `1` (e.g., `1` for full opacity).
         * @default 1.0
         */
        activeMaxAlpha?: number

        /**
         * The minimum opacity (alpha) at the outer edge of the spotlight.
         * Accepts a value between `0` and `1` (e.g., a low value for a soft, subtle fade).
         * @default 0.5
         */
        activeMinAlpha?: number

        /**
         * Optional CSS class name to apply to the canvas or its wrapper.
         */
        className?: string
      }

      export function DotGridSpotlight({
        dotColor = "rgba(255, 255, 255, 0.05)",
        activeDotColor = "rgba(255, 255, 255, 0.1)",
        spacing = 10,
        baseRadius = 1,
        activeRadius = 2,
        interactionRadius = 128,
        activeMaxAlpha = 1.0,
        activeMinAlpha = 0.5,
        className,
      }: DotGridSpotlightProps) {
        const canvasRef = useRef<HTMLCanvasElement>(null)
        const mouse = useRef({ x: -1000, y: -1000, isActive: false })

        useEffect(() => {
          const canvas = canvasRef.current
          if (!canvas) return

          const ctx = canvas.getContext("2d")
          if (!ctx) return

          let width = 0
          let height = 0
          let renderFrameId: number | null = null

          const draw = () => {
            ctx.clearRect(0, 0, width, height)

            const offsetX = (width % spacing) / 2
            const offsetY = (height % spacing) / 2

            for (let x = offsetX; x <= width; x += spacing) {
              for (let y = offsetY; y <= height; y += spacing) {
                const dx = x - mouse.current.x
                const dy = y - mouse.current.y
                const distance = Math.sqrt(dx * dx + dy * dy)

                let currentRadius = baseRadius
                let currentColor = dotColor
                let currentAlpha = 1.0

                if (mouse.current.isActive && distance < interactionRadius) {
                  const factor = 1 - distance / interactionRadius
                  currentRadius = baseRadius + (activeRadius - baseRadius) * factor
                  currentColor = activeDotColor
                  currentAlpha =
                    activeMinAlpha + (activeMaxAlpha - activeMinAlpha) * factor
                }

                ctx.globalAlpha = currentAlpha
                ctx.beginPath()
                ctx.arc(x, y, currentRadius, 0, Math.PI * 2)
                ctx.fillStyle = currentColor
                ctx.fill()
              }
            }
            ctx.globalAlpha = 1.0
            console.log("rendering")
          }

          const resizeCanvas = () => {
            const parent = canvas.parentElement
            if (!parent) return

            const dpr = window.devicePixelRatio || 1
            width = parent.clientWidth
            height = parent.clientHeight

            if (width === 0 || height === 0) return

            canvas.width = width * dpr
            canvas.height = height * dpr
            canvas.style.width = `${width}px`
            canvas.style.height = `${height}px`
            ctx.scale(dpr, dpr)

            draw()

            requestAnimationFrame(() => {
              canvas.dataset.ready = "true"
            })
          }

          const handleMouseMove = (e: MouseEvent) => {
            const rect = canvas.getBoundingClientRect()
            mouse.current = {
              x: e.clientX - rect.left,
              y: e.clientY - rect.top,
              isActive: true,
            }

            if (renderFrameId === null) {
              renderFrameId = requestAnimationFrame(() => {
                draw()
                renderFrameId = null
              })
            }
          }

          const handleMouseLeave = () => {
            mouse.current.isActive = false
            if (renderFrameId === null) {
              renderFrameId = requestAnimationFrame(() => {
                draw()
                renderFrameId = null
              })
            }
          }

          canvas.addEventListener("mousemove", handleMouseMove)
          canvas.addEventListener("mouseleave", handleMouseLeave)

          const resizeObserver = new ResizeObserver(() => resizeCanvas())
          if (canvas.parentElement) resizeObserver.observe(canvas.parentElement)

          resizeCanvas()

          return () => {
            canvas.removeEventListener("mousemove", handleMouseMove)
            canvas.removeEventListener("mouseleave", handleMouseLeave)
            resizeObserver.disconnect()
            if (renderFrameId !== null) cancelAnimationFrame(renderFrameId)
          }
        }, [
          spacing,
          baseRadius,
          activeRadius,
          interactionRadius,
          dotColor,
          activeDotColor,
          activeMaxAlpha,
          activeMinAlpha,
        ])

        const handleMouseMove = (e: React.MouseEvent<HTMLCanvasElement>) => {
          const rect = canvasRef.current?.getBoundingClientRect()
          if (rect) {
            mouse.current = {
              x: e.clientX - rect.left,
              y: e.clientY - rect.top,
              isActive: true,
            }
          }
        }

        const handleMouseLeave = () => {
          mouse.current.isActive = false
        }

        return (
          <canvas
            ref={canvasRef}
            data-ready="false"
            className={cn(
              "pointer-events-auto absolute inset-0 block opacity-0 transition-opacity! duration-500 data-[ready=true]:opacity-100",
              className
            )}
            onMouseMove={handleMouseMove}
            onMouseLeave={handleMouseLeave}
          />
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { DotGridSpotlight } from "@/components/dot-grid-spotlight"
```

```tsx
<div className="relative aspect-square w-xs">
  <DotGridSpotlight />
</div>
```

## API Reference

### DotGridSpotlight

<TypeTable
  id="type-table-dot-grid-spotlight.tsx-DotGridSpotlightProps"
  type={{
  "id": "dot-grid-spotlight.tsx-DotGridSpotlightProps",
  "name": "DotGridSpotlightProps",
  "description": "",
  "entries": [
    {
      "name": "dotColor",
      "description": "The base color of the default/inactive dots.",
      "tags": [
        {
          "name": "default",
          "text": "\"rgba(255, 255, 255, 0.05)\""
        }
      ],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "activeDotColor",
      "description": "The color of the active dots when illuminated by the cursor's spotlight.",
      "tags": [
        {
          "name": "default",
          "text": "\"rgba(255, 255, 255, 0.1)\""
        }
      ],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "spacing",
      "description": "The distance (in pixels) between each dot in the grid.",
      "tags": [
        {
          "name": "default",
          "text": "10"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "baseRadius",
      "description": "The default radius of the dots when they are outside the interaction area.",
      "tags": [
        {
          "name": "default",
          "text": "1"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "activeRadius",
      "description": "The maximum radius of a dot when it is at the exact center of the cursor.",
      "tags": [
        {
          "name": "default",
          "text": "2"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "interactionRadius",
      "description": "The radius (in pixels) of the interaction area (spotlight) around the cursor.",
      "tags": [
        {
          "name": "default",
          "text": "128"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "activeMaxAlpha",
      "description": "The maximum opacity (alpha) at the exact center of the spotlight.\nAccepts a value between `0` and `1` (e.g., `1` for full opacity).",
      "tags": [
        {
          "name": "default",
          "text": "1.0"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "activeMinAlpha",
      "description": "The minimum opacity (alpha) at the outer edge of the spotlight.\nAccepts a value between `0` and `1` (e.g., a low value for a soft, subtle fade).",
      "tags": [
        {
          "name": "default",
          "text": "0.5"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "className",
      "description": "Optional CSS class name to apply to the canvas or its wrapper.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

## References

* Inspired by the image-generating effect of [ChatGPT](https://chatgpt.com)


Last updated on May 22, 2026

---
title: "Icon Swap"
description: "Animate icon swaps with scale, blur, and fade transitions."
last_updated: "May 18, 2026"
source: "https://syedmoinuddin.com/blog/icon-swap"
---

# Icon Swap

Animate icon swaps with scale, blur, and fade transitions.

```tsx
"use client"

import { useState } from "react"
import { MonitorIcon, MoonIcon, SunIcon } from "lucide-react"

import { Button } from "@/components/ui/button"
import {
  IconSwap,
  IconSwapItem,
} from "@/components/icon-swap"

const ICONS = {
  sun: SunIcon,
  moon: MoonIcon,
  monitor: MonitorIcon,
} as const

type IconKey = keyof typeof ICONS

export default function IconSwapDemo() {
  const [icon, setIcon] = useState<IconKey>("sun")

  const Icon = ICONS[icon]

  return (
    <div className="flex flex-col items-center gap-4">
      <Button className="relative" variant="outline" size="icon-sm">
        <IconSwap>
          <IconSwapItem key={icon}>
            <Icon />
          </IconSwapItem>
        </IconSwap>
      </Button>

      <div className="flex gap-0.5 rounded-lg p-0.5 ring-1 ring-line">
        {Object.keys(ICONS).map((key) => (
          <Button
            key={key}
            className="rounded-md border-none capitalize"
            size="xs"
            variant={icon === key ? "secondary" : "ghost"}
            onClick={() => setIcon(key as IconKey)}
          >
            {key}
          </Button>
        ))}
      </div>
    </div>
  )
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/icon-swap
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install motion
      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/icon-swap.tsx" 
      "use client"

      import type { AnimatePresenceProps, HTMLMotionProps } from "motion/react"
      import { AnimatePresence, motion } from "motion/react"

      export function IconSwap(props: React.PropsWithChildren<AnimatePresenceProps>) {
        return <AnimatePresence mode="popLayout" initial={false} {...props} />
      }

      type MotionElement = typeof motion.div | typeof motion.span

      export function IconSwapItem({
        as: Component = motion.div,
        ...props
      }: HTMLMotionProps<"div"> & {
        as?: MotionElement
      }) {
        return (
          <Component
            initial={{ opacity: 0, scale: 0.25, filter: "blur(4px)" }}
            animate={{ opacity: 1, scale: 1, filter: "blur(0px)" }}
            exit={{ opacity: 0, scale: 0.25, filter: "blur(4px)" }}
            transition={{
              type: "spring",
              duration: 0.3,
              bounce: 0,
            }}
            {...props}
          />
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { IconSwap, IconSwapItem } from "@/components/icon-swap"
```

```tsx
<IconSwap>
  <IconSwapItem key={isCopied ? "check" : "copy"}>
    {isCopied ? <CheckIcon /> : <CopyIcon />}
  </IconSwapItem>
</IconSwap>
```

Change the `key` on `IconSwapItem` whenever the icon should swap.

## Composition

Use the following composition to build an `IconSwap`

```text
IconSwap
└── IconSwapItem
    └── {icon}
```

## References

* [Use blur when nothing else works](https://emilkowal.ski/ui/7-practical-animation-tips#7.-use-blur-when-nothing-else-works)


Last updated on May 18, 2026

---
title: "Brand Assets Menu"
description: "Context menu for copying brand SVGs and opening asset links."
last_updated: "May 7, 2026"
source: "https://syedmoinuddin.com/blog/brand-assets-menu"
---

# Brand Assets Menu

Context menu for copying brand SVGs and opening asset links.

```tsx
"use client"

import Link from "next/link"

import { BrandAssetsMenu } from "@/components/brand-assets-menu"

export default function BrandAssetsMenuDemo() {
  return (
    <div className="flex flex-col items-center gap-4">
      <BrandAssetsMenu
        logomark={<SyedMoinMark />}
        logomarkSVG={LOGOMARK_SVG}
        logotypeSVG={LOGOTYPE_SVG}
        brandGuidelinesURL="https://syedmoinuddin.com"
        brandAssetsURL="https://syedmoinuddin.com"
      >
        <Link href="/" aria-label="Home">
          <span
            className="block text-4xl leading-none tracking-tight text-foreground"
            style={{ fontFamily: "var(--font-audio-nugget)" }}
          >
            SM
          </span>
        </Link>
      </BrandAssetsMenu>

      <div className="text-sm text-muted-foreground">
        <span className="hidden pointer-fine:inline-block">
          Right-click the logo
        </span>
        <span className="hidden pointer-coarse:inline-block">
          Press & hold the logo
        </span>
      </div>
    </div>
  )
}

const LOGOMARK_SVG =
  '<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 200 100"><text x="100" y="72" text-anchor="middle" font-family="system-ui, -apple-system, sans-serif" font-size="64" font-weight="800" letter-spacing="-2" fill="currentColor">SM</text></svg>'

const LOGOTYPE_SVG =
  '<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 800 100"><text x="400" y="72" text-anchor="middle" font-family="system-ui, -apple-system, sans-serif" font-size="64" font-weight="700" letter-spacing="-2" fill="currentColor">Syed Moinuddin</text></svg>'

function SyedMoinMark(props: React.ComponentProps<"svg">) {
  return (
    <svg
      xmlns="http://www.w3.org/2000/svg"
      fill="none"
      viewBox="0 0 200 100"
      aria-hidden
      {...props}
    >
      <text
        x="100"
        y="72"
        textAnchor="middle"
        fontFamily="system-ui, -apple-system, sans-serif"
        fontSize="64"
        fontWeight="800"
        letterSpacing="-2"
        fill="currentColor"
      >
        SM
      </text>
    </svg>
  )
}

```

## Features

* Copy mark and logotype SVGs to the clipboard with toast feedback.
* Link out to brand guidelines and asset downloads from one menu.
* Wrap any element to use it as a right-click or press-and-hold trigger.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/brand-assets-menu
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge lucide-react
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Install the required components</Step>

      * [Context Menu](https://ui.shadcn.com/docs/components/context-menu)
      * [Sonner](https://ui.shadcn.com/docs/components/sonner)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/brand-assets-menu.tsx" 
      "use client"

      import { useTiks } from "@rexa-developer/tiks/react"
      import { toast } from "sonner"

      import {
        ContextMenu,
        ContextMenuContent,
        ContextMenuItem,
        ContextMenuSeparator,
        ContextMenuTrigger,
      } from "@/components/ui/context-menu"
      import { IconPlaceholder } from "@/registry/icons/icon-placeholder"

      export type BrandAssetsMenuProps = {
        logomark: React.ReactElement
        logomarkSVG: string
        logotypeSVG: string
        brandGuidelinesURL: string
        brandAssetsURL: string
        children: React.ReactElement
      }

      export function BrandAssetsMenu({
        logomark,
        logomarkSVG,
        logotypeSVG,
        brandGuidelinesURL,
        brandAssetsURL,
        children,
      }: BrandAssetsMenuProps) {
        const { success } = useTiks()

        return (
          <ContextMenu>
            <ContextMenuTrigger asChild>{children}</ContextMenuTrigger>

            <ContextMenuContent className="w-fit">
              <ContextMenuItem
                onClick={() => {
                  copyText(logomarkSVG)
                  toast.success("Logomark as SVG copied")
                  success()
                }}
              >
                {logomark}
                Copy Logomark as SVG
              </ContextMenuItem>

              <ContextMenuItem
                onClick={() => {
                  copyText(logotypeSVG)
                  toast.success("Logotype as SVG copied")
                  success()
                }}
              >
                <IconPlaceholder
                  lucide="TypeIcon"
                  tabler="IconLetterT"
                  hugeicons="TextIcon"
                  phosphor="TextTIcon"
                  remixicon="RiText"
                />
                Copy Logotype as SVG
              </ContextMenuItem>

              <ContextMenuSeparator />

              <ContextMenuItem asChild>
                <a
                  href={brandGuidelinesURL}
                  target="_blank"
                  rel="noopener noreferrer"
                >
                  <IconPlaceholder
                    lucide="SquareDashedIcon"
                    tabler="IconShape"
                    hugeicons="DashedLine02Icon"
                    phosphor="BoundingBoxIcon"
                    remixicon="RiShapeLine"
                  />
                  Brand Guidelines
                </a>
              </ContextMenuItem>

              <ContextMenuItem asChild>
                <a
                  href={brandAssetsURL}
                  target="_blank"
                  rel="noopener noreferrer"
                  download
                >
                  <IconPlaceholder
                    lucide="DownloadIcon"
                    tabler="IconDownload"
                    hugeicons="Download01Icon"
                    phosphor="DownloadSimpleIcon"
                    remixicon="RiDownloadLine"
                  />
                  Download Brand Assets
                </a>
              </ContextMenuItem>
            </ContextMenuContent>
          </ContextMenu>
        )
      }

      const copyText = async (text: string) => {
        try {
          await navigator.clipboard.writeText(text)
          return true
        } catch {
          return false
        }
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { BrandAssetsMenu } from "@/components/brand-assets-menu"
```

```tsx
<BrandAssetsMenu
  logomark={<SyedMoinMark />}
  logomarkSVG="<svg>...</svg>"
  logotypeSVG="<svg>...</svg>"
  brandAssetsURL="https://assets.syedmoinuddin.com/syedmoin-brand.zip"
>
  <Link />
</BrandAssetsMenu>
```

## API Reference

### BrandAssetsMenu

<TypeTable
  id="type-table-brand-assets-menu.tsx-BrandAssetsMenuProps"
  type={{
  "id": "brand-assets-menu.tsx-BrandAssetsMenuProps",
  "name": "BrandAssetsMenuProps",
  "description": "",
  "entries": [
    {
      "name": "logomark",
      "description": "",
      "tags": [],
      "type": "React.ReactElement<unknown, string | React.JSXElementConstructor<any>>",
      "simplifiedType": "object",
      "required": true,
      "deprecated": false
    },
    {
      "name": "logomarkSVG",
      "description": "",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "logotypeSVG",
      "description": "",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "brandGuidelinesURL",
      "description": "",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "brandAssetsURL",
      "description": "",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "children",
      "description": "",
      "tags": [],
      "type": "React.ReactElement<unknown, string | React.JSXElementConstructor<any>>",
      "simplifiedType": "object",
      "required": true,
      "deprecated": false
    }
  ]
}}
/>


Last updated on May 7, 2026

---
title: "TOC Minimap"
description: "Navigate page sections with a compact, hoverable TOC minimap."
last_updated: "April 27, 2026"
source: "https://syedmoinuddin.com/blog/toc-minimap"
---

# TOC Minimap

Navigate page sections with a compact, hoverable TOC minimap.

```tsx
import type { TOCItemType } from "@/components/toc-minimap"
import { TOCMinimap } from "@/components/toc-minimap"

export default function TOCMinimapDemo() {
  return <TOCMinimap items={ITEMS} />
}

const ITEMS: TOCItemType[] = [
  { title: "Installation", url: "#installation", depth: 2 },
  { title: "Usage", url: "#usage", depth: 2 },
  { title: "API Reference", url: "#api-reference", depth: 2 },
  { title: "TOCMinimap", url: "#tocminimap", depth: 3 },
  { title: "TOCItemType", url: "#tocitemtype", depth: 3 },
  { title: "References", url: "#references", depth: 2 },
]

```

## Features

* Active heading state updates as readers scroll through the page.
* Nested heading depth is represented in both the minimap and expanded TOC.
* Hovering the minimap reveals a scrollable table of contents.
* Section links update the URL hash and scroll smoothly to the target heading.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/toc-minimap
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Install the required components</Step>

      * [Hover Card](https://ui.shadcn.com/docs/components/hover-card)
      * [@soundcn/u-mini-map-open](https://www.soundcn.xyz/?sound=u-mini-map-open)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/toc-minimap.tsx" 
      "use client"

      import { useEffect, useMemo, useState } from "react"

      import { uMiniMapOpenSound } from "@/lib/soundcn/u-mini-map-open"
      import { cn } from "@/lib/utils"
      import { useSound } from "@/hooks/soundcn/use-sound"
      import {
        HoverCard,
        HoverCardContent,
        HoverCardTrigger,
      } from "@/components/ui/hover-card"

      export type TOCItemType = {
        title: React.ReactNode
        url: string
        depth: number
      }

      export type TOCMinimapProps = {
        /** @fumadocsHref #tocitemtype */
        items: TOCItemType[]
        className?: string
      }

      export function TOCMinimap({ items, className }: TOCMinimapProps) {
        const itemIds = useMemo(
          () => items.map((item) => item.url.replace("#", "")),
          [items]
        )

        const activeHeading = useActiveHeading(itemIds)

        const [play] = useSound(uMiniMapOpenSound, { volume: 0.3 })

        if (!items.length) {
          return null
        }

        return (
          <div className={cn("ml-auto w-18", className)}>
            <HoverCard
              openDelay={0}
              closeDelay={0}
              onOpenChange={(open) => {
                if (open) play()
              }}
            >
              <HoverCardTrigger asChild>
                <div className="flex max-h-[50dvh] flex-col gap-3 overflow-hidden py-3 pl-6 opacity-100 transition-opacity duration-200 data-popup-open:opacity-0">
                  {items.map((item) => (
                    <div
                      key={item.url}
                      data-depth={item.depth}
                      data-active={item.url === `#${activeHeading}`}
                      className={cn(
                        "h-0.5 w-6 shrink-0 rounded-xs bg-ring/50 transition-[background-color] duration-200",
                        "data-[depth=3]:ml-2 data-[depth=3]:w-4",
                        "data-[depth=4]:ml-4 data-[depth=4]:w-2",
                        "data-active:bg-foreground"
                      )}
                    />
                  ))}
                </div>
              </HoverCardTrigger>

              <HoverCardContent
                className="w-56 overflow-hidden p-0 duration-200 data-[side=left]:slide-in-from-right-3 data-[side=left]:slide-out-to-right-3 data-open:zoom-in-100 data-closed:zoom-out-100"
                align="start"
                alignOffset={0}
                side="left"
                sideOffset={-60}
              >
                <div className="flex max-h-[50dvh] overflow-y-auto overscroll-contain">
                  <ul className="flex size-full flex-col px-6 py-4 text-sm">
                    {items.map((item) => (
                      <li key={item.url} className="flex py-1">
                        <a
                          href={item.url}
                          data-depth={item.depth}
                          data-active={item.url === `#${activeHeading}`}
                          className={cn(
                            "line-clamp-2 w-full transition-[color] duration-200",
                            "text-muted-foreground hover:text-foreground data-active:text-foreground",
                            "data-[depth=3]:pl-4 data-[depth=4]:pl-8"
                          )}
                          onClick={handleItemClick}
                        >
                          {item.title}
                        </a>
                      </li>
                    ))}
                  </ul>
                </div>
              </HoverCardContent>
            </HoverCard>
          </div>
        )
      }

      export function useActiveHeading(itemIds: string[]) {
        const [activeId, setActiveId] = useState<string | null>(null)

        useEffect(() => {
          const observer = new IntersectionObserver(
            (entries) => {
              for (const entry of entries) {
                if (entry.isIntersecting) {
                  setActiveId(entry.target.id)
                }
              }
            },
            { rootMargin: "0% 0% -80% 0%", threshold: 0.98 }
          )

          for (const id of itemIds ?? []) {
            const element = document.getElementById(id)
            if (element) {
              observer.observe(element)
            }
          }

          return () => {
            for (const id of itemIds ?? []) {
              const element = document.getElementById(id)
              if (element) {
                observer.unobserve(element)
              }
            }
          }
        }, [itemIds])

        return activeId
      }

      function handleItemClick(e: React.MouseEvent<HTMLAnchorElement>) {
        e.preventDefault()
        const url = e.currentTarget.getAttribute("href") ?? ""
        scrollToHeading(url)
      }

      function scrollToHeading(url: string) {
        history.pushState(null, "", url)
        document.getElementById(url.replace("#", ""))?.scrollIntoView({
          behavior: "smooth",
        })
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { TOCMinimap } from "@/components/toc-minimap"
```

```tsx
<TOCMinimap items={toc} />
```

## API Reference

### TOCMinimap

<TypeTable
  id="type-table-toc-minimap.tsx-TOCMinimapProps"
  type={{
  "id": "toc-minimap.tsx-TOCMinimapProps",
  "name": "TOCMinimapProps",
  "description": "",
  "entries": [
    {
      "name": "items",
      "description": "",
      "tags": [
        {
          "name": "fumadocsHref",
          "text": "#tocitemtype"
        }
      ],
      "type": "TOCItemType[]",
      "simplifiedType": "array",
      "required": true,
      "deprecated": false,
      "typeHref": "#tocitemtype"
    },
    {
      "name": "className",
      "description": "",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

### TOCItemType

<TypeTable
  id="type-table-toc-minimap.tsx-TOCItemType"
  type={{
  "id": "toc-minimap.tsx-TOCItemType",
  "name": "TOCItemType",
  "description": "",
  "entries": [
    {
      "name": "title",
      "description": "",
      "tags": [],
      "type": "React.ReactNode",
      "simplifiedType": "ReactNode",
      "required": true,
      "deprecated": false
    },
    {
      "name": "url",
      "description": "",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "depth",
      "description": "",
      "tags": [],
      "type": "number",
      "simplifiedType": "number",
      "required": true,
      "deprecated": false
    }
  ]
}}
/>

## References

* [Notion](https://www.notion.com), inspired by its compact document navigation.
* [Vercel Knowledge Base](https://vercel.com/kb), inspired by its minimal documentation navigation.
* [soundcn](https://www.soundcn.xyz), for the u-mini-map-open sound effect.


Last updated on April 27, 2026

---
title: "GitHub Contributions"
description: "Visualize year-long GitHub contribution activity with daily counts, tooltips, and a profile link."
last_updated: "May 8, 2026"
source: "https://syedmoinuddin.com/blog/github-contributions"
---

# GitHub Contributions

Visualize year-long GitHub contribution activity with daily counts, tooltips, and a profile link.

```tsx
import { Suspense } from "react"

import {
  GitHubContributions,
  GitHubContributionsFallback,
} from "@/components/github-contributions"
import { getCachedContributions } from "@/components/github-contributions/lib/get-cached-contributions"

const GITHUB_USERNAME = "SyedMoin-lab"
const GITHUB_PROFILE_URL = "https://github.com/SyedMoin-lab"

export default function GitHubContributionsDemo() {
  const contributions = getCachedContributions(GITHUB_USERNAME)

  return (
    <Suspense fallback={<GitHubContributionsFallback />}>
      <GitHubContributions
        contributions={contributions}
        githubProfileUrl={GITHUB_PROFILE_URL}
      />
    </Suspense>
  )
}

```

## Features

* Built on Kibo UI [Contribution Graph](https://www.kibo-ui.com/components/contribution-graph) for the calendar grid, legend, and yearly total.
* Loads contribution data from Jonathan Gruber's [GitHub Contributions API](https://github.com/grubersjoe/github-contributions-api).
* Uses Next.js `unstable_cache` with a one-day revalidation window, then passes a `Promise` into the client and resolves it with React `use()`

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/github-contributions
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the required shadcn/ui components</Step>

      * [https://ui.shadcn.com/docs/components/tooltip](https://ui.shadcn.com/docs/components/tooltip)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/contribution-graph.tsx" 
      // Thanks https://www.kibo-ui.com/components/contribution-graph

      "use client"

      import {
        createContext,
        Fragment,
        useContext,
        useMemo,
        type CSSProperties,
        type HTMLAttributes,
        type ReactNode,
      } from "react"
      import type { Day as WeekDay } from "date-fns"
      import {
        differenceInCalendarDays,
        eachDayOfInterval,
        formatISO,
        getDay,
        getMonth,
        getYear,
        nextDay,
        parseISO,
        subWeeks,
      } from "date-fns"

      import { cn } from "@/lib/utils"

      export type Activity = {
        date: string
        count: number
        level: number
      }

      type Week = Array<Activity | undefined>

      export type Labels = {
        months?: string[]
        weekdays?: string[]
        totalCount?: string
        legend?: {
          less?: string
          more?: string
        }
      }

      type MonthLabel = {
        weekIndex: number
        label: string
      }

      const DEFAULT_MONTH_LABELS = [
        "Jan",
        "Feb",
        "Mar",
        "Apr",
        "May",
        "Jun",
        "Jul",
        "Aug",
        "Sep",
        "Oct",
        "Nov",
        "Dec",
      ]

      const DEFAULT_LABELS: Labels = {
        months: DEFAULT_MONTH_LABELS,
        weekdays: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"],
        totalCount: "{{count}} activities in {{year}}",
        legend: {
          less: "Less",
          more: "More",
        },
      }

      const THEME = cn(
        'data-[level="0"]:fill-muted-foreground/5',
        'data-[level="1"]:fill-muted-foreground/20',
        'data-[level="2"]:fill-muted-foreground/40',
        'data-[level="3"]:fill-muted-foreground/60',
        'data-[level="4"]:fill-muted-foreground/80'
      )

      type ContributionGraphContextType = {
        data: Activity[]
        weeks: Week[]
        blockMargin: number
        blockRadius: number
        blockSize: number
        fontSize: number
        labels: Labels
        labelHeight: number
        maxLevel: number
        totalCount: number
        weekStart: WeekDay
        year: number
        width: number
        height: number
      }

      const ContributionGraphContext =
        createContext<ContributionGraphContextType | null>(null)

      const useContributionGraph = () => {
        const context = useContext(ContributionGraphContext)

        if (!context) {
          throw new Error(
            "ContributionGraph components must be used within a ContributionGraph"
          )
        }

        return context
      }

      const fillHoles = (activities: Activity[]): Activity[] => {
        if (activities.length === 0) {
          return []
        }

        // Sort activities by date to ensure correct date range
        const sortedActivities = [...activities].sort((a, b) =>
          a.date.localeCompare(b.date)
        )

        const calendar = new Map<string, Activity>(activities.map((a) => [a.date, a]))

        const firstActivity = sortedActivities[0] as Activity
        const lastActivity = sortedActivities.at(-1)

        if (!lastActivity) {
          return []
        }

        return eachDayOfInterval({
          start: parseISO(firstActivity.date),
          end: parseISO(lastActivity.date),
        }).map((day) => {
          const date = formatISO(day, { representation: "date" })

          if (calendar.has(date)) {
            return calendar.get(date) as Activity
          }

          return {
            date,
            count: 0,
            level: 0,
          }
        })
      }

      const groupByWeeks = (
        activities: Activity[],
        weekStart: WeekDay = 0
      ): Week[] => {
        if (activities.length === 0) {
          return []
        }

        const normalizedActivities = fillHoles(activities)
        const firstActivity = normalizedActivities[0] as Activity
        const firstDate = parseISO(firstActivity.date)
        const firstCalendarDate =
          getDay(firstDate) === weekStart
            ? firstDate
            : subWeeks(nextDay(firstDate, weekStart), 1)

        const paddedActivities = [
          ...(new Array(differenceInCalendarDays(firstDate, firstCalendarDate)).fill(
            undefined
          ) as Activity[]),
          ...normalizedActivities,
        ]

        const numberOfWeeks = Math.ceil(paddedActivities.length / 7)

        return new Array(numberOfWeeks)
          .fill(undefined)
          .map((_, weekIndex) =>
            paddedActivities.slice(weekIndex * 7, weekIndex * 7 + 7)
          )
      }

      const getMonthLabels = (
        weeks: Week[],
        monthNames: string[] = DEFAULT_MONTH_LABELS
      ): MonthLabel[] => {
        return weeks
          .reduce<MonthLabel[]>((labels, week, weekIndex) => {
            const firstActivity = week.find((activity) => activity !== undefined)

            if (!firstActivity) {
              throw new Error(
                `Unexpected error: Week ${weekIndex + 1} is empty: [${week}].`
              )
            }

            const month = monthNames[getMonth(parseISO(firstActivity.date))]

            if (!month) {
              const monthName = new Date(firstActivity.date).toLocaleString("en-US", {
                month: "short",
              })
              throw new Error(
                `Unexpected error: undefined month label for ${monthName}.`
              )
            }

            const prevLabel = labels.at(-1)

            if (weekIndex === 0 || !prevLabel || prevLabel.label !== month) {
              return labels.concat({ weekIndex, label: month })
            }

            return labels
          }, [])
          .filter(({ weekIndex }, index, labels) => {
            const minWeeks = 3

            if (index === 0) {
              return labels[1] && labels[1].weekIndex - weekIndex >= minWeeks
            }

            if (index === labels.length - 1) {
              return weeks.slice(weekIndex).length >= minWeeks
            }

            return true
          })
      }

      export type ContributionGraphProps = HTMLAttributes<HTMLDivElement> & {
        data: Activity[]
        blockMargin?: number
        blockRadius?: number
        blockSize?: number
        fontSize?: number
        labels?: Labels
        maxLevel?: number
        style?: CSSProperties
        totalCount?: number
        weekStart?: WeekDay
        children: ReactNode
        className?: string
      }

      export const ContributionGraph = ({
        data,
        blockMargin = 4,
        blockRadius = 2,
        blockSize = 12,
        fontSize = 14,
        labels: labelsProp = undefined,
        maxLevel: maxLevelProp = 4,
        style = {},
        totalCount: totalCountProp = undefined,
        weekStart = 0,
        className,
        ...props
      }: ContributionGraphProps) => {
        const maxLevel = Math.max(1, maxLevelProp)
        const weeks = useMemo(() => groupByWeeks(data, weekStart), [data, weekStart])
        const LABEL_MARGIN = 8

        const labels = { ...DEFAULT_LABELS, ...labelsProp }
        const labelHeight = fontSize + LABEL_MARGIN

        const year =
          data.length > 0 ? getYear(parseISO(data[0].date)) : new Date().getFullYear()

        const totalCount =
          typeof totalCountProp === "number"
            ? totalCountProp
            : data.reduce((sum, activity) => sum + activity.count, 0)

        const width = weeks.length * (blockSize + blockMargin) - blockMargin
        const height = labelHeight + (blockSize + blockMargin) * 7 - blockMargin

        if (data.length === 0) {
          return null
        }

        return (
          <ContributionGraphContext.Provider
            value={{
              data,
              weeks,
              blockMargin,
              blockRadius,
              blockSize,
              fontSize,
              labels,
              labelHeight,
              maxLevel,
              totalCount,
              weekStart,
              year,
              width,
              height,
            }}
          >
            <div
              className={cn("flex w-max max-w-full flex-col gap-2", className)}
              style={{ fontSize, ...style }}
              {...props}
            />
          </ContributionGraphContext.Provider>
        )
      }

      export type ContributionGraphBlockProps = HTMLAttributes<SVGRectElement> & {
        activity: Activity
        dayIndex: number
        weekIndex: number
      }

      export const ContributionGraphBlock = ({
        activity,
        dayIndex,
        weekIndex,
        className,
        ...props
      }: ContributionGraphBlockProps) => {
        const { blockSize, blockMargin, blockRadius, labelHeight, maxLevel } =
          useContributionGraph()

        if (activity.level < 0 || activity.level > maxLevel) {
          throw new RangeError(
            `Provided activity level ${activity.level} for ${activity.date} is out of range. It must be between 0 and ${maxLevel}.`
          )
        }

        return (
          <rect
            className={cn(THEME, className)}
            data-count={activity.count}
            data-date={activity.date}
            data-level={activity.level}
            height={blockSize}
            rx={blockRadius}
            ry={blockRadius}
            width={blockSize}
            x={(blockSize + blockMargin) * weekIndex}
            y={labelHeight + (blockSize + blockMargin) * dayIndex}
            {...props}
          />
        )
      }

      export type ContributionGraphCalendarProps = Omit<
        HTMLAttributes<HTMLDivElement>,
        "children"
      > & {
        hideMonthLabels?: boolean
        className?: string
        children: (props: {
          activity: Activity
          dayIndex: number
          weekIndex: number
        }) => ReactNode
      }

      export const ContributionGraphCalendar = ({
        title = "Contribution Graph",
        hideMonthLabels = false,
        className,
        children,
        ...props
      }: ContributionGraphCalendarProps) => {
        const { weeks, width, height, blockSize, blockMargin, labels } =
          useContributionGraph()

        const monthLabels = useMemo(
          () => getMonthLabels(weeks, labels.months),
          [weeks, labels.months]
        )

        return (
          <div
            className={cn("max-w-full overflow-x-auto overflow-y-hidden", className)}
            {...props}
          >
            <svg
              className="block overflow-visible"
              height={height}
              viewBox={`0 0 ${width} ${height}`}
              width={width}
            >
              <title>{title}</title>
              {!hideMonthLabels && (
                <g className="fill-current selection:fill-selection-foreground">
                  {monthLabels.map(({ label, weekIndex }) => (
                    <text
                      dominantBaseline="hanging"
                      key={weekIndex}
                      x={(blockSize + blockMargin) * weekIndex}
                    >
                      {label}
                    </text>
                  ))}
                </g>
              )}
              {weeks.map((week, weekIndex) =>
                week.map((activity, dayIndex) => {
                  if (!activity) {
                    return null
                  }

                  return (
                    <Fragment key={`${weekIndex}-${dayIndex}`}>
                      {children({ activity, dayIndex, weekIndex })}
                    </Fragment>
                  )
                })
              )}
            </svg>
          </div>
        )
      }

      export type ContributionGraphFooterProps = HTMLAttributes<HTMLDivElement>

      export const ContributionGraphFooter = ({
        className,
        ...props
      }: ContributionGraphFooterProps) => (
        <div
          className={cn(
            "flex flex-wrap gap-1 whitespace-nowrap sm:gap-x-4",
            className
          )}
          {...props}
        />
      )

      export type ContributionGraphTotalCountProps = Omit<
        HTMLAttributes<HTMLDivElement>,
        "children"
      > & {
        children?: (props: { totalCount: number; year: number }) => ReactNode
      }

      export const ContributionGraphTotalCount = ({
        className,
        children,
        ...props
      }: ContributionGraphTotalCountProps) => {
        const { totalCount, year, labels } = useContributionGraph()

        if (children) {
          return <>{children({ totalCount, year })}</>
        }

        return (
          <div className={cn("text-muted-foreground", className)} {...props}>
            {labels.totalCount
              ? labels.totalCount
                  .replace("{{count}}", String(totalCount))
                  .replace("{{year}}", String(year))
              : `${totalCount} activities in ${year}`}
          </div>
        )
      }

      export type ContributionGraphLegendProps = Omit<
        HTMLAttributes<HTMLDivElement>,
        "children"
      > & {
        children?: (props: { level: number }) => ReactNode
      }

      export const ContributionGraphLegend = ({
        className,
        children,
        ...props
      }: ContributionGraphLegendProps) => {
        const { labels, maxLevel, blockSize, blockRadius } = useContributionGraph()

        return (
          <div
            className={cn("ml-auto flex items-center gap-0.75", className)}
            {...props}
          >
            <span className="mr-1 text-muted-foreground">
              {labels.legend?.less || "Less"}
            </span>
            {new Array(maxLevel + 1).fill(undefined).map((_, level) =>
              children ? (
                <Fragment key={level}>{children({ level })}</Fragment>
              ) : (
                <svg height={blockSize} key={level} width={blockSize}>
                  <title>{`${level} contributions`}</title>
                  <rect
                    className={cn(THEME)}
                    data-level={level}
                    height={blockSize}
                    rx={blockRadius}
                    ry={blockRadius}
                    width={blockSize}
                  />
                </svg>
              )
            )}
            <span className="ml-1 text-muted-foreground">
              {labels.legend?.more || "More"}
            </span>
          </div>
        )
      }

      ```

      ```tsx title="components/github-contributions.tsx" 
      "use client"

      import { use } from "react"
      import { format } from "date-fns"

      import { cn } from "@/lib/utils"
      import { Spinner } from "@/components/ui/spinner"
      import {
        Tooltip,
        TooltipContent,
        TooltipTrigger,
      } from "@/components/ui/tooltip"
      import type { Activity } from "@/components/contribution-graph"
      import {
        ContributionGraph,
        ContributionGraphBlock,
        ContributionGraphCalendar,
        ContributionGraphFooter,
        ContributionGraphLegend,
        ContributionGraphTotalCount,
      } from "@/components/contribution-graph"

      export function GitHubContributions({
        contributions,
        githubProfileUrl,
        className,
      }: {
        contributions: Promise<Activity[]>
        githubProfileUrl: string
        className?: string
      }) {
        const data = use(contributions)

        return (
          <ContributionGraph
            className={cn("mx-auto py-2", className)}
            data={data}
            blockSize={11}
            blockMargin={3}
            blockRadius={2}
          >
            <ContributionGraphCalendar
              className="no-scrollbar px-2"
              title="GitHub Contributions"
            >
              {({ activity, dayIndex, weekIndex }) => (
                <Tooltip>
                  <TooltipTrigger asChild>
                    <g>
                      <ContributionGraphBlock
                        activity={activity}
                        dayIndex={dayIndex}
                        weekIndex={weekIndex}
                      />
                    </g>
                  </TooltipTrigger>
                  <TooltipContent className="font-sans">
                    <p>
                      {activity.count} contribution{activity.count > 1 ? "s" : null}{" "}
                      on {format(new Date(activity.date), "dd.MM.yyyy")}
                    </p>
                  </TooltipContent>
                </Tooltip>
              )}
            </ContributionGraphCalendar>

            <ContributionGraphFooter className="px-2">
              <ContributionGraphTotalCount>
                {({ totalCount, year }) => (
                  <div className="text-muted-foreground">
                    {totalCount.toLocaleString("en")} contributions in {year} on{" "}
                    <a
                      className="text-foreground link-underline"
                      href={githubProfileUrl}
                      target="_blank"
                      rel="noopener"
                    >
                      GitHub
                    </a>
                    .
                  </div>
                )}
              </ContributionGraphTotalCount>

              <ContributionGraphLegend />
            </ContributionGraphFooter>
          </ContributionGraph>
        )
      }

      export function GitHubContributionsFallback() {
        return (
          <div className="flex h-40.5 w-full items-center justify-center">
            <Spinner className="text-muted-foreground" />
          </div>
        )
      }

      ```

      ```ts title="lib/get-cached-contributions.tsx" 
      import { unstable_cache } from "next/cache"

      import type { Activity } from "@/components/contribution-graph"

      type GitHubContributionsResponse = {
        contributions: Activity[]
      }

      export const getCachedContributions = unstable_cache(
        async (username: string): Promise<Activity[]> => {
          try {
            const res = await fetch(
              `${process.env.GITHUB_CONTRIBUTIONS_API_URL || `https://github-contributions-api.jogruber.de`}/v4/${username}?y=last`,
              { signal: AbortSignal.timeout(8000) }
            )
            if (!res.ok) return []
            const data = (await res.json()) as GitHubContributionsResponse
            return data.contributions ?? []
          } catch {
            return []
          }
        },
        ["github-contributions"],
        { revalidate: 86400 } // Cache for 1 day (86400 seconds)
      )

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx  
import { Suspense } from "react"

import {
  GitHubContributions,
  GitHubContributionsFallback,
} from "@/components/github-contributions"
import { getCachedContributions } from "@/components/github-contributions/lib/get-cached-contributions"

const GITHUB_USERNAME = "SyedMoin-lab"
const GITHUB_PROFILE_URL = "https://github.com/SyedMoin-lab"

export default function GitHubContributionsDemo() {
  const contributions = getCachedContributions(GITHUB_USERNAME)

  return (
    <Suspense fallback={<GitHubContributionsFallback />}>
      <GitHubContributions
        contributions={contributions}
        githubProfileUrl={GITHUB_PROFILE_URL}
      />
    </Suspense>
  )
}

```

## API Reference

### GitHubContributions

<TypeTable
  id="type-table-props.ts-GitHubContributionsProps"
  type={{
  "id": "props.ts-GitHubContributionsProps",
  "name": "GitHubContributionsProps",
  "description": "",
  "entries": [
    {
      "name": "contributions",
      "description": "",
      "tags": [],
      "type": "Promise<Activity[]>",
      "simplifiedType": "object",
      "required": true,
      "deprecated": false
    },
    {
      "name": "githubProfileUrl",
      "description": "",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "className",
      "description": "",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

## Examples

### GitHub Default Theme

```tsx
import { Suspense } from "react"

import { cn } from "@/lib/utils"
import {
  GitHubContributions,
  GitHubContributionsFallback,
} from "@/components/github-contributions"
import { getCachedContributions } from "@/components/github-contributions/lib/get-cached-contributions"

const GITHUB_USERNAME = "SyedMoin-lab"
const GITHUB_PROFILE_URL = "https://github.com/ncdai"

export default function GitHubContributionsDemo02() {
  const contributions = getCachedContributions(GITHUB_USERNAME)

  return (
    <Suspense fallback={<GitHubContributionsFallback />}>
      <GitHubContributions
        contributions={contributions}
        githubProfileUrl={GITHUB_PROFILE_URL}
        className={cn(
          // GitHub Default Theme
          '**:data-[level="0"]:fill-[#eff2f5] dark:**:data-[level="0"]:fill-[#151b23]',
          '**:data-[level="1"]:fill-[#aceebb] dark:**:data-[level="1"]:fill-[#033a16]',
          '**:data-[level="2"]:fill-[#4ac26b] dark:**:data-[level="2"]:fill-[#196c2e]',
          '**:data-[level="3"]:fill-[#2da44e] dark:**:data-[level="3"]:fill-[#2ea043]',
          '**:data-[level="4"]:fill-[#116329] dark:**:data-[level="4"]:fill-[#56d364]'
        )}
      />
    </Suspense>
  )
}

```

### GitHub Winter Theme

```tsx
import { Suspense } from "react"

import { cn } from "@/lib/utils"
import {
  GitHubContributions,
  GitHubContributionsFallback,
} from "@/components/github-contributions"
import { getCachedContributions } from "@/components/github-contributions/lib/get-cached-contributions"

const GITHUB_USERNAME = "SyedMoin-lab"
const GITHUB_PROFILE_URL = "https://github.com/ncdai"

export default function GitHubContributionsDemo03() {
  const contributions = getCachedContributions(GITHUB_USERNAME)

  return (
    <Suspense fallback={<GitHubContributionsFallback />}>
      <GitHubContributions
        contributions={contributions}
        githubProfileUrl={GITHUB_PROFILE_URL}
        className={cn(
          // GitHub Winter Theme
          '**:data-[level="0"]:fill-[#eff2f5] dark:**:data-[level="0"]:fill-[#151b23]',
          '**:data-[level="1"]:fill-[#b6e3ff] dark:**:data-[level="1"]:fill-[#0c2d6b]',
          '**:data-[level="2"]:fill-[#54aeff] dark:**:data-[level="2"]:fill-[#1158c7]',
          '**:data-[level="3"]:fill-[#0969da] dark:**:data-[level="3"]:fill-[#58a6ff]',
          '**:data-[level="4"]:fill-[#0a3069] dark:**:data-[level="4"]:fill-[#cae8ff]'
        )}
      />
    </Suspense>
  )
}

```

### GitHub Halloween Theme

```tsx
import { Suspense } from "react"

import { cn } from "@/lib/utils"
import {
  GitHubContributions,
  GitHubContributionsFallback,
} from "@/components/github-contributions"
import { getCachedContributions } from "@/components/github-contributions/lib/get-cached-contributions"

const GITHUB_USERNAME = "SyedMoin-lab"
const GITHUB_PROFILE_URL = "https://github.com/ncdai"

export default function GitHubContributionsDemo04() {
  const contributions = getCachedContributions(GITHUB_USERNAME)

  return (
    <Suspense fallback={<GitHubContributionsFallback />}>
      <GitHubContributions
        contributions={contributions}
        githubProfileUrl={GITHUB_PROFILE_URL}
        className={cn(
          // GitHub Halloween Theme
          '**:data-[level="0"]:fill-[#eff2f5] dark:**:data-[level="0"]:fill-[#151b23]',
          '**:data-[level="1"]:fill-[#f0db3d] dark:**:data-[level="1"]:fill-[#fac68f]',
          '**:data-[level="2"]:fill-[#ffd642] dark:**:data-[level="2"]:fill-[#c46212]',
          '**:data-[level="3"]:fill-[#f68c41] dark:**:data-[level="3"]:fill-[#984b10]',
          '**:data-[level="4"]:fill-[#1f2328] dark:**:data-[level="4"]:fill-[#e3d04f]'
        )}
      />
    </Suspense>
  )
}

```

## References

* [Contribution Graph](https://www.kibo-ui.com/components/contribution-graph) from Kibo UI
* [GitHub Contributions API](https://github-contributions-api.jogruber.de) by Jonathan Gruber


Last updated on May 8, 2026

---
title: "Theme Toggle Effect"
description: "Animated transitions when switching between light and dark themes."
last_updated: "April 10, 2026"
source: "https://syedmoinuddin.com/blog/theme-toggle-effect"
---

# Theme Toggle Effect

Animated transitions when switching between light and dark themes.

```tsx
"use client"

import { MoonIcon, SunMediumIcon } from "lucide-react"
import { useTheme } from "next-themes"

import { useClickSound } from "@/hooks/soundcn/use-click-sound"
import { Button } from "@/components/ui/button"

import { ThemeToggleEffectSelector } from "./theme-toggle-effect-selector"

export default function ThemeToggleEffectDemo() {
  const { resolvedTheme, setTheme } = useTheme()

  const [click] = useClickSound()

  const switchTheme = () => {
    setTheme(resolvedTheme === "dark" ? "light" : "dark")
  }

  const handleThemeToggleClick = () => {
    click()
    if (!document.startViewTransition) switchTheme()
    else document.startViewTransition(switchTheme)
  }

  return (
    <div className="flex gap-2">
      <ThemeToggleEffectSelector />

      <Button
        variant="outline"
        size="icon"
        aria-label="Theme Toggle"
        onClick={handleThemeToggleClick}
      >
        <MoonIcon className="hidden [html.dark_&]:block" />
        <SunMediumIcon className="hidden [html.light_&]:block" />
      </Button>
    </div>
  )
}

```

<Testimonial authorAvatar="https://unavatar.io/x/orcdev" authorName="OrcDev" authorTagline="Creator of 8bitcn.com" url="https://x.com/orcdev/status/2042294526589518083" quote="oh I love this one, have to implement it on orcdev.com" date="2026-04-10" />

## Browser Compatibility

This component uses the [View Transitions API](https://developer.mozilla.org/en-US/docs/Web/API/View_Transition_API). Check the latest [browser compatibility on MDN](https://developer.mozilla.org/en-US/docs/Web/API/View_Transition_API#browser_compatibility) before using in production.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ### Triangle

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-triangle
    ```

    ### Triangle Blur

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-triangle-blur
    ```

    ### Circle

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-circle
    ```

    ### Circle Blur

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-circle-blur
    ```

    ### Circle Blur (Top Left)

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-circle-blur-top-left
    ```

    ### Polygon

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-polygon
    ```

    ### Polygon Gradient

    ```bash
    npx shadcn@latest add @syedmoin/theme-toggle-effect-polygon-gradient
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Add the easing variable to your global CSS</Step>

      ```css
      :root {
        --expo-out: linear(
          0 0%,
          0.1684 2.66%,
          0.3165 5.49%,
          0.446 8.52%,
          0.5581 11.78%,
          0.6535 15.29%,
          0.7341 19.11%,
          0.8011 23.3%,
          0.8557 27.93%,
          0.8962 32.68%,
          0.9283 38.01%,
          0.9529 44.08%,
          0.9711 51.14%,
          0.9833 59.06%,
          0.9915 68.74%,
          1 100%
        );
      }
      ```

      <Step>Add the effect CSS to your global CSS</Step>

      Choose one effect and copy its CSS into your `globals.css`

      **Triangle**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: none;
          animation-fill-mode: both;
          z-index: -1;
        }

        ::view-transition-new(root) {
          mask: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40"><path d="m20 0 20 35H0z" fill="white"/></svg>')
            center / 0 no-repeat;
          animation: scale 0.7s;
          animation-fill-mode: both;
        }

        @keyframes scale {
          to {
            mask-size: 300vmax;
          }
        }
      }
      ```

      **Triangle Blur**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: none;
          animation-fill-mode: both;
          z-index: -1;
        }

        ::view-transition-new(root) {
          mask: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40"><path d="m20 0 20 35H0z" fill="white" filter="url(%23blur)"/><defs><filter id="blur"><feGaussianBlur stdDeviation="1"/></filter></defs></svg>')
            center / 0 no-repeat;
          animation: scale 0.7s;
          animation-fill-mode: both;
        }

        @keyframes scale {
          to {
            mask-size: 300vmax;
          }
        }
      }
      ```

      **Circle**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: none;
          animation-fill-mode: both;
          z-index: -1;
        }

        ::view-transition-new(root) {
          mask: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40"><circle cx="20" cy="20" r="20" fill="white"/></svg>')
            center / 0 no-repeat;
          animation: scale 1s;
          animation-fill-mode: both;
        }

        @keyframes scale {
          to {
            mask-size: 200vmax;
          }
        }
      }
      ```

      **Circle Blur**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: none;
          animation-fill-mode: both;
          z-index: -1;
        }

        ::view-transition-new(root) {
          mask: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40"><defs><filter id="blur"><feGaussianBlur stdDeviation="2"/></filter></defs><circle cx="20" cy="20" r="18" fill="white" filter="url(%23blur)"/></svg>')
            center / 0 no-repeat;
          animation: scale 1s;
          animation-fill-mode: both;
        }

        .dark::view-transition-new(root) {
          animation: scale 1s;
          animation-fill-mode: both;
        }

        @keyframes scale {
          to {
            mask-size: 200vmax;
          }
        }
      }
      ```

      **Circle Blur (Top Left)**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-new(root) {
          mask: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40"><defs><filter id="blur"><feGaussianBlur stdDeviation="2"/></filter></defs><circle cx="0" cy="0" r="18" fill="white" filter="url(%23blur)"/></svg>')
            top left / 0 no-repeat;
          mask-origin: content-box;
          animation: scale 1s;
          animation-fill-mode: both;
          transform-origin: top left;
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: scale 1s;
          animation-fill-mode: both;
          transform-origin: top left;
          z-index: -1;
        }

        @keyframes scale {
          to {
            mask-size: 350vmax;
          }
        }
      }
      ```

      **Polygon**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-duration: 0.7s;
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-new(root) {
          animation-name: reveal-light;
          animation-fill-mode: both;
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: none;
          animation-fill-mode: both;
          z-index: -1;
        }

        .dark::view-transition-new(root) {
          animation-name: reveal-dark;
          animation-fill-mode: both;
        }

        @keyframes reveal-dark {
          from {
            clip-path: polygon(50% -71%, -50% 71%, -50% 71%, 50% -71%);
          }
          to {
            clip-path: polygon(50% -71%, -50% 71%, 50% 171%, 171% 50%);
          }
        }

        @keyframes reveal-light {
          from {
            clip-path: polygon(171% 50%, 50% 171%, 50% 171%, 171% 50%);
          }
          to {
            clip-path: polygon(171% 50%, 50% 171%, -50% 71%, 50% -71%);
          }
        }
      }
      ```

      **Polygon Gradient**

      ```css
      @layer base {
        ::view-transition-group(root) {
          animation-timing-function: var(--expo-out);
        }

        ::view-transition-new(root) {
          mask: url('data:image/svg+xml,<svg width="40" height="40" viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg"><path d="M0 0H40L0 40V0Z" fill="url(%23paint0_linear_16_14)"/><defs><linearGradient id="paint0_linear_16_14" x1="0" y1="0" x2="20.5" y2="20.5" gradientUnits="userSpaceOnUse"><stop stop-color="current"/><stop offset="0.84506" stop-color="current" stop-opacity="0.99"/><stop offset="0.9506" stop-color="current" stop-opacity="0"/><stop offset="1" stop-color="current" stop-opacity="0"/></linearGradient></defs></svg>')
            top left / 0 no-repeat;
          mask-origin: top left;
          animation: scale 1.5s;
          animation-fill-mode: both;
        }

        ::view-transition-old(root),
        .dark::view-transition-old(root) {
          animation: scale 1.5s;
          animation-fill-mode: both;
          z-index: -1;
          transform-origin: top left;
        }

        @keyframes scale {
          to {
            mask-size: 200vmax;
          }
        }
      }
      ```

      <Step>Use startViewTransition in your theme toggle</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

Wrap your theme setter with `document.startViewTransition` to trigger the effect:

```tsx
const { setTheme } = useTheme()

function toggleTheme(theme: string) {
  if (!document.startViewTransition) {
    setTheme(theme)
    return
  }

  document.startViewTransition(() => setTheme(theme))
}
```

## References

* [theme-toggle.rdsx.dev](https://theme-toggle.rdsx.dev) by [@rds_agi](https://x.com/rds_agi)
* [View Transition API](https://developer.mozilla.org/en-US/docs/Web/API/View_Transition_API)


Last updated on April 10, 2026

---
title: "Middle Truncation"
description: "Truncate text in the middle while preserving start and end."
last_updated: "April 1, 2026"
source: "https://syedmoinuddin.com/blog/middle-truncation"
---

# Middle Truncation

Truncate text in the middle while preserving start and end.

```tsx
"use client"

import {
  ResizableHandle,
  ResizablePanel,
  ResizablePanelGroup,
} from "@/components/ui/resizable"
import { MiddleTruncation } from "@/components/middle-truncation"

export default function MiddleTruncationDemo() {
  return (
    <ResizablePanelGroup orientation="horizontal" className="w-full max-w-md">
      <ResizablePanel minSize="30%" defaultSize="100%" className="pr-0.5">
        <ExampleCard>
          <ExampleItem>
            <ExampleLabel>{`<MiddleTruncation>`}</ExampleLabel>
            <MiddleTruncation>
              /Users/syedmoin/Code/syedmoinuddin.com/src/components/ui/button.tsx
            </MiddleTruncation>
          </ExampleItem>

          <ExampleItem>
            <ExampleLabel>{`<MiddleTruncation end={4}>`}</ExampleLabel>
            <MiddleTruncation end={4}>
              FY26_Q1_Consolidated_Financial_Statements.pdf
            </MiddleTruncation>
          </ExampleItem>

          <ExampleItem>
            <ExampleLabel>{`<MiddleTruncation minEnd={12}>`}</ExampleLabel>
            <MiddleTruncation minEnd={12}>
              /Users/syedmoin/Code/syedmoinuddin.com/node_modules/shadcn/package.json
            </MiddleTruncation>
          </ExampleItem>

          <ExampleItem>
            <ExampleLabel>{`<MiddleTruncation ellipsis=" ... ">`}</ExampleLabel>
            <MiddleTruncation ellipsis=" ... ">
              https://www.apple.com/newsroom/pdfs/fy2026-q1/FY26_Q1_Consolidated_Financial_Statements.pdf
            </MiddleTruncation>
          </ExampleItem>
        </ExampleCard>
      </ResizablePanel>

      <ResizableHandle
        className="relative w-2 bg-transparent p-0 after:absolute after:top-1/2 after:right-0 after:left-0.5 after:h-12 after:w-1.5 after:translate-x-0 after:-translate-y-1/2 after:rounded-full after:bg-foreground/10 after:transition-all focus-visible:ring-0 focus-visible:ring-offset-0 data-[separator=active]:after:scale-y-125 data-[separator=active]:after:bg-foreground/30 data-[separator=hover]:after:bg-foreground/20"
        disableDoubleClick
      />

      <ResizablePanel minSize="0%" defaultSize="0%" />
    </ResizablePanelGroup>
  )
}

function ExampleCard({ children }: { children: React.ReactNode }) {
  return (
    <div className="flex flex-col gap-6 rounded-xl border bg-card p-6 text-sm">
      {children}
    </div>
  )
}

function ExampleItem({ children }: { children: React.ReactNode }) {
  return <div className="flex w-full flex-col gap-1.5">{children}</div>
}

function ExampleLabel({ children }: { children: React.ReactNode }) {
  return (
    <div className="truncate font-mono text-xs whitespace-nowrap text-muted-foreground">
      {children}
    </div>
  )
}

```

## Features

* Three truncation strategies: fixed end, flexible with minimum, or even split.
* Pixel-accurate measurement based on actual rendered text width.
* Automatically recalculates when container resizes.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/middle-truncation
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/middle-truncation.tsx" 
      "use client"

      import React, { useLayoutEffect, useRef, useState } from "react"

      import { cn } from "@/lib/utils"

      let cachedCanvas: HTMLCanvasElement | null = null
      let cachedCtx: CanvasRenderingContext2D | null = null

      /**
       * Returns a singleton canvas 2D context for text measurement.
       * Creates the canvas on first call and reuses it for all subsequent calls.
       *
       * @throws {Error} If canvas 2D context creation fails.
       */
      function getCanvas(): CanvasRenderingContext2D {
        if (!cachedCtx) {
          cachedCanvas = document.createElement("canvas")
          const ctx = cachedCanvas.getContext("2d")
          if (!ctx) {
            throw new Error("Failed to get 2d context from canvas")
          }
          cachedCtx = ctx
        }
        return cachedCtx
      }

      function measureText(text: string, font: string) {
        const ctx = getCanvas()
        ctx.font = font
        return ctx.measureText(text).width
      }

      function getComputedFont(el: HTMLElement) {
        const cs = window.getComputedStyle(el)
        return `${cs.fontStyle} ${cs.fontWeight} ${cs.fontSize} ${cs.fontFamily}`
      }

      /**
       * Creates a debounced version of a function that syncs execution with the browser's paint cycle.
       *
       * Combines debouncing (waits for inactivity) with requestAnimationFrame (syncs with browser rendering)
       * to ensure smooth UI updates without jank.
       *
       * @template Args - The argument types of the function.
       * @template Return - The return type of the function (ignored in debounced version).
       * @param fn - The function to debounce.
       * @param delay - Milliseconds to wait before executing after the last call.
       * @returns A debounced version that executes on the next animation frame after the delay.
       *
       * @example
       * const debouncedScroll = debounceWithRAF(handleScroll, 150)
       * window.addEventListener('scroll', debouncedScroll)
       */
      function debounceWithRAF<Args extends unknown[], Return = void>(
        fn: (...args: Args) => Return,
        delay: number
      ): (...args: Args) => void {
        let timeoutId: ReturnType<typeof setTimeout> | undefined
        let rafId: number | undefined

        return (...args: Args): void => {
          if (timeoutId !== undefined) {
            clearTimeout(timeoutId)
          }
          if (rafId !== undefined) {
            cancelAnimationFrame(rafId)
          }

          timeoutId = setTimeout(() => {
            rafId = requestAnimationFrame(() => {
              fn(...args)
            })
          }, delay)
        }
      }

      /**
       * Truncates text in the middle, preserving the start and end portions.
       *
       * Uses binary search to find the optimal truncation point based on pixel width,
       * ensuring the result fits within the container. The truncated text will be in
       * the format: "start{ellipsis}end".
       *
       * @param text - The text to truncate.
       * @param end - Fixed number of characters to preserve at the end. Mutually exclusive with minEnd.
       * @param minEnd - Minimum characters at the end when splitting evenly. Mutually exclusive with end.
       * @param containerW - Available width in pixels.
       * @param font - CSS font string for accurate measurement.
       * @param ellipsis - The string to use as separator in the middle.
       * @returns The original text if it fits, otherwise truncated text with ellipsis in the middle.
       *
       * @example
       * // Fixed end: always preserve exactly 4 chars at the end
       * computeTruncated("very-long-filename.txt", 4, undefined, 100, "16px Arial", "...")
       * // Returns: "very-long-file...txt"
       *
       * @example
       * // MinEnd: split evenly, but ensure at least 4 chars at the end
       * computeTruncated("document.pdf", undefined, 4, 100, "16px Arial", "...")
       * // Returns: "doc....pdf" (prioritizes minEnd when width is small)
       *
       * @example
       * // No constraints: split evenly in the middle
       * computeTruncated("abcdefghijklmnop", undefined, undefined, 100, "16px Arial", "...")
       * // Returns: "abcd...mnop"
       */
      function computeTruncated(
        text: string,
        end: number | undefined,
        minEnd: number | undefined,
        containerW: number,
        font: string,
        ellipsis: string
      ): string {
        const fullW = measureText(text, font)
        if (fullW <= containerW) return text

        // Strategy 1: Fixed end (always preserve exactly X chars at the end)
        if (end !== undefined) {
          const endStr = text.slice(-end)
          const endW = measureText(ellipsis + endStr, font)
          const available = containerW - endW

          let lo = 0
          let hi = text.length - end
          while (lo < hi) {
            const mid = Math.ceil((lo + hi) / 2)
            if (measureText(text.slice(0, mid), font) <= available) lo = mid
            else hi = mid - 1
          }

          return text.slice(0, lo) + ellipsis + endStr
        }

        // Strategy 2: Split evenly (with optional minEnd constraint)
        const ellipsisW = measureText(ellipsis, font)
        const availableForText = containerW - ellipsisW

        let lo = 0
        let hi = text.length
        while (lo < hi) {
          const mid = Math.ceil((lo + hi) / 2)

          let startLen: number
          let endLen: number

          if (minEnd !== undefined) {
            endLen = Math.max(Math.ceil(mid / 2), minEnd)
            startLen = Math.max(0, mid - endLen)
          } else {
            startLen = Math.floor(mid / 2)
            endLen = Math.ceil(mid / 2)
          }

          const startStr = text.slice(0, startLen)
          const endStr = text.slice(-endLen)
          const combinedW = measureText(startStr + endStr, font)

          if (combinedW <= availableForText) lo = mid
          else hi = mid - 1
        }

        let startLen: number
        let endLen: number

        if (minEnd !== undefined) {
          endLen = Math.max(Math.ceil(lo / 2), minEnd)
          startLen = Math.max(0, lo - endLen)
        } else {
          startLen = Math.floor(lo / 2)
          endLen = Math.ceil(lo / 2)
        }

        return text.slice(0, startLen) + ellipsis + text.slice(-endLen)
      }

      type BaseProps = React.ComponentPropsWithoutRef<"span"> & {
        /** The text content to truncate. */
        children: string
        /** Custom ellipsis string to show in the middle. @default "..." */
        ellipsis?: string
      }

      export type MiddleTruncationProps = BaseProps &
        (
          | {
              /** Fixed number of characters to always preserve at the end. Cannot be used with minEnd. */
              end: number
              minEnd?: never
            }
          | {
              /** When splitting evenly, ensure at least this many characters at the end. Cannot be used with end. */
              minEnd: number
              end?: never
            }
          | {
              /** When neither end nor minEnd is provided, splits text evenly in the middle. */
              end?: never
              minEnd?: never
            }
        )

      export function MiddleTruncation({
        className,
        children,
        end,
        minEnd,
        ellipsis = "...",
        ...props
      }: MiddleTruncationProps) {
        const containerRef = useRef<HTMLSpanElement>(null)
        const [displayed, setDisplayed] = useState<string>(children)

        useLayoutEffect(() => {
          const el = containerRef.current
          if (!el) return

          const recalculate = (width: number) => {
            const font = getComputedFont(el)
            setDisplayed(
              computeTruncated(children, end, minEnd, width, font, ellipsis)
            )
          }

          const debouncedRecalculate = debounceWithRAF(recalculate, 150)

          const ro = new ResizeObserver(([entry]) => {
            debouncedRecalculate(entry.contentRect.width)
          })

          recalculate(el.offsetWidth)
          ro.observe(el)

          return () => ro.disconnect()
        }, [children, end, minEnd, ellipsis])

        return (
          <span
            ref={containerRef}
            className={cn(
              "block overflow-hidden text-ellipsis whitespace-nowrap",
              className
            )}
            title={children}
            {...props}
          >
            {displayed}
          </span>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { MiddleTruncation } from "@/components/middle-truncation"
```

```tsx
<MiddleTruncation>
  /Users/syedmoin/Code/syedmoinuddin.com/src/components/ui/button.tsx
</MiddleTruncation>
```

## API Reference

### MiddleTruncation

<TypeTable
  id="type-table-props.ts-MiddleTruncationProps"
  type={{
  "id": "props.ts-MiddleTruncationProps",
  "name": "MiddleTruncationProps",
  "description": "",
  "entries": [
    {
      "name": "children",
      "description": "The text content to truncate.",
      "tags": [],
      "type": "React.ReactNode & string",
      "simplifiedType": "union",
      "required": true,
      "deprecated": false
    },
    {
      "name": "className",
      "description": "",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "ellipsis",
      "description": "Custom ellipsis string to show in the middle.",
      "tags": [
        {
          "name": "default",
          "text": "\"...\""
        }
      ],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "end",
      "description": "Fixed number of characters to always preserve at the end. Cannot be used with minEnd.\nWhen neither end nor minEnd is provided, splits text evenly in the middle.",
      "tags": [],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "minEnd",
      "description": "When splitting evenly, ensure at least this many characters at the end. Cannot be used with end.",
      "tags": [],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

## Examples

### Fixed End

Always preserve exactly a fixed number of characters at the end.

```tsx
<MiddleTruncation end={4}>
  FY26_Q1_Consolidated_Financial_Statements.pdf
</MiddleTruncation>
```

### Flexible with Minimum

Split text evenly, but ensure at least a minimum number of characters at the end.

```tsx
<MiddleTruncation minEnd={12}>
  /Users/syedmoin/Code/syedmoinuddin.com/node_modules/shadcn/package.json
</MiddleTruncation>
```

### Even Split

Split text evenly in the middle when no constraints are provided.

```tsx
<MiddleTruncation>
  /Users/syedmoin/Code/syedmoinuddin.com/src/components/ui/button.tsx
</MiddleTruncation>
```

## References

* [Middle Truncation by @pqoqubbw](https://x.com/pqoqubbw/status/2039034994581000700)


Last updated on April 1, 2026

---
title: "Testimonial Spotlight"
description: "Testimonial card with spotlight effect on hover."
last_updated: "May 23, 2026"
source: "https://syedmoinuddin.com/blog/testimonial-spotlight"
---

# Testimonial Spotlight

Testimonial card with spotlight effect on hover.

```tsx
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
  TestimonialVerifiedBadge,
} from "@/components/testimonial"
import { TestimonialSpotlight } from "@/components/testimonial-spotlight"

export default function TestimonialSpotlightDemo() {
  return (
    <a
      className="block w-72 max-w-full"
      href="https://x.com/shadcn/status/2032193591133495700"
      target="_blank"
      rel="noopener noreferrer"
    >
      <TestimonialSpotlight className="[--spotlight-color:rgba(219,39,119,0.15)] dark:[--spotlight-color:rgba(255,255,255,0.2)]">
        <Testimonial>
          <TestimonialQuote className="font-serif">
            <p>You’re doing amazing work.</p>
          </TestimonialQuote>

          <TestimonialAuthor>
            <TestimonialAvatar>
              <TestimonialAvatarImg
                src="https://unavatar.io/x/shadcn"
                alt="shadcn"
              />
              <TestimonialAvatarRing />
            </TestimonialAvatar>

            <TestimonialAuthorName>
              shadcn
              <TestimonialVerifiedBadge className="text-info">
                <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
                  <path
                    fill="currentColor"
                    d="M24 12a4.454 4.454 0 0 0-2.564-3.91 4.437 4.437 0 0 0-.948-4.578 4.436 4.436 0 0 0-4.577-.948A4.44 4.44 0 0 0 12 0a4.423 4.423 0 0 0-3.9 2.564 4.434 4.434 0 0 0-2.43-.178 4.425 4.425 0 0 0-2.158 1.126 4.42 4.42 0 0 0-1.12 2.156 4.42 4.42 0 0 0 .183 2.421A4.456 4.456 0 0 0 0 12a4.465 4.465 0 0 0 2.576 3.91 4.433 4.433 0 0 0 .936 4.577 4.459 4.459 0 0 0 4.577.95A4.454 4.454 0 0 0 12 24a4.439 4.439 0 0 0 3.91-2.563 4.26 4.26 0 0 0 5.526-5.526A4.453 4.453 0 0 0 24 12Zm-13.709 4.917-4.38-4.378 1.652-1.663 2.646 2.646L15.83 7.4l1.72 1.591-7.258 7.926Z"
                  />
                </svg>
              </TestimonialVerifiedBadge>
            </TestimonialAuthorName>

            <TestimonialAuthorTagline>
              Creator of shadcn/ui
            </TestimonialAuthorTagline>
          </TestimonialAuthor>
        </Testimonial>
      </TestimonialSpotlight>
    </a>
  )
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/testimonial-spotlight
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/testimonial.tsx" 
      import type { ComponentProps } from "react"

      import { cn } from "@/lib/utils"

      export function Testimonial({ className, ...props }: ComponentProps<"figure">) {
        return (
          <figure
            data-slot="testimonial"
            className={cn("flex h-full flex-col", className)}
            {...props}
          />
        )
      }

      export function TestimonialQuote({
        className,
        ...props
      }: ComponentProps<"blockquote">) {
        return (
          <blockquote
            data-slot="testimonial-quote"
            className={cn(
              "grow px-4 py-3 text-base text-pretty text-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthor({
        className,
        ...props
      }: ComponentProps<"figcaption">) {
        return (
          <figcaption
            data-slot="testimonial-author"
            className={cn(
              "grid grid-cols-[auto_1fr] grid-rows-2 items-center gap-x-3.5 px-4 pt-1 pb-3",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAvatar({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-avatar"
            className={cn("relative row-span-2 size-8 shrink-0", className)}
            {...props}
          />
        )
      }

      export function TestimonialAvatarImg({
        className,
        src,
        alt,
        ...props
      }: ComponentProps<"img">) {
        return (
          <img
            data-slot="testimonial-avatar-img"
            className={cn("size-8 rounded-full select-none", className)}
            src={src}
            alt={alt}
            {...props}
          />
        )
      }

      export function TestimonialAvatarRing({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-avatar-ring"
            className={cn(
              "pointer-events-none absolute inset-0 rounded-full inset-ring-1 inset-ring-black/10 dark:inset-ring-white/15",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthorName({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-author-name"
            className={cn(
              "flex items-center gap-1.5 text-sm leading-4.5 font-semibold text-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthorTagline({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-author-tagline"
            className={cn(
              "text-xs leading-4 text-balance text-muted-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialVerifiedBadge({
        className,
        ...props
      }: ComponentProps<"span">) {
        return (
          <span
            data-slot="testimonial-verified-badge"
            className={cn(
              "flex [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-3.5",
              className
            )}
            aria-hidden
            {...props}
          />
        )
      }

      ```

      ```tsx title="components/testimonial-spotlight.tsx" 
      "use client"

      import { useRef } from "react"

      import { cn } from "@/lib/utils"

      export type TestimonialSpotlightProps = Omit<
        React.ComponentPropsWithoutRef<"div">,
        "children" | "onMouseMove"
      > & {
        children: React.ReactNode
      }

      export function TestimonialSpotlight({
        children,
        className,
        ...props
      }: TestimonialSpotlightProps) {
        const itemRef = useRef<HTMLDivElement>(null)

        const handleMouseMove: React.MouseEventHandler<HTMLDivElement> = (e) => {
          if (!itemRef.current) return

          const rect = itemRef.current.getBoundingClientRect()

          itemRef.current.style.setProperty(
            "--spotlight-x",
            `${e.clientX - rect.left}px`
          )
          itemRef.current.style.setProperty(
            "--spotlight-y",
            `${e.clientY - rect.top}px`
          )
        }

        return (
          <div
            ref={itemRef}
            data-slot="testimonial-spotlight"
            className={cn(
              "group/testimonial-spotlight relative overflow-hidden rounded-xl bg-card/50 inset-ring-1 inset-ring-foreground/10",
              "*:data-[slot=testimonial]:relative *:data-[slot=testimonial]:z-1",
              className
            )}
            onMouseMove={handleMouseMove}
            {...props}
          >
            <div
              className="pointer-events-none absolute inset-0 opacity-0 transition-opacity duration-500 ease-in-out group-hover/testimonial-spotlight:opacity-(--spotlight-opacity,0.5)"
              style={{
                background: `radial-gradient(circle at var(--spotlight-x) var(--spotlight-y), var(--spotlight-color,rgba(255,255,255,0.2)), transparent var(--spotlight-size,60%))`,
              }}
            />
            {children}
          </div>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorInfo,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
  TestimonialVerifiedBadge,
} from "@/components/testimonial"
import { TestimonialSpotlight } from "@/components/testimonial-spotlight"
```

```tsx
<TestimonialSpotlight>
  <Testimonial>
    <TestimonialQuote />

    <TestimonialAuthor>
      <TestimonialAvatar>
        <TestimonialAvatarImg />
        <TestimonialAvatarRing />
      </TestimonialAvatar>

      <TestimonialAuthorName>
        <TestimonialVerifiedBadge />
      </TestimonialAuthorName>

      <TestimonialAuthorTagline />
    </TestimonialAuthor>
  </Testimonial>
</TestimonialSpotlight>
```

## Composition

Use the following composition to build a `TestimonialSpotlight`

```text
TestimonialSpotlight
└── Testimonial
    ├── TestimonialQuote
    └── TestimonialAuthor
        ├── TestimonialAvatar
        │   ├── TestimonialAvatarImg
        │   └── TestimonialAvatarRing
        ├── TestimonialAuthorName
        │   └── TestimonialVerifiedBadge
        └── TestimonialAuthorTagline
```

## API Reference

### TestimonialSpotlight

<TypeTable
  id="type-table-props.ts-TestimonialSpotlightProps"
  type={{
  "id": "props.ts-TestimonialSpotlightProps",
  "name": "TestimonialSpotlightProps",
  "description": "",
  "entries": [
    {
      "name": "className",
      "description": "",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "style",
      "description": "",
      "tags": [],
      "type": "React.CSSProperties | undefined",
      "simplifiedType": "object",
      "required": false,
      "deprecated": false
    },
    {
      "name": "children",
      "description": "",
      "tags": [],
      "type": "React.ReactNode",
      "simplifiedType": "ReactNode",
      "required": true,
      "deprecated": false
    }
  ]
}}
/>

<div data-table-nowrap="">
  | CSS Variable          | Description                                                                     | Default                 |
  | --------------------- | ------------------------------------------------------------------------------- | ----------------------- |
  | `--spotlight-color`   | The color of the spotlight effect.                                              | `rgba(255,255,255,0.2)` |
  | `--spotlight-size`    | The size of the spotlight effect, defined as the radius of the radial gradient. | `60%`                   |
  | `--spotlight-opacity` | The opacity of the spotlight effect when hovered.                               | `0.5`                   |
</div>

## Examples

### Custom color, size, and opacity

Tailwind CSS:

```tsx
<TestimonialSpotlight
  className={cn(
    "[--spotlight-color:rgba(219,39,119,0.15)] dark:[--spotlight-color:rgba(255,255,255,0.2)]",
    "[--spotlight-opacity:0.8] [--spotlight-size:50%]"
  )}
>
  ...
</TestimonialSpotlight>
```

Or with inline style:

```tsx
<TestimonialSpotlight
  style={
    {
      "--spotlight-color": "rgba(219,39,119,0.15)",
      "--spotlight-size": "50%",
      "--spotlight-opacity": "0.8",
    } as React.CSSProperties
  }
>
  ...
</TestimonialSpotlight>
```


Last updated on May 23, 2026

---
title: "Text Flip"
description: "Animated text that cycles through items with a smooth flip transition."
last_updated: "February 20, 2026"
source: "https://syedmoinuddin.com/blog/text-flip"
---

# Text Flip

Animated text that cycles through items with a smooth flip transition.

```tsx
"use client"

import { useRef } from "react"
import { motion, useInView, usePageInView } from "motion/react"

import { TextFlip } from "@/components/text-flip"

export default function TextFlipDemo() {
  const ref = useRef<HTMLDivElement>(null)
  const isPageInView = usePageInView()
  const isInView = useInView(ref)
  const play = isPageInView && isInView

  return (
    <div ref={ref} className="text-2xl font-medium text-muted-foreground">
      <span>I am a </span>
      <TextFlip
        as={motion.span}
        className="min-w-32 text-foreground"
        play={play}
      >
        <span>Developer</span>
        <span>Designer</span>
        <span>Creator</span>
        <span>Builder</span>
      </TextFlip>
    </div>
  )
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/text-flip
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install motion clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/text-flip.tsx" 
      "use client"

      import { Children, useEffect, useState } from "react"
      import type { Transition, Variants } from "motion/react"
      import { AnimatePresence, motion } from "motion/react"

      import { cn } from "@/lib/utils"

      const defaultVariants: Variants = {
        initial: { y: -8, opacity: 0 },
        animate: { y: 0, opacity: 1 },
        exit: { y: 8, opacity: 0 },
      }

      type MotionElement = typeof motion.p | typeof motion.span | typeof motion.code

      export type TextFlipProps = {
        /**
         * Motion element to render.
         * @defaultValue motion.p
         * */
        as?: MotionElement
        className?: string
        /** Array of children to cycle through. */
        children: React.ReactNode[]

        /**
         * Time in seconds between each flip.
         * @defaultValue 2
         * */
        interval?: number
        /**
         * Motion transition configuration.
         * @defaultValue { duration: 0.3 }
         * */
        transition?: Transition
        /** Motion variants for enter/exit animations. */
        variants?: Variants

        /** Controls whether the flip animation runs. */
        play?: boolean

        /** Called with the new index after each flip. */
        onIndexChange?: (index: number) => void
      }

      export function TextFlip({
        as: Component = motion.p,
        className,
        children,

        interval = 2,
        transition = { duration: 0.3 },
        variants = defaultVariants,
        play = true,

        onIndexChange,
      }: TextFlipProps) {
        const [currentIndex, setCurrentIndex] = useState(0)

        const items = Children.toArray(children)

        useEffect(() => {
          if (!play) return

          const timer = setInterval(() => {
            setCurrentIndex((prev) => {
              const next = (prev + 1) % items.length
              onIndexChange?.(next)
              return next
            })
          }, interval * 1000)

          return () => clearInterval(timer)
        }, [play, interval, items.length, onIndexChange])

        return (
          <AnimatePresence mode="wait" initial={false}>
            <Component
              key={currentIndex}
              className={cn("inline-block", className)}
              initial="initial"
              animate="animate"
              exit="exit"
              transition={transition}
              variants={variants}
            >
              {items[currentIndex]}
            </Component>
          </AnimatePresence>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { TextFlip } from "@/components/text-flip"
```

```tsx
<TextFlip>
  <span>Developer</span>
  <span>Designer</span>
  <span>Creator</span>
</TextFlip>
```

## API Reference

### TextFlip

<TypeTable
  id="type-table-text-flip.tsx-TextFlipProps"
  type={{
  "id": "text-flip.tsx-TextFlipProps",
  "name": "TextFlipProps",
  "description": "",
  "entries": [
    {
      "name": "as",
      "description": "Motion element to render.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "motion.p"
        }
      ],
      "type": "MotionElement | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    },
    {
      "name": "className",
      "description": "",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "children",
      "description": "Array of children to cycle through.",
      "tags": [],
      "type": "React.ReactNode[]",
      "simplifiedType": "array",
      "required": true,
      "deprecated": false
    },
    {
      "name": "interval",
      "description": "Time in seconds between each flip.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "2"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "transition",
      "description": "Motion transition configuration.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "{ duration: 0.3 }"
        }
      ],
      "type": "Transition | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    },
    {
      "name": "variants",
      "description": "Motion variants for enter/exit animations.",
      "tags": [],
      "type": "Variants | undefined",
      "simplifiedType": "object",
      "required": false,
      "deprecated": false
    },
    {
      "name": "play",
      "description": "Controls whether the flip animation runs.",
      "tags": [],
      "type": "boolean | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    },
    {
      "name": "onIndexChange",
      "description": "Called with the new index after each flip.",
      "tags": [],
      "type": "((index: number) => void) | undefined",
      "simplifiedType": "function",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>


Last updated on February 20, 2026

---
title: "Copy Button"
description: "Copy text to clipboard with visual, haptic, and audio feedback."
last_updated: "May 18, 2026"
source: "https://syedmoinuddin.com/blog/copy-button"
---

# Copy Button

Copy text to clipboard with visual, haptic, and audio feedback.

```tsx
import { CopyButton } from "@/components/copy-button"

export default function CopyButtonDemo() {
  return (
    <div className="flex items-center gap-2">
      <CopyButton
        className="relative"
        variant="secondary"
        size="icon-sm"
        text="Text 1"
      />

      <CopyButton
        className="relative gap-1.5 pr-2.5 pl-2"
        variant="outline"
        size="sm"
        text="Text 2"
      >
        Copy
      </CopyButton>
    </div>
  )
}

```

## Features

* Animated icon transitions across idle, success, and error states.
* Haptic feedback confirms copy success on supported devices.
* UI sounds play distinct success and error cues.
* Accepts a string or function for dynamic content.
* Callback support for success and error events.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/copy-button
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge class-variance-authority lucide-react motion radix-ui
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Install the required components</Step>

      * [Button](https://ui.shadcn.com/docs/components/button)

      <Step>Copy and paste the following code into your project</Step>

      ```ts title="hooks/use-copy-to-clipboard.ts" 
      "use client"

      import { useCallback, useRef, useState } from "react"
      import { useTiks } from "@rexa-developer/tiks/react"
      import { useWebHaptics } from "web-haptics/react"

      export type CopyState = "idle" | "done" | "error"

      export type UseCopyToClipboardOptions = {
        onCopySuccess?: (text: string) => void
        onCopyError?: (error: Error) => void
        resetDelay?: number
      }

      export function useCopyToClipboard({
        onCopySuccess,
        onCopyError,
        resetDelay = 1500,
      }: UseCopyToClipboardOptions = {}) {
        const [state, setState] = useState<CopyState>("idle")
        const resetTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null)

        const { trigger: haptic } = useWebHaptics()
        const { success: tiksSuccess, error: tiksError } = useTiks()

        const copy = useCallback(
          async (text: string | (() => string)) => {
            // Clear any pending reset
            if (resetTimeoutRef.current) {
              clearTimeout(resetTimeoutRef.current)
            }

            try {
              const finalText = typeof text === "function" ? text() : text
              await navigator.clipboard.writeText(finalText)

              setState("done")

              haptic("success")
              tiksSuccess()

              onCopySuccess?.(finalText)
            } catch (error) {
              setState("error")

              haptic("error")
              tiksError()

              onCopyError?.(error instanceof Error ? error : new Error("Copy failed"))
            } finally {
              // Schedule reset to idle
              resetTimeoutRef.current = setTimeout(() => {
                setState("idle")
              }, resetDelay)
            }
          },
          [onCopySuccess, onCopyError, haptic, tiksSuccess, tiksError, resetDelay]
        )

        return { state, copy } as const
      }

      ```

      ```tsx title="components/icon-swap.tsx" 
      "use client"

      import type { AnimatePresenceProps, HTMLMotionProps } from "motion/react"
      import { AnimatePresence, motion } from "motion/react"

      export function IconSwap(props: React.PropsWithChildren<AnimatePresenceProps>) {
        return <AnimatePresence mode="popLayout" initial={false} {...props} />
      }

      type MotionElement = typeof motion.div | typeof motion.span

      export function IconSwapItem({
        as: Component = motion.div,
        ...props
      }: HTMLMotionProps<"div"> & {
        as?: MotionElement
      }) {
        return (
          <Component
            initial={{ opacity: 0, scale: 0.25, filter: "blur(4px)" }}
            animate={{ opacity: 1, scale: 1, filter: "blur(0px)" }}
            exit={{ opacity: 0, scale: 0.25, filter: "blur(4px)" }}
            transition={{
              type: "spring",
              duration: 0.3,
              bounce: 0,
            }}
            {...props}
          />
        )
      }

      ```

      ```tsx title="components/copy-button.tsx" 
      "use client"

      import type { ComponentProps } from "react"
      import { motion } from "motion/react"

      import type { CopyState } from "@/hooks/use-copy-to-clipboard"
      import { useCopyToClipboard } from "@/hooks/use-copy-to-clipboard"
      import { Button } from "@/components/ui/button"
      import { IconSwap, IconSwapItem } from "@/components/icon-swap"
      import { IconPlaceholder } from "@/registry/icons/icon-placeholder"

      export type CopyStateIconProps = {
        state: CopyState
        /** Custom icon for idle state. */
        idleIcon?: React.ReactNode
        /** Custom icon for done state. */
        doneIcon?: React.ReactNode
        /** Custom icon for error state. */
        errorIcon?: React.ReactNode
      }

      export function CopyStateIcon({
        state,
        idleIcon,
        doneIcon,
        errorIcon,
      }: CopyStateIconProps) {
        return (
          <IconSwap>
            <IconSwapItem key={state} as={motion.span}>
              {state === "idle" &&
                (idleIcon ?? (
                  <IconPlaceholder
                    data-slot="idle-icon"
                    lucide="CopyIcon"
                    tabler="IconCopy"
                    hugeicons="Copy01Icon"
                    phosphor="CopyIcon"
                    remixicon="RiFileCopyLine"
                  />
                ))}

              {state === "done" &&
                (doneIcon ?? (
                  <IconPlaceholder
                    data-slot="done-icon"
                    lucide="CheckIcon"
                    tabler="IconCheck"
                    hugeicons="Tick02Icon"
                    phosphor="CheckIcon"
                    remixicon="RiCheckLine"
                  />
                ))}

              {state === "error" &&
                (errorIcon ?? (
                  <IconPlaceholder
                    data-slot="error-icon"
                    lucide="CircleXIcon"
                    tabler="IconX"
                    hugeicons="CancelCircleIcon"
                    phosphor="XCircleIcon"
                    remixicon="RiCloseCircleLine"
                  />
                ))}
            </IconSwapItem>
          </IconSwap>
        )
      }

      export type CopyButtonProps = ComponentProps<typeof Button> & {
        /** The text to copy, or a function that returns the text. */
        text: string | (() => string)
        /** Called with the copied text on successful copy. */
        onCopySuccess?: (text: string) => void
        /** Called with the error if the copy operation fails. */
        onCopyError?: (error: Error) => void
      } & Omit<CopyStateIconProps, "state">

      export function CopyButton({
        size = "icon",
        children,
        text,
        idleIcon,
        doneIcon,
        errorIcon,
        onClick,
        onCopySuccess,
        onCopyError,
        ...props
      }: CopyButtonProps) {
        const { state, copy } = useCopyToClipboard({
          onCopySuccess,
          onCopyError,
        })

        return (
          <Button
            size={size}
            onClick={(e) => {
              copy(text)
              onClick?.(e)
            }}
            aria-label="Copy"
            {...props}
          >
            <CopyStateIcon
              state={state}
              idleIcon={idleIcon}
              doneIcon={doneIcon}
              errorIcon={errorIcon}
            />
            {children}
          </Button>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { CopyButton } from "@/components/copy-button"
```

```tsx
<CopyButton text="Some text to copy" />
```

## API Reference

### CopyButton

Extends [Button](https://ui.shadcn.com/docs/components/radix/button) with clipboard functionality.

<TypeTable
  id="type-table-props.ts-CopyButtonProps"
  type={{
  "id": "props.ts-CopyButtonProps",
  "name": "CopyButtonProps",
  "description": "",
  "entries": [
    {
      "name": "idleIcon",
      "description": "Custom icon for idle state.",
      "tags": [],
      "type": "React.ReactNode",
      "simplifiedType": "ReactNode",
      "required": false,
      "deprecated": false
    },
    {
      "name": "doneIcon",
      "description": "Custom icon for done state.",
      "tags": [],
      "type": "React.ReactNode",
      "simplifiedType": "ReactNode",
      "required": false,
      "deprecated": false
    },
    {
      "name": "errorIcon",
      "description": "Custom icon for error state.",
      "tags": [],
      "type": "React.ReactNode",
      "simplifiedType": "ReactNode",
      "required": false,
      "deprecated": false
    },
    {
      "name": "text",
      "description": "The text to copy, or a function that returns the text.",
      "tags": [],
      "type": "string | (() => string)",
      "simplifiedType": "union",
      "required": true,
      "deprecated": false
    },
    {
      "name": "onCopySuccess",
      "description": "Called with the copied text on successful copy.",
      "tags": [],
      "type": "((text: string) => void) | undefined",
      "simplifiedType": "function",
      "required": false,
      "deprecated": false
    },
    {
      "name": "onCopyError",
      "description": "Called with the error if the copy operation fails.",
      "tags": [],
      "type": "((error: Error) => void) | undefined",
      "simplifiedType": "function",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

See [shadcn/ui](https://ui.shadcn.com/docs/components/radix/button#api-reference) documentation for more information.

## References

* [WebHaptics](https://haptics.lochie.me) by [@lochieaxon](https://x.com/lochieaxon)
* [tiks](https://github.com/rexa-developer/tiks)


Last updated on May 18, 2026

---
title: "Code Block Command"
description: "Display install commands with package manager switcher and copy button."
last_updated: "April 6, 2026"
source: "https://syedmoinuddin.com/blog/code-block-command"
---

# Code Block Command

Display install commands with package manager switcher and copy button.

```tsx
"use client"

import { CodeBlockCommand } from "@/components/code-block-command"

export default function CodeBlockCommandDemo() {
  return (
    <div className="w-full max-w-sm">
      <CodeBlockCommand
        pnpm="pnpm dlx cortexcn add button"
        yarn="yarn cortexcn add button"
        npm="npx cortexcn add button"
        bun="bunx --bun cortexcn add button"
      />
    </div>
  )
}

```

## Features

* Switch between pnpm, yarn, npm, and bun with a single click.
* Optional `prompt` tab for displaying a natural language instruction for AI agents to install packages or components.
* Automatically saves the user’s preferred package manager for future visits.
* Copy commands instantly with smooth animations showing success or failure states.
* `convertNpmCommand` utility to auto-convert a standard npm command to all package managers.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/code-block-command
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge class-variance-authority lucide-react motion jotai radix-ui @base-ui/react
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Install the required components</Step>

      * [Copy Button](https://syedmoinuddin.com/components/copy-button)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/tabs.tsx" 
      "use client"

      import { Tabs as TabsPrimitive } from "@base-ui/react/tabs"

      import { cn } from "@/lib/utils"

      function Tabs({ className, ...props }: TabsPrimitive.Root.Props) {
        return (
          <TabsPrimitive.Root
            data-slot="tabs"
            className={cn("flex flex-col gap-2", className)}
            {...props}
          />
        )
      }

      function TabsList({ className, ...props }: TabsPrimitive.List.Props) {
        return (
          <TabsPrimitive.List
            data-slot="tabs-list"
            className={cn(
              "relative z-0 flex h-8 w-fit items-center justify-center rounded-lg p-0.5",
              "bg-zinc-50 text-muted-foreground dark:bg-zinc-900",
              "inset-ring-1 inset-ring-border/64",
              className
            )}
            {...props}
          />
        )
      }

      function TabsIndicator({ className, ...props }: TabsPrimitive.Indicator.Props) {
        return (
          <TabsPrimitive.Indicator
            data-slot="tabs-indicator"
            className={cn(
              "absolute bottom-0 left-0 -z-1 h-(--active-tab-height) w-(--active-tab-width) translate-x-(--active-tab-left) -translate-y-(--active-tab-bottom) rounded-md bg-white transition-[width,translate] duration-200 ease-in-out dark:bg-muted",
              "inset-ring-1 inset-ring-foreground/10 dark:inset-ring-foreground/6",
              className
            )}
            {...props}
          />
        )
      }

      function TabsTrigger({ className, ...props }: TabsPrimitive.Tab.Props) {
        return (
          <TabsPrimitive.Tab
            data-slot="tabs-trigger"
            className={cn(
              "flex flex-1 shrink-0 items-center justify-center gap-2 rounded-md px-4 py-1 font-sans text-sm font-medium whitespace-nowrap transition-[color,background-color] outline-none hover:text-foreground focus-visible:inset-ring-1 focus-visible:inset-ring-ring disabled:pointer-events-none disabled:opacity-50 data-active:text-foreground [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-4",
              className
            )}
            {...props}
          />
        )
      }

      function TabsContent({ className, ...props }: TabsPrimitive.Panel.Props) {
        return (
          <TabsPrimitive.Panel
            data-slot="tabs-content"
            className={cn("flex-1 outline-none", className)}
            {...props}
          />
        )
      }

      export { Tabs, TabsContent, TabsIndicator, TabsList, TabsTrigger }

      ```

      ````tsx title="components/code-block-command.tsx" 
      "use client"

      import { useMemo } from "react"
      import { ScrollArea } from "@base-ui/react/scroll-area"
      import { useAtom } from "jotai"
      import { atomWithStorage } from "jotai/utils"

      import { cn } from "@/lib/utils"
      import {
        Tabs,
        TabsContent,
        TabsIndicator,
        TabsList,
        TabsTrigger,
      } from "@/components/ui/tabs"
      import { CopyButton } from "@/components/copy-button"
      import { IconSwap, IconSwapItem } from "@/components/icon-swap"
      import { IconPlaceholder } from "@/registry/icons/icon-placeholder"

      export type PackageManager = "prompt" | "pnpm" | "yarn" | "npm" | "bun"

      const packageManagerAtom = atomWithStorage<PackageManager>(
        "packageManager",
        "pnpm"
      )

      export function usePackageManager() {
        return useAtom(packageManagerAtom)
      }

      /**
       * Props for the CodeBlockCommand component.
       */
      export type CodeBlockCommandProps = {
        /**
         * Natural language instruction for AI agents to install a package or component.
         */
        prompt?: string
        /**
         * Command to execute with pnpm package manager.
         */
        pnpm?: string

        /**
         * Command to execute with yarn package manager.
         */
        yarn?: string

        /**
         * Command to execute with npm package manager.
         */
        npm?: string

        /**
         * Command to execute with bun package manager.
         */
        bun?: string

        /**
         * Callback invoked when a command is successfully copied to clipboard.
         *
         * Receives an object containing the selected package manager and the copied command text.
         * Useful for tracking user interactions or showing custom success notifications.
         *
         * @param data - Object containing copy operation details
         * @param data.packageManager - The package manager that was selected when copying
         * @param data.command - The actual command text that was copied
         *
         * @example
         * ```tsx
         * <CodeBlockCommand
         *   pnpm="pnpm add react"
         *   onCopySuccess={({ packageManager, command }) => {
         *     console.log(`Copied ${command} for ${packageManager}`)
         *   }}
         * />
         * ```
         */
        onCopySuccess?: (data: {
          packageManager: PackageManager
          command: string
        }) => void

        /**
         * Callback invoked when copying to clipboard fails.
         *
         * Receives the error object for debugging or showing custom error messages.
         *
         * @param error - The error that occurred during the copy operation
         *
         * @example
         * ```tsx
         * <CodeBlockCommand
         *   pnpm="pnpm add react"
         *   onCopyError={(error) => {
         *     console.error('Copy failed:', error)
         *   }}
         * />
         * ```
         */
        onCopyError?: (error: Error) => void
      }

      export function CodeBlockCommand({
        prompt,
        pnpm,
        yarn,
        npm,
        bun,
        onCopySuccess,
        onCopyError,
      }: CodeBlockCommandProps) {
        const [packageManager, setPackageManager] = usePackageManager()

        const tabs = useMemo(() => {
          return {
            prompt,
            pnpm,
            yarn,
            npm,
            bun,
          }
        }, [prompt, pnpm, yarn, npm, bun])

        const tabsFiltered = useMemo(
          () => Object.entries(tabs).filter(([, value]) => !!value),
          [tabs]
        )

        return (
          <div className="relative overflow-hidden rounded-xl bg-code">
            <Tabs
              className="gap-0"
              value={packageManager}
              onValueChange={(value) => {
                setPackageManager(value as PackageManager)
              }}
            >
              <ScrollArea.Root className="w-full pr-10 shadow-[inset_0_-1px_0_0] shadow-border">
                <TabsList
                  className={cn(
                    "h-10 max-w-full justify-start rounded-none bg-transparent p-0 pl-4 inset-ring-0 dark:bg-transparent [&_svg]:size-4 [&_svg]:shrink-0 [&_svg]:text-muted-foreground",
                    "[--scroll-area-overflow-x-end:inherit] [--scroll-area-overflow-x-start:inherit]",
                    "mask-linear-[to_right,transparent_0,black_min(2.5rem,var(--scroll-area-overflow-x-start)),black_calc(100%-min(2.5rem,var(--scroll-area-overflow-x-end,2.5rem))),transparent_100%]"
                  )}
                  render={<ScrollArea.Viewport />}
                >
                  <IconSwap>
                    <IconSwapItem className="mr-2" key={packageManager}>
                      {getIconForPackageManager(packageManager)}
                    </IconSwapItem>
                  </IconSwap>

                  {tabsFiltered.map(([key]) => {
                    return (
                      <TabsTrigger
                        key={key}
                        className="h-7 rounded-lg p-0 px-2 font-mono"
                        value={key}
                      >
                        {key}
                      </TabsTrigger>
                    )
                  })}

                  <TabsIndicator className="h-0.5 translate-y-0 rounded-none bg-foreground ring-0 dark:bg-foreground" />
                </TabsList>
              </ScrollArea.Root>

              {tabsFiltered.map(([key, value]) => {
                return (
                  <TabsContent key={key} value={key}>
                    <pre
                      data-pm={key}
                      className="group/tabs-content-pre overscroll-x-contain p-4 leading-6 not-data-[pm=prompt]:overflow-x-auto"
                    >
                      <code
                        data-slot="code-block"
                        data-language="bash"
                        className="font-mono text-sm/none text-muted-foreground group-data-[pm=prompt]/tabs-content-pre:whitespace-normal"
                      >
                        <span className="select-none group-data-[pm=prompt]/tabs-content-pre:hidden">
                          ${" "}
                        </span>
                        {value}
                      </code>
                    </pre>
                  </TabsContent>
                )
              })}
            </Tabs>

            <CopyButton
              className="absolute top-2 right-2 z-10 size-6 rounded-md border-none [&_svg:not([class*='size-'])]:size-3.5"
              variant="ghost"
              size="icon-sm"
              text={tabs[packageManager] || ""}
              onCopySuccess={(copiedCommand) => {
                onCopySuccess?.({
                  packageManager,
                  command: copiedCommand,
                })
              }}
              onCopyError={onCopyError}
            />
          </div>
        )
      }

      function getIconForPackageManager(manager: PackageManager) {
        switch (manager) {
          case "prompt":
            return (
              <IconPlaceholder
                lucide="TextAlignStartIcon"
                tabler="IconAlignLeft"
                hugeicons="TextAlignLeftIcon"
                phosphor="TextAlignLeftIcon"
                remixicon="RiAlignLeft"
              />
            )
          case "pnpm":
            return (
              <svg viewBox="0 0 24 24">
                <path
                  d="M0 0v7.5h7.5V0zm8.25 0v7.5h7.498V0zm8.25 0v7.5H24V0zM8.25 8.25v7.5h7.498v-7.5zm8.25 0v7.5H24v-7.5zM0 16.5V24h7.5v-7.5zm8.25 0V24h7.498v-7.5zm8.25 0V24H24v-7.5z"
                  fill="currentColor"
                />
              </svg>
            )
          case "yarn":
            return (
              <svg viewBox="0 0 24 24">
                <path
                  d="M12 0C5.375 0 0 5.375 0 12s5.375 12 12 12 12-5.375 12-12S18.625 0 12 0zm.768 4.105c.183 0 .363.053.525.157.125.083.287.185.755 1.154.31-.088.468-.042.551-.019.204.056.366.19.463.375.477.917.542 2.553.334 3.605-.241 1.232-.755 2.029-1.131 2.576.324.329.778.899 1.117 1.825.278.774.31 1.478.273 2.015a5.51 5.51 0 0 0 .602-.329c.593-.366 1.487-.917 2.553-.931.714-.009 1.269.445 1.353 1.103a1.23 1.23 0 0 1-.945 1.362c-.649.158-.95.278-1.821.843-1.232.797-2.539 1.242-3.012 1.39a1.686 1.686 0 0 1-.704.343c-.737.181-3.266.315-3.466.315h-.046c-.783 0-1.214-.241-1.45-.491-.658.329-1.51.19-2.122-.134a1.078 1.078 0 0 1-.58-1.153 1.243 1.243 0 0 1-.153-.195c-.162-.25-.528-.936-.454-1.946.056-.723.556-1.367.88-1.71a5.522 5.522 0 0 1 .408-2.256c.306-.727.885-1.348 1.32-1.737-.32-.537-.644-1.367-.329-2.21.227-.602.412-.936.82-1.08h-.005c.199-.074.389-.153.486-.259a3.418 3.418 0 0 1 2.298-1.103c.037-.093.079-.185.125-.283.31-.658.639-1.029 1.024-1.168a.94.94 0 0 1 .328-.06zm.006.7c-.507.016-1.001 1.519-1.001 1.519s-1.27-.204-2.266.871c-.199.218-.468.334-.746.44-.079.028-.176.023-.417.672-.371.991.625 2.094.625 2.094s-1.186.839-1.626 1.881c-.486 1.144-.338 2.261-.338 2.261s-.843.732-.899 1.487c-.051.663.139 1.2.343 1.515.227.343.51.176.51.176s-.561.653-.037.931c.477.25 1.283.394 1.71-.037.31-.31.371-1.001.486-1.283.028-.065.12.111.209.199.097.093.264.195.264.195s-.755.324-.445 1.066c.102.246.468.403 1.066.398.222-.005 2.664-.139 3.313-.296.375-.088.505-.283.505-.283s1.566-.431 2.998-1.357c.917-.598 1.293-.76 2.034-.936.612-.148.57-1.098-.241-1.084-.839.009-1.575.44-2.196.825-1.163.718-1.742.672-1.742.672l-.018-.032c-.079-.13.371-1.293-.134-2.678-.547-1.515-1.413-1.881-1.344-1.997.297-.5 1.038-1.297 1.334-2.78.176-.899.13-2.377-.269-3.151-.074-.144-.732.241-.732.241s-.616-1.371-.788-1.483a.271.271 0 0 0-.157-.046z"
                  fill="currentColor"
                />
              </svg>
            )
          case "npm":
            return (
              <svg viewBox="0 0 24 24">
                <path
                  d="M1.763 0C.786 0 0 .786 0 1.763v20.474C0 23.214.786 24 1.763 24h20.474c.977 0 1.763-.786 1.763-1.763V1.763C24 .786 23.214 0 22.237 0zM5.13 5.323l13.837.019-.009 13.836h-3.464l.01-10.382h-3.456L12.04 19.17H5.113z"
                  fill="currentColor"
                />
              </svg>
            )
          case "bun":
            return (
              <svg viewBox="0 0 24 24">
                <path
                  d="M12 22.596c6.628 0 12-4.338 12-9.688 0-3.318-2.057-6.248-5.219-7.986-1.286-.715-2.297-1.357-3.139-1.89C14.058 2.025 13.08 1.404 12 1.404c-1.097 0-2.334.785-3.966 1.821a49.92 49.92 0 0 1-2.816 1.697C2.057 6.66 0 9.59 0 12.908c0 5.35 5.372 9.687 12 9.687v.001ZM10.599 4.715c.334-.759.503-1.58.498-2.409 0-.145.202-.187.23-.029.658 2.783-.902 4.162-2.057 4.624-.124.048-.199-.121-.103-.209a5.763 5.763 0 0 0 1.432-1.977Zm2.058-.102a5.82 5.82 0 0 0-.782-2.306v-.016c-.069-.123.086-.263.185-.172 1.962 2.111 1.307 4.067.556 5.051-.082.103-.23-.003-.189-.126a5.85 5.85 0 0 0 .23-2.431Zm1.776-.561a5.727 5.727 0 0 0-1.612-1.806v-.014c-.112-.085-.024-.274.114-.218 2.595 1.087 2.774 3.18 2.459 4.407a.116.116 0 0 1-.049.071.11.11 0 0 1-.153-.026.122.122 0 0 1-.022-.083 5.891 5.891 0 0 0-.737-2.331Zm-5.087.561c-.617.546-1.282.76-2.063 1-.117 0-.195-.078-.156-.181 1.752-.909 2.376-1.649 2.999-2.778 0 0 .155-.118.188.085 0 .304-.349 1.329-.968 1.874Zm4.945 11.237a2.957 2.957 0 0 1-.937 1.553c-.346.346-.8.565-1.286.62a2.178 2.178 0 0 1-1.327-.62 2.955 2.955 0 0 1-.925-1.553.244.244 0 0 1 .064-.198.234.234 0 0 1 .193-.069h3.965a.226.226 0 0 1 .19.07c.05.053.073.125.063.197Zm-5.458-2.176a1.862 1.862 0 0 1-2.384-.245 1.98 1.98 0 0 1-.233-2.447c.207-.319.503-.566.848-.713a1.84 1.84 0 0 1 1.092-.11c.366.075.703.261.967.531a1.98 1.98 0 0 1 .408 2.114 1.931 1.931 0 0 1-.698.869v.001Zm8.495.005a1.86 1.86 0 0 1-2.381-.253 1.964 1.964 0 0 1-.547-1.366c0-.384.11-.76.32-1.079.207-.319.503-.567.849-.713a1.844 1.844 0 0 1 1.093-.108c.367.076.704.262.968.534a1.98 1.98 0 0 1 .4 2.117 1.932 1.932 0 0 1-.702.868Z"
                  fill="currentColor"
                />
              </svg>
            )
          default:
            return (
              <IconPlaceholder
                lucide="TerminalIcon"
                tabler="IconTerminal"
                hugeicons="TerminalIcon"
                phosphor="TerminalIcon"
                remixicon="RiTerminalLine"
              />
            )
        }
      }

      /**
       * Result of converting an npm command to all package managers.
       */
      export type ConvertNpmCommandResult = {
        /**
         * Command for pnpm package manager.
         */
        pnpm: string

        /**
         * Command for yarn package manager.
         */
        yarn: string

        /**
         * Command for npm package manager.
         */
        npm: string

        /**
         * Command for bun package manager.
         */
        bun: string
      }

      /**
       * Converts a standard npm command into equivalent commands for pnpm, yarn, npm,
       * and bun. The result can be spread directly into `CodeBlockCommand` props.
       *
       * Supported command patterns:
       * - `npm install <pkg>` -> add commands for each manager
       * - `npx create-<name>` -> create commands for each manager
       * - `npm create <name>` -> create commands for each manager
       * - `npx <command>` -> execute commands for each manager
       * - `npm run <script>` -> run commands for each manager
       *
       * Unrecognized commands are returned as-is for all package managers.
       *
       * @param npmCommand - A standard npm/npx command string.
       * @returns An object with `pnpm`, `yarn`, `npm`, and `bun` command strings.
       *
       * @example
       * ```tsx
       * import { CodeBlockCommand, convertNpmCommand } from "@/components/ncdai/code-block-command"
       *
       * <CodeBlockCommand {...convertNpmCommand("npx shadcn add button")} />
       * ```
       */
      export function convertNpmCommand(npmCommand: string): ConvertNpmCommandResult {
        // npm install
        if (npmCommand.startsWith("npm install")) {
          return {
            pnpm: npmCommand.replaceAll("npm install", "pnpm add"),
            yarn: npmCommand.replaceAll("npm install", "yarn add"),
            npm: npmCommand,
            bun: npmCommand.replaceAll("npm install", "bun add"),
          }
        }

        // npx create- (must be checked before generic npx)
        if (npmCommand.startsWith("npx create-")) {
          return {
            pnpm: npmCommand.replace("npx create-", "pnpm create "),
            yarn: npmCommand.replace("npx create-", "yarn create "),
            npm: npmCommand,
            bun: npmCommand.replace("npx", "bunx --bun"),
          }
        }

        // npm create
        if (npmCommand.startsWith("npm create")) {
          return {
            pnpm: npmCommand.replace("npm create", "pnpm create"),
            yarn: npmCommand.replace("npm create", "yarn create"),
            npm: npmCommand,
            bun: npmCommand.replace("npm create", "bun create"),
          }
        }

        // npx (general)
        if (npmCommand.startsWith("npx")) {
          return {
            pnpm: npmCommand.replace("npx", "pnpm dlx"),
            yarn: npmCommand.replace("npx", "yarn dlx"),
            npm: npmCommand,
            bun: npmCommand.replace("npx", "bunx --bun"),
          }
        }

        // npm run
        if (npmCommand.startsWith("npm run")) {
          return {
            pnpm: npmCommand.replace("npm run", "pnpm"),
            yarn: npmCommand.replace("npm run", "yarn"),
            npm: npmCommand,
            bun: npmCommand.replace("npm run", "bun"),
          }
        }

        return {
          pnpm: npmCommand,
          yarn: npmCommand,
          npm: npmCommand,
          bun: npmCommand,
        }
      }

      ````

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import {
  CodeBlockCommand,
  convertNpmCommand,
} from "@/components/code-block-command"
```

```tsx
<CodeBlockCommand
  prompt="Add the button component to my project"
  pnpm="pnpm dlx shadcn add button"
  yarn="yarn dlx shadcn add button"
  npm="npx shadcn add button"
  bun="bunx --bun shadcn add button"
/>
```

Or use `convertNpmCommand` to auto-convert from a standard npm command:

```tsx
<CodeBlockCommand
  prompt="Add the button component to my project"
  {...convertNpmCommand("npx shadcn add button")}
/>
```

## API Reference

### CodeBlockCommand

<TypeTable
  id="type-table-code-block-command.tsx-CodeBlockCommandProps"
  type={{
  "id": "code-block-command.tsx-CodeBlockCommandProps",
  "name": "CodeBlockCommandProps",
  "description": "Props for the CodeBlockCommand component.",
  "entries": [
    {
      "name": "prompt",
      "description": "Natural language instruction for AI agents to install a package or component.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "pnpm",
      "description": "Command to execute with pnpm package manager.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "yarn",
      "description": "Command to execute with yarn package manager.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "npm",
      "description": "Command to execute with npm package manager.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "bun",
      "description": "Command to execute with bun package manager.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "onCopySuccess",
      "description": "Callback invoked when a command is successfully copied to clipboard.\n\nReceives an object containing the selected package manager and the copied command text.\nUseful for tracking user interactions or showing custom success notifications.",
      "tags": [
        {
          "name": "param",
          "text": "data - Object containing copy operation details"
        },
        {
          "name": "param",
          "text": "data.packageManager - The package manager that was selected when copying"
        },
        {
          "name": "param",
          "text": "data.command - The actual command text that was copied"
        },
        {
          "name": "example",
          "text": "```tsx\n<CodeBlockCommand\n  pnpm=\"pnpm add react\"\n  onCopySuccess={({ packageManager, command }) => {\n    console.log(`Copied ${command} for ${packageManager}`)\n  }}\n/>\n```"
        }
      ],
      "type": "((data: { packageManager: PackageManager; command: string; }) => void) | undefined",
      "simplifiedType": "function",
      "required": false,
      "deprecated": false
    },
    {
      "name": "onCopyError",
      "description": "Callback invoked when copying to clipboard fails.\n\nReceives the error object for debugging or showing custom error messages.",
      "tags": [
        {
          "name": "param",
          "text": "error - The error that occurred during the copy operation"
        },
        {
          "name": "example",
          "text": "```tsx\n<CodeBlockCommand\n  pnpm=\"pnpm add react\"\n  onCopyError={(error) => {\n    console.error('Copy failed:', error)\n  }}\n/>\n```"
        }
      ],
      "type": "((error: Error) => void) | undefined",
      "simplifiedType": "function",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

### convertNpmCommand

Converts a standard npm/npx command into equivalent commands for all package managers. The result can be spread directly into `CodeBlockCommand` props.

<TypeTable
  id="type-table-code-block-command.tsx-ConvertNpmCommandResult"
  type={{
  "id": "code-block-command.tsx-ConvertNpmCommandResult",
  "name": "ConvertNpmCommandResult",
  "description": "Result of converting an npm command to all package managers.",
  "entries": [
    {
      "name": "pnpm",
      "description": "Command for pnpm package manager.",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "yarn",
      "description": "Command for yarn package manager.",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "npm",
      "description": "Command for npm package manager.",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "bun",
      "description": "Command for bun package manager.",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    }
  ]
}}
/>

Supported command patterns:

<div data-table-nowrap="">
  | npm command         | pnpm                 | yarn                 | bun                        |
  | ------------------- | -------------------- | -------------------- | -------------------------- |
  | `npm install`       | `pnpm add`           | `yarn add`           | `bun add`                  |
  | `npx create-<name>` | `pnpm create <name>` | `yarn create <name>` | `bunx --bun create-<name>` |
  | `npm create`        | `pnpm create`        | `yarn create`        | `bun create`               |
  | `npx`               | `pnpm dlx`           | `yarn dlx`           | `bunx --bun`               |
  | `npm run`           | `pnpm`               | `yarn`               | `bun`                      |
</div>

## Examples

### Convert from npm

Use `convertNpmCommand` to avoid manually writing commands for each package manager.

```tsx
"use client"

import {
  CodeBlockCommand,
  convertNpmCommand,
} from "@/components/code-block-command"

export default function CodeBlockCommandConvertDemo() {
  return (
    <div className="w-full max-w-sm">
      <CodeBlockCommand {...convertNpmCommand("npx shadcn add button")} />
    </div>
  )
}

```

### Analytics Tracking

Track user interactions with analytics services like [PostHog](https://posthog.com), [OpenPanel](https://openpanel.dev), or [Google Analytics](https://analytics.google.com).

```tsx {3,12}
<CodeBlockCommand
  {...convertNpmCommand("npx shadcn add button")}
  onCopySuccess={({ packageManager, command }) => {
    trackEvent({
      name: "command_copied",
      properties: {
        packageManager,
        command,
      },
    })
  }}
  onCopyError={(error) => {
    trackEvent({
      name: "command_copy_failed",
      properties: { error: error.message },
    })
  }}
/>
```


Last updated on April 6, 2026

---
title: "Testimonial"
description: "Display user feedback with author info, avatar, and verified badge."
last_updated: "March 28, 2026"
source: "https://syedmoinuddin.com/blog/testimonial"
---

# Testimonial

Display user feedback with author info, avatar, and verified badge.

```tsx
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
  TestimonialVerifiedBadge,
} from "@/components/testimonial"

export default function TestimonialDemo() {
  return (
    <a
      className="block w-80 max-w-full rounded-xl inset-ring-1 inset-ring-foreground/10 transition-[background-color] ease-out hover:bg-accent/50"
      href="https://x.com/rauchg/status/1978913158514237669"
      target="_blank"
      rel="noopener noreferrer"
    >
      <Testimonial>
        <TestimonialQuote className="font-serif">
          <p>
            awesome. Love the components, especially slide-to-unlock. Great job
          </p>
        </TestimonialQuote>

        <TestimonialAuthor>
          <TestimonialAvatar>
            <TestimonialAvatarImg
              src="https://unavatar.io/x/rauchg"
              alt="Guillermo Rauch"
            />
            <TestimonialAvatarRing />
          </TestimonialAvatar>

          <TestimonialAuthorName>
            Guillermo Rauch
            <TestimonialVerifiedBadge className="text-info">
              <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
                <path
                  fill="currentColor"
                  d="M24 12a4.454 4.454 0 0 0-2.564-3.91 4.437 4.437 0 0 0-.948-4.578 4.436 4.436 0 0 0-4.577-.948A4.44 4.44 0 0 0 12 0a4.423 4.423 0 0 0-3.9 2.564 4.434 4.434 0 0 0-2.43-.178 4.425 4.425 0 0 0-2.158 1.126 4.42 4.42 0 0 0-1.12 2.156 4.42 4.42 0 0 0 .183 2.421A4.456 4.456 0 0 0 0 12a4.465 4.465 0 0 0 2.576 3.91 4.433 4.433 0 0 0 .936 4.577 4.459 4.459 0 0 0 4.577.95A4.454 4.454 0 0 0 12 24a4.439 4.439 0 0 0 3.91-2.563 4.26 4.26 0 0 0 5.526-5.526A4.453 4.453 0 0 0 24 12Zm-13.709 4.917-4.38-4.378 1.652-1.663 2.646 2.646L15.83 7.4l1.72 1.591-7.258 7.926Z"
                />
              </svg>
            </TestimonialVerifiedBadge>
          </TestimonialAuthorName>
          <TestimonialAuthorTagline>CEO @Vercel</TestimonialAuthorTagline>
        </TestimonialAuthor>
      </Testimonial>
    </a>
  )
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/testimonial
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/testimonial.tsx" 
      import type { ComponentProps } from "react"

      import { cn } from "@/lib/utils"

      export function Testimonial({ className, ...props }: ComponentProps<"figure">) {
        return (
          <figure
            data-slot="testimonial"
            className={cn("flex h-full flex-col", className)}
            {...props}
          />
        )
      }

      export function TestimonialQuote({
        className,
        ...props
      }: ComponentProps<"blockquote">) {
        return (
          <blockquote
            data-slot="testimonial-quote"
            className={cn(
              "grow px-4 py-3 text-base text-pretty text-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthor({
        className,
        ...props
      }: ComponentProps<"figcaption">) {
        return (
          <figcaption
            data-slot="testimonial-author"
            className={cn(
              "grid grid-cols-[auto_1fr] grid-rows-2 items-center gap-x-3.5 px-4 pt-1 pb-3",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAvatar({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-avatar"
            className={cn("relative row-span-2 size-8 shrink-0", className)}
            {...props}
          />
        )
      }

      export function TestimonialAvatarImg({
        className,
        src,
        alt,
        ...props
      }: ComponentProps<"img">) {
        return (
          <img
            data-slot="testimonial-avatar-img"
            className={cn("size-8 rounded-full select-none", className)}
            src={src}
            alt={alt}
            {...props}
          />
        )
      }

      export function TestimonialAvatarRing({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-avatar-ring"
            className={cn(
              "pointer-events-none absolute inset-0 rounded-full inset-ring-1 inset-ring-black/10 dark:inset-ring-white/15",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthorName({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-author-name"
            className={cn(
              "flex items-center gap-1.5 text-sm leading-4.5 font-semibold text-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthorTagline({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-author-tagline"
            className={cn(
              "text-xs leading-4 text-balance text-muted-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialVerifiedBadge({
        className,
        ...props
      }: ComponentProps<"span">) {
        return (
          <span
            data-slot="testimonial-verified-badge"
            className={cn(
              "flex [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-3.5",
              className
            )}
            aria-hidden
            {...props}
          />
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorInfo,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
  TestimonialVerifiedBadge,
} from "@/components/testimonial"
```

```tsx
<Testimonial>
  <TestimonialQuote />

  <TestimonialAuthor>
    <TestimonialAvatar>
      <TestimonialAvatarImg />
      <TestimonialAvatarRing />
    </TestimonialAvatar>

    <TestimonialAuthorName>
      <TestimonialVerifiedBadge />
    </TestimonialAuthorName>

    <TestimonialAuthorTagline />
  </TestimonialAuthor>
</Testimonial>
```

## Composition

Use the following composition to build a `Testimonial`

```text
Testimonial
├── TestimonialQuote
└── TestimonialAuthor
    ├── TestimonialAvatar
    │   ├── TestimonialAvatarImg
    │   └── TestimonialAvatarRing
    ├── TestimonialAuthorName
    │   └── TestimonialVerifiedBadge
    └── TestimonialAuthorTagline
```

## Examples

* [testimonials-01 block](https://syedmoinuddin.com/blocks/marketing#testimonials-01)
* [testimonials-02 block](https://syedmoinuddin.com/blocks/marketing#testimonials-02)
* [testimonial-spotlight](https://syedmoinuddin.com/components/testimonial-spotlight)
* [testimonials-marquee](https://syedmoinuddin.com/components/testimonials-marquee)


Last updated on March 28, 2026

---
title: "Scroll Fade Effect"
description: "Fade content edges as you scroll, for both vertical and horizontal layouts."
last_updated: "February 20, 2026"
source: "https://syedmoinuddin.com/blog/scroll-fade-effect"
---

# Scroll Fade Effect

Fade content edges as you scroll, for both vertical and horizontal layouts.

```tsx
import * as React from "react"

import { Separator } from "@/components/ui/separator"
import { ScrollFadeEffect } from "@/components/scroll-fade-effect"

const tags = Array.from({ length: 50 }).map(
  (_, i, a) => `v1.2.0-beta.${a.length - i}`
)

export default function ScrollFadeEffectDemo() {
  return (
    <div data-slot="scroll-fade-effect-demo" className="rounded-lg border">
      <ScrollFadeEffect className="h-72 w-48">
        <div className="p-4">
          <h4 className="mb-4 text-sm leading-none font-medium">Tags</h4>
          {tags.map((tag) => (
            <React.Fragment key={tag}>
              <div className="text-sm">{tag}</div>
              <Separator className="my-2" />
            </React.Fragment>
          ))}
        </div>
      </ScrollFadeEffect>
    </div>
  )
}

```

## Features

* Content fades in and out smoothly as you scroll.
* Supports both vertical and horizontal scrolling.

## Browser Compatibility

This component uses CSS `animation-timeline: scroll()`. Check the latest [browser compatibility on MDN](https://developer.mozilla.org/en-US/docs/Web/CSS/animation-timeline#browser_compatibility) before using in production.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/scroll-fade-effect
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Add Tailwind CSS utilities and animations</Step>

      ```css title="globals.css" 
      @layer base {
        @keyframes show-top-mask {
          to {
            --top-mask-height: var(--mask-height);
          }
        }

        @keyframes hide-bottom-mask {
          to {
            --bottom-mask-height: 0px;
          }
        }

        @keyframes show-left-mask {
          to {
            --left-mask-width: var(--mask-width);
          }
        }

        @keyframes hide-right-mask {
          to {
            --right-mask-width: 0px;
          }
        }
      }

      @property --top-mask-height {
        syntax: "<length>";
        inherits: true;
        initial-value: 0px;
      }

      @property --bottom-mask-height {
        syntax: "<length>";
        inherits: true;
        initial-value: 64px;
      }

      @property --left-mask-width {
        syntax: "<length>";
        inherits: true;
        initial-value: 0px;
      }

      @property --right-mask-width {
        syntax: "<length>";
        inherits: true;
        initial-value: 64px;
      }

      @utility scroll-fade-effect-y {
        --mask-height: 64px;
        --mask-offset-top: 0px;
        --mask-offset-bottom: 0px;
        --scroll-buffer: 2rem;

        /* Set up the mask layers */
        mask-image:
          linear-gradient(to top, transparent, black 90%),
          linear-gradient(to bottom, transparent 0%, black 100%),
          linear-gradient(black, black);

        mask-size:
          100% var(--top-mask-height),
          100% var(--bottom-mask-height),
          100% 100%;
        mask-repeat: no-repeat, no-repeat, no-repeat;
        mask-position:
          0 var(--mask-offset-top),
          0 calc(100% - var(--mask-offset-bottom)),
          0 0;
        /* Exclude the gradient areas from the solid mask */
        mask-composite: exclude;

        animation-name: show-top-mask, hide-bottom-mask;
        animation-timeline: scroll(self), scroll(self);
        animation-range:
          0 var(--scroll-buffer),
          calc(100% - var(--scroll-buffer)) 100%;
        animation-fill-mode: both;
      }

      @utility scroll-fade-effect-x {
        --mask-width: 64px;
        --mask-offset-left: 0px;
        --mask-offset-right: 0px;
        --scroll-buffer: 2rem;

        mask-image:
          linear-gradient(to left, transparent, black 90%),
          linear-gradient(to right, transparent 0%, black 100%),
          linear-gradient(black, black);

        mask-size:
          var(--left-mask-width) 100%,
          var(--right-mask-width) 100%,
          100% 100%;
        mask-repeat: no-repeat, no-repeat, no-repeat;
        mask-position:
          var(--mask-offset-left) 0,
          calc(100% - var(--mask-offset-right)) 0,
          0 0;
        mask-composite: exclude;

        animation-name: show-left-mask, hide-right-mask;
        animation-timeline: scroll(self inline), scroll(self inline);
        animation-range:
          0 var(--scroll-buffer),
          calc(100% - var(--scroll-buffer)) 100%;
        animation-fill-mode: both;
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/scroll-fade-effect.tsx" 
      import type { ComponentProps } from "react"

      import { cn } from "@/lib/utils"

      export type ScrollFadeEffectProps = ComponentProps<"div"> & {
        /**
         * Scroll direction to apply the fade effect.
         * @defaultValue "vertical"
         * */
        orientation?: "horizontal" | "vertical"
      }

      export function ScrollFadeEffect({
        className,
        orientation = "vertical",
        ...props
      }: ScrollFadeEffectProps) {
        return (
          <div
            data-orientation={orientation}
            className={cn(
              "data-[orientation=horizontal]:overflow-x-auto data-vertical:overflow-y-auto",
              "data-[orientation=horizontal]:scroll-fade-effect-x data-vertical:scroll-fade-effect-y",
              className
            )}
            {...props}
          />
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { ScrollFadeEffect } from "@/components/scroll-fade-effect"
```

```tsx
<div className="rounded-lg border">
  <ScrollFadeEffect className="h-72 w-48">
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
    tempor incididunt ut labore et dolore magna aliqua. Turpis egestas pretium
    aenean pharetra. Orci eu lobortis elementum nibh tellus molestie. Vulputate
    dignissim suspendisse in est. Vel pharetra vel turpis nunc. Malesuada nunc
    vel risus commodo. Nisi vitae suscipit tellus mauris. Posuere morbi leo urna
    molestie at elementum eu. Urna duis convallis convallis tellus. Urna
    molestie at elementum eu. Nunc sed blandit libero volutpat.
  </ScrollFadeEffect>
</div>
```

## API Reference

### ScrollFadeEffect

<TypeTable
  id="type-table-props.ts-ScrollFadeEffectProps"
  type={{
  "id": "props.ts-ScrollFadeEffectProps",
  "name": "ScrollFadeEffectProps",
  "description": "",
  "entries": [
    {
      "name": "orientation",
      "description": "Scroll direction to apply the fade effect.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "\"vertical\""
        }
      ],
      "type": "\"horizontal\" | \"vertical\" | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

## Examples

### Horizontal Scrolling

```tsx
import Image from "next/image"

import { ScrollFadeEffect } from "@/components/scroll-fade-effect"

export default function ScrollFadeEffectHorizontalDemo() {
  return (
    <div className="rounded-lg border">
      <ScrollFadeEffect className="w-72 sm:w-96" orientation="horizontal">
        <div className="flex w-max gap-4 p-4">
          {works.map((artwork) => (
            <figure key={artwork.artist} className="shrink-0">
              <Image
                src={artwork.art}
                alt={`Photo by ${artwork.artist}`}
                className="aspect-3/4 h-fit w-fit rounded-sm object-cover"
                width={300}
                height={400}
              />

              <figcaption className="pt-2 text-xs text-muted-foreground">
                Photo by{" "}
                <span className="font-semibold text-foreground">
                  {artwork.artist}
                </span>
              </figcaption>
            </figure>
          ))}
        </div>
      </ScrollFadeEffect>
    </div>
  )
}

interface Artwork {
  artist: string
  art: string
}

const works: Artwork[] = [
  {
    artist: "Ornella Binni",
    art: "https://images.unsplash.com/photo-1465869185982-5a1a7522cbcb?auto=format&fit=crop&w=300&q=80",
  },
  {
    artist: "Tom Byrom",
    art: "https://images.unsplash.com/photo-1548516173-3cabfa4607e9?auto=format&fit=crop&w=300&q=80",
  },
  {
    artist: "Vladimir Malyavko",
    art: "https://images.unsplash.com/photo-1494337480532-3725c85fd2ab?auto=format&fit=crop&w=300&q=80",
  },
]

```

### shadcn/ui Scroll Area

```tsx
import * as React from "react"

import { cn } from "@/lib/utils"
import { ScrollArea } from "@/components/ui/scroll-area"
import { Separator } from "@/components/ui/separator"

const tags = Array.from({ length: 50 }).map(
  (_, i, a) => `v1.2.0-beta.${a.length - i}`
)

export default function ScrollAreaDemo() {
  return (
    <ScrollArea
      className={cn(
        "h-72 w-48 rounded-lg border",
        "**:data-[slot=scroll-area-viewport]:scroll-fade-effect-y"
        // "**:data-[slot=scroll-area-viewport]:[--mask-offset-top:8px]",
        // "**:data-[slot=scroll-area-viewport]:[--mask-offset-bottom:8px]"
      )}
    >
      <div className="p-4">
        <h4 className="mb-4 text-sm leading-none font-medium">Tags</h4>
        {tags.map((tag) => (
          <React.Fragment key={tag}>
            <div className="text-sm">{tag}</div>
            <Separator className="my-2" />
          </React.Fragment>
        ))}
      </div>
    </ScrollArea>
  )
}

```

### shadcn/ui Scroll Area – Horizontal Scrolling

```tsx
import Image from "next/image"

import { cn } from "@/lib/utils"
import { ScrollArea, ScrollBar } from "@/components/ui/scroll-area"

export default function ScrollAreaHorizontalDemo() {
  return (
    <ScrollArea
      className={cn(
        "w-72 rounded-lg border whitespace-nowrap sm:w-96",
        "**:data-[slot=scroll-area-viewport]:scroll-fade-effect-x"
        // "**:data-[slot=scroll-area-viewport]:[--mask-offset-left:8px]",
        // "**:data-[slot=scroll-area-viewport]:[--mask-offset-right:8px]"
      )}
    >
      <div className="flex w-max gap-4 p-4">
        {works.map((artwork) => (
          <figure key={artwork.artist} className="shrink-0">
            <Image
              src={artwork.art}
              alt={`Photo by ${artwork.artist}`}
              className="aspect-3/4 h-fit w-fit rounded-sm object-cover"
              width={300}
              height={400}
            />

            <figcaption className="pt-2 text-xs text-muted-foreground">
              Photo by{" "}
              <span className="font-semibold text-foreground">
                {artwork.artist}
              </span>
            </figcaption>
          </figure>
        ))}
      </div>
      <ScrollBar orientation="horizontal" />
    </ScrollArea>
  )
}

interface Artwork {
  artist: string
  art: string
}

const works: Artwork[] = [
  {
    artist: "Ornella Binni",
    art: "https://images.unsplash.com/photo-1465869185982-5a1a7522cbcb?auto=format&fit=crop&w=300&q=80",
  },
  {
    artist: "Tom Byrom",
    art: "https://images.unsplash.com/photo-1548516173-3cabfa4607e9?auto=format&fit=crop&w=300&q=80",
  },
  {
    artist: "Vladimir Malyavko",
    art: "https://images.unsplash.com/photo-1494337480532-3725c85fd2ab?auto=format&fit=crop&w=300&q=80",
  },
]

```

## References

* [Scroll-Driven Animations](https://craft.rohitsinghrawat.com/crafts/scroll-timeline)
* [Scroll Area](https://ui.shadcn.com/docs/components/scroll-area)
* [animation-timeline](https://developer.mozilla.org/en-US/docs/Web/CSS/animation-timeline#browser_compatibility)


Last updated on February 20, 2026

---
title: "GitHub Stars"
description: "Display GitHub repo star count with formatted numbers and full-count tooltip."
last_updated: "March 28, 2026"
source: "https://syedmoinuddin.com/blog/github-stars"
---

# GitHub Stars

Display GitHub repo star count with formatted numbers and full-count tooltip.

```tsx
import { GitHubStars } from "@/components/github-stars"

export default function GitHubStarsDemo() {
  return <GitHubStars repo="SyedMoin-lab/syedmoin-v10" stargazersCount={1800} />
}

```

## Features

* Displays the star count of a specified GitHub repository.
* Optical alignment for better visual balance with the GitHub icon.
* Formats large numbers for better readability (e.g., 1.2k for 1200).
* Includes a tooltip that shows the full star count on hover.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/github-stars
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the required shadcn/ui components</Step>

      * [https://ui.shadcn.com/docs/components/button](https://ui.shadcn.com/docs/components/button)
      * [https://ui.shadcn.com/docs/components/tooltip](https://ui.shadcn.com/docs/components/tooltip)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/github-stars.tsx" 
      import { Button } from "@/components/ui/button"
      import {
        Tooltip,
        TooltipContent,
        TooltipTrigger,
      } from "@/components/ui/tooltip"

      export type GitHubStarsProps = {
        /** GitHub repository in `owner/repo` format. */
        repo: string
        /** Number of stars to display. */
        stargazersCount: number
        /**
         * Optional locales for number formatting.
         * See [MDN - Intl - locales argument](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Intl#locales_argument).
         * @defaultValue "en-US"
         */
        locales?: Intl.LocalesArgument
      }

      export function GitHubStars({
        repo,
        stargazersCount,
        locales = "en-US",
      }: GitHubStarsProps) {
        return (
          <Tooltip>
            <TooltipTrigger asChild>
              <Button className="gap-1.5 pr-1.5 pl-2" variant="ghost" asChild>
                <a href={`https://github.com/${repo}`} target="_blank" rel="noopener">
                  <svg className="-translate-y-px" viewBox="0 0 24 24">
                    <path
                      d="M12 .297c-6.63 0-12 5.373-12 12 0 5.303 3.438 9.8 8.205 11.385.6.113.82-.258.82-.577 0-.285-.01-1.04-.015-2.04-3.338.724-4.042-1.61-4.042-1.61C4.422 18.07 3.633 17.7 3.633 17.7c-1.087-.744.084-.729.084-.729 1.205.084 1.838 1.236 1.838 1.236 1.07 1.835 2.809 1.305 3.495.998.108-.776.417-1.305.76-1.605-2.665-.3-5.466-1.332-5.466-5.93 0-1.31.465-2.38 1.235-3.22-.135-.303-.54-1.523.105-3.176 0 0 1.005-.322 3.3 1.23.96-.267 1.98-.399 3-.405 1.02.006 2.04.138 3 .405 2.28-1.552 3.285-1.23 3.285-1.23.645 1.653.24 2.873.12 3.176.765.84 1.23 1.91 1.23 3.22 0 4.61-2.805 5.625-5.475 5.92.42.36.81 1.096.81 2.22 0 1.606-.015 2.896-.015 3.286 0 .315.21.69.825.57C20.565 22.092 24 17.592 24 12.297c0-6.627-5.373-12-12-12"
                      fill="currentColor"
                    />
                  </svg>
                  <span className="text-[0.8125rem] text-muted-foreground tabular-nums">
                    {new Intl.NumberFormat(locales, {
                      notation: "compact",
                      compactDisplay: "short",
                    })
                      .format(stargazersCount)
                      .toLowerCase()}
                  </span>
                </a>
              </Button>
            </TooltipTrigger>

            <TooltipContent className="tabular-nums">
              {new Intl.NumberFormat(locales).format(stargazersCount)} stars
            </TooltipContent>
          </Tooltip>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { GithubStars } from "@/components/github-stars"
```

```tsx
<GithubStars repo="SyedMoin-lab/syedmoin-v10" stargazersCount={1800} />
```

## API Reference

### GitHubStars

<TypeTable
  id="type-table-github-stars.tsx-GitHubStarsProps"
  type={{
  "id": "github-stars.tsx-GitHubStarsProps",
  "name": "GitHubStarsProps",
  "description": "",
  "entries": [
    {
      "name": "repo",
      "description": "GitHub repository in `owner/repo` format.",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "stargazersCount",
      "description": "Number of stars to display.",
      "tags": [],
      "type": "number",
      "simplifiedType": "number",
      "required": true,
      "deprecated": false
    },
    {
      "name": "locales",
      "description": "Optional locales for number formatting.\nSee [MDN - Intl - locales argument](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Intl#locales_argument).",
      "tags": [
        {
          "name": "defaultValue",
          "text": "\"en-US\""
        }
      ],
      "type": "Intl.LocalesArgument",
      "simplifiedType": "LocalesArgument",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

## Examples

### Fetching GitHub Stars with Server Component

```tsx  
import { SOURCE_CODE_GITHUB_REPO } from "@/config/site"
import { GitHubStars } from "@/components/github-stars"

export function NavItemGitHub() {
  return <GitHubStars repo={SOURCE_CODE_GITHUB_REPO} stargazersCount={900} />
}

```


Last updated on March 28, 2026

---
title: "Shimmering Text"
description: "Smooth, light-sweeping shimmer animation for text."
last_updated: "February 20, 2026"
source: "https://syedmoinuddin.com/blog/shimmering-text"
---

# Shimmering Text

Smooth, light-sweeping shimmer animation for text.

```tsx
import { ShimmeringText } from "@/components/shimmering-text"

export default function ShimmeringTextDemo1() {
  return (
    <ShimmeringText className="text-2xl font-medium" text="Shimmering Text" />
  )
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/shimmering-text
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install motion clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/shimmering-text.tsx" 
      "use client"

      import * as React from "react"
      import type { Variants } from "motion/react"
      import { motion } from "motion/react"

      import { cn } from "@/lib/utils"

      export type ShimmeringTextProps = Omit<
        React.ComponentProps<typeof motion.span>,
        "children"
      > & {
        /** The text to render with the shimmering effect. */
        text: string
        /**
         * Duration in seconds for one shimmer cycle.
         * @defaultValue 1 */
        duration?: number
        /**
         * Whether the shimmer animation is paused.
         * @defaultValue false */
        isStopped?: boolean
      }

      export function ShimmeringText({
        text,
        duration = 1,
        isStopped = false,
        className,
        ...props
      }: ShimmeringTextProps) {
        const createCharVariants = React.useCallback(
          (charIndex: number): Variants => ({
            running: {
              color: ["var(--color)", "var(--shimmering-color)", "var(--color)"],
              transition: {
                duration,
                repeat: Infinity,
                repeatType: "loop" as const,
                repeatDelay: text.length * 0.05,
                delay: (charIndex * duration) / text.length,
                ease: "easeInOut",
              },
            },
            stopped: {
              color: "var(--color)",
              transition: {
                duration: duration * 0.5,
                ease: "easeOut",
              },
            },
          }),
          [duration, text.length]
        )

        return (
          <motion.span
            className={cn(
              "inline-block select-none",
              "[--color:var(--muted-foreground)] [--shimmering-color:var(--foreground)]",
              className
            )}
            {...props}
          >
            {text?.split("")?.map((char, i) => (
              <motion.span
                key={i}
                className="inline-block whitespace-pre"
                initial="stopped"
                animate={isStopped ? "stopped" : "running"}
                variants={createCharVariants(i)}
              >
                {char}
              </motion.span>
            ))}
          </motion.span>
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { ShimmeringText } from "@/components/shimmering-text"
```

```tsx
<ShimmeringText text="slide to unlock" />
```

## API Reference

### ShimmeringText

<TypeTable
  id="type-table-props.ts-ShimmeringTextProps"
  type={{
  "id": "props.ts-ShimmeringTextProps",
  "name": "ShimmeringTextProps",
  "description": "",
  "entries": [
    {
      "name": "text",
      "description": "The text to render with the shimmering effect.",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "duration",
      "description": "Duration in seconds for one shimmer cycle.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "1"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "isStopped",
      "description": "Whether the shimmer animation is paused.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "false"
        }
      ],
      "type": "boolean | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

## Examples

### Custom Color

```tsx
import { ShimmeringText } from "@/components/shimmering-text"

export default function ShimmeringTextDemo2() {
  return (
    <ShimmeringText
      className="font-medium [--color:#fbbf24] [--shimmering-color:#ca8a04] dark:[--color:#f59e0b] dark:[--shimmering-color:#fcd34d]"
      text="Processing your request with AI ..."
    />
  )
}

```

CSS Variables explanation:

* `--color`: Base text color (the default/resting state of characters)
* `--shimmering-color`: Peak highlight color (the bright color characters transition to during the shimmer effect)


Last updated on February 20, 2026

---
title: "Testimonials Marquee"
description: "Scrolling marquee to showcase user testimonials."
last_updated: "March 27, 2025"
source: "https://syedmoinuddin.com/blog/testimonials-marquee"
---

# Testimonials Marquee

Scrolling marquee to showcase user testimonials.

```tsx
import {
  Marquee,
  MarqueeContent,
  MarqueeFade,
  MarqueeItem,
} from "@/components/kibo-ui/marquee"
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
} from "@/components/testimonial"

export default function TestimonialsMarqueeDemo1() {
  return (
    <div className="w-full bg-background">
      <Marquee
        data-slot="marquee"
        className="border-y border-line [&_.rfm-initial-child-container]:items-stretch! [&_.rfm-marquee]:items-stretch!"
      >
        <MarqueeFade side="left" />
        <MarqueeFade side="right" />

        <MarqueeContent>
          {TESTIMONIALS.map((item) => (
            <MarqueeItem
              key={item.url}
              className="mx-0 h-full w-xs border-r border-line"
            >
              <a
                className="block h-full transition-[background-color] ease-out hover:bg-accent/20"
                href={item.url}
                target="_blank"
                rel="noopener noreferrer"
              >
                <Testimonial>
                  <TestimonialQuote className="font-serif">
                    <p>{item.quote}</p>
                  </TestimonialQuote>

                  <TestimonialAuthor>
                    <TestimonialAvatar>
                      <TestimonialAvatarImg src={item.authorAvatar} />
                      <TestimonialAvatarRing />
                    </TestimonialAvatar>

                    <TestimonialAuthorName>
                      {item.authorName}
                    </TestimonialAuthorName>

                    <TestimonialAuthorTagline>
                      {item.authorTagline}
                    </TestimonialAuthorTagline>
                  </TestimonialAuthor>
                </Testimonial>
              </a>
            </MarqueeItem>
          ))}
        </MarqueeContent>
      </Marquee>
    </div>
  )
}

const TESTIMONIALS = [
  {
    authorAvatar: "https://unavatar.io/x/rauchg",
    authorName: "Guillermo Rauch",
    authorTagline: "CEO @Vercel",
    url: "https://x.com/rauchg/status/1978913158514237669",
    quote:
      "awesome. Love the components, especially slide-to-unlock. Great job",
  },
  {
    authorAvatar: "https://unavatar.io/x/orcdev",
    authorName: "OrcDev",
    authorTagline: "Creator of 8bitcn.com",
    url: "https://x.com/orcdev/status/1980378575170859446",
    quote:
      "Seriously, this is one of the best portfolio templates I’ve ever seen.",
  },
  {
    authorAvatar: "https://unavatar.io/x/iamsahaj_xyz",
    authorName: "Sahaj",
    authorTagline: "Creator of tweakcn.com",
    url: "https://x.com/iamsahaj_xyz/status/1982814244501381239",
    quote:
      "remember seeing it on @mannupaaji’s review. it’s one of the best looking ones I’ve seen",
  },
  {
    authorAvatar: "https://unavatar.io/x/steventey",
    authorName: "Steven Tey",
    authorTagline: "Founder @Dub.co",
    url: "https://x.com/steventey/status/1936934909370830924",
    quote: "whoa, this is really dope – needs to get added to @shadcn UI",
  },
  {
    authorAvatar: "https://unavatar.io/x/kapehe_ok",
    authorName: "Kap",
    authorTagline: "Head of Developer Community @Vercel",
    url: "https://x.com/kapehe_ok/status/1948104774358106612",
    quote: "one of my favorite projects that submitted! you are crushing it!",
  },
  {
    authorAvatar: "https://unavatar.io/x/initjean",
    authorName: "Jean P.D. Meijer",
    authorTagline: "Building analog.now",
    url: "https://x.com/initjean/status/1948159885960438151",
    quote:
      "congrats you deserve it! react wheel picker is so smooth, its insane",
  },
  {
    authorAvatar: "https://unavatar.io/x/GithubProjects",
    authorName: "GitHub Projects Community",
    authorTagline: "UNOFFICIAL, but followed by @github",
    url: "https://x.com/GithubProjects/status/1931034244337271044",
    quote:
      "Everything you’d want in a picker, minus the styling headaches. Awesome job!",
  },
]

```

## Features

* Continuous scrolling marquee with fade edges.
* Single and multiple row layouts.
* Composable with the Testimonial component.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/testimonials-marquee
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge react-fast-marquee
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/testimonial.tsx" 
      import type { ComponentProps } from "react"

      import { cn } from "@/lib/utils"

      export function Testimonial({ className, ...props }: ComponentProps<"figure">) {
        return (
          <figure
            data-slot="testimonial"
            className={cn("flex h-full flex-col", className)}
            {...props}
          />
        )
      }

      export function TestimonialQuote({
        className,
        ...props
      }: ComponentProps<"blockquote">) {
        return (
          <blockquote
            data-slot="testimonial-quote"
            className={cn(
              "grow px-4 py-3 text-base text-pretty text-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthor({
        className,
        ...props
      }: ComponentProps<"figcaption">) {
        return (
          <figcaption
            data-slot="testimonial-author"
            className={cn(
              "grid grid-cols-[auto_1fr] grid-rows-2 items-center gap-x-3.5 px-4 pt-1 pb-3",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAvatar({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-avatar"
            className={cn("relative row-span-2 size-8 shrink-0", className)}
            {...props}
          />
        )
      }

      export function TestimonialAvatarImg({
        className,
        src,
        alt,
        ...props
      }: ComponentProps<"img">) {
        return (
          <img
            data-slot="testimonial-avatar-img"
            className={cn("size-8 rounded-full select-none", className)}
            src={src}
            alt={alt}
            {...props}
          />
        )
      }

      export function TestimonialAvatarRing({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-avatar-ring"
            className={cn(
              "pointer-events-none absolute inset-0 rounded-full inset-ring-1 inset-ring-black/10 dark:inset-ring-white/15",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthorName({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-author-name"
            className={cn(
              "flex items-center gap-1.5 text-sm leading-4.5 font-semibold text-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialAuthorTagline({
        className,
        ...props
      }: ComponentProps<"div">) {
        return (
          <div
            data-slot="testimonial-author-tagline"
            className={cn(
              "text-xs leading-4 text-balance text-muted-foreground",
              className
            )}
            {...props}
          />
        )
      }

      export function TestimonialVerifiedBadge({
        className,
        ...props
      }: ComponentProps<"span">) {
        return (
          <span
            data-slot="testimonial-verified-badge"
            className={cn(
              "flex [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-3.5",
              className
            )}
            aria-hidden
            {...props}
          />
        )
      }

      ```

      ```tsx title="components/kibo-ui/marquee/index.tsx" 
      "use client"

      import type { HTMLAttributes } from "react"
      import type { MarqueeProps as FastMarqueeProps } from "react-fast-marquee"
      import FastMarquee from "react-fast-marquee"

      import { cn } from "@/lib/utils"

      export type MarqueeProps = HTMLAttributes<HTMLDivElement>

      export const Marquee = ({ className, ...props }: MarqueeProps) => (
        <div
          className={cn("relative w-full overflow-hidden", className)}
          {...props}
        />
      )

      export type MarqueeContentProps = FastMarqueeProps

      export const MarqueeContent = ({
        loop = 0,
        autoFill = true,
        pauseOnHover = true,
        ...props
      }: MarqueeContentProps) => (
        <FastMarquee
          autoFill={autoFill}
          loop={loop}
          pauseOnHover={pauseOnHover}
          {...props}
        />
      )

      export type MarqueeFadeProps = HTMLAttributes<HTMLDivElement> & {
        side: "left" | "right"
      }

      export const MarqueeFade = ({
        className,
        side,
        ...props
      }: MarqueeFadeProps) => (
        <div
          className={cn(
            "pointer-events-none absolute top-0 bottom-0 z-10 h-full w-20 from-background to-transparent",
            side === "left" ? "left-0 bg-linear-to-r" : "right-0 bg-linear-to-l",
            className
          )}
          {...props}
        />
      )

      export type MarqueeItemProps = HTMLAttributes<HTMLDivElement>

      export const MarqueeItem = ({ className, ...props }: MarqueeItemProps) => (
        <div className={cn("mx-2 shrink-0 object-contain", className)} {...props} />
      )

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import {
  Marquee,
  MarqueeContent,
  MarqueeFade,
  MarqueeItem,
} from "@/components/kibo-ui/marquee"
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorInfo,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
  TestimonialVerifiedBadge,
} from "@/components/testimonial"
```

```tsx
<Marquee>
  <MarqueeFade />
  <MarqueeFade />

  <MarqueeContent>
    <MarqueeItem>
      <Testimonial>
        <TestimonialQuote />

        <TestimonialAuthor>
          <TestimonialAvatar>
            <TestimonialAvatarImg />
            <TestimonialAvatarRing />
          </TestimonialAvatar>

          <TestimonialAuthorName>
            <TestimonialVerifiedBadge />
          </TestimonialAuthorName>

          <TestimonialAuthorTagline />
        </TestimonialAuthor>
      </Testimonial>
    </MarqueeItem>
  </MarqueeContent>
</Marquee>
```

## Composition

Use the following composition to build a `Testimonials Marquee`

```text
Marquee
├── MarqueeFade
├── MarqueeFade
└── MarqueeContent
    └── MarqueeItem
        └── Testimonial
            ├── TestimonialQuote
            └── TestimonialAuthor
                ├── TestimonialAvatar
                │   ├── TestimonialAvatarImg
                │   └── TestimonialAvatarRing
                ├── TestimonialAuthorName
                │   └── TestimonialVerifiedBadge
                └── TestimonialAuthorTagline
```

## API Reference

* [Marquee](https://www.kibo-ui.com/components/marquee)
* [React FAST Marquee](https://www.react-fast-marquee.com)

## Examples

### Single Row

```tsx
import {
  Marquee,
  MarqueeContent,
  MarqueeFade,
  MarqueeItem,
} from "@/components/kibo-ui/marquee"
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
} from "@/components/testimonial"

export default function TestimonialsMarqueeDemo1() {
  return (
    <div className="w-full bg-background">
      <Marquee
        data-slot="marquee"
        className="border-y border-line [&_.rfm-initial-child-container]:items-stretch! [&_.rfm-marquee]:items-stretch!"
      >
        <MarqueeFade side="left" />
        <MarqueeFade side="right" />

        <MarqueeContent>
          {TESTIMONIALS.map((item) => (
            <MarqueeItem
              key={item.url}
              className="mx-0 h-full w-xs border-r border-line"
            >
              <a
                className="block h-full transition-[background-color] ease-out hover:bg-accent/20"
                href={item.url}
                target="_blank"
                rel="noopener noreferrer"
              >
                <Testimonial>
                  <TestimonialQuote className="font-serif">
                    <p>{item.quote}</p>
                  </TestimonialQuote>

                  <TestimonialAuthor>
                    <TestimonialAvatar>
                      <TestimonialAvatarImg src={item.authorAvatar} />
                      <TestimonialAvatarRing />
                    </TestimonialAvatar>

                    <TestimonialAuthorName>
                      {item.authorName}
                    </TestimonialAuthorName>

                    <TestimonialAuthorTagline>
                      {item.authorTagline}
                    </TestimonialAuthorTagline>
                  </TestimonialAuthor>
                </Testimonial>
              </a>
            </MarqueeItem>
          ))}
        </MarqueeContent>
      </Marquee>
    </div>
  )
}

const TESTIMONIALS = [
  {
    authorAvatar: "https://unavatar.io/x/rauchg",
    authorName: "Guillermo Rauch",
    authorTagline: "CEO @Vercel",
    url: "https://x.com/rauchg/status/1978913158514237669",
    quote:
      "awesome. Love the components, especially slide-to-unlock. Great job",
  },
  {
    authorAvatar: "https://unavatar.io/x/orcdev",
    authorName: "OrcDev",
    authorTagline: "Creator of 8bitcn.com",
    url: "https://x.com/orcdev/status/1980378575170859446",
    quote:
      "Seriously, this is one of the best portfolio templates I’ve ever seen.",
  },
  {
    authorAvatar: "https://unavatar.io/x/iamsahaj_xyz",
    authorName: "Sahaj",
    authorTagline: "Creator of tweakcn.com",
    url: "https://x.com/iamsahaj_xyz/status/1982814244501381239",
    quote:
      "remember seeing it on @mannupaaji’s review. it’s one of the best looking ones I’ve seen",
  },
  {
    authorAvatar: "https://unavatar.io/x/steventey",
    authorName: "Steven Tey",
    authorTagline: "Founder @Dub.co",
    url: "https://x.com/steventey/status/1936934909370830924",
    quote: "whoa, this is really dope – needs to get added to @shadcn UI",
  },
  {
    authorAvatar: "https://unavatar.io/x/kapehe_ok",
    authorName: "Kap",
    authorTagline: "Head of Developer Community @Vercel",
    url: "https://x.com/kapehe_ok/status/1948104774358106612",
    quote: "one of my favorite projects that submitted! you are crushing it!",
  },
  {
    authorAvatar: "https://unavatar.io/x/initjean",
    authorName: "Jean P.D. Meijer",
    authorTagline: "Building analog.now",
    url: "https://x.com/initjean/status/1948159885960438151",
    quote:
      "congrats you deserve it! react wheel picker is so smooth, its insane",
  },
  {
    authorAvatar: "https://unavatar.io/x/GithubProjects",
    authorName: "GitHub Projects Community",
    authorTagline: "UNOFFICIAL, but followed by @github",
    url: "https://x.com/GithubProjects/status/1931034244337271044",
    quote:
      "Everything you’d want in a picker, minus the styling headaches. Awesome job!",
  },
]

```

### Multiple Rows

```tsx
import {
  Marquee,
  MarqueeContent,
  MarqueeFade,
  MarqueeItem,
} from "@/components/kibo-ui/marquee"
import {
  Testimonial,
  TestimonialAuthor,
  TestimonialAuthorName,
  TestimonialAuthorTagline,
  TestimonialAvatar,
  TestimonialAvatarImg,
  TestimonialAvatarRing,
  TestimonialQuote,
} from "@/components/testimonial"

export default function TestimonialsMarqueeDemo2() {
  return (
    <div className="w-full space-y-4 bg-background [&_.rfm-initial-child-container]:items-stretch! [&_.rfm-marquee]:items-stretch!">
      {[TESTIMONIALS_1, TESTIMONIALS_2].map((list, index) => (
        <Marquee key={index} className="border-y border-line">
          <MarqueeFade side="left" />
          <MarqueeFade side="right" />

          <MarqueeContent direction={index % 2 === 1 ? "right" : "left"}>
            {list.map((item) => (
              <MarqueeItem
                key={item.url}
                className="mx-0 h-full w-xs border-r border-line"
              >
                <a
                  className="block h-full transition-[background-color] ease-out hover:bg-accent/20"
                  href={item.url}
                  target="_blank"
                  rel="noopener noreferrer"
                >
                  <Testimonial>
                    <TestimonialQuote className="font-serif">
                      <p>{item.quote}</p>
                    </TestimonialQuote>

                    <TestimonialAuthor>
                      <TestimonialAvatar>
                        <TestimonialAvatarImg src={item.authorAvatar} />
                        <TestimonialAvatarRing />
                      </TestimonialAvatar>

                      <TestimonialAuthorName>
                        {item.authorName}
                      </TestimonialAuthorName>

                      <TestimonialAuthorTagline>
                        {item.authorTagline}
                      </TestimonialAuthorTagline>
                    </TestimonialAuthor>
                  </Testimonial>
                </a>
              </MarqueeItem>
            ))}
          </MarqueeContent>
        </Marquee>
      ))}
    </div>
  )
}

const TESTIMONIALS_1 = [
  {
    authorAvatar: "https://unavatar.io/x/rauchg",
    authorName: "Guillermo Rauch",
    authorTagline: "CEO @Vercel",
    url: "https://x.com/rauchg/status/1978913158514237669",
    quote:
      "awesome. Love the components, especially slide-to-unlock. Great job",
  },
  {
    authorAvatar: "https://unavatar.io/x/orcdev",
    authorName: "OrcDev",
    authorTagline: "Creator of 8bitcn.com",
    url: "https://x.com/orcdev/status/1980378575170859446",
    quote:
      "Seriously, this is one of the best portfolio templates I’ve ever seen.",
  },
  {
    authorAvatar: "https://unavatar.io/x/iamsahaj_xyz",
    authorName: "Sahaj",
    authorTagline: "Creator of tweakcn.com",
    url: "https://x.com/iamsahaj_xyz/status/1982814244501381239",
    quote:
      "remember seeing it on @mannupaaji’s review. it’s one of the best looking ones I’ve seen",
  },
  {
    authorAvatar: "https://unavatar.io/x/steventey",
    authorName: "Steven Tey",
    authorTagline: "Founder @Dub.co",
    url: "https://x.com/steventey/status/1936934909370830924",
    quote: "whoa, this is really dope – needs to get added to @shadcn UI",
  },
  {
    authorAvatar: "https://unavatar.io/x/kapehe_ok",
    authorName: "Kap",
    authorTagline: "Head of Developer Community @Vercel",
    url: "https://x.com/kapehe_ok/status/1948104774358106612",
    quote: "one of my favorite projects that submitted! you are crushing it!",
  },
  {
    authorAvatar: "https://unavatar.io/x/initjean",
    authorName: "Jean P.D. Meijer",
    authorTagline: "Building analog.now",
    url: "https://x.com/initjean/status/1948159885960438151",
    quote:
      "congrats you deserve it! react wheel picker is so smooth, its insane",
  },
  {
    authorAvatar: "https://unavatar.io/x/GithubProjects",
    authorName: "GitHub Projects Community",
    authorTagline: "UNOFFICIAL, but followed by @github",
    url: "https://x.com/GithubProjects/status/1931034244337271044",
    quote:
      "Everything you’d want in a picker, minus the styling headaches. Awesome job!",
  },
]

export const TESTIMONIALS_2 = [
  {
    authorAvatar: "https://unavatar.io/x/mannupaaji",
    authorName: "Manu Arora",
    authorTagline: "Creator of ui.aceternity.com",
    url: "https://x.com/mannupaaji/status/1944755561117163597",
    quote: "Great work on the portfolio",
  },
  {
    authorAvatar: "https://unavatar.io/x/MaxPrilutskiy",
    authorName: "Max Prilutskiy",
    authorTagline: "CEO @Lingo.dev",
    url: "https://x.com/MaxPrilutskiy/status/1923952193893466379",
    quote: "i like your style! :)",
  },
  {
    authorAvatar: "https://unavatar.io/x/aaronmahlke",
    authorName: "Aaron",
    authorTagline: "Founding Design Engineer @Mail0",
    url: "https://x.com/aaronmahlke/status/1955606729657344490",
    quote: "super cool portfolio!",
  },
  {
    authorAvatar: "https://unavatar.io/x/jordwalke",
    authorName: "jordwalke",
    authorTagline: "Creator of React",
    url: "https://x.com/jordwalke/status/1937165909778657589",
    quote: "Looks great",
  },
  {
    authorAvatar: "https://unavatar.io/x/YonathanDejene",
    authorName: "Yonaries",
    authorTagline: "Making orabrowser.com",
    url: "https://x.com/YonathanDejene/status/1984529637309886639",
    quote: "incredible portfolio i’ve seen by far",
  },
  {
    authorAvatar: "https://unavatar.io/x/zaidmukaddam",
    authorName: "Zaid",
    authorTagline: "Creator of scira.ai",
    url: "https://x.com/zaidmukaddam/status/1984599685974409374",
    quote: "super clean",
  },
]

```


Last updated on March 27, 2025

---
title: "Slide to Unlock"
description: "Interactive slider inspired by the classic iPhone “slide to unlock” gesture."
last_updated: "February 20, 2026"
source: "https://syedmoinuddin.com/blog/slide-to-unlock"
---

# Slide to Unlock

Interactive slider inspired by the classic iPhone “slide to unlock” gesture.

```tsx
"use client"

import { toast } from "sonner"

import { useSound } from "@/hooks/sound/use-sound"
import { ShimmeringText } from "@/components/shimmering-text"
import {
  SlideToUnlock,
  SlideToUnlockHandle,
  SlideToUnlockText,
  SlideToUnlockTrack,
} from "@/components/slide-to-unlock"

export default function SlideToUnlockDemo1() {
  const [play] = useSound(
    "https://assets.syedmoinuddin.com/sounds/ios/unlock.mp3",
    {
      volume: 0.5,
    }
  )

  return (
    <SlideToUnlock
      onUnlock={() => {
        play()
        toast.success("Unlocked")
      }}
    >
      <SlideToUnlockTrack>
        <SlideToUnlockText>
          {({ isDragging }) => (
            <ShimmeringText text="slide to unlock" isStopped={isDragging} />
          )}
        </SlideToUnlockText>
        <SlideToUnlockHandle />
      </SlideToUnlockTrack>
    </SlideToUnlock>
  )
}

```

<Testimonial authorAvatar="https://unavatar.io/x/rauchg" authorName="Guillermo Rauch" authorTagline="CEO @Vercel" url="https://x.com/rauchg/status/1978913158514237669" quote="awesome. Love the components, especially slide-to-unlock. Great job" date="2025-10-17" />

## Features

* Smooth drag interaction with spring physics via Motion.
* Composable compound components (track, handle, text).
* Customizable handle and colors.
* Built-in shimmering text effect.

<Callout>
  Want to build animations like Slide to Unlock? I highly recommend [Emil
  Kowalski](https://x.com/emilkowalski)’s animations.dev course. [Take the
  course](https://animations.dev)
</Callout>

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/slide-to-unlock
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install motion clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/shimmering-text.tsx" 
      "use client"

      import * as React from "react"
      import type { Variants } from "motion/react"
      import { motion } from "motion/react"

      import { cn } from "@/lib/utils"

      export type ShimmeringTextProps = Omit<
        React.ComponentProps<typeof motion.span>,
        "children"
      > & {
        /** The text to render with the shimmering effect. */
        text: string
        /**
         * Duration in seconds for one shimmer cycle.
         * @defaultValue 1 */
        duration?: number
        /**
         * Whether the shimmer animation is paused.
         * @defaultValue false */
        isStopped?: boolean
      }

      export function ShimmeringText({
        text,
        duration = 1,
        isStopped = false,
        className,
        ...props
      }: ShimmeringTextProps) {
        const createCharVariants = React.useCallback(
          (charIndex: number): Variants => ({
            running: {
              color: ["var(--color)", "var(--shimmering-color)", "var(--color)"],
              transition: {
                duration,
                repeat: Infinity,
                repeatType: "loop" as const,
                repeatDelay: text.length * 0.05,
                delay: (charIndex * duration) / text.length,
                ease: "easeInOut",
              },
            },
            stopped: {
              color: "var(--color)",
              transition: {
                duration: duration * 0.5,
                ease: "easeOut",
              },
            },
          }),
          [duration, text.length]
        )

        return (
          <motion.span
            className={cn(
              "inline-block select-none",
              "[--color:var(--muted-foreground)] [--shimmering-color:var(--foreground)]",
              className
            )}
            {...props}
          >
            {text?.split("")?.map((char, i) => (
              <motion.span
                key={i}
                className="inline-block whitespace-pre"
                initial="stopped"
                animate={isStopped ? "stopped" : "running"}
                variants={createCharVariants(i)}
              >
                {char}
              </motion.span>
            ))}
          </motion.span>
        )
      }

      ```

      ````tsx title="components/slide-to-unlock.tsx" 
      "use client"

      import type { ComponentProps, ComponentPropsWithoutRef, JSX } from "react"
      import { createContext, useCallback, useContext, useRef, useState } from "react"
      import {
        animate,
        motion,
        useMotionValue,
        useTransform,
        type MotionValue,
      } from "motion/react"

      import { cn } from "@/lib/utils"

      type SlideToUnlockContextValue = {
        x: MotionValue<number>
        trackRef: React.RefObject<HTMLDivElement | null>
        isDragging: boolean
        handleWidth: number
        textOpacity: MotionValue<number>
        onDragStart: () => void
        onDragEnd: () => void
      }

      const SlideToUnlockContext = createContext<SlideToUnlockContextValue | null>(
        null
      )

      function useSlideToUnlock() {
        const context = useContext(SlideToUnlockContext)
        if (!context) {
          throw new Error(
            `SlideToUnlock components must be used within SlideToUnlock`
          )
        }
        return context
      }

      export type SlideToUnlockRootProps = ComponentProps<"div"> & {
        /**
         * Width of the drag handle in pixels.
         * @defaultValue 56
         * */
        handleWidth?: number
        /** Called when the handle is dragged fully to the end. */
        onUnlock?: () => void
      }

      export function SlideToUnlock({
        className,
        handleWidth = 56,
        children,
        onUnlock,
        ...props
      }: SlideToUnlockRootProps) {
        const trackRef = useRef<HTMLDivElement>(null)
        const [isDragging, setIsDragging] = useState(false)
        const x = useMotionValue(0)

        const fadeDistance = handleWidth
        const textOpacity = useTransform(x, [0, fadeDistance], [1, 0])

        const handleDragStart = useCallback(() => {
          setIsDragging(true)
        }, [])

        const handleDragEnd = useCallback(() => {
          setIsDragging(false)

          const trackWidth = trackRef.current?.offsetWidth || 0
          const maxX = trackWidth - handleWidth

          if (x.get() >= maxX) {
            onUnlock?.()
          } else {
            animate(x, 0, { type: "spring", bounce: 0, duration: 0.25 })
          }
        }, [x, onUnlock, handleWidth])

        return (
          <SlideToUnlockContext.Provider
            value={{
              x,
              trackRef,
              isDragging,
              handleWidth,
              textOpacity,
              onDragStart: handleDragStart,
              onDragEnd: handleDragEnd,
            }}
          >
            <div
              data-slot="slide-to-unlock"
              className={cn(
                "w-54 rounded-xl bg-muted p-1 shadow-inner inset-ring-1 inset-ring-foreground/10",
                className
              )}
              {...props}
            >
              {children}
            </div>
          </SlideToUnlockContext.Provider>
        )
      }

      export type SlideToUnlockTrackProps = ComponentProps<"div">

      export function SlideToUnlockTrack({
        className,
        children,
        ...props
      }: SlideToUnlockTrackProps) {
        const { trackRef } = useSlideToUnlock()

        return (
          <div
            ref={trackRef}
            data-slot="track"
            className={cn(
              "relative flex h-10 items-center justify-center",
              className
            )}
            {...props}
          >
            {children}
          </div>
        )
      }

      export type SlideToUnlockTextProps = Omit<
        ComponentPropsWithoutRef<typeof motion.div>,
        "children"
      > & {
        /**
         * Accepts a render function as `children` to react to the dragging state.
         *
         * @example
         * ```tsx
         * <SlideToUnlockText>
         *   {({ isDragging }) => <span>{isDragging ? "Release..." : "Slide to unlock"}</span>}
         * </SlideToUnlockText>
         * ```
         */
        children: JSX.Element | ((props: { isDragging: boolean }) => JSX.Element)
      }

      export function SlideToUnlockText({
        className,
        children,
        style,
        ...props
      }: SlideToUnlockTextProps) {
        const { handleWidth, textOpacity, isDragging } = useSlideToUnlock()

        return (
          <motion.div
            data-slot="text"
            data-dragging={isDragging}
            className={cn("pl-1 text-lg font-medium", className)}
            style={{ marginLeft: handleWidth, opacity: textOpacity, ...style }}
            {...props}
          >
            {typeof children === "function" ? children({ isDragging }) : children}
          </motion.div>
        )
      }

      export type SlideToUnlockHandleProps = ComponentPropsWithoutRef<
        typeof motion.div
      >

      export function SlideToUnlockHandle({
        className,
        children,
        style,
        ...props
      }: SlideToUnlockHandleProps) {
        const {
          x,
          trackRef,
          onDragStart,
          onDragEnd,
          handleWidth: width,
        } = useSlideToUnlock()

        return (
          <motion.div
            data-slot="handle"
            className={cn(
              "absolute top-0 left-0 flex h-10 cursor-grab items-center justify-center rounded-lg bg-white text-zinc-400 shadow-sm active:cursor-grabbing",
              "[&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-6",
              className
            )}
            style={{ width, x, ...style }}
            drag="x"
            dragConstraints={trackRef}
            dragElastic={0}
            dragMomentum={false}
            onDragStart={onDragStart}
            onDragEnd={onDragEnd}
            {...props}
          >
            {children ?? (
              <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" aria-hidden>
                <path
                  d="M24 12 12.75 3v4.696H0v8.608h12.75V21z"
                  fill="currentColor"
                />
              </svg>
            )}
          </motion.div>
        )
      }

      ````

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { ShimmeringText } from "@/components/shimmering-text"
import {
  SlideToUnlock,
  SlideToUnlockHandle,
  SlideToUnlockText,
  SlideToUnlockTrack,
} from "@/components/slide-to-unlock"
```

```tsx
<SlideToUnlock>
  <SlideToUnlockTrack>
    <SlideToUnlockText>
      <ShimmeringText />
    </SlideToUnlockText>
    <SlideToUnlockHandle />
  </SlideToUnlockTrack>
</SlideToUnlock>
```

## Composition

Use the following composition to build a `SlideToUnlock`

```text
SlideToUnlock
└── SlideToUnlockTrack
    ├── SlideToUnlockText
    │   └── ShimmeringText
    └── SlideToUnlockHandle
```

## API Reference

### SlideToUnlock

<TypeTable
  id="type-table-props.ts-SlideToUnlockRootProps"
  type={{
  "id": "props.ts-SlideToUnlockRootProps",
  "name": "SlideToUnlockRootProps",
  "description": "",
  "entries": [
    {
      "name": "handleWidth",
      "description": "Width of the drag handle in pixels.",
      "tags": [
        {
          "name": "defaultValue",
          "text": "56"
        }
      ],
      "type": "number | undefined",
      "simplifiedType": "number",
      "required": false,
      "deprecated": false
    },
    {
      "name": "onUnlock",
      "description": "Called when the handle is dragged fully to the end.",
      "tags": [],
      "type": "(() => void) | undefined",
      "simplifiedType": "function",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

### SlideToUnlockText

<TypeTable
  id="type-table-props.ts-SlideToUnlockTextProps"
  type={{
  "id": "props.ts-SlideToUnlockTextProps",
  "name": "SlideToUnlockTextProps",
  "description": "",
  "entries": [
    {
      "name": "children",
      "description": "Accepts a render function as `children` to react to the dragging state.",
      "tags": [
        {
          "name": "example",
          "text": "```tsx\n<SlideToUnlockText>\n  {({ isDragging }) => <span>{isDragging ? \"Release...\" : \"Slide to unlock\"}</span>}\n</SlideToUnlockText>\n```"
        }
      ],
      "type": "React.JSX.Element | ((props: { isDragging: boolean; }) => React.JSX.Element)",
      "simplifiedType": "union",
      "required": true,
      "deprecated": false
    }
  ]
}}
/>

## Examples

### Custom Color

```tsx
"use client"

import { toast } from "sonner"

import { ShimmeringText } from "@/components/shimmering-text"
import {
  SlideToUnlock,
  SlideToUnlockHandle,
  SlideToUnlockText,
  SlideToUnlockTrack,
} from "@/components/slide-to-unlock"

export default function SlideToUnlockDemo2() {
  return (
    <>
      <SlideToUnlock
        className="bg-linear-to-b from-zinc-800 to-zinc-900"
        onUnlock={() => {
          const myPromise = new Promise((resolve) => {
            setTimeout(() => {
              resolve(true)
            }, 1000)
          })

          toast.promise(myPromise, {
            loading: "Connecting...",
            success: () => `Connected`,
            error: ({ message }) => `Error: ${message}`,
          })
        }}
      >
        <SlideToUnlockTrack>
          <SlideToUnlockText>
            {({ isDragging }) => (
              <ShimmeringText
                className="[--color:var(--color-zinc-600)] [--shimmering-color:var(--color-zinc-50)]"
                text="slide to answer"
                isStopped={isDragging}
              />
            )}
          </SlideToUnlockText>

          <SlideToUnlockHandle className="bg-linear-to-b from-emerald-500 to-emerald-700 text-white" />
        </SlideToUnlockTrack>
      </SlideToUnlock>
    </>
  )
}

```

### Custom Handle

```tsx
"use client"

import { toast } from "sonner"

import { ShimmeringText } from "@/components/shimmering-text"
import {
  SlideToUnlock,
  SlideToUnlockHandle,
  SlideToUnlockText,
  SlideToUnlockTrack,
} from "@/components/slide-to-unlock"

export default function SlideToUnlockDemo3() {
  return (
    <SlideToUnlock
      className="w-45 rounded-full ring-0"
      handleWidth={40}
      onUnlock={() => toast.success("Stopped")}
    >
      <SlideToUnlockTrack>
        <SlideToUnlockText className="pl-0">
          {({ isDragging }) => (
            <ShimmeringText text="slide to stop" isStopped={isDragging} />
          )}
        </SlideToUnlockText>

        <SlideToUnlockHandle className="w-10 rounded-full dark:bg-zinc-700">
          <svg
            className="size-5 dark:text-white"
            xmlns="http://www.w3.org/2000/svg"
            viewBox="0 0 256 256"
          >
            <path
              d="M216,56V200a16,16,0,0,1-16,16H56a16,16,0,0,1-16-16V56A16,16,0,0,1,56,40H200A16,16,0,0,1,216,56Z"
              fill="currentColor"
            />
          </svg>
        </SlideToUnlockHandle>
      </SlideToUnlockTrack>
    </SlideToUnlock>
  )
}

```


Last updated on February 20, 2026

---
title: "Work Experience"
description: "Display work experiences with role details, company logos, and durations."
last_updated: "March 28, 2026"
source: "https://syedmoinuddin.com/blog/work-experience-component"
---

# Work Experience

Display work experiences with role details, company logos, and durations.

```tsx
import { CodeXmlIcon } from "lucide-react"

import type { ExperienceItemType } from "@/components/work-experience"
import { WorkExperience } from "@/components/work-experience"

export default function WorkExperienceDemo() {
  return <WorkExperience className="w-full" experiences={WORK_EXPERIENCE} />
}

const WORK_EXPERIENCE: ExperienceItemType[] = [
  {
    id: "perssonify-virallens",
    companyName: "Perssonify & Virallens",
    positions: [
      {
        id: "1",
        title: "Full Stack Engineer",
        employmentPeriod: {
          start: "06.2025",
        },
        employmentType: "Full-time",
        icon: <CodeXmlIcon />,
        description: `- Built the Perssonify company website from scratch in Next.js, Tailwind CSS, and Framer Motion — owning the full frontend from layout and design system to animations and production deployment.
- Built HelixCrawl, a high-throughput web-crawling platform on a fully Go (1.25) microservices backend, processing ~50K pages/day across nine specialized services (bfs-frontier, crawl-engine, doc-parser, http-fetcher, and more).
- Designed the HelixCrawl data pipeline around Kafka, Redis, and bloom-filter deduplication, enabling reliable concurrent crawling at scale without redundant fetches.
- Engineered HelixCrawl's anti-bot fetching layer (TLS fingerprinting via utls + go-rod), lifting successful crawl rates on protected targets from ~60% to ~90%.
- Re-architected the crawl backend from a Celery/Temporal pipeline to a Kafka-driven Go system, tripling throughput (~3x) while cutting infrastructure cost by ~35%.
- Designed and built the UI dashboard for the Stock Drop Analysis platform, a securities-fraud detection tool for law firms — delivering a clean, law-firm-grade interface in IBM Plex Sans with a teal/navy design system.
- Built Content publishing platform now used by clients in production — powering blog content published live on the ZLK (Levi & Korsinsky) website.`,
        skills: [
          "Go",
          "Go Services",
          "TypeScript",
          "Next.js",
          "Tailwind CSS",
          "Framer Motion",
          "FastAPI",
          "Kafka",
          "Redis",
          "Microservices",
          "Temporal",
          "Celery",
          "utls",
          "go-rod",
          "AWS",
          "EC2",
          "ECS",
          "S3",
          "Monday.com",
          "PR Review",
        ],
        isExpanded: true,
      },
    ],
    isCurrentEmployer: true,
  },
  {
    id: "freelance",
    companyName: "Freelance",
    positions: [
      {
        id: "2",
        title: "Full-stack Developer",
        employmentPeriod: {
          start: "2018",
          end: "2020",
        },
        employmentType: "Part-time",
        icon: <CodeXmlIcon />,
        description: `- Built an order management website with real-time delivery tracking.
- Developed an e-commerce site for bird’s nest products.
- Created a map to display monitoring station data.
- Designed a customizable WordPress landing page.`,
        skills: [
          "Laravel",
          "React",
          "Express.js",
          "Socket.IO",
          "MongoDB",
          "Firebase",
          "WordPress",
          "Docker",
          "NGINX",
        ],
      },
    ],
  },
  {
    id: "education",
    companyName: "Education",
    positions: [
      {
        id: "1",
        title: "REVA University",
        employmentPeriod: {
          start: "08.2019",
          end: "08.2023",
        },
        icon: (
          <img
            src="/edu/reva_university_logo.jpg"
            alt="REVA University"
            className="size-4 rounded-sm object-contain"
          />
        ),
        description:
          "Bachelor of Technology - BTech, Mechatronics, Robotics, and Automation Engineering",
        skills: [
          "C++",
          "Python",
          "Control Systems",
          "Data Structures & Algorithms",
          "PCB Design",
          "AutoCAD",
          "SolidWorks",
          "MATLAB",
          "Simulink",
          "FastAPI",
          "Robotics",
          "Automation",
          "Mechatronics",
          "Embedded Systems",
          "Microcontrollers",
          "Arduino",
          "Sensors & Actuators",
          "Mechanical Engineering",
          "Electronics & Communication",
          "Computer Science",
        ],
        isExpanded: true,
      },
    ],
  },
]

```

## Features

* Supports multiple positions per company.
* Markdown rendering for position descriptions.
* Company logos and duration display.

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/work-experience
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install clsx tailwind-merge react-markdown lucide-react motion
      ```

      ```bash
      npm install -D @tailwindcss/typography
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Add a Tailwind CSS plugin and utility</Step>

      ```css title="globals.css"
      @import "tailwindcss";
      @plugin "@tailwindcss/typography";

      @utility link {
        @apply decoration-1 underline-offset-3 hover:underline;
      }

      @utility link-underline {
        @apply underline decoration-current/30 decoration-1 underline-offset-3 transition-colors hover:decoration-current;
      }

      @utility prose-syedmoin {
        @apply prose-headings:tracking-tight prose-headings:text-balance prose-h2:font-semibold;
        @apply prose-a:font-normal prose-a:wrap-break-word prose-a:text-foreground prose-a:link-underline;
        @apply prose-code:rounded-md prose-code:border prose-code:bg-muted/50 prose-code:px-[0.3rem] prose-code:py-[0.2rem] prose-code:text-sm prose-code:font-normal prose-code:before:content-none prose-code:after:content-none;
        @apply prose-strong:font-medium;
      }
      ```

      <Step>Install the required shadcn/ui components</Step>

      * [https://ui.shadcn.com/docs/components/collapsible](https://ui.shadcn.com/docs/components/collapsible)
      * [https://ui.shadcn.com/docs/components/separator](https://ui.shadcn.com/docs/components/separator)

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/chevrons-up-down-icon.tsx" 
      "use client"

      import { forwardRef, useImperativeHandle } from "react"
      import { motion, useAnimation } from "motion/react"

      export type ChevronsUpDownIconHandle = {
        startAnimation: () => void
        stopAnimation: () => void
      }

      export type ChevronsUpDownIconProps = React.ComponentProps<"svg"> & {
        duration?: number
      }

      const ChevronsUpDownIcon = forwardRef<
        ChevronsUpDownIconHandle,
        ChevronsUpDownIconProps
      >(({ duration = 0.3, ...props }, ref) => {
        const controls = useAnimation()

        useImperativeHandle(ref, () => {
          return {
            startAnimation: () => controls.start("animate"),
            stopAnimation: () => controls.start("normal"),
          }
        })

        return (
          <svg
            xmlns="http://www.w3.org/2000/svg"
            width="24"
            height="24"
            viewBox="0 0 24 24"
            fill="none"
            stroke="currentColor"
            strokeWidth="2"
            strokeLinecap="round"
            strokeLinejoin="round"
            aria-hidden
            {...props}
          >
            <motion.path
              d="M7 15L12 20L17 15"
              variants={{
                normal: {
                  d: "M7 15L12 20L17 15",
                },
                animate: {
                  d: "M7 20L12 15L17 20",
                },
              }}
              initial="normal"
              animate={controls}
              transition={{
                duration,
              }}
            />
            <motion.path
              d="M7 9L12 4L17 9"
              variants={{
                normal: {
                  d: "M7 9L12 4L17 9",
                },
                animate: {
                  d: "M7 4L12 9L17 4",
                },
              }}
              initial="normal"
              animate={controls}
              transition={{
                duration,
              }}
            />
          </svg>
        )
      })

      ChevronsUpDownIcon.displayName = "ChevronsUpDownIcon"

      export { ChevronsUpDownIcon }

      ```

      ```tsx title="components/work-experience.tsx" 
      "use client"

      import { useCallback, useRef, type ComponentProps } from "react"
      import { differenceInMonths, parse } from "date-fns"
      import ReactMarkdown from "react-markdown"

      import { cn } from "@/lib/utils"
      import {
        Collapsible,
        CollapsibleContent,
        CollapsibleTrigger,
      } from "@/components/ui/collapsible"
      import { Separator } from "@/components/ui/separator"
      import type { ChevronsUpDownIconHandle } from "@/components/chevrons-up-down-icon"
      import { ChevronsUpDownIcon } from "@/components/chevrons-up-down-icon"
      import { IconPlaceholder } from "@/registry/icons/icon-placeholder"

      export type ExperiencePositionItemType = {
        /** Unique identifier for the position */
        id: string
        /** The job title or position name */
        title: string
        /**
         * Employment period of the position.
         * Use "MM.YYYY" or "YYYY" format. Omit `end` for current roles.
         */
        employmentPeriod: {
          /** Start date (e.g., "10.2022" or "2020"). */
          start: string
          /** End date; leave undefined for "Present". */
          end?: string
        }
        /** The type of employment (e.g., "Full-time", "Part-time", "Contract") */
        employmentType?: string
        /** A brief description of the position or responsibilities */
        description?: string
        /** An icon representing the position */
        icon?: React.ReactElement
        /** A list of skills associated with the position */
        skills?: string[]
        /** Indicates if the position details are expanded in the UI */
        isExpanded?: boolean
      }

      export type ExperienceItemType = {
        /** Unique identifier for the experience item */
        id: string
        /** Name of the company where the experience was gained */
        companyName: string
        /** URL or path to the company's logo image */
        companyLogo?: string
        /** URL to the company's website. */
        companyWebsite?: string
        /**
         * List of positions held at the company
         * @fumadocsHref #experiencepositionitemtype
         * */
        positions: ExperiencePositionItemType[]
        /** Indicates if this is the user's current employer */
        isCurrentEmployer?: boolean
      }

      export type WorkExperienceProps = {
        className?: string
        /** @fumadocsHref #experienceitemtype */
        experiences: ExperienceItemType[]
      }

      export function WorkExperience({
        className,
        experiences,
      }: WorkExperienceProps) {
        return (
          <div className={cn("bg-background px-4 text-foreground", className)}>
            {experiences.map((experience) => (
              <ExperienceItem key={experience.id} experience={experience} />
            ))}
          </div>
        )
      }

      export type ExperienceItemProps = {
        experience: ExperienceItemType
      }

      export function ExperienceItem({ experience }: ExperienceItemProps) {
        return (
          <div className="space-y-4 py-4">
            <div className="not-prose flex items-center gap-3">
              <div className="flex size-6 shrink-0 items-center justify-center">
                {experience.companyLogo ? (
                  <img
                    src={experience.companyLogo}
                    alt={experience.companyName}
                    className="size-6 rounded-full"
                    aria-hidden
                  />
                ) : (
                  <span className="flex size-2 rounded-full bg-zinc-300 dark:bg-zinc-600" />
                )}
              </div>

              <h3 className="text-lg leading-snug font-semibold">
                {experience.companyWebsite ? (
                  <a
                    className="link"
                    href={experience.companyWebsite}
                    target="_blank"
                    rel="noopener noreferrer"
                  >
                    {experience.companyName}
                  </a>
                ) : (
                  experience.companyName
                )}
              </h3>

              {experience.isCurrentEmployer && (
                <span
                  className="relative flex items-center justify-center"
                  aria-label="Current Employer"
                >
                  <span className="absolute inline-flex size-3 animate-ping rounded-full bg-sky-500 opacity-50" />
                  <span className="relative inline-flex size-2 rounded-full bg-sky-500" />
                </span>
              )}
            </div>

            <div className="relative space-y-4 before:absolute before:left-3 before:h-full before:w-px before:bg-border">
              {experience.positions.map((position) => (
                <ExperiencePositionItem key={position.id} position={position} />
              ))}
            </div>
          </div>
        )
      }

      export type ExperiencePositionItemProps = {
        position: ExperiencePositionItemType
      }

      export function ExperiencePositionItem({
        position,
      }: ExperiencePositionItemProps) {
        const chevronsIconRef = useRef<ChevronsUpDownIconHandle>(null)

        const handleOpenChange = useCallback((open: boolean) => {
          const controls = chevronsIconRef.current
          if (!controls) return

          if (open) {
            controls.startAnimation()
          } else {
            controls.stopAnimation()
          }
        }, [])

        const { start, end } = position.employmentPeriod
        const isOngoing = !end
        const duration = formatDuration(start, end)

        return (
          <Collapsible
            defaultOpen={position.isExpanded}
            onOpenChange={handleOpenChange}
            disabled={!position.description}
            asChild
          >
            <div className="relative last:before:absolute last:before:h-full last:before:w-4 last:before:bg-background">
              <CollapsibleTrigger
                className={cn(
                  "group/experience-position not-prose block w-full text-left select-none",
                  "relative before:absolute before:-top-1 before:-right-1 before:-bottom-1.5 before:left-7 before:rounded-lg hover:before:bg-muted/30",
                  "data-disabled:before:content-none"
                )}
              >
                <div className="relative z-1 mb-1 flex items-center gap-3">
                  <div
                    className={cn(
                      "flex size-6 shrink-0 items-center justify-center rounded-lg",
                      "bg-muted text-muted-foreground",
                      "border border-muted-foreground/15 ring-1 ring-line ring-offset-1 ring-offset-background",
                      "[&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-4"
                    )}
                  >
                    {position.icon ?? (
                      <IconPlaceholder
                        lucide="BriefcaseBusinessIcon"
                        tabler="IconBriefcase"
                        hugeicons="Briefcase01Icon"
                        phosphor="BriefcaseIcon"
                        remixicon="RiBriefcaseLine"
                      />
                    )}
                  </div>

                  <h4 className="flex-1 text-base font-medium text-balance text-foreground">
                    {position.title}
                  </h4>

                  <div className="shrink-0 text-muted-foreground group-disabled/experience-position:hidden [&_svg]:size-4">
                    <ChevronsUpDownIcon ref={chevronsIconRef} duration={0.15} />
                  </div>
                </div>

                <div className="relative z-1 flex items-center gap-2 pl-9 text-sm text-muted-foreground">
                  {position.employmentType && (
                    <>
                      <dl>
                        <dt className="sr-only">Employment Type</dt>
                        <dd>{position.employmentType}</dd>
                      </dl>

                      <Separator
                        className="data-vertical:h-4 data-vertical:self-center"
                        orientation="vertical"
                      />
                    </>
                  )}

                  <dl>
                    <dt className="sr-only">Employment Period</dt>
                    <dd className="flex items-center gap-0.5 tabular-nums">
                      <span>{start}</span>
                      <span className="font-mono">—</span>
                      {isOngoing ? (
                        <IconPlaceholder
                          lucide="InfinityIcon"
                          tabler="IconInfinity"
                          hugeicons="Infinity01Icon"
                          phosphor="InfinityIcon"
                          remixicon="RiInfinityFill"
                          className="size-4.5 translate-y-[0.5px]"
                          aria-label="Present"
                        />
                      ) : (
                        <span>{end}</span>
                      )}
                    </dd>
                  </dl>

                  {duration && (
                    <>
                      <Separator
                        className="data-vertical:h-4 data-vertical:self-center"
                        orientation="vertical"
                      />
                      <dl>
                        <dt className="sr-only">Duration</dt>
                        <dd className="tabular-nums">{duration}</dd>
                      </dl>
                    </>
                  )}
                </div>
              </CollapsibleTrigger>

              <CollapsibleContent className="overflow-hidden">
                {position.description && (
                  <Prose className="pt-2 pl-9">
                    <ReactMarkdown>{position.description}</ReactMarkdown>
                  </Prose>
                )}
              </CollapsibleContent>

              {Array.isArray(position.skills) && position.skills.length > 0 && (
                <ul className="not-prose flex flex-wrap gap-1.5 pt-3 pl-9">
                  {position.skills.map((skill, index) => (
                    <li key={index} className="flex">
                      <Skill>{skill}</Skill>
                    </li>
                  ))}
                </ul>
              )}
            </div>
          </Collapsible>
        )
      }

      function Prose({ className, ...props }: ComponentProps<"div">) {
        return (
          <div
            className={cn(
              "prose max-w-none prose-ncdai prose-zinc dark:prose-invert",
              className
            )}
            {...props}
          />
        )
      }

      function Skill({ className, ...props }: ComponentProps<"span">) {
        return (
          <span
            className={cn(
              "inline-flex items-center rounded-md border bg-muted/50 px-1.5 py-0.5 font-mono text-xs text-muted-foreground",
              className
            )}
            {...props}
          />
        )
      }

      function formatDuration(start: string, end?: string): string {
        const startHasMonth = start.includes(".")
        const endHasMonth = end ? end.includes(".") : true

        // Both year-only: granularity is years, no month arithmetic needed.
        if (!startHasMonth && end && !endHasMonth) {
          const years = parseInt(end, 10) - parseInt(start, 10)
          if (years <= 0) {
            return ""
          }
          return `${years}y`
        }

        const startDate = parsePeriodDate(start, "first")
        const endDate = end ? parsePeriodDate(end, "last") : new Date()

        // +1 to count both the start and end months inclusively.
        const totalMonths = differenceInMonths(endDate, startDate) + 1
        if (totalMonths <= 0) {
          return ""
        }

        if (totalMonths < 12) {
          return `${totalMonths}m`
        }

        const years = Math.floor(totalMonths / 12)
        const months = totalMonths % 12
        if (months === 0) {
          return `${years}y`
        }
        return `${years}y ${months}m`
      }

      function parsePeriodDate(str: string, fallbackMonth: "first" | "last"): Date {
        if (str.includes(".")) {
          return parse(str, "MM.yyyy", new Date())
        }
        return parse(
          `${fallbackMonth === "last" ? "12" : "01"}.${str}`,
          "MM.yyyy",
          new Date()
        )
      }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { WorkExperience } from "@/components/work-experience"
import type { ExperienceItemType } from "@/components/work-experience"
```

```tsx
const experiences: ExperienceItemType[] = []

<WorkExperience experiences={experiences} />
```

## API Reference

### WorkExperience

<TypeTable
  id="type-table-work-experience.tsx-WorkExperienceProps"
  type={{
  "id": "work-experience.tsx-WorkExperienceProps",
  "name": "WorkExperienceProps",
  "description": "",
  "entries": [
    {
      "name": "className",
      "description": "",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "experiences",
      "description": "",
      "tags": [
        {
          "name": "fumadocsHref",
          "text": "#experienceitemtype"
        }
      ],
      "type": "ExperienceItemType[]",
      "simplifiedType": "array",
      "required": true,
      "deprecated": false,
      "typeHref": "#experienceitemtype"
    }
  ]
}}
/>

### ExperienceItemType

<TypeTable
  id="type-table-work-experience.tsx-ExperienceItemType"
  type={{
  "id": "work-experience.tsx-ExperienceItemType",
  "name": "ExperienceItemType",
  "description": "",
  "entries": [
    {
      "name": "id",
      "description": "Unique identifier for the experience item",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "companyName",
      "description": "Name of the company where the experience was gained",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "companyLogo",
      "description": "URL or path to the company's logo image",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "companyWebsite",
      "description": "URL to the company's website.",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "positions",
      "description": "List of positions held at the company",
      "tags": [
        {
          "name": "fumadocsHref",
          "text": "#experiencepositionitemtype"
        }
      ],
      "type": "ExperiencePositionItemType[]",
      "simplifiedType": "array",
      "required": true,
      "deprecated": false,
      "typeHref": "#experiencepositionitemtype"
    },
    {
      "name": "isCurrentEmployer",
      "description": "Indicates if this is the user's current employer",
      "tags": [],
      "type": "boolean | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>

### ExperiencePositionItemType

<TypeTable
  id="type-table-work-experience.tsx-ExperiencePositionItemType"
  type={{
  "id": "work-experience.tsx-ExperiencePositionItemType",
  "name": "ExperiencePositionItemType",
  "description": "",
  "entries": [
    {
      "name": "id",
      "description": "Unique identifier for the position",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "title",
      "description": "The job title or position name",
      "tags": [],
      "type": "string",
      "simplifiedType": "string",
      "required": true,
      "deprecated": false
    },
    {
      "name": "employmentPeriod",
      "description": "Employment period of the position.\nUse \"MM.YYYY\" or \"YYYY\" format. Omit `end` for current roles.",
      "tags": [],
      "type": "{ start: string; end?: string; }",
      "simplifiedType": "object",
      "required": true,
      "deprecated": false
    },
    {
      "name": "employmentType",
      "description": "The type of employment (e.g., \"Full-time\", \"Part-time\", \"Contract\")",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "description",
      "description": "A brief description of the position or responsibilities",
      "tags": [],
      "type": "string | undefined",
      "simplifiedType": "string",
      "required": false,
      "deprecated": false
    },
    {
      "name": "icon",
      "description": "An icon representing the position",
      "tags": [],
      "type": "React.ReactElement<unknown, string | React.JSXElementConstructor<any>> | undefined",
      "simplifiedType": "object",
      "required": false,
      "deprecated": false
    },
    {
      "name": "skills",
      "description": "A list of skills associated with the position",
      "tags": [],
      "type": "string[] | undefined",
      "simplifiedType": "array",
      "required": false,
      "deprecated": false
    },
    {
      "name": "isExpanded",
      "description": "Indicates if the position details are expanded in the UI",
      "tags": [],
      "type": "boolean | undefined",
      "simplifiedType": "union",
      "required": false,
      "deprecated": false
    }
  ]
}}
/>


Last updated on March 28, 2026

---
title: "Theme Switcher"
description: "Toggle between system, light, and dark themes in Next.js apps."
last_updated: "February 12, 2026"
source: "https://syedmoinuddin.com/blog/theme-switcher"
---

# Theme Switcher

Toggle between system, light, and dark themes in Next.js apps.

```tsx
import { ThemeSwitcher } from "@/components/theme-switcher"

export default function ThemeSwitcherDemo() {
  return <ThemeSwitcher />
}

```

## Installation

<CodeTabs>
  <TabsListInstallType />

  <TabsContent value="cli">
    ```bash
    npx shadcn@latest add @syedmoin/theme-switcher
    ```
  </TabsContent>

  <TabsContent value="manual">
    <Steps>
      <Step>Install the following dependencies</Step>

      ```bash
      npm install next-themes lucide-react motion clsx tailwind-merge
      ```

      <Step>Add a cn helper</Step>

      ```ts title="lib/utils.ts" 
      import type { ClassValue } from "clsx"
      import { clsx } from "clsx"
      import { twMerge } from "tailwind-merge"

      export const cn = (...inputs: ClassValue[]) => {
        return twMerge(clsx(inputs))
      }

      ```

      <Step>Copy and paste the following code into your project</Step>

      ```tsx title="components/theme-switcher.tsx" 
      "use client"

      import type { JSX } from "react"
      import { useSyncExternalStore } from "react"
      import { motion } from "motion/react"
      import { useTheme } from "next-themes"

      import { IconPlaceholder } from "@/registry/icons/icon-placeholder"

      function ThemeOption({
        icon,
        value,
        isActive,
        onClick,
      }: {
        icon: JSX.Element
        value: string
        isActive?: boolean
        onClick: (value: string) => void
      }) {
        return (
          <button
            data-active={isActive}
            className="relative flex size-8 items-center justify-center rounded-full text-muted-foreground transition-[color] hover:text-foreground data-[active=true]:text-foreground [&_svg]:size-4"
            role="radio"
            aria-checked={isActive}
            aria-label={`Switch to ${value} theme`}
            onClick={() => onClick(value)}
          >
            {icon}

            {isActive && (
              <motion.span
                layoutId="theme-option"
                transition={{ type: "spring", bounce: 0.3, duration: 0.6 }}
                className="absolute inset-0 rounded-full border"
              />
            )}
          </button>
        )
      }

      const THEME_OPTIONS = [
        {
          icon: (
            <IconPlaceholder
              lucide="MonitorIcon"
              tabler="IconDeviceDesktop"
              hugeicons="ComputerIcon"
              phosphor="DesktopIcon"
              remixicon="RiComputerLine"
            />
          ),
          value: "system",
        },
        {
          icon: (
            <IconPlaceholder
              lucide="SunIcon"
              tabler="IconSun"
              hugeicons="Sun03Icon"
              phosphor="SunIcon"
              remixicon="RiSunLine"
            />
          ),
          value: "light",
        },
        {
          icon: (
            <IconPlaceholder
              lucide="MoonIcon"
              tabler="IconMoon"
              hugeicons="Moon02Icon"
              phosphor="MoonIcon"
              remixicon="RiMoonLine"
            />
          ),
          value: "dark",
        },
      ]

      function ThemeSwitcher() {
        const { theme, setTheme } = useTheme()

        const isMounted = useSyncExternalStore(
          () => () => {},
          () => true,
          () => false
        )

        if (!isMounted) {
          return <div className="flex h-8 w-24" />
        }

        return (
          <motion.div
            key={String(isMounted)}
            initial={{ opacity: 0 }}
            animate={{ opacity: 1 }}
            transition={{ duration: 0.3 }}
            className="inline-flex items-center overflow-clip rounded-full bg-background inset-ring-1 inset-ring-border"
            role="radiogroup"
          >
            {THEME_OPTIONS.map((option) => (
              <ThemeOption
                key={option.value}
                icon={option.icon}
                value={option.value}
                isActive={theme === option.value}
                onClick={setTheme}
              />
            ))}
          </motion.div>
        )
      }

      export { ThemeSwitcher }

      ```

      <Step>Update the import paths to match your project setup</Step>
    </Steps>
  </TabsContent>
</CodeTabs>

## Usage

```tsx
import { ThemeSwitcher } from "@/components/theme-switcher"
```

```tsx
<ThemeSwitcher />
```

## References

* [Registry](https://ui.shadcn.com/docs/registry)
* [Dark Mode with Next.js](https://ui.shadcn.com/docs/dark-mode/next)
* [next-themes](https://github.com/pacocoursey/next-themes)
* [Motion component](https://motion.dev/docs/react-motion-component)


Last updated on February 12, 2026