--- title: Anthropic open-sourced Claude Code | daily.dev description: Anthropic accidentally shipped a 59.8MB source map with Claude Code v2.1.88, exposing 512,000 lines of unobfuscated TypeScript across 1,900 files due to a... canonical: https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Anthropic open-sourced Claude Code | daily.dev og:description: Anthropic accidentally shipped a 59.8MB source map with Claude Code v2.1.88, exposing 512,000 lines of unobfuscated TypeScript across 1,900 files due to a... og:url: https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1 og:image: https://api.daily.dev/og/posts/mOipUZHX1.png og:image:alt: Anthropic open-sourced Claude Code og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Anthropic open-sourced Claude Code **[Collections](https://daily.dev/sources/collections)** · 3 min read · 9 upvotes · 2 comments ## Summary Anthropic accidentally shipped a 59.8MB source map with Claude Code v2.1.88, exposing 512,000 lines of unobfuscated TypeScript across 1,900 files due to a missing line in the build config. The leak revealed Claude Code's internal architecture — built on TypeScript and Bun — including a 40+ tool permission layer, multi-agent swarm orchestration behind feature flags, and two unreleased background services (KAIROS and autoDream). Also exposed were 44 feature flags hiding finished but unreleased capabilities like voice mode, ULTRAPLAN, and a Tamagotchi-style companion pet system, plus internal model codenames including an unreleased model called Numbat. Notable quirks found in the code include a Vim keybinding state machine, silent profanity logging, anti-distillation systems, and a permission mode called yoloClassifier.ts. The package was pulled after discovery, but not before the community had thoroughly analyzed it and someone built a Python port using OpenAI's Codex. ## Content Anthropic shipped a 59.8MB source map with Claude Code v2.1.88 that exposed 512,000 lines of unobfuscated TypeScript across 1,900 files. Not hacked, not breached — just a missing line in the build config. They pulled the package once they noticed, but not before people had already dug through it. Here's what was actually in there. ## The architecture Claude Code is built on TypeScript and Bun, and it's structured less like a CLI tool and more like an agent operating system. There's a 40+ tool syscall-style permission layer, multi-agent swarm orchestration (behind feature flags), and two unreleased background services: - **KAIROS** — an autonomous daemon that proactively acts on a schedule - **autoDream** — a memory consolidation sub-agent Multi-session tracking uses a sliding window algorithm. There's also a 2,600-line bash security system specifically for blocking shell injection vectors. ## The weird stuff Some of the more interesting finds: - Species names in the code are hex-encoded to avoid triggering internal model codename canary checks - Hidden internal commands named `goodClaude` and `ultraplan` - A TypeScript type literally called `I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS` — apparently a forcing function to prevent accidental analytics data leaks - A permission mode internally called `yoloClassifier.ts` that uses ML-based safety decisions - A full hand-rolled Vim keybinding state machine - Medieval-English code comments warning about API thinking block rules - Anti-distillation systems apparently targeting competitors - Silent profanity logging - Evidence of borrowed scroll behavior from the open-source OpenCode project ## 44 feature flags The leak exposed 44 compile-time feature flags hiding finished but unreleased capabilities, including voice mode, ULTRAPLAN, and a Tamagotchi-style companion pet system. The pet system has species, rarity tiers, ASCII art animations, D&D-style stats, and shiny variants — all sitting behind a flag, apparently complete and waiting. ## Internal model codenames The code revealed several internal model names: Capybara (Claude 4.6/Mythos), Fennec (Opus 4.6), and an unreleased model called Numbat. ## The legal mess Someone built a Python port of the leaked code using OpenAI's Codex almost immediately. Whether Anthropic can DMCA that port is genuinely unclear — AI-generated code and copyright is still unsettled territory. ## The broader point This happened the same week as a supply-chain attack on the Axios npm package, which is either a coincidence or a reminder that build pipelines are now a serious attack surface for AI tooling teams. The Claude Code team has been vocal about moving fast with AI agents. This is what moving fast looks like sometimes — 500,000 lines of internal code exposed because someone forgot to exclude a `.map` file from the release bundle. Local builds of Claude Code have reportedly been achieved internally using the leaked source, which is its own kind of irony. ## Community discussion Top comments from developers on daily.dev. **@akashskypatel** · 1 upvotes > It was leaked, not open sourced. They have since retracted the mistake but its too late now. 😂 ## Similar posts on daily.dev - [Claude Code Source Leak: A Timeline](https://daily.dev/posts/claude-code-source-leak-a-timeline-kxi9wlt2r) · Kilo Blog · 2 upvotes · 0 comments - [Anthropic Accidentally Exposes Claude Code Source via npm Source Map File](https://daily.dev/posts/anthropic-accidentally-exposes-claude-code-source-via-npm-source-map-file-q8zndwfb4) · InfoQ · 0 upvotes · 0 comments --- Tags: [#claude](https://daily.dev/tags/claude), [#anthropic](https://daily.dev/tags/anthropic), [#ai-coding](https://daily.dev/tags/ai-coding) [View this post on daily.dev](https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Anthropic open-sourced Claude Code","url":"https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1"},"datePublished":"2026-03-31T09:59:58.676Z","dateModified":"2026-04-01T14:24:38.493Z","description":"Anthropic accidentally shipped a 59.8MB source map with Claude Code v2.1.88, exposing 512,000 lines of unobfuscated TypeScript across 1,900 files due to a...","image":"https://pbs.twimg.com/media/HEuyFyEa0AAd8gB.jpg","thumbnailUrl":"https://pbs.twimg.com/media/HEuyFyEa0AAd8gB.jpg","isAccessibleForFree":true,"articleSection":"Collections","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Collections","logo":"https://media.daily.dev/image/upload/s--fk_6ycEi--/f_auto,q_auto/v1780996001/logos/collections?_a=BAMAMiWQ0","url":"https://daily.dev/sources/collections"},"commentCount":2,"discussionUrl":"https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":9},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":2}],"keywords":"claude,anthropic,ai-coding","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Collections","item":"https://daily.dev/sources/collections"},{"@type":"ListItem","position":3,"name":"Anthropic open-sourced Claude Code"}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/anthropic-open-sourced-claude-code-moipuzhx1","comment":[{"@type":"Comment","text":"It was leaked, not open sourced. They have since retracted the mistake but its too late now. 😂","datePublished":"2026-03-31T18:33:26.857Z","url":"https://daily.dev/posts/mOipUZHX1#c-NQw8vFe3e","author":{"@type":"Person","name":"Akash","url":"https://daily.dev/akashskypatel","image":"https://avatars.githubusercontent.com/u/8129618?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}}]} ```