Security researcher Chaofan Shou discovered on March 31 that Anthropic had accidentally included a 60MB source-map file in its Claude Code package on npm, the public registry where developers download software updates. The file allowed anyone to reconstruct nearly 2,000 files containing 500,000 lines of internal TypeScript code.

Within hours, developers mirrored the complete codebase on GitHub.

Anthropic Exposed Nearly 3,000 Internal Files in CMS Misconfiguration
The files, ranging from draft blog posts to images and documents, could be accessed by anyone who knew how to request them.
TechloyOgbonda Chivumnovu

Unannounced Features Anthropic Already Built

The leaked source shows features Anthropic built but never announced. Claude Code can apparently review its own work sessions to learn from mistakes, run in background mode while you're not actively using it, and accept remote commands from phones or browsers. The code also reveals how the command-line tool works internally, the agent architecture behind it, and what tools Anthropic uses for development.

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