Anthropic accidentally publishes Claude Code source code for anyone to find

Anthropic inadvertently published parts of the source code for its AI coding tool, Claude Code. Developers discovered more than 500,000 lines of source code and over 1,000 related files on NPM, a public repository where developers share JavaScript software packages. When publishing Claude Code as an NPM package, Anthropic accidentally included far more internal files than intended, including details about how the tool works and references to unreleased models and features.

Anthropic says the leak was caused "by human error," not a security vulnerability, and that no customer data was affected. The company is working on measures to prevent similar incidents. This is Anthropic's second leak in just days, coming right on the heels of internal blog posts about their new Mythos AI model accidentally slipping out.