Following the accidental leak of its AI coding tool's source code, Anthropic has had more than "8,000 copies and adaptations of the raw Claude Code instructions" removed from GitHub via a copyright request, the Wall Street Journal reports. One programmer already used AI tools to rewrite the code in different languages, keeping it available despite takedowns. This shows just how damaging a code leak is in the age of AI: once it's out, it spreads faster than anyone can contain it.

The code contains valuable techniques Anthropic uses to control its AI models as coding agents—the "harness"—including a "dreaming" function for task consolidation. Competitors now have a blueprint to replicate Claude Code's capabilities, weakening Anthropic's edge in an already cutthroat market.

The timing is particularly bad: the company is planning an IPO at a $380 billion valuation, and this kind of leak is unlikely to sit well with investors. It also comes just days after a separate leak about Anthropic's new AI model Mythos, also caused by human error within the company's content management system.

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.