Quick Take
  • Anthropic accidentally published 512,000 lines of Claude Code’s proprietary source code through a debug file bundled into a routine npm update on March 31.
  • The leak exposed the full architecture of the company’s flagship AI coding tool, which generates an estimated $2.5 billion in annualized recurring revenue.
  • Security researcher Chaofan Shou spotted the exposed source map file in Claude Code version 2.1.88 and posted a download link on X (Twitter).
  • The codebase spread across GitHub within hours, accumulating tens of thousands of forks before Anthropic’s DMCA takedowns hit.

What Happened

Second Lapse in Five Days Raises IPO Questions

The incident landed just five days after a separate CMS misconfiguration exposed roughly 3,000 internal files, including details on the unreleased “Mythos” model.

Korean-Canadian developer Sigrid Jin, profiled by the Wall Street Journal for consuming 25 billion Claude Code tokens last year, completed a clean-room Python rewrite before sunrise.

The leaked files revealed an internal feature called “Undercover Mode,” built specifically to prevent Claude from leaking Anthropic’s secrets.

Market Context

The code also exposed 44 feature flags, an unreleased background daemon called KAIROS, and internal model codenames, including “Capybara” for a Claude 4.6 variant.

Why It Matters

Anthropic accidentally published 512,000 lines of Claude Code’s proprietary source code through a debug file bundled into a routine npm update on March 31.

The leak exposed the full architecture of the company’s flagship AI coding tool, which generates an estimated $2.5 billion in annualized recurring revenue.

Details

Security researcher Chaofan Shou spotted the exposed source map file in Claude Code version 2.1.88 and posted a download link on X (Twitter).

The codebase spread across GitHub within hours, accumulating tens of thousands of forks before Anthropic’s DMCA takedowns hit.

Two accidental disclosures in one week raise operational questions for a company valued at $350 billion and reportedly considering an IPO in Q4 2026.

The Code Is Now Permanent

His repository, claw-code, hit 50,000 GitHub stars within two hours of publication.

Anthropic confirmed the leak to multiple outlets, calling it a packaging error caused by human error. Enterprise clients, who account for 80% of Claude Code’s revenue, now face a tool whose security logic and permission bypass techniques sit on the open internet.

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