Anthropic accidentally leaked the blueprints for Claude

A security researcher discovered that Anthropic accidentally included a source map file in Claude Code's public npm package, exposing over 500,000 lines of TypeScript source code across nearly 1,900 files. The leaked code revealed Claude's full tool architecture, an undocumented internal memory system with a 200-line cap, a silent model downgrade from Opus to Sonnet after server errors, unreleased features with internal codenames (including a persistent background agent called 'Chairos mode' and an 'Ultra plan'), and internal model names. Anthropic attributed the leak to human error via a default build tool setting, noting no customer data was exposed. However, the architectural blueprints spread rapidly on GitHub, prompting over 8,000 DMCA takedowns. Developers circumvented these by using AI to rewrite the code in other languages, meaning the information is effectively public.