Anthropic source code leaks reveal unannounced Claude features and internal model

Anthropic, the company behind Claude, has experienced two significant source code leaks in 2025 that reveal unannounced features and internal developments. The most recent leak exposed approximately 500,000 lines of code across nearly 2,000 files, which developers quickly mirrored and analyzed on GitHub.

What the leaks revealed

The leaked code contains several unannounced Claude features:

• KAIROS: A feature that allows Claude to run in the background and send push notifications
• Dream mode: Enables Claude to "think constantly in the background"
• Undercover Mode: Allows Claude to make "stealth contributions to open source projects"
• Capybara: An internal model that wasn't previously known to the public

Timeline and context

This is the second such leak in 2025, with the first occurring in February. The code was publicly accessible for hours before being taken down, during which time developers had already mirrored and dissected the content. The leaks come as Anthropic is reportedly preparing for an IPO as early as October 2025.

The incident raises questions about security practices at a company that positions itself as the "responsible AI company" with safety and ethics as core brand elements. The source material suggests this represents a gap between AI companies' public messaging and their internal operations.