Anthropic's blockbuster Claude chatbot recently suffered an accidental source code leak, drawing widespread attention from the online community. Netizens swiftly delved into the leaked code, uncovering numerous intriguing features.
In an extensive thread on the r/ClaudeAI subreddit, one user claimed to have found a "Tamagotchi"-like system buried within the code. This complete "buddy" pet system, invoked by typing "/buddy," allows users to hatch a unique ASCII companion based on their user ID. This virtual pet would then sit beside the input box and react to the user's coding activities.
The user reported discovering 18 different pet species, including a duck, dragon, capybara, and a "chonk," along with a rarity system resembling those found in Gacha games, which assigns a user a pet based on chance. However, an included string reading "friend-2026-401" strongly suggests that Anthropic likely intended this feature as a one-off April Fools' joke for 2026.
Beyond the "Tamagotchi," internet sleuths also uncovered a more significant feature called "Kairos." This purportedly serves as an always-on AI agent, designed to run constantly in the background and take actions autonomously on a user's behalf without explicit requests. Users who viewed the code claimed it could even send push notifications to a phone or desktop to grab attention.
Other findings included an "undercover" mode, intended to mask Claude's AI identity when contributing code to public repositories. A mood tracking feature was also discovered, which measures a coder’s "frustration" levels based on their messages and indicators like swear words. One user even unearthed a developer's comment left in the code, admitting that "memoization here increases complexity by a lot, and I'm not sure it really improves performance."
While no "smoking guns" were found, the leak provides an intriguing glimpse behind the curtain of Anthropic's technology, offering valuable insights and potential fodder for competitors looking to reverse engineer the company's tech.
For Anthropic, this represents an undoubtedly embarrassing blunder. As explained by The Register, the codebase appears to have been leaked after a source map file was accidentally left in a public release of the company's 2.1.88 of Claude Code npm package. A map file links bundled code back to the original source, and one resourceful programmer utilized it to locate where Claude's source code was stored, subsequently backing the entire repository up on GitHub.
Anthropic promptly moved to pull the exposed source code by issuing copyright takedowns, though at this point, it may already be widely distributed across the internet.