TL;DRAnthropic reveals that Claude now writes over 80% of its production code, with engineers shipping 8x more code per quarter than in 2024. The company’s new Anthropic Institute paper maps the path to recursive self-improvement and calls for a verifiable global pause mechanism.
One of Anthropic’s engineers hasn’t written a line of code in five months. Not because the work dried up, but because Claude does it now. As of May 2026, more than 80% of the code merged into Anthropic’s production codebase was authored by Claude, up from low single digits when Claude Code launched in February 2025.
That figure, published Wednesday in a new Anthropic Institute paper titled “When AI builds itself,” is not the headline the company wants you to focus on. The headline is what comes next: AI that can design and train its own successor. Anthropic says it isn’t there yet, but it might be closer than most institutions are prepared for.
The numbers behind the shift
The productivity gains are stark. In Q2 2026, the typical Anthropic engineer merged eight times as much code per day as in 2024. An internal poll of 130 research staff found that the median respondent estimated roughly four times as much output with Anthropic’s latest model, Mythos Preview, compared to working without AI.
