Anthropic puts a number on "AI building AI"

The Karpathy hire below was the staffing thesis. This is the measurement. Anthropic's new research arm, the Anthropic Institute, published When AI builds itself — a look at how much AI is already speeding up the development of AI. The number that lands: as of May 2026, Claude authored more than 80% of the code merged into Anthropic's production codebase, up from low single digits before Claude Code launched in February 2025. The typical engineer now merges 8× as much code per day as they did in 2024 — directing and reviewing instead of typing. On the most open-ended engineering tasks, Claude's success rate jumped from ~26% to 76% in six months.

The frame is recursive self-improvement — an AI system that can fully autonomously design and build its own successor. Anthropic is careful to say we're not there: "We're not at recursive self-improvement yet, but it could come sooner than most expect." The gap they keep pointing at is judgment — choosing which goals to pursue, not just executing them. Co-founder Jack Clark puts better-than-even odds on it anyway: by the end of 2028, more likely than not, "you would be able to say to it: 'Make a better version of yourself.' And it just goes off and does that completely autonomously."

Practical read: strip the sci-fi framing and this is the same loop running through half the entries in this chapter — Cursor's Targeted RL with Textual Feedback, Composer's 25× synthetic-task expansion, Anthropic putting an OpenAI cofounder on pre-training. The difference is that Anthropic is now publishing the metrics instead of letting them sit in a hiring announcement. 80% of merged code and an 8× throughput multiplier are not predictions — they're this quarter's internal numbers. Whether that curve bends toward "make a better version of yourself" by 2028 is the open question; that it's already reshaping how the model gets built is not.