There’s a sentence that sounds like science fiction but isn’t: the AI is writing most of its own code now. As of May 2026, over 80% of the code merged into Anthropic’s production codebase was authored by Claude Code, the company’s AI coding agent. Before its research preview launched in February 2025, AI-authored code at Anthropic sat in the low single digits.
The numbers behind the shift
Anthropic engineers are now merging roughly eight times as much code per day compared to 2024 levels. On internal optimization benchmarks, Claude achieved approximately 52x speedups by May 2026. For context, the same benchmarks showed roughly 3x speedups for skilled human programmers back in May 2025. In the span of twelve months, the AI went from modestly outpacing humans to lapping them dozens of times over.
One Anthropic engineer reportedly hasn’t written any code personally for about five months. Their job still exists, but it looks nothing like what “software engineer” meant two years ago. The role has shifted almost entirely toward direction, review, and architecture.
What the engineers actually do now