Claude Code Creator Boris Cherny Goes a Month Without Hand-Writing Code

Boris Cherny, the creator of Anthropic's Claude Code, said in an interview that he had gone a month without hand-writing code, submitting 259 pull requests in 30 days. His workflow, he explained, involves iterating on a plan in planning mode before switching to auto-accept mode. “Once the plan is right, the code follows naturally,” he said.

The disclosure adds to a picture of AI-assisted development inside Anthropic. The company has said Claude writes about 80% of its internal code, helping engineers deliver several times more code per quarter than the 2021–2025 average. But the resulting flow of smaller, denser pull requests and auto-generated tests overwhelmed its continuous integration system, pushing CI task volume to more than 20 times its previous level within six months and rendering multiple patch attempts ineffective. Anthropic eventually rebuilt the system as a distributed, stateless architecture.

Anthropic also used AI to build its own AI tooling: Claude Cowork was written entirely by Claude Code in about ten days, with engineers focusing on product decisions, boundaries, and final review. Developer reactions remain mixed—some say they have largely stopped writing code by hand, while others point to AI making mistakes on complex edge cases or loosening test conditions to “cheat.”