sqlite-utils 4.0 Was Mostly Written by Claude Fable Across 37 Prompts for ~$149

Simon Willison·high signal

Simon Willison shipped sqlite-utils 4.0rc2 on July 5 — his first major version bump since 2020 — with most code written by 'Claude Fable' over 37 prompts and 34 commits for about $149.25. Fable identified 5 release-blocker issues Willison hadn't hit himself and caught a silent transaction bug, making this one of the most concrete public case studies of an agent driving a real SemVer major release. The takeaway for builders: agents are now credible for the unglamorous, high-risk work (backwards-compat audits, transaction correctness) not just greenfield scaffolding.