source: simon willison: sqlite-utils 4.0rc2, mostly written by claude fable (for about $149.25)
level: technical
simon willison released sqlite-utils 4.0rc2, a near-final version of his python library for sqlite, with most changes driven by claude fable. the work cost about $149 in api usage under his claude max subscription. the release fixes several breaking issues found by the model, including a data-loss bug in delete_where() that left transactions open and silently discarded writes. other fixes address transaction handling, upsert behavior, and migration reliability.
the new version changes how transactions work. every write method now commits automatically unless wrapped in db.atomic() or a user-managed transaction. db.query() executes sql immediately instead of lazily, raising errors at the call site. validation errors now raise valueerror instead of assertionerror. the library also rejects connections created with python 3.12's autocommit options, which caused silent data loss. these changes aim to make the library safer and more predictable.
willison used 37 prompts and 34 commits over 30 files, often checking progress from his phone during a parade. he also had gpt-5.5 review the changes, which caught two edge cases in db.query() that were then fixed. the release notes were written by the model, which willison found more thorough than his own manual notes. he plans to rely more on cheaper sub-models for future work.
why it matters: this shows how ai coding agents can handle complex library maintenance, catching subtle bugs and improving documentation at a fraction of the cost of manual work.
source: simon willison: sqlite-utils 4.0rc2, mostly written by claude fable (for about $149.25)