sqlite-utils 4.0rc2, mostly written by Claude Fable (for about $149.25)
Simon Willison · Simon Willison · 2026-07-05
Simon Willison releases sqlite-utils 4.0rc2 built almost entirely with Claude Fable over 37 prompts and 34 commits at an estimated $149.25, after the AI agent identified a critical data-loss bug in delete_where() and two additional P1 transaction bugs found by cross-model review with GPT-5.5.
Appears in
Extraction
Topics: sqlite-utilscoding-agentsllm-assisted-developmenttransaction-handlingopen-source-python
Claims
- Claude Fable identified a critical bug where delete_where() never committed its changes, leaving the connection in a broken transaction state and silently discarding subsequent writes on close.
- The sqlite-utils 4.0rc2 work spanned 37 prompts, 34 commits, and +1,321/-190 code changes across 30 files, with an estimated unsubsidized API cost of $149.25.
- Cross-model review — GPT-5.5 auditing Fable's output — surfaced two additional P1 bugs in db.query() that would have shipped in the release.
- The new transaction model auto-commits every write method immediately on return, eliminating the need for explicit commit() calls in normal usage.
- Python 3.12+ connections using the autocommit parameter are now explicitly rejected by Database() because their commit/rollback semantics break the library's transaction guarantees.
Key quotes
That's a really bad bug! Very glad I didn't ship that, although at least it would have been a bug I could fix in a 4.0.1 point release, not a design flaw that would force a 5.0.
I've started habitually having Anthropic's best model review OpenAI's work and vice versa, because I've had that turn up interesting results often enough to be valuable.
Release notes are a great example of writing that I'm OK to outsource to agents because they need to be boring, predictable and accurate.