sqlite-utils 4.0rc2, mostly written by Claude Fable (for about $149.25)

I wrote about the sqlite-utils 4.0rc1 release a couple of weeks ago. Since we only have Claude Fable on our Max subscriptions for a few more days, I decided to see if it could help me get to a 4.0 stable release that I felt truly comfortable about, since I try to keep to SemVer and like my incompatible major versions to be as rare as possible.

I started with this prompt, in Claude Code for web on my iPhone:

Final review before shipping a stable 4.0 release - very important to spot any last minute things that would be a breaking change if we fix them later

Here’s that initial report it created for me. There were some significant problems that I hadn’t myself encountered yet—5 that Fable categorized as “release blockers”. Here’s the worst of the bunch:

1. delete_where() never commits and poisons the connection (data loss) Table.delete_where() ( sqlite_utils/db.py:2948 ) runs its DELETE via a bare self.db.execute() with no atomic() wrapper — compare Table.delete() at db.py:2944 , which wraps correctly. The connection is left in_transaction=True , so every subsequent atomic() call takes the savepoint branch ( db.py:430-440 ) and never commits either. Reproduced end-to-end: db = sqlite_utils . Database ( "dw.db" ) db [ "t" ]. insert_all ([{ "id" : i } for i in range ( 3 )], pk = "id" ) db [ "t" ]. delete_where ( "id = ?" , [ 0 ]) # conn.in_transaction is now True db [ "t" ]. insert ({ "id" : 50 }) db [ "u" ]. insert ({ "a" : 1 }) db . close () # Reopen: rows are [0, 1, 2] — the delete, row 50, AND table u are all gone.

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.

Over the course of 37 prompts, 34 commits and +1,321 -190 code changes over 30 separate files, we worked through the entire set of feedback in turn, making several other design improvements along the way.

A weird thing about coding agents is that harder tasks like this one actually provide more opportunity to do other things at the same time, since the agent sometimes needs 10-15 minutes to churn away on a new task. I went out to enjoy the Half Moon Bay 4th of July parade, occasionally checking in and prompting the next step for Fable from my phone.

Full details in the PR and this shared transcript. I switched to my laptop for the final review, which I conducted through GitHub’s PR interface.

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