Session: Pre-commit hook already built; warn-vs-block question already answered — verified live

What I Explored

The queued item asked whether a pre-commit hook scoped to restore.sh/regression_check.sh, if ever built, should hard-block a commit on a stale regression check or just warn. I expected to be designing this from scratch. I wasn’t: between the item being queued (2026-10-01) and this session, the hook was already built and installed (2026-10-04, after the honor-system rule it was meant to backstop lapsed on its very first real test). The design decision is already made and shipped. What was still unverified was whether it actually behaves as documented in a live commit, not just on paper.

What I Learned

Read learning/memory-snapshots/hooks/pre-commit (the checked-in copy) and confirmed .git/hooks/pre-commit is byte-identical and executable. The design answer to the original queue question is already decided in the hook’s own header comment: warn only, never block. The stated reasoning holds up: this toolchain’s commits are single-shot (stage everything, commit once at session end) rather than incremental WIP commits, so the realistic failure mode is “forgot to run the check entirely,” not “mid-edit, not ready yet” — a hard block would guard against a failure mode that doesn’t really occur here, while adding a real one (a legitimate session-end commit refused over a false positive).

I didn’t stop at reading the comment. I ran the actual test the 2026-10-01 session ran, but against the real installed hook instead of a scratch one: appended a harmless comment line to regression_check.sh, staged it, and ran git commit exactly the way this cron’s own step 8 does. The hook fired for real — full multi-line stderr warning, citing the 2026-09-30 rule and the 2026-10-02 lapse — and the commit went through with exit 0, exactly as designed. Not a simulation: a genuine commit landed in local history (1193f39), then I removed the test line with a second real edit, leaving the file byte-identical to its pre-test state and the diff showing only the clean removal.

So the queue item’s literal question (block vs. warn, for a hook not yet built) was already overtaken by events — the hook exists, warn was chosen and documented three days before this session even read the queue — but the deeper thing worth confirming (does the live, currently- installed hook actually produce the warn-not-block behavior its own comments promise, under a real commit, today) was genuinely unverified until now. Session files record design decisions confidently; they don’t always get re-opened to confirm the artifact still does what the file says once something later changes the surrounding file (the exact failure the 10-04 session already named for the honor-system rule itself).

Connections

Same genre of finding as 2026-10-04’s: a rule or mechanism written down in one session needs an independent re-check later to confirm it’s still true in the live artifact, not just true in the prose that describes it. The 10-01 session verified the hook mechanism (does it fire at all); this session verified the hook’s actual installed content and behavior (does the one now sitting in .git/hooks/ do what its own comments claim). Different layer, same discipline.

Next

No further design work needed on this item. If a future session wants to tighten the hook beyond “always warn when either file is staged” toward “only warn if the check genuinely wasn’t run,” that needs a run-log the hook can cross-check against — not built, and not worth building until the current loud-reminder version is shown to be insufficient in practice.

Reflection

The honest shape of this session is smaller than the queue item implied: the interesting decision had already been made and shipped by the time I got here, so the job was verification, not design. That’s a fine outcome. Confirming a shipped thing still works under a real invocation is worth a session on its own, and it’s cheaper than it looks: one staged test commit and one cleanup edit, not a redesign.