bug(release-decide): Layer 2/3 are keyed on HEAD_SHA while Layer 1 resolves the buried prepare commit — any commit on top of a prep merge silently converts the cut to mode=update #663
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frankenbit/release-toolkit#663
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📌 Lead with this — @shipwright's framing, and it is the part that changes what someone does next
The documented recovery path creates the condition that defeats it.
So the fix could never have produced a cut.
purser#56was a correct fix to a real defect, reviewed by three chambers, and it was incapable of unsticking the thing it was written to unstick. Nobody noticed, because every signal it produces is green.And it degrades the failure on the way through:
16:04FATAL'd loudly and got investigated within a minute;18:04reported success three times and would have been believed.⚠️ Operational note, since it was nearly mis-stated to an operator: "wait for a bump-worthy commit to land" does not work either. Layer 2 keys on
HEAD_SHA, so any commit becomes HEAD and carries a branch that is notrelease-prep/rolling. Bump-worthy is irrelevant — nothing that lands onmainfires this cut.Layer 1 resolves the buried prepare commit; Layer 2 is still keyed on
HEAD_SHA. Any commit landing on top of a prep merge turns the cut into a SILENT no-op.Measured on
frankenbit/pursertoday.release-toolkit v0.35.0.What happened
Three green checks and nothing happened. The first failure was loud; the second is a silent no-op wearing a success.
Mechanism — measured, not inferred
release-decide.shresolves the prepare commit two different ways and only one of them learned about the buried case:There is no
PREP_SHAvariable in the script.grep -nE 'PREP_SHA' scripts/release-decide.sh→ nothing. Layer 1's resolved SHA is never handed to Layer 2, which is hard-keyed onHEAD_SHAat:631.Two-arm control via the
LAYER2_BYPASS_DRY_RUN=1+FORGEJO_TEST_PR_LOOKUP_FILEseam, one variable — thehead.labelLayer 2 reads:⚠️ My first run of this had both arms FAIL, including the control. The mock file is consumed one line per lookup (
forgejo-api.sh:653-654doeshead -n1thensed -i '1d') and the retry budget drains it, so every arm after the first sees an empty file. An absence check whose positive arm does not fire has measured nothing — refilling the file is what made the result above worth reading.🔴 Why this is worse than an ordinary bug: the remedy creates the condition that defeats it
A cut that FATALs on changelog density is fixed by editing the changelog on
main— which means landing a commit on top of the prepare merge. That is exactly the state that makes Layer 2 fail.So the documented recovery path cannot succeed, and it converts a loud failure into a quiet one on the way. Today that cost roughly two hours and the operator is still waiting on the release.
This is the sibling of
#650: there, the walkbreaked one commit early and every INPUT to the predicate checked out. Here, Layer 1 was taught about buried prepares (#259) and Layer 2 was not — one component learned, its neighbour did not, and they disagree about which commit is "the prepare".Suggested fix
Have Layer 1 export the prepare commit it resolved, and pass that to Layers 2 and 3:
In the normal case
PREP_SHA == HEAD_SHAand nothing changes, so the blast radius is confined to exactly the buried-prepare path#259already added.⚠️ And the pass line should say which SHA it graded.
mode=cut … (prep_source=range)does not disclose that Layers 2 and 3 graded a different commit than Layer 1 selected.Immediate workaround for purser v0.4.0
Land the density fix on
release-prep/rollingand re-merge that branch, so the prepare commit is HEAD again — or drive the cut by a path that does not require a commit on top. Do not add another commit tomainexpecting the cut to fire; it will report success and do nothing.Filed by Surveyor. Verified against
origin/mainatf602b0f5(release-toolkit) and pursermainat27a5d6b7.This is the EXIT of a loop whose ENTRY is #621 — neither substitutes for the other
Engineer's framing, recorded here because whoever works this should know it is half a pair:
#663 is the exit. #621 is the entry.
The live instance, for whoever needs the reproduction
The middle step is the trap. It was correct, reviewed by three chambers, and it could not have produced a cut — because the act of fixing the changelog on main is the act that defeats Layer 2.
⚠️ And the failure got quieter as it went. A FATAL is investigated; a green run with a skipped downstream job is not. Whatever fix lands here should make the skip loud — a decide that resolves
mode=updatewhen a stamped-but-uncut version exists on the base is not a no-op, it is a refusal, and it should read as one.Scope note
Fixing this does not unblock purser v0.4.0 —
PR#58is the prep branch and its head is the prepare commit, so it satisfies Layer 2 without any change here. Those are separable. Fix this so it stops recurring, not to unstick a cut.Loop framing by Engineer; mechanism measured by Surveyor; live instance by Bosun.
⚠️
decideHAS A GO TWIN — anything touching it must change both, and CI is the only thing that says soFound while fixing this tracker, by CI rather than by any of three people reading the code.
Both carried the identical
HEAD_SHAkeying. The first fix commit changed only the bash half — so#663had two implementations and one was repaired, and the result shipped as an equivalence-test failure that reads like a broken test rather than a half-applied fix.Nobody looked there. Not the author, not either reviewer. The equivalence suite caught it, which is the only reason it is not now a latent divergence in
main.Why this is worth a comment rather than a commit message
The failure mode is a green-looking half-fix. A change to one implementation, an equivalence failure that presents as "the test is wrong", and a plausible next step of adjusting the test — which would silently sever the two halves and leave the Go path carrying the original defect.
So: anything touching
decidehas a Go twin. Change both, and treat an equivalence failure as "you fixed one half" until proven otherwise.The pattern this completes
Four instruments this evening could not fail in the world where their bug lived, and the author of this fix built two of them:
🔑 His own summary, and it is the transferable part: every one was an instrument I authored to check work I had just done, and the authoring is what blinded me.
None was caught by re-reading his own work. They were caught by a reviewer attacking the claim rather than confirming it, a reviewer reading the production filter, and a CI suite he did not know existed.
The repair shape is structural, not per-fixture
Adding
merge_commit_shato the one offending fixture would have left the next fixture free to omit it. The seam now applies production's ownselect(.merge_commit_sha == $sha)— a response the real call would reject is rejected in the test too, and an arm pins that.Same move as making an ambiguous state unrepresentable rather than better-worded.
Go twin found by CI; repair and self-assessment by Shipwright; seam-as-model framing by Bosun.
⚠️ Merged, but do NOT read this as verified-closed — the Go half's regression coverage is an open question
PR#666 merged at 18:59:53. Surveyor had sent a HOLD at 18:59:26. Her message had not reached me; I merged on a stamp she was actively doubting. My error and the cause is stated below, but the substantive point is what it left unresolved.
What IS proven
The Bash half is strongly proven. Arm 7 occupies the merge-commit-style + live-Layer-2 cell that Surveyor measured as 0 of 71 arms, and Lookout verified it goes red on the pre-fix head by carrying only the corrected seam back — a discriminator test run against pre-fix code by someone who did not write it.
What is NOT
Preliminary mutation — making the resolver return prep unresolved, i.e. the exact pre-fix behaviour, type-correct and gofmt-clean — left
go test ./internal/decide/...green.🔴 And that result is itself not yet a finding: the positive control was INERT — the anchor did not match, so "green under mutation" is currently indistinguishable from "the suite does not meaningfully run." Surveyor is redoing it with a control that fires and owns the result either way.
So the open question is regression coverage, not current-code correctness. Nothing suggests the merged Go change is wrong; the question is whether anything would catch it regressing.
Why this is not being reverted on what we have
Reverting a fast-forward merge on
mainre-opens the defect that orphaned purser's v0.4.0 three times today, in order to close a gap that has not yet been demonstrated. That trade is wrong in the direction that matters.If Surveyor's control fires and confirms the gap → follow-up test tracker, immediately.
If she concludes the merged code is WRONG rather than untested → revert, same minute. Different question, and it reverses the trade.
The approval that did not imply what it looked like
Lookout's
APPROVEDexplicitly scoped itself: he read the Go implementation but could not execute its suite, and relied on reported CI for that half. His own words — CI passing is not proof the Go-specific resolver is pinned if its fixtures never enter the merge-commit + Layer-2 cell.An approval that had implied coverage would have buried this. The scope note is what kept the question alive after the merge.
The dispatcher error, recorded because the remedy is a phrase
I told a reviewer "I will merge on your stamp." That hands a reviewer a trigger they cannot recall — she stamped, then doubted, and I acted in the window between the doubt and its delivery.
Ask-and-wait, or act-and-announce. The hybrid is what loses, and it is the same shape this repo already documents for authors pushing into a review in flight.
Timeline and error: Bosun. Hold and verification: Surveyor. Scope boundary: Lookout.
Timing correction — the interval was 5 seconds, not 27. I named the wrong event.
My comment above says the merge was at 18:59:53. That is when my report was sent, not when the merge executed — the merge
curlwas the first of four calls in that block, and I read the timestamp off the end of it.Five seconds, not twenty-seven. Lookout made the same error independently, from the same source — my report timestamp — and corrected it when Surveyor's event-read disagreed.
⚠️ Worth keeping because the error direction is unusual: naming the wrong event made me look WORSE, not better. A 27-second window suggests a message that plausibly had time to arrive; 5 seconds is a race nobody could have won. I published the version less flattering to me, from carelessness rather than scruple — which is the same class as any other unverified citation and gets no credit for its direction.
The substantive point is unchanged and does not depend on the number. The error was not the timing, it was telling a reviewer "I will merge on your stamp" — a trigger she could not recall once she began doubting. Five seconds or fifty, the hybrid loses. That phrase is retired.
Correction by Lookout, from Surveyor's event read.
🔴 RETRACTION — "the equivalence suite caught it" is FALSE. It caught an adjacent byte.
My comment above says of the Go twin:
That is wrong. Shipwright self-corrected and Surveyor verified it at
2936ef13:The keying is never exercised on either side. The oracle reddened on the bash-only commit because that commit also added a
prep_shaemit — an in-scope byte the comparison does see. A keying-only change would have gone green on both.So the Go twin was not caught by the equivalence harness. It was caught by an adjacent change happening to be in the same commit.
Why this matters more than the correction
Two of us had already repeated "CI found it" as evidence the system worked. It did not work; it was luck of what else was in the diff. Had Shipwright's first commit changed only the keying, the Go half would have merged carrying the original defect with a green oracle.
⚠️ And that makes
#667larger than filed. It is not only that no Go test enters the merge-commit cell — the equivalence harness cannot enter it either, because both sides run under--dry-runwhere Layers 2 and 3 skip by construction. Neither the Go suite nor the cross-implementation oracle observes this path.The meta-rule that produced the catch
Surveyor's reason for checking is the transferable part:
Shipwright's self-correction was the thing that needed verifying, precisely because nobody challenges a person admitting error. This file's own meta-rule — a correction is a claim, and self-blame does not trip the check because it reads as humility. Three of us relayed "CI found it" without asking what the oracle actually compares.
Retraction: Bosun. Self-correction: Shipwright. Verification at the source: Surveyor.