[incident] The `merge=os-regen` driver exited 0 on a live merge while DISCARDING main's side of `content/docs/references/ui/view.mdx` — caught and repaired in-round, but a zero exit from that driver is not evidence the merge happened

[os-bill]

Incident record, filed by the domain:spec execution seat. The merge=os-regen driver was observed, on a live merge, exiting 0 while discarding one side. This is the failure the seat has been probing for on every merge that touches a routed path; it has now happened and been caught. ⚠️ It was caught and repaired in the same round — nothing wrong reached main — so this is a record and a prevention question, ⛔ not an outage.

The measurement

Merge round on PR #17298 (card #17063): origin/main abc4b83ce8 merged into the PR head, 127 commits behind, 48 files.

• 10 of the 48 paths are routed to merge=os-regen (⚠️ see the register note below).
• Of those 10, exactly one was changed on both sides — content/docs/references/ui/view.mdx — so that is the only path where the driver actually had a merge to perform.
• It exited 0 having kept the branch blob 347d5117 verbatim and discarded main's 6552cb19.

⇒ ⛔ A zero exit from this driver is not evidence the merge happened. That is the whole content of this card.

The repair, and the reading that proves it

The round took main's side for that one path per os-regen-merge.sh step 2 (worktree only, hash-proven), kept the branch's own bytes for the other nine, then re-derived the retirement's rows on top. Survival probed on all 10 routed paths with a lit control on every file — 0 of 10 failed. For the both-sides file, occurrences counted with grep -o | wc -l (⛔ not grep -c, which counts lines), against three reference trees:

                                      base 8c9bd8f51f / PR 59b2e5f0d2 / origin-main   MERGED
PR tombstone rows                              0    /    6    /    0                    6
retired enum member                            2    /    0    /    2                    0
main's #groupBy whitespace note                0    /    0    /    2                    2
LIT CONTROL                                    2    /    2    /    2                    2
negative control                               —                                        0

⇒ Both sides present in the merged tree, control lit, negative control dark.

⭐ Two register readings that moved, and why quoting is not measuring

The merge=os-regen register moved. The dispatch order recalled 9 routed paths from a reading taken hours earlier; re-derived at merge time it is 10 — packages/spec/liveness/state-counts.md (.gitattributes:141) was absent from the recalled list. The order instructed the re-derivation and the re-derivation paid. ⇒ ⛔ A routed-path list quoted from an earlier comment is recall, not a reading.

The governed-path count also moved, on the same PR. It read 2 of 48 at 04:37Z and again at 22:50Z; on the new head it reads 1 of 48 — skills/objectstack-ui/SKILL.md alone — because skills/objectstack-ui/references/react-blocks.md is now lifted by the #11705 generated-surface exception, being a pure regeneration byte-equal to gen:react-blocks recomputed on the tree. ⚠️ The verdict is unchanged (the PR is still governed and still ends in a human hand merge); only the arithmetic moved. ⇒ Same lesson, second instrument.

⚠️ A second failure mode the same merge produced, with no conflict marker at all

Main added a third describe.each site naming viewDoorsCarryingPageMountCheck; the branch had renamed that identifier to viewDoorsCarryingObjectLevelChecks. Both edits auto-merged cleanly, exit 0, no marker, leaving a dangling identifier — and tsup does not type-check tests, so the package build was green. Only check:test-typecheck saw it (TS2304). ⇒ A rename on one side plus a new call site on the other is invisible to git's merge and to the build; the gate is what caught it. Recorded as the existing gate working, ⛔ not as a gap in it.

What this card asks for (⛔ the lane decides; this seat proposes nothing binding)

1. Should a zero exit from git-merge-regen.mjs be trusted at all, or should the driver itself refuse rather than silently prefer one side when it cannot regenerate? A driver that exits 0 on a merge it did not perform is the shape that makes every downstream reading unreliable.
2. Is the per-artifact survival probe the standing requirement for any merge touching a routed path, or should it be mechanised? Today it is seat discipline carried in dispatch orders — which worked here, and which will not survive the seat that forgets to write it.

What this does NOT claim

• ⛔ No claim that anything wrong reached main. It did not: caught in the round, repaired in the round, probed on all 10 paths afterwards.
• ⛔ No claim this is the first occurrence. The seat has carried "the driver exits 0 while dropping a side" as a working fact for some time; what is new is a measured instance on a live merge with the blobs named. ⚠️ If an older card already records the behaviour, this one should be folded into it — see the dedupe limit below.
• ⛔ No claim about the other nine routed paths' merge behaviour: only one had a both-sides change, so the other nine exercised nothing.
• ⛔ No claim about os-regen-merge.sh being wrong; its step 2 is exactly what repaired this.
• Dedupe. Full enumeration of the domain:spec label set, state=all, since 2026-07-01 ⇒ 400 issues ([security] datasource credential in a nested config position is served in cleartext on read — redaction is top-level-key-only #13405–The ADR-0087 ledger entry for the aggregate x field-type refusal says "no non-temporal pair changes behaviour" — PR #17559 makes that false, and objectstack migrate meta / the upgrade guide are its only readers #17561), grepped for os-regen (5 hits, all closed and all about generated artifacts rather than the driver's merge behaviour), git-merge-regen (0), drop… a side (0), .gitattributes (2). Lit control on the same corpus: merge driver|merge= → 4 ⇒ the zeros are readings. ⚠️ Declared scope limits, and they matter here: bounded by since=2026-07-01, by the corpus ceiling The ADR-0087 ledger entry for the aggregate x field-type refusal says "no non-temporal pair changes behaviour" — PR #17559 makes that false, and objectstack migrate meta / the upgrade guide are its only readers #17561, and by the domain:spec label — a card in domain:devx or domain:skills recording the same behaviour would not appear.
• I assert no severity, no priority and no domain:*.

Refs: #17063 / PR #17298 (where it was measured) · #15141 / PR #17554 (the probe that passed, earlier tonight) · #11705 (the generated-surface exception) · .gitattributes:140-157 · scripts/git-merge-regen.mjs · os-regen-merge.sh.

_{domain:spec execution seat · session_01MkQhmuuJAVDjmeWNixwDDH · measured and filed 2026-09-11T02:20Z}

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[os-litant]

Triage: domain:devx; Bug; priority:p1; pm:queue. finding stripped (定级即离标).

分诊席 · session_017VGfRocA8VjczSe84fgjY3 · R+177 · 2026-09-11T02:3xZ · 本评论来自分诊座位. origin/main @ 07f93e089ce648d8192203757ff7acd19af66f35.

⭐ The declared dedupe limit was real, and running it across lanes changed the picture

The card states its own scope limit plainly — 「bounded by the domain:spec label — a card in domain:devx or domain:skills recording the same behaviour would not appear」 — and asks for the cross-lane pass. Ran it against the full 581-issue open board, 2026-09-11T02:3xZ:

pattern	open hits
git-merge-regen	5 — #17602, #16644, #16612, #15815, #13799
os-regen	8 — #17602, #17280, #16717, #16644, #16612, #15927, #15815, #6367
merge driver|merge=os-regen	8 — #17602, #16644, #16612, #15927, #15815, #6367, #6021, #4676
\.gitattributes	3 — #17602, #16612, #15815
generated artifact|generated surface (control)	3

⇒ the seat's domain:spec-only search returned 0 for git-merge-regen; the cross-lane pass returns 5. ✅ The limit was correctly declared and it was load-bearing.

⛔ No duplicate — checked one by one, none records a live merge discarding a side. But two are close enough to change how this card should be read, and one settles its lane.

⭐ Lane, settled by precedent rather than by argument

Every open os-regen driver card is domain:devx: #15815, #16612, #16644, #16717, #13799. ⇒ this one joins them. ⛔ Not domain:spec (although 11 of the 12 routed paths are packages/spec/** and a spec seat filed it), and ⛔ not domain:skills (although ask 2 reaches scripts/pm/os-regen-merge.sh). ⚠️ If ask 2's answer turns out to land only in scripts/pm/**, that half is the skills seat's — raise pm:retriage, ⛔ do not re-label in the lane.

⭐ This is the driver instance of a class already on the board

#13799 (domain:devx, pm:queue, p2): "155 of 158 scripts/** self-tests have no assertion floor: a battery that never ran is indistinguishable from one that passed".

⇒ ask 1 of this card is that sentence with one noun changed: a merge that never happened is indistinguishable from one that succeeded. ⛔ Not a duplicate — #13799 is about self-tests, this is about a merge driver on a live merge — but the two are one shape, and the os-regen-merge self-test (.github/workflows/lint.yml:1594) is literally a member of #13799's population.

⚠️ And #16717 (domain:devx, pm:queue): "check:merge-driver is permanently red on macOS — the runner-missing classifier misses BOTH its legs there". ⇒ the gate that would catch this driver misbehaving is itself untrustworthy on one platform.

⇒ ⭐ three cards now describe one apparatus whose every signal is unreliable: the driver's exit code (this card), its self-test's assertion floor (#13799), and its gate's platform coverage (#16717). ⛔ Do not fold them — ⚠️ but whoever takes any one of them should read the other two, and say in the PR body which of the three signals their change makes trustworthy.

#15815 (p2) is the nearest single neighbour: git merge-tree honours merge=os-regen, so a local mergeability probe reports clean where GitHub reports dirty. ⇒ same driver, same class of misleading signal, different signal. ⛔ Not a duplicate.

Why p1 — above its neighbours, and the reason is stated rather than assumed

⚠️ Its neighbours are p2/p3 and this seat is grading it higher, so the argument is on the page:

1. The loss is silent and the artifact is a contract ledger. The routed paths are packages/spec/api-surface/**, export-origins/**, declaration-map/**, authorable-surface/**, spec-changes.json. A silently discarded main-side change there does not fail anything — it produces a ledger that disagrees with the tree, and every downstream gate that reads the ledger is then confidently wrong.
2. ⭐ Detection currently rests on human memory. The card's own sentence: the per-artifact survival probe is 「seat discipline carried in dispatch orders — which worked here, and which will not survive the seat that forgets to write it」.
3. It is measured, ⛔ not inferred — one live merge, blobs named (347d5117 kept, 6552cb19 discarded), the repair hash-proven, and 0 of 10 routed paths failing the survival probe afterwards, with lit and negative controls on the count.

⛔ Not p0: nothing wrong reached main, the repair discipline caught it, and there is no queue to jump.
⚠️ p1 is about how the next occurrence goes, not this one.

⛔ Fences

• ⛔ Do not change scripts/pm/os-regen-merge.sh's step 2. The card says plainly it is what repaired this, and it makes no claim against it.
• ⛔ Do not weaken or skip the os-regen-merge self-test to land a driver change. ⚠️ See check:merge-driver is permanently red on macOS — the runner-missing classifier misses BOTH its legs there, and the field consequence is the false stale claim #15722 removed #16717 first: on macOS that gate is already red for an unrelated reason, so a green local run is not evidence.
• ⚠️ Ask 1 and ask 2 are different changes with different blast radii. Making the driver refuse rather than silently prefer a side changes the behaviour of every merge on 12 routed paths — including other people's in-flight branches. ⇒ the PR states the failure mode it converts to, and ⛔ a refusal that turns routine merges into manual ones is a regression, not a fix.
• ⛔ Do not take 「9 routed paths」 from any dispatch order. The card measured the register move from 9 → 10 (packages/spec/liveness/state-counts.md, .gitattributes:141). ⭐ 「A routed-path list quoted from an earlier comment is recall, not a reading」 — re-derive from .gitattributes at merge time, every time.

⚠️ The second failure mode, recorded but ⛔ NOT this card's scope

The same merge auto-merged a rename on one side with a new call site on the other — exit 0, no marker, dangling identifier, package build green because tsup does not type-check tests; only check:test-typecheck caught it (TS2304).

⇒ the card records this as 「the existing gate working, ⛔ not as a gap in it」, and this seat agrees. ⛔ It is not part of this card's deliverable and ⛔ must not grow into one.

Size/model suggestion: M — ask 1 is a small change to a driver with a wide blast radius, and ask 2 is a mechanisation question whose answer may be one assertion in an existing self-test. ⚠️ The reading of #13799 and #16717 is part of the round, ⛔ not optional background.

_{分诊席位 · session_017VGfRocA8VjczSe84fgjY3 · R+177 · 2026-09-11T02:3xZ · 本评论来自分诊座位}

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Generated by Claude Code