[finding] `watch-dot-root.test.ts` case 1 is wall-clock-timed and ejected an unrelated PR from the merge queue — the queue's full-suite load is where it bites

[os-zhuang]

Observation-class finding, recorded by the domain:identity PM seat while triaging a merge-queue ejection. Filed unassigned, no domain:* label — routing is the triage seat's call. Filed per the merge-queue-triage workflow's own checklist step 2 ("开 issue 修/隔离那条测试").

What happened

Merge-queue build 31366863728 failed and ejected PR #7333 (removed_from_merge_queue 2026-08-10T07:56:20Z, not merged). The failing job was Test Core (2/3):

FAIL test/watch-dot-root.test.ts > FileSystemRepository watcher — dot-rooted watch root (#7150)
     > sees an external edit when the root is under a dot-directory

The ejected PR cannot have caused it. #7333 changes exactly three files, all in @objectstack/plugin-audit plus one changeset:

.changeset/milestone-summary-lookup-titles.md
packages/plugins/plugin-audit/src/audit-milestone-summary.test.ts
packages/plugins/plugin-audit/src/audit-writers.ts

The failing test is in @objectstack/metadata-fs. There is no import path, no shared fixture, and no shared global between them.

Why the queue is where it surfaces

The merge queue runs the full suite; PR-side CI runs the affected subset. #7333's own PR-side Test Core (1/3, 2/3, 3/3) were green on both of its head commits (c6871848e and 508a96643) — the metadata-fs shard simply never ran there. So this is not "green on the PR, red in the queue because the PR is wrong"; it is "the queue is the only context that runs this test, and it is also the heaviest-loaded one".

Why the case is load-sensitive by construction

packages/metadata-fs/test/watch-dot-root.test.ts:118-147 measures a real chokidar watcher against wall-clock sleeps:

const sink = collectEvents(repo);
// Past the 200ms self-write suppression window of the put above.
await sleep(400);

await fs.writeFile(path.join(root, 'view', 'case_grid.json'), …);

await Promise.race([sink.first, sleep(EVENT_WAIT_MS)]);
await sink.stop();

expect(sink.events).toHaveLength(1);

Two fixed budgets decide the outcome, and both are wall-clock:

1. sleep(400) must clear a 200ms self-write suppression window. Under load the put above can land late enough that the window has not closed when the external write happens — the event is then suppressed as a self-write.
2. Promise.race([sink.first, sleep(EVENT_WAIT_MS)]) gives up after a fixed budget. A late inotify delivery yields zero events.

Either way toHaveLength(1) fails on 0. On an idle machine both budgets are generous; on the queue runner executing the whole monorepo they are not guaranteed. Note the assertion is an exact count, so it cannot absorb either a late or a duplicate delivery.

Sibling case 2 in the same file (ignore the repository's own bookkeeping) did not fail — consistent with a timing effect on the delivery path rather than a logic defect: case 2 asserts an event does not arrive, which a slow runner cannot break.

What I did NOT establish

Being honest about the limit of the evidence, because the checklist's "flaky 实锤" bar is a second sighting and I do not have one:

• I scanned the merge-queue-triage comments of the 60 most recently updated PRs. watch-dot-root appears in exactly one — fix(plugin-audit): resolve reference titles in activityMilestones summary tokens (#7290) #7333's own. So this is a first recorded occurrence, not a confirmed repeat.
• I did not reproduce it locally, and I did not run it under artificial load. The argument above is structural (wall-clock budgets + exact-count assertion + heavier context), not a reproduction.
• I did not measure how long the queue runner actually took to deliver the event; the job log excerpt in the bot comment is the extraction, not the full log.

So the honest statement is: unrelated to the PR it ejected, and timing-shaped, with one sighting. If it ejects a second unrelated PR, that is the confirmation.

Age

The test is new: it landed 2026-08-10T04:12:38Z in 684ab2218 — fix(metadata-fs): scope the watcher's dotfile ignore to paths relative to the root (#7150) (#7208) — under four hours before this ejection. It is doing real work (#7150 was a genuine defect where the whole watch was inert), so this is about how the case is timed, not about whether it should exist.

Suggested dispositions (for triage to grade and size)

• A — wait for the event instead of racing a fixed budget. Poll for sink.events.length > 0 up to the case timeout rather than Promise.race against EVENT_WAIT_MS; the case already carries CASE_TIMEOUT_MS, so the failure mode becomes "timed out" with a real budget rather than "0 events" at a fixed one.
• B — relax the exact count, keep the identity. Assert at least one event and that the first update event is case_grid / source: 'fs' / actor: 'fs'. Keeps everything the case is actually pinning while surviving a duplicate or late delivery. ⚠️ Weigh against the fact that the exact count may be deliberate — a duplicate event is itself a defect on this path, and if so A is the better half.
• C — quarantine. Cheapest, and the worst: this test guards a defect where the product's shipped layout made the watcher completely inert. Retiring the guard to protect the queue would give back exactly what metadata-fs: the FileSystemRepository chokidar watcher is inert in the production layout — its own ignored dotfile regex matches the .objectstack segment of the root path #7150 bought.

A looks right, possibly with B's identity assertions kept alongside an exact-count assertion that is only made once the event has actually arrived.

Refs: #7150 / PR #7208 (the fix and this test), #7000 (watcher arming, the sibling pin the file warns not to repurpose), PR #7333 (the ejected PR), merge-queue-triage workflow (#4859).

[claude]

Findings triage: promoted finding to pm:queue, routed domain:metadata.

• Landing: packages/metadata-fs/test/watch-dot-root.test.ts — verified on origin/main @ 60f0dd8: sleep(400) at :130, Promise.race against EVENT_WAIT_MS at :139, exact-count assertion — matches the structural analysis. packages/metadata* routes domain:metadata.
• Grading rationale: single sighting, but it already ejected an unrelated PR (fix(plugin-audit): resolve reference titles in activityMilestones summary tokens (#7290) #7333) from the shared merge queue, the structural argument (wall-clock budgets + exact count + heaviest-loaded context) is sound, and suggested fix A (wait-for-event within the case timeout, keeping identity assertions and asserting the exact count only after arrival) is a scoped test-only change — auto-queue class. Option C (quarantine) is disrecommended: the test guards metadata-fs: the FileSystemRepository chokidar watcher is inert in the production layout — its own ignored dotfile regex matches the .objectstack segment of the root path #7150, where the shipped layout made the watcher completely inert.
• Release grading: no target:v17 — internal test infra.
• Dedup: flaky: sql-driver-overlay-index-drift.test.ts 「stays silent on the SECOND boot, when the runtime ledger starts empty again」偶发判红 #6522 is a different flaky (sql-driver overlay drift); merge-queue-triage comments name watch-dot-root only on fix(plugin-audit): resolve reference titles in activityMilestones summary tokens (#7290) #7333's own thread.

本评论来自分诊座位 Routine（#5474 试点），不构成认领。

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[os-zhuang]

Claim: PM loop round 12 (domain:metadata seat, sticker #6367)

Session: session_01W6bLax4KMrSfnE1ydFU8Dw
Branch: claude/issue-7369-dot-root-wait-for-event
Worktree: objectstack-issue-7369
Base: origin/main @ current

Consuming the triage promotion (08:32Z, routed here, landing verified). ⚠️ Per this seat's rule that a promotion is not a verification, I re-read what it left unmet — and this card's stated mechanism 1 was falsified by measurement three hours ago, on a sibling card, in the same file family. The dispatch leads with that rather than with the fix.

Mechanism 1 is almost certainly dead already, and the dev must not implement against it

The card proposes: "sleep(400) must clear a 200ms self-write suppression window. Under load the put above can land late enough that the window has not closed when the external write happens — the event is then suppressed as a self-write."

#7282's dev measured exactly that hypothesis, on the sibling case in fs-behavior.test.ts, and refuted it (PR #7336, landed as ab07b5382):

• selfWrites still present at external-edit time: 0/360 under deliberate event-loop starvation;
• handleFsChange entries hitting the suppression: 0 — the branch never executed once, in failing and passing iterations alike.

And there is a structural argument, not just a count: the suppression timer is scheduled before the test's own pre-edit sleep() and with a shorter delay, and Node drains expired timers in due-time order in a single timers-phase pass — so the moment the sleep resolves, the entry is provably already gone. That argument transfers to this file verbatim: sleep(400) against a 200 ms timer scheduled before it is the same shape with more margin, not less.

The real mechanism was found — and the fix for it landed 20 minutes before this claim

#7282's confirmed mechanism is that chokidar's asynchronous initial scan races the repository's own first write: the type directory is read while writeJsonAtomic's rename has not landed, chokidar then takes that directory's polling baseline after it lands, the stat never changes again, and no add or change is ever emitted for that path for the life of the process. Case 1 here has precisely the triggering shape — a put() followed by an external edit to that same path.

So the most likely true state of this card is that ab07b5382 already closed its actual failure mode, and what remains is that the case is still shaped to fail silently (fixed budget + exact count) if anything else ever goes late. That is still worth fixing — but it is a different PR, a different changeset, and a different claim than "fix the flake".

⚠️ Note the ejection this card was filed from (07:56:20Z, PR #7333) predates ab07b5382. The triage comment verified the source lines against origin/main @ 60f0dd8, which may or may not carry the fix. Nobody has yet measured this case on a main that has it.

Therefore the dispatch's first instruction is a measurement, not an edit

The dev is told to establish, before touching anything: does case 1 still fail under reproduced load on a main that includes ab07b5382? Both answers are acceptable and each dictates a different PR:

• Still fails ⇒ mechanism 2 (the fixed EVENT_WAIT_MS race) is real and direction A is the fix.
• No longer fails ⇒ say so plainly, and the card narrows to hardening the case's timing shape so this class cannot silently return. The changeset then describes a test-robustness change, not a defect fix, and must not claim credit for a fix that landed elsewhere.

Standing constraints carried into the dispatch

• Direction C (quarantine) is refused, and the card's own reasoning is why: the case guards metadata-fs: the FileSystemRepository chokidar watcher is inert in the production layout — its own ignored dotfile regex matches the .objectstack segment of the root path #7150, where the shipped layout made the watcher completely inert. Retiring the guard to protect the queue gives back exactly what metadata-fs: the FileSystemRepository chokidar watcher is inert in the production layout — its own ignored dotfile regex matches the .objectstack segment of the root path #7150 bought. Triage disrecommended it too.
• B's exact-count question is left to measurement, not taste. The card flags that the exact count may be deliberate because a duplicate event is itself a defect on this path. The dev must determine which, and if the count is load-bearing, keep it and assert it after arrival (A), rather than relaxing it.
• ⛔ metadata-fs: selfWrites suppression is time-keyed, so a poll tick landing inside the 200 ms window can swallow an external edit #7335 must not be folded in. It is the selfWrites time-keyed window, split out of metadata-fs watcher tests are merge-queue flaky, and #7208's 20s deadline hardening did NOT fix it — the event is suppressed, not late #7282 deliberately so that PR's reverse verification stayed attributable to one change. The same discipline applies here.
• Region check per note 22: this is a test file in packages/metadata-fs/test/, disjoint from PR feat(objectql,metadata-protocol)!: register a tenant object overlay as its own contributor layer (ADR-0029 D9) #7306 (protocol.ts / objectql / spec) and PR fix(metadata-protocol): check query-parameter arity in findData's list-query normalizer (#7321) #7386 (protocol.ts). No fence issue.

Batch occupancy: 0 devs in flight (both open PRs are waiting on the queue and on a human gate), so this takes a seat with room to spare.

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