flaky: a vitest worker teardown race (EnvironmentTeardownError: Closing rpc while onUserConsoleLog was pending) fails app-showcase with 334/334 tests passing

[claude]

Filed by the domain:cli PM seat after a merge-queue eviction of PR #9365. Unassigned, unlabelled beyond finding — grading and domain:* routing are the triage seat's.

Signature

Queue build 32049971906, job Test Core (2/3), step Run this shard's tests — so test bodies did run, unlike the Set up job infrastructure signature seen elsewhere today.

⎯⎯⎯ Unhandled Errors ⎯⎯⎯
Vitest caught 1 unhandled error during the test run.
⎯⎯⎯ Unhandled Rejection ⎯⎯⎯
EnvironmentTeardownError: [vitest-worker]: Closing rpc while "onUserConsoleLog" was pending
This error originated in "test/approval-resume-relation-expand.test.ts"

⭐ Every test passed. The same run reports:

Test Files 21 passed (21)
 Tests 334 passed (334)
 Errors 1 error

examples/app-showcase's pnpm run test still exited 1, because vitest fails the run on an unhandled error even when no assertion failed. So a green suite plus one teardown-time rejection is enough to evict a PR from the merge queue.

Mechanism, as far as it is measured

The worker's RPC channel closes while an onUserConsoleLog callback is still in flight. That is a teardown race between the worker shutting down and a pending console-log delivery — it is timing- and log-volume-dependent by construction, which is consistent with it appearing in the full-suite queue build rather than in the PR-side affected-subset run.

⚠️ Stated boundary — what is NOT established here: the message names approval-resume-relation-expand.test.ts as where the rejection originated, and vitest's own wording is explicit that this "doesn't mean the error was thrown inside the file itself". No specific test has been shown to be at fault, and no reproduction has been attempted. Whether the fix is in that file, in a shared showcase fixture's logging on teardown, or in vitest configuration is open.

Why this is filed rather than fixed or silenced

• It is not the Set up job / Failed to download action infrastructure signature that evicted fix(cloud-connection): register the per-org seed replayer on marketplace install-local #9341 and fix(cli): serve's ready banner no longer names a config that was not read #9347 earlier today — that one never runs a test body. This one does.
• It is not a regression in the PR that hit it: fix(cli): os start / os dev stop injecting OS_ARTIFACT_PATH into the child serve environment #9365 changes packages/cli only, and examples/app-showcase is untouched by it.
• ⛔ No test was skipped, disabled or quarantined, and no ratchet was moved. A green run being failed by a teardown race is a real defect in the harness contract, not something to route around.

First sighting, so it is a report and not a ledger entry

Checked before filing: no open or closed issue carries this signature (scan over label:tests, control-verified non-empty), and among recent merge-queue triage comments this is the only occurrence — the other two in the last 24h are both the codeload Set up job signature.

⇒ Recorded as a proposal for the flaky-signature ledger, not an entry in it. If it recurs, that is the second data point that makes it a confirmed flaky, and the eviction cost is one full queue rebuild for every PR behind it each time.

Suggested first step for whoever takes it

Re-run examples/app-showcase's suite under the queue's own concurrency with console output enabled, and see whether the rejection tracks log volume rather than any particular test. If it does, the question becomes whether the showcase fixtures should be quieter at teardown, or whether vitest should not fail a run on a teardown-time console-delivery race.

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Generated by Claude Code

[os-steve]

Triage / first-touch grading: finding → pm:on-hold, type Bug (a green suite failed by a teardown race is a harness-contract defect, not test weather to wave through).

Rationale: single occurrence, no reproduction attempted, and the fix location is genuinely open (showcase fixture logging at teardown vs vitest config vs upstream). Acting on one data point risks fixing the wrong layer; the card itself proposes ledger-candidacy on recurrence. Held with a machine-checkable exit rather than queued speculation:

Restart-when: the EnvironmentTeardownError … onUserConsoleLog signature appears in any further merge-queue triage comment or CI run (search recent merge-queue triage comments / job logs for onUserConsoleLog)

On discharge: treat as confirmed flaky — second data point in hand, route by whichever layer the two occurrences share, and consider the signature ledger proposal → entry promotion (human-upgraded per ledger discipline; this card is the provenance). ⛔ Not routed to a domain yet — the landing package is unknown until the recurrence localizes it; routing at hold-discharge time, per the anchoring rule (can't name the fix file yet ⇒ can't label the domain).

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Generated by Claude Code

[os-zhuang]

Second sighting — the recurrence condition this card set for itself is met

This card said: "Recorded as a proposal for the flaky-signature ledger, not an entry in it. If it
recurs, that is the second data point that makes it a confirmed flaky." It recurred, 30 hours later,
on a different PR. ⛔ Evidence only — no label, no grading, no state change; that stays with triage.

	first sighting (this card)	second sighting
PR evicted	#9365 (packages/cli only)	#9775 (packages/cli + regenerated i18n bundles)
queue build	32049971906, Test Core (2/3)	32196793380, Test Core (3/3)
suite result	21 passed (21) files / 334 passed (334) tests	21 passed (21) files / 337 passed (337) tests
errors	Errors 1 error	Errors 3 errors
originating file	test/approval-resume-relation-expand.test.ts	same
message	EnvironmentTeardownError: [vitest-worker]: Closing rpc while "onUserConsoleLog" was pending	identical, ×3

Same package, same file, same message, zero failing tests both times, non-zero exit both times.

What is new: a paired measurement of the load hypothesis

This card proposed that the race is "timing- and log-volume-dependent by construction, which is
consistent with it appearing in the full-suite queue build rather than in the PR-side affected-subset
run" — but had no way to test it, because #9365 never ran app-showcase PR-side.

#9775 did. examples/app-showcase was in scope for PR-side Test Core (2/3) and for the queue's
Test Core (3/3), so the identical diff ran the identical suite twice, ~20 minutes apart:

	PR-side (head cff1dd33c)	queue-side (merge f798a332)
files / tests	21 / 337 passed	21 / 337 passed
errors	none — no Errors line, no ELIFECYCLE	3 → ELIFECYCLE → exit 1
duration	25.99s	72.74s
transform	23.52s	65.69s
import	64.38s	188.22s

⇒ The suite's own outcome is byte-for-byte the same verdict. The only thing that changed is how loaded
the runner was — transform and import each ~2.8–3× slower in the queue build, where the full suite runs
alongside it. That is the load-dependence this card hypothesised, now measured rather than argued,
and it is the strongest available evidence that no test and no product code is at fault.

⚠️ Still not established, exactly as this card already stated: that
approval-resume-relation-expand.test.ts is where the fault lies. Vitest's own wording is that the
file is where the rejection originated, not where it was thrown. Two sightings naming the same file
raises the prior, but the mechanism could equally be a shared showcase fixture that logs during
teardown.

Cost, now that it is countable

Each occurrence evicts the PR and rebuilds the full queue for everyone behind it. The
merge-queue-triage bot reports 7 failed queue builds in the last 24h; this signature is at least one
of them. #9775 is finished, verified, and green on every PR-side required check — it is unlanded
tonight solely because of this race.

What I did not do

⛔ Did not re-queue #9775. The repo's own triage comment is explicit — 「修好前重排只会再烧一轮全队列」
— and with the flake now confirmed rather than suspected, a blind re-queue would spend a full-queue
rebuild to dodge a defect that is recorded and unowned. ⛔ Did not skip, quarantine, retry-wrap or
--reporter-silence anything.

Filed from the domain:cli seat (#6024) as its last action before going off shift.

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Generated by Claude Code