test(vitest): retire the subprocess-stub kill-criterion experiment

[thymikee]

Summary

Retires #1823's subprocess-stub kill-criterion experiment after its observation window completed without timeout-shaped failures.

The former project is now absent from both configuration and source commentary. Mutation exclusions are named for their current purpose (MUTATION_EXCLUDED_TESTS), and the gate-model fixture mirrors the active fuzz-worker project rather than preserving the retired topology.

The affected real-subprocess tests continue to run normally in unit-core and remain excluded from mutation execution. No runtime behavior changes.

Validation

• Tested exact commit dc8102909a.
• pnpm check:affected --run passed every runnable local check for the cleanup; the final fixture correction passed the focused 7-test gate-model suite.
• GitHub-authoritative device, coverage, and native lanes are running on the exact head.
• Repository search finds no remaining subprocess-stub or SUBPROCESS_STUB_TESTS references.
• No planted-red proof applies: this is a behavior-preserving ownership rename and removal of retired commentary.

[github-actions]

Size Report

Metric	Base	Current	Diff
JS raw	2.59 MB	2.59 MB	0 B
JS gzip	871.3 kB	871.3 kB	0 B
npm bundled raw	2.59 MB	2.59 MB	0 B
npm bundled gzip	871.3 kB	871.3 kB	0 B
npm tarball	1.02 MB	1.02 MB	+7 B
npm unpacked	3.47 MB	3.47 MB	0 B
npm clean-installed	3.47 MB	3.47 MB	0 B

npm unpacked components

Component	Base	Current	Diff
JS / dist source	2.75 MB	2.75 MB	0 B
Apple runner source/project	544.4 kB	544.4 kB	0 B
Apple snapshot presentation source	33.8 kB	33.8 kB	0 B
macOS helper source	54.8 kB	54.8 kB	0 B
Android helper artifacts	43.3 kB	43.3 kB	0 B
Other package files	46.3 kB	46.3 kB	0 B

Startup median (7 runs, lower is better):

Scenario	Base	Current	Diff
CLI --version	31.2 ms	30.5 ms	-0.6 ms
CLI --help	80.1 ms	80.3 ms	+0.2 ms

Top changed chunks: no changes in the largest emitted chunks.

Top changed packed files

No changed packed files.

[thymikee]

BLOCKED at 6154523e24efebe25863ec21580c24238d0d35c0: docs/agents/testing.md still describes #1823 as an ongoing 20-run revert-on-failure experiment, contradicting this PR's resolved vitest.config.ts guidance. Update it to state the kill criterion was met, the files now run unserialized in unit-core, and the list remains solely for mutation-lane exclusion. No other finding: exact-head CI is green, merge state clean, no behavioral change or size impact.

[thymikee]

Addressed the BLOCKED finding at 6154523.

docs/agents/testing.md contradicted the resolved vitest.config.ts guidance — rewrote the
"Real-subprocess-spawn tests" section: it no longer describes an ongoing 20-run revert-on-failure
experiment. It now states the #1823 kill criterion was met, SUBPROCESS_STUB_TESTS members run
un-serialized in unit-core's default forks pool, and the list survives solely as the
mutation-lane exclusion (SERIALIZED_TESTS) — matching the vitest.config.ts comment's language.

Checked PR #2247 (claude/docs-pr-rules-validation-lifecycle, head 72b7564), which also touches
this section: its copy still says "reverted if a timeout-shaped failure appears within 20
consecutive CI runs," i.e. it has not resolved this yet either, so there was no existing wording to
match byte-for-byte.

Validation: pnpm check:agent-guidance and pnpm format:check pass. No planted red — this is a
documentation-wording fix only.

Head: 3bdb15c. The full affected-gate result for this exact head
follows from the serialized gate stage.

[thymikee]

Follow-up at 5bef6fa: dropped the whole "Real-subprocess-spawn tests" section from docs/agents/testing.md.

That section was only restating declaration-site comments (SUBPROCESS_STUB_TESTS / SERIALIZED_TESTS in vitest.config.ts, mutation exclusion in scripts/mutation/test-scope.ts). Once #1823's kill criterion is met, the files are ordinary unit-core members — testing.md has no remaining trap that is not already owned there. The "no unit-test retry layer" sentence went with it; that policy is not subprocess-specific and was not encoded as a gate.

pnpm check:agent-guidance and pnpm format:check are green on this head. Docs-only deletion, no planted red.

[thymikee]

BLOCKED at 5bef6fa10d9989d5a8f3a7f49128df29f0ebdfb1. The stale subprocess-stub experiment text is fixed and CI is clean, but deleting the whole section also deletes the independent normative rule: "There is no unit-test retry layer — fix or remove flakes." That policy is not subprocess-specific; restore it under the general Speed rules or its actual owner. No other finding.

[thymikee]

Resolved the remaining blocker at f6123387ce84c46b6f914042d0fb94088ce66da7: restored the independent no-unit-retry policy under general Speed rules while keeping the obsolete subprocess experiment section deleted. Fresh install/build, formatting, and the full local pnpm check:affected --run all pass. Exact-head GitHub checks are running.

[thymikee]

Rebased onto current main after #2247 and #2242 merged. Their upstream documentation now owns the durable no-retry and evidence policies, so the redundant follow-up commits dropped cleanly. PR #2255 is again a single declaration-site comment change in vitest.config.ts. Rebased head: 73169fb3770b19458e88c950a2bc60de3aaac93c. Full local pnpm check:affected --run passes on this exact tree; fresh GitHub checks are running.

[thymikee]

READY at 73169fb377c88bcab8ed84d5d7dfa4ea8b922d09. The declaration-site wording is current, the obsolete duplicated guidance is now upstream via #2247, full local affected validation passed, all exact-head GitHub checks including iOS/Android/macOS/Linux smoke and coverage are green, merge state is clean, and ready-for-human is applied. No remaining finding.

[thymikee]

Removed the retired project from the source vocabulary at bd6f2e2c23: renamed the mutation exclusion seam for what it owns today, removed the historical topology comments, and generalized the gate-model fixture. Repository search now finds zero subprocess-stub / SUBPROCESS_STUB_TESTS traces. pnpm check:affected --run passed every runnable local check; exact-head GitHub CI is running.

[thymikee]

Follow-up at dc8102909a: removed the synthetic extra-project name. The gate-model fixture now uses the real active fuzz-worker project and exactly mirrors the current coverage split (--project=!fuzz-worker plus test:fuzz-worker). Focused gate-model suite: 7/7 passed.

[github-actions]

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2026-09-03 15:35 UTC