test: full-suite subprocess-spawn contention causes 12 intermittent failures across 7 files

[dean0x]

Problem

A full npm test (4103 tests / 114 files) produced 12 failures across 7 files. All 7 files pass 3/3 in isolation — 21 isolated runs, zero failures. The failures are load-induced subprocess-spawn contention, not logic bugs.

Affected Files and Symptoms

File	Failures	Type
tests/redact-secrets.test.ts	3 assertion failures (spawned script exit 1 instead of 0) + 1 timeout	Hard assertion + timeout
tests/decisions/ledger-ops.test.ts	2 × 5s timeouts	Timeout
tests/shell-hooks.test.ts	2 × 5s timeouts (json-helper.js operations describe)	Timeout
tests/eager-memory-refresh.test.ts	2 × 5s timeouts (this file spawns real claude)	Timeout
tests/decisions/decisions-usage-scan.test.ts	timing violation: 11088ms against 8000ms limit	Timing
tests/build-mds.test.ts	beforeAll hook timeout at 10000ms	Timeout
tests/compliance-e2e.test.ts	beforeEach hook timeout at 10000ms	Timeout

Open Thread

The redact-secrets exit-1 failures were not root-caused — they were dismissed on the strength of 3/3 clean isolated runs (inference from absence). If that file ever fails in CI, run the underlying redaction script by hand with the same fixture and capture stderr before assuming contention.

Evidence

All 7 files pass in isolation (21 clean runs). The pattern is consistent with vitest's default unlimited concurrency saturating the subprocess pool when the full suite runs.

Filing this so a future CI failure is not re-diagnosed from scratch.

Fix Directions

• Raise per-test timeouts on spawn-heavy files (ledger-ops, shell-hooks, redact-secrets, eager-memory-refresh, build-mds, compliance-e2e)
• Cap vitest concurrency for spawn-heavy files via pool: 'forks' + poolOptions.forks.maxForks in their vitest config, or use --reporter=verbose --sequence.concurrent=false for those files
• Separate spawn-heavy tests into their own vitest project with a lower concurrency cap

Found during review of PR #327.