fix(ci): budget native Windows coverage timing

scripts/ci-workflow.spec.ts

@@ -64,6 +64,9 @@ describe('CI workflow', () => {
     expect(windowsNative['runs-on']).toContain('dsh-windows-2025-16core')
     expect(windowsNative.name).toBe('windows node 24 / native complete')
     expect(windowsNative.if).toBe("github.event_name == 'pull_request'")
+    expect(windowsNative.env).toMatchObject({
+      DSH_COVERAGE_TEST_TIMEOUT_MS: '15000',
+    })
     const nativeCommandSteps = (windowsNative.steps as unknown[]).filter((step): step is Record<string, unknown> & { run: string } => (
       isRecord(step) && typeof step.run === 'string'
     ))

scripts/run-gates.spec.ts

@@ -92,6 +92,35 @@ describe('gate graph validation', () => {
     expect(byId.get('duplication')?.allowFailure).toBe(true)
   })
 
+  it('applies one configured test and polling timeout to both coverage gates', () => {
+    const gates = withEnv('DSH_COVERAGE_TEST_TIMEOUT_MS', '15000', () =>
+      withPnpmEntrypoint(() => gatesForMode('ci-windows-complete')))
+
+    for (const id of ['coverage', 'coverage-exempt-heavy']) {
+      expect(gates.find(subject => subject.id === id)?.args).toEqual(expect.arrayContaining([
+        '--testTimeout=15000',
+        '--expect.poll.timeout=15000',
+      ]))
+    }
+  })
+
+  it('keeps Vitest timeout defaults when the coverage override is absent', () => {
+    const gates = withEnv('DSH_COVERAGE_TEST_TIMEOUT_MS', undefined, () =>
+      withPnpmEntrypoint(() => gatesForMode('ci-windows-complete')))
+
+    for (const id of ['coverage', 'coverage-exempt-heavy']) {
+      expect(gates.find(subject => subject.id === id)?.args).not.toEqual(expect.arrayContaining([
+        expect.stringMatching(/^--(?:testTimeout|expect\.poll\.timeout)=/),
+      ]))
+    }
+  })
+
+  it('rejects an invalid coverage timeout before starting a gate', () => {
+    expect(() => withEnv('DSH_COVERAGE_TEST_TIMEOUT_MS', '0', () =>
+      withPnpmEntrypoint(() => gatesForMode('ci-windows-complete'))))
+      .toThrow('DSH_COVERAGE_TEST_TIMEOUT_MS must be a positive integer')
+  })
+
   it.each([
     ['empty', [], /gate graph has no gates/],
     ['duplicate ids', [gate('same'), gate('same')], /duplicate gate id "same"/],

scripts/run-gates.ts

@@ -481,6 +481,9 @@ function lintGate(options: { needs?: string[] } = {}): Gate {
 // small share. A budget of 1 gives each gate 1 worker; lanes that need a
 // strict total of one (the serial reference jobs) also set
 // DSH_GATE_CONCURRENCY=1, which keeps the gates from overlapping at all.
+// DSH_COVERAGE_TEST_TIMEOUT_MS raises Vitest's per-test and expect.poll
+// defaults together for instrumented lanes whose scheduling overhead exceeds
+// those defaults. Explicit fixture timeouts remain authoritative.
 function coverageWorkerArgs(): { instrumented: string[]; exempt: string[] } {
   const [flag] = positiveIntArg('DSH_COVERAGE_MAX_WORKERS', '--maxWorkers')
   if (flag === undefined) return { instrumented: [], exempt: [] }
@@ -493,14 +496,23 @@ function coverageWorkerArgs(): { instrumented: string[]; exempt: string[] } {
   }
 }
 
+function coverageTimeoutArgs(): string[] {
+  return [
+    ...positiveIntArg('DSH_COVERAGE_TEST_TIMEOUT_MS', '--testTimeout'),
+    ...positiveIntArg('DSH_COVERAGE_TEST_TIMEOUT_MS', '--expect.poll.timeout'),
+  ]
+}
+
 function coverageGates(): Gate[] {
   const workers = coverageWorkerArgs()
+  const timeouts = coverageTimeoutArgs()
   return [
     pnpmExec('coverage', [
       'vitest',
       'run',
       '--coverage',
       ...workers.instrumented,
+      ...timeouts,
     ], {
       label: 'test:coverage',
       env: { [COVERAGE_EXEMPT_ENV]: '1' },
@@ -510,6 +522,7 @@ function coverageGates(): Gate[] {
       'run',
       ...coverageExemptHeavySuites.map(suite => suite.filter),
       ...workers.exempt,
+      ...timeouts,
     ], {
       label: 'test:coverage-exempt-heavy',
     }),