perf: keep affected coverage on CI

docs/agents/testing.md

@@ -188,9 +188,9 @@ hand-maintained path map:
   implicitly.
 - **Always-on gates** (`lint`, `typecheck`, `layering`, `fallow`, `format`) fire
   for their input categories and are never silently skipped. Legacy
-  `src/platforms/` source also selects provider-integration and coverage.
+  `src/platforms/` source also selects provider-integration and reports coverage as CI-owned.
   `packages/platform-*` source selects the shared runtime-contract unit lane,
-  provider-integration, and coverage so a package move cannot narrow its evidence.
+  provider-integration, and CI-owned coverage so a package move cannot narrow its evidence.
 - **Commands** are resolved from real `package.json` scripts, so a renamed
   script fails loudly instead of dropping a gate.
 - A **small explicit build-ownership layer** covers the paths whose owning build
@@ -224,11 +224,10 @@ docs-only short-circuit its path would otherwise take. If the matrix moves
 again, move that entry with it.
 The plan documents the rule and changed path behind every selected check.
 
-Local coverage reuses the affected Vitest run as its LCOV producer and applies the changed-line
-coverage gate to that report. It does not run the full instrumented suite; global coverage
-thresholds and full unit/provider matrices remain authoritative in GitHub CI. When coverage is
-selected, `vitest-related` is folded into this one affected coverage run, and full unit/provider
-aggregates are not repeated locally.
+Coverage is never instrumented by `check:affected --run`. The plan still reports the coverage
+obligation and its authoritative GitHub job, while the local path runs plain `vitest related` and
+deduplicates full unit/provider aggregates. When CI reports a coverage failure, reproduce it in
+isolation with the coverage command named by that job; do not make every pre-push loop pay for LCOV.
 
 Model and catalog live under `scripts/check-affected/`; the derivation is guarded
 by `pnpm check:affected:test` (the `Affected-check Selector` CI job).

scripts/check-affected/checks.ts

@@ -49,7 +49,7 @@ export const CHECK_CATALOG: readonly CheckSpec[] = [
     localRunnable: true,
   },
   gate('unit', 'Unit + smoke suite', 'check:unit'),
-  gate('coverage', 'Affected LCOV + changed-line coverage', 'check:coverage-changed'),
+  gate('coverage', 'Changed-line coverage', 'check:coverage-changed', false),
   gate('provider-integration', 'Provider-backed integration suite', 'test:integration:provider'),
   gate(
     'integration-progress',
@@ -78,8 +78,9 @@ export const CHECK_CATALOG: readonly CheckSpec[] = [
   // steps; before the registry became canonical, nothing in the repo could name
   // them, so nothing could ask whether they still ran.
   //
-  // `unit-ci` is the CI form of the unit suite. Locally you run `unit` and
-  // `coverage`, which together repeat it.
+  // `unit-ci` is the CI form of the unit suite under coverage. Local affected
+  // checks use Vitest's related graph without instrumentation; CI owns the
+  // full coverage run and changed-line verdict.
   gate('unit-ci', 'CI unit suite under coverage', 'test:coverage:ci', false),
   gate('affected-selector', 'Affected-check selector model', 'check:affected:test'),
   gate('gate-manifest', 'Gate manifest — every gate owned and wired', 'check:gate-manifest'),

scripts/check-affected/model.ts

@@ -97,7 +97,7 @@ export const ALL_CHECKS: readonly CheckId[] = [
   'build',
   'package',
   // Real daemon/process integration owns host-global lifecycle state and must
-  // run before the high-parallelism coverage workload heats the host.
+  // run before Vitest's related-project workload heats the host.
   'integration-node',
   'vitest-related',
   'unit',

scripts/check-affected/run.test.ts

@@ -10,7 +10,6 @@ import path from 'node:path';
 import { test } from 'node:test';
 import { runCmdSync } from '../../src/utils/exec.ts';
 import { CHECK_CATALOG } from './checks.ts';
-import { DEFAULT_VITEST_MAX_WORKERS } from '../lib/vitest-concurrency.ts';
 import { selectChecks } from './model.ts';
 import { type CommandExecutor, readChangedFiles, runChecks } from './run.ts';
 
@@ -171,26 +170,29 @@ test('runChecks skips GitHub-authoritative checks and passes when locals succeed
   }
 });
 
-test('runChecks combines related tests with lightweight changed-line coverage', async () => {
+test('runChecks leaves coverage to CI and runs plain related tests once', async () => {
   const executed: string[][] = [];
   const execute: CommandExecutor = async (command) => {
     executed.push(command);
     return 0;
   };
   const plan = selectChecks({ changedFiles: ['unknown/path.xyz'], packageEntryFiles: [] });
+  assert.equal(
+    CHECK_CATALOG.find((spec) => spec.id === 'coverage')?.localRunnable,
+    false,
+    'coverage must stay visible in the plan but must not run locally',
+  );
 
   const code = await runChecks(plan, { scripts: ALL_SCRIPTS }, ARGS, { execute, cwd: '.' });
 
   assert.equal(code, 0);
   const related = executed.filter((command) => command.includes('related'));
   assert.equal(related.length, 1);
-  assert.ok(related[0]?.includes('--coverage'));
-  assert.ok(related[0]?.includes('--coverage.reporter=lcov'));
-  assert.ok(related[0]?.includes(`--maxWorkers=${DEFAULT_VITEST_MAX_WORKERS}`));
+  assert.equal(related[0]?.includes('--coverage'), false);
   assert.ok(
     executed.findIndex((command) => command.includes('test:integration:node')) <
       executed.findIndex((command) => command.includes('related')),
-    'process-lifecycle integration must run before high-parallelism affected coverage',
+    'process-lifecycle integration must run before the related-project workload',
   );
   assert.equal(
     executed.some((command) => command.includes('test:coverage')),
@@ -206,6 +208,6 @@ test('runChecks combines related tests with lightweight changed-line coverage',
   );
   assert.equal(
     executed.some((command) => command.includes('check:coverage-changed')),
-    true,
+    false,
   );
 });

scripts/check-affected/run.ts

@@ -11,7 +11,6 @@ import { pathToFileURL } from 'node:url';
 import { runCmdStreaming, runCmdSync } from '../../src/utils/exec.ts';
 import { parseScriptArgs } from '../lib/cli-args.ts';
 import { runEntrypoint } from '../lib/cli-entrypoint.ts';
-import { DEFAULT_VITEST_MAX_WORKERS } from '../lib/vitest-concurrency.ts';
 import {
   assertCatalogComplete,
   CHECK_CATALOG,
@@ -191,24 +190,22 @@ export async function runChecks(
   const execute = options.execute ?? streamingExecutor;
   const runnable = plan.checks.map(getCheckSpec).filter((spec: CheckSpec) => spec.localRunnable);
   const skipped = plan.checks.map(getCheckSpec).filter((spec: CheckSpec) => !spec.localRunnable);
-  const coverageSelected = plan.checks.includes('coverage');
+  const relatedSelected = plan.checks.includes('vitest-related');
   const ciJobs = skipped.length > 0 ? ciJobsByCheck() : new Map<CheckId, string[]>();
   for (const spec of skipped) {
     process.stdout.write(`\n[skip] ${spec.id} — ${describeOwner(spec.id, ciJobs)}\n`);
   }
   for (const spec of runnable) {
-    if (isCoveredByAffectedCoverage(spec, coverageSelected)) {
-      process.stdout.write(`\n[dedupe] ${spec.id} — covered by affected LCOV or GitHub CI\n`);
+    if (isCoveredByRelatedTests(spec, relatedSelected)) {
+      process.stdout.write(`\n[dedupe] ${spec.id} — covered by related tests or GitHub CI\n`);
       continue;
     }
-    const commands = resolveCheckCommands(spec, pkg, args, options.changedFiles ?? []);
-    for (const command of commands) {
-      process.stdout.write(`\n[run] ${spec.id}: ${command.join(' ')}\n`);
-      const exitCode = await execute(command, cwd);
-      if (exitCode !== 0) {
-        process.stderr.write(`\ncheck:affected: ${spec.id} failed.\n`);
-        return 1;
-      }
+    const command = resolveCommand(spec, pkg.scripts, args.base, options.changedFiles ?? []);
+    process.stdout.write(`\n[run] ${spec.id}: ${command.join(' ')}\n`);
+    const exitCode = await execute(command, cwd);
+    if (exitCode !== 0) {
+      process.stderr.write(`\ncheck:affected: ${spec.id} failed.\n`);
+      return 1;
     }
   }
   process.stdout.write('\ncheck:affected: all runnable checks passed.\n');
@@ -223,54 +220,8 @@ function describeOwner(id: CheckId, ciJobs: ReadonlyMap<CheckId, string[]>): str
   return `GitHub-authoritative (jobs: ${(ciJobs.get(id) ?? []).join(', ')})`;
 }
 
-function isCoveredByAffectedCoverage(spec: CheckSpec, coverageSelected: boolean): boolean {
-  return (
-    coverageSelected &&
-    (spec.id === 'vitest-related' || spec.id === 'unit' || spec.id === 'provider-integration')
-  );
-}
-
-function resolveCheckCommands(
-  spec: CheckSpec,
-  pkg: PackageJson,
-  args: Args,
-  changedFiles: readonly string[],
-): string[][] {
-  return spec.id === 'coverage'
-    ? resolveAffectedCoverageCommands(pkg.scripts, args.base, changedFiles)
-    : [resolveCommand(spec, pkg.scripts, args.base, changedFiles)];
-}
-
-function resolveAffectedCoverageCommands(
-  scripts: Readonly<Record<string, string>>,
-  base: string,
-  changedFiles: readonly string[],
-): string[][] {
-  if (!('check:coverage-changed' in scripts)) {
-    throw new Error('Required package.json script "check:coverage-changed" does not exist.');
-  }
-  return [
-    [
-      'pnpm',
-      'exec',
-      'vitest',
-      'related',
-      '--run',
-      '--passWithNoTests',
-      // `related` spans every configured Vitest project for broad diffs. The
-      // machine-derived default can start enough projects concurrently to
-      // starve otherwise-green subprocess/provider tests past their exact
-      // timeout budgets. Bound this aggregate feedback lane without changing
-      // the suites' own timeout or serialization contracts.
-      `--maxWorkers=${DEFAULT_VITEST_MAX_WORKERS}`,
-      '--coverage',
-      '--coverage.reporter=lcov',
-      '--coverage.thresholds.statements=0',
-      '--coverage.thresholds.lines=0',
-      ...changedFiles,
-    ],
-    ['pnpm', 'run', 'check:coverage-changed', '--base', base],
-  ];
+function isCoveredByRelatedTests(spec: CheckSpec, relatedSelected: boolean): boolean {
+  return relatedSelected && (spec.id === 'unit' || spec.id === 'provider-integration');
 }
 
 async function main(argv = process.argv.slice(2)): Promise<number> {