perf(test): drop rstest maxWorkers pins, isolate per RSTEST_WORKER_ID

packages/agent-bundle/tests/dev-workbench-packaging.test.ts

@@ -1,5 +1,5 @@
 import { execFile as executeFile } from 'node:child_process';
-import { access, mkdtemp, mkdir, readFile, readdir, rm, writeFile } from 'node:fs/promises';
+import { access, cp, mkdtemp, mkdir, readFile, readdir, rm, writeFile } from 'node:fs/promises';
 import { createServer } from 'node:net';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
@@ -16,13 +16,7 @@ const workbenchRoot = join(workspaceRoot, 'packages', 'workbench');
 const appRendererLicense = join('src', 'mcp', 'APP-RENDERER-LICENSE');
 let built: Promise<void> | undefined;
 
-const buildPackage = async (force = false): Promise<void> => {
-  if (force) {
-    // The stale-asset pruning test rebuilds on purpose; the prebuilt seam
-    // never skips it because the rebuild itself is the behavior under test.
-    await execFile('pnpm', ['build'], { cwd: workspaceRoot });
-    return;
-  }
+const buildPackage = async (): Promise<void> => {
   if (process.env['AGENT_BUNDLE_PACKAGE_PREBUILT'] === '1') return;
   built ??= execFile('pnpm', ['build'], { cwd: workspaceRoot }).then(() => undefined);
   await built;
@@ -57,17 +51,26 @@ it('copies stable prebuilt workbench assets and the exact app-renderer license i
 
 it('prunes stale copied workbench assets without removing the package library output', async () => {
   await buildPackage();
-  const workbench = join(packageRoot, 'dist', 'workbench');
-  const stale = join(workbench, 'static', 'js', 'async', 'stale-nested.js');
-  await mkdir(join(workbench, 'static', 'js', 'async'), { recursive: true });
-  await writeFile(stale, 'obsolete workbench output\n');
-  await expect(access(stale)).resolves.toBeUndefined();
-
-  await buildPackage(true);
-
-  await expect(access(stale)).rejects.toThrow();
-  await expect(access(join(packageRoot, 'dist', 'cli.js'))).resolves.toBeUndefined();
-  expect(await readdir(workbench, { recursive: true })).not.toContain('index.js.map');
+  const isolatedRoot = await mkdtemp(join(tmpdir(), 'agent-bundle-workbench-prune-'));
+  const isolatedDist = join(isolatedRoot, 'dist');
+  try {
+    await cp(join(packageRoot, 'dist'), isolatedDist, { recursive: true });
+    const workbench = join(isolatedDist, 'workbench');
+    const stale = join(workbench, 'static', 'js', 'async', 'stale-nested.js');
+    await mkdir(join(workbench, 'static', 'js', 'async'), { recursive: true });
+    await writeFile(stale, 'obsolete workbench output\n');
+    await expect(access(stale)).resolves.toBeUndefined();
+    await execFile(join(workspaceRoot, 'node_modules', '.bin', 'rslib'), [
+      'build',
+      '--config', join(packageRoot, 'rslib.config.ts'),
+      '--dist-path', isolatedDist,
+    ], { cwd: workspaceRoot });
+    await expect(access(stale)).rejects.toThrow();
+    await expect(access(join(isolatedDist, 'cli.js'))).resolves.toBeUndefined();
+    expect(await readdir(workbench, { recursive: true })).not.toContain('index.js.map');
+  } finally {
+    await rm(isolatedRoot, { force: true, recursive: true });
+  }
 }, 60_000);
 
 it('serves prebuilt workbench assets from an installed tarball without the repository source tree', async () => {
@@ -83,7 +86,7 @@ it('serves prebuilt workbench assets from an installed tarball without the repos
     expect(listing.stdout).not.toMatch(/package\/dist\/workbench\/.*-[a-f0-9]{8,}/iu);
 
     await writeFile(join(consumer, 'package.json'), '{"type":"module"}\n');
-    await execFile('npm', ['install', ...npmInstallArguments, tarball], { cwd: consumer });
+    await execFile('npm', ['install', ...npmInstallArguments, tarball], { cwd: consumer, env: installedEnvironment() });
     await mkdir(join(project, 'skills', 'review'), { recursive: true });
     await Promise.all([
       writeFile(join(project, 'package.json'), '{"type":"module"}\n'),
@@ -99,7 +102,7 @@ it('serves prebuilt workbench assets from an installed tarball without the repos
       '  console.log(JSON.stringify({ body: await response.text(), status: response.status }));',
       '} finally { await session.close(); }',
     ].join('\n');
-    const served = await execFile(process.execPath, ['--input-type=module', '--eval', script], { cwd: consumer });
+    const served = await execFile(process.execPath, ['--input-type=module', '--eval', script], { cwd: consumer, env: installedEnvironment() });
     expect(JSON.parse(served.stdout)).toMatchObject({
       body: expect.stringContaining('Agent Bundle workbench'),
       status: 200,
@@ -115,7 +118,7 @@ it('runs the Agent API from an omit-dev installed tarball with its runtime MCP d
   const project = join(consumer, 'project');
   try {
     await writeFile(join(consumer, 'package.json'), '{"type":"module"}\n');
-    await execFile('npm', ['install', '--omit=dev', ...npmInstallArguments, tarball], { cwd: consumer });
+    await execFile('npm', ['install', '--omit=dev', ...npmInstallArguments, tarball], { cwd: consumer, env: installedEnvironment() });
     await mkdir(join(project, 'skills', 'review'), { recursive: true });
     await Promise.all([
       writeFile(join(project, 'package.json'), '{"type":"module"}\n'),

packages/agent-bundle/tests/helpers/project-fixture.ts

@@ -1,7 +1,8 @@
 import { mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises';
-import { tmpdir } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
 
+import { rstestWorkerRoot } from '../../../../rstest.worker-isolation.ts';
+
 export interface ProjectFixture {
   configPath: string;
   imagePath: string;
@@ -33,7 +34,7 @@ const sourceEntryPoint = resolve(
 export const createProjectFixture = async (
   options: ProjectFixtureOptions = {},
 ): Promise<ProjectFixture> => {
-  const root = await mkdtemp(join(tmpdir(), options.prefix ?? 'agent-bundle-config-'));
+  const root = await mkdtemp(join(rstestWorkerRoot(), options.prefix ?? 'agent-bundle-config-'));
   const skillDir = join(root, 'skills/review');
   const skillSource = join(skillDir, 'SKILL.md');
   const imagePath = join(skillDir, 'assets/diagram.png');

packages/agent-bundle/tests/public-api-packed.test.ts

@@ -6,6 +6,7 @@ import { promisify } from 'node:util';
 
 import { expect, it } from '@rstest/core';
 
+import { isolatedCommandEnvironment } from '../../../rstest.worker-isolation.ts';
 import { writeFixtureManifest } from './support/manifest.ts';
 import { npmInstallArguments, sharedPackedTarball } from './support/shared-pack.ts';
 
@@ -59,7 +60,7 @@ it('writes the package version as the producer of a packed CLI manifest', async
     await writeFile(join(consumerRoot, 'package.json'), '{"type":"module"}\n');
     await execFile(
       'npm', ['install', ...npmInstallArguments, tarball],
-      { cwd: consumerRoot },
+      { cwd: consumerRoot, env: isolatedCommandEnvironment() },
     );
 
     const project = await createBuildProject(consumerRoot);
@@ -91,7 +92,7 @@ it('imports the externalized config entry from a packed npm consumer', async ()
     await execFile(
       'npm',
       ['install', ...npmInstallArguments, tarball],
-      { cwd: consumerRoot },
+      { cwd: consumerRoot, env: isolatedCommandEnvironment() },
     );
 
     expect((await stat(join(packageRoot, 'dist/config.js'))).size).toBeLessThan(
@@ -106,7 +107,7 @@ it('imports the externalized config entry from a packed npm consumer', async ()
           "import { defineConfig } from 'agent-bundle/config';",
           'if (defineConfig !== rootDefineConfig) throw new Error(\'config factory identity mismatch\');',
         ].join('\n'),
-      ], { cwd: consumerRoot }),
+      ], { cwd: consumerRoot, env: isolatedCommandEnvironment() }),
     ).resolves.toMatchObject({ stderr: '', stdout: '' });
     await symlink(
       join(workspaceRoot, 'node_modules', '@types'),
@@ -138,7 +139,7 @@ it('imports the externalized config entry from a packed npm consumer', async ()
       '--target', 'es2022',
       '--types', 'node',
       'config.mts',
-    ], { cwd: consumerRoot })).resolves.toMatchObject({ stderr: '', stdout: '' });
+    ], { cwd: consumerRoot, env: isolatedCommandEnvironment() })).resolves.toMatchObject({ stderr: '', stdout: '' });
   } finally {
     await rm(consumerRoot, { force: true, recursive: true });
   }
@@ -199,7 +200,7 @@ it('invokes a prebuilt MCP server from a clean packed consumer', async () => {
     await execFile(
       'npm',
       ['install', ...npmInstallArguments, tarball],
-      { cwd: consumerRoot },
+      { cwd: consumerRoot, env: isolatedCommandEnvironment() },
     );
     const { stdout } = await execFile(process.execPath, [
       '--input-type=module',
@@ -209,7 +210,7 @@ it('invokes a prebuilt MCP server from a clean packed consumer', async () => {
         "const result = await new McpService().invoke({ artifact: './artifact', input: {}, server: 'fixture', target: 'portable', tool: 'inspect' });",
         'console.log(JSON.stringify(result));',
       ].join('\n'),
-    ], { cwd: consumerRoot });
+    ], { cwd: consumerRoot, env: isolatedCommandEnvironment() });
     expect(JSON.parse(stdout)).toMatchObject({
       result: {
         content: [{ text: 'packed result', type: 'text' }],

packages/agent-bundle/tests/release-audit.test.ts

@@ -6,13 +6,14 @@ import { promisify } from 'node:util';
 
 import { expect, it } from '@rstest/core';
 
+import { isolatedCommandEnvironment } from '../../../rstest.worker-isolation.ts';
 import { npmInstallArguments, sharedPackedTarball } from './support/shared-pack.ts';
 
 const execFile = promisify(executeFile);
 const workspaceRoot = process.cwd();
 const packageRoot = join(workspaceRoot, 'packages', 'agent-bundle');
 
-const releaseEnvironment = (): NodeJS.ProcessEnv => ({ ...process.env, NODE_ENV: 'production' });
+const releaseEnvironment = (): NodeJS.ProcessEnv => isolatedCommandEnvironment({ ...process.env, NODE_ENV: 'production' });
 
 it('audits an externally installed production tarball and generates its CycloneDX SBOM', async () => {
   const { stdout } = await execFile(process.execPath, ['scripts/audit-packed-release.mjs'], {

packages/agent-bundle/tests/rsc-runtime-optional-packaging.test.ts

@@ -1,12 +1,12 @@
 import { execFile as executeFile } from 'node:child_process';
-import { cp, mkdtemp, readdir, rm } from 'node:fs/promises';
+import { cp, mkdtemp, readdir, rm, writeFile } from 'node:fs/promises';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { promisify } from 'node:util';
 
 import { describe, expect, it } from '@rstest/core';
 
-import { npmInstallArguments, sharedPackedTarball } from './support/shared-pack.ts';
+import { installedEnvironment, npmInstallArguments, sharedPackedTarball } from './support/shared-pack.ts';
 
 const execFile = promisify(executeFile);
 const workspaceRoot = process.cwd();
@@ -42,11 +42,12 @@ describe.sequential('optional RSC runtime package boundary', () => {
     const project = join(consumer, 'project');
     const artifact = join(project, '.agent-bundle', 'artifact');
     try {
+      await writeFile(join(consumer, 'package.json'), '{"name":"rsc-optional-consumer","type":"module"}\n');
       const tarListing = (await execFile('tar', ['-tf', tarball])).stdout;
       expect(tarListing).not.toMatch(/examples\/rsc-agent-runtime|react-server-dom-rspack|rsbuild-plugin-rsc/u);
 
-      await execFile('npm', ['install', ...npmInstallArguments, tarball], { cwd: consumer });
-      const dependencyTree = JSON.parse((await execFile('npm', ['ls', '--all', '--json'], { cwd: consumer })).stdout) as InstalledDependencyTree;
+      await execFile('npm', ['install', ...npmInstallArguments, tarball], { cwd: consumer, env: installedEnvironment() });
+      const dependencyTree = JSON.parse((await execFile('npm', ['ls', '--all', '--json'], { cwd: consumer, env: installedEnvironment() })).stdout) as InstalledDependencyTree;
       const installedNames = installedDependencyNames(dependencyTree);
       for (const name of ['react', 'react-dom', 'react-server-dom-rspack', 'rsbuild-plugin-rsc']) {
         expect(installedNames).not.toContain(name);
@@ -69,7 +70,7 @@ describe.sequential('optional RSC runtime package boundary', () => {
         "  process.stdout.write(JSON.stringify({ diagnostics: validated.diagnostics, runtimeBody: await runtimeResponse.json(), runtimeStatus: runtimeResponse.status, status: session.status(), surfacesBody: await surfacesResponse.json(), surfacesStatus: surfacesResponse.status, targets: inspected.model.targets.map(({ name }) => name) }));",
         '} finally { await session.close(); }',
       ].join('\n');
-      const result = JSON.parse((await execFile(process.execPath, ['--input-type=module', '--eval', script], { cwd: consumer })).stdout) as Readonly<{
+      const result = JSON.parse((await execFile(process.execPath, ['--input-type=module', '--eval', script], { cwd: consumer, env: installedEnvironment() })).stdout) as Readonly<{
         readonly diagnostics: unknown;
         readonly runtimeBody: unknown;
         readonly runtimeStatus: number;

packages/agent-bundle/tests/support/shared-pack.ts

@@ -5,6 +5,8 @@ import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { promisify } from 'node:util';
 
+import { isolatedCommandEnvironment } from '../../../../rstest.worker-isolation.ts';
+
 const execFile = promisify(executeFile);
 const workspaceRoot = process.cwd();
 
@@ -21,10 +23,12 @@ export interface SharedPack {
 
 export type SharedPackPackage = 'agent-bundle' | 'create-agent-bundle';
 
-export const installedEnvironment = (): NodeJS.ProcessEnv => {
-  const { NODE_PATH: _nodePath, ...environment } = process.env;
-  return environment;
-};
+/**
+ * NODE_PATH-free environment with per-command npm cache and tmp roots under
+ * the worker's RSTEST_WORKER_ID directory (see rstest.worker-isolation.ts),
+ * so concurrent workers never contend on shared npm or tmp state.
+ */
+export const installedEnvironment = (): NodeJS.ProcessEnv => isolatedCommandEnvironment();
 
 /** Canonical flags for installing a packed tarball into a consumer fixture. */
 export const npmInstallArguments = ['--ignore-scripts', '--no-audit', '--no-fund'] as const;

packages/agent-bundle/tests/support/time-scale.ts

@@ -5,9 +5,10 @@
  * costs nothing on green runs - polling assertions return on success - and
  * the workflow-level timeout-minutes still bounds real hangs.
  *
- * AGENT_BUNDLE_TEST_TIME_SCALE (set by rstest.integration.config.ts when the
- * pool runs multiple workers) covers the same contention on development
+ * AGENT_BUNDLE_TEST_TIME_SCALE covers the same contention on development
  * machines, where concurrent Chrome + dev-server + rsbuild pairs share cores.
+ * rstest.integration.config.ts sets it locally from core count without pinning
+ * workers. CI always uses 4, independent of pool size.
  */
 const localScale = Number(process.env['AGENT_BUNDLE_TEST_TIME_SCALE'] ?? '');
 export const timeScale = process.env['CI'] !== undefined

rstest.config.ts

@@ -9,9 +9,7 @@ export default defineConfig({
     'packages/**/tests/**/*.test.ts',
   ],
   exclude: [...templateTestFiles],
-  // Several integration tests run Rslib, whose build cache and configured
-  // output paths are process-shared. Keep those builds from racing each other.
-  pool: { maxWorkers: 1 },
+  setupFiles: ['./rstest.setup.ts'],
   // isolate: false would cut Playwright startup cost, but the log pipeline
   // suites rely on per-file module isolation (verified: logs-real.e2e fails
   // when sharing a worker with the other log suites).

rstest.integration-tests.ts

@@ -73,8 +73,8 @@ export const integrationTestFiles: readonly string[] = [
  * native-host-smoke workflow keep them covered — and stay excluded from the
  * parallel unit pool. packed-release.e2e lives here (not in the integration
  * pool) so `pnpm test` and the release gates don't each run the same long
- * packed-browser suite; `rstest.packed.config.ts` keeps `test:packed` on one
- * worker.
+ * packed-browser suite. `rstest.packed.config.ts` does not cap `test:packed`
+ * workers; pack destinations and tmp roots are per RSTEST_WORKER_ID.
  */
 export const packedTestFiles: readonly string[] = [
   'packages/agent-bundle/tests/dev-workbench-packaging.test.ts',

rstest.integration.config.ts

@@ -6,53 +6,43 @@ import { integrationTestFiles } from './rstest.integration-tests.ts';
 import { withAgentBundleRslibConfig } from './rstest.rslib.ts';
 
 /**
- * Worker count for the parallel integration pool. Half the cores keeps
- * browser + dev-server pairs from starving each other and the cap of 4 bounds
- * memory on large machines. CI pins one worker explicitly: hosted runners
- * report 4 cores (which would compute 2 workers), but each Chrome +
- * dev-server + rsbuild pair already saturates them, and 2-worker matrix runs
- * flaked on a rotating test per leg even at timeScale 4. Parallelism is a
- * development-machine speedup; CI keeps the serialized shape it was tuned
- * for. AGENT_BUNDLE_INTEGRATION_MAX_WORKERS overrides the computed value
- * (e.g. to measure a parallel CI run or bisect locally in serial).
+ * Rstest computes worker count from CPU and command mode when pool.maxWorkers
+ * is omitted. Shared cache, tmp, and pack roots are isolated per worker via
+ * RSTEST_WORKER_ID (see rstest.setup.ts).
  */
-const overrideWorkers = Number(process.env['AGENT_BUNDLE_INTEGRATION_MAX_WORKERS'] ?? '');
-const maxWorkers = Number.isSafeInteger(overrideWorkers) && overrideWorkers >= 1
-  ? overrideWorkers
-  : process.env['CI'] !== undefined
-    ? 1
-    : Math.max(1, Math.min(4, Math.floor(availableParallelism() / 2)));
 
 /**
- * Polling budgets scale with contention. A multi-worker pool needs at least
- * 2 (see the env comment below); an externally set
- * AGENT_BUNDLE_TEST_TIME_SCALE raises it further when the machine is shared —
- * scripts/local-ci.mjs passes 4 (hosted CI's own scale) because it runs
- * three Node legs plus the release gates concurrently. The external value
- * never lowers the scale below what the pool shape requires.
+ * Polling budgets scale with contention. The auto-sized pool runs multiple
+ * workers on any multi-core machine, which needs at least 2 (see the env
+ * comment below); an externally set AGENT_BUNDLE_TEST_TIME_SCALE raises it
+ * further when the machine is shared — scripts/local-ci.mjs passes 4 (hosted
+ * CI's own scale) because it runs three Node legs plus the release gates
+ * concurrently. The external value never lowers the scale below what the
+ * pool shape requires.
  */
 const externalTimeScale = Number(process.env['AGENT_BUNDLE_TEST_TIME_SCALE'] ?? '');
-const poolTimeScale = maxWorkers > 1 ? 2 : 1;
+const poolTimeScale = availableParallelism() > 1 ? 2 : 1;
 const timeScale = Number.isSafeInteger(externalTimeScale) && externalTimeScale >= 1
   ? Math.max(externalTimeScale, poolTimeScale)
   : poolTimeScale;
 
 /**
  * Build- and process-running tests that only read workspace-shared artifacts;
  * files that WRITE shared locations (root builds, `npm pack`) run through the
- * single-worker `test:packed` script instead (see rstest.integration-tests.ts).
+ * `test:packed` script instead (see rstest.integration-tests.ts).
  */
 export default defineConfig({
   extends: withAgentBundleRslibConfig(),
   include: [...integrationTestFiles],
-  pool: { maxWorkers },
+  setupFiles: ['./rstest.setup.ts'],
+  // isolate: false would cut Playwright startup cost, but the log pipeline
+  // suites rely on per-file module isolation (verified: logs-real.e2e fails
+  // when sharing a worker with the other log suites).
+  isolate: true,
   // Concurrent Chrome + dev-server + rsbuild pairs contend for cores, so
   // parallel runs double the polling budgets (see tests/support/time-scale.ts)
   // and raise the 5s default test timeout, which real in-process builds can
   // exceed when workers share the machine. Explicit per-test timeouts win.
   env: { AGENT_BUNDLE_TEST_TIME_SCALE: String(timeScale) },
   testTimeout: 30_000,
-  // isolate: false would cut Playwright startup cost, but the log pipeline
-  // suites rely on per-file module isolation (verified: logs-real.e2e fails
-  // when sharing a worker with the other log suites).
 });