feat: add Pi subagent scheduler and child runtime

tests/unit/pi-worker-process-real.test.ts

@@ -73,4 +73,53 @@ describe('locked Pi worker process smoke', () => {
       await extensionHost.close();
     }
   }, 15_000);
+
+  it('starts a real ephemeral read-only child with the child extension role', async () => {
+    const requireFromProject = createRequire(resolve('package.json'));
+    const electronExecutable = requireFromProject('electron') as string;
+    const packageRoot = realpathSync(resolve(
+      'node_modules',
+      '@earendil-works',
+      'pi-coding-agent',
+    ));
+    const root = await mkdtemp(join(tmpdir(), 'makelore-pi-real-child-'));
+    scratchRoots.push(root);
+    const configDir = join(root, 'config');
+    const sessionDir = join(root, 'sessions');
+    const cwd = join(root, 'project');
+    await Promise.all([mkdir(configDir), mkdir(sessionDir), mkdir(cwd)]);
+
+    const extensionHost = new PiManagedExtensionHost();
+    const extension = await extensionHost.registerWorker({
+      conversationId: 'real-parent',
+      generation: 1,
+      projectId: 'real-project',
+      extensionsDir: join(root, 'extensions'),
+      role: 'child',
+      runId: 'real-parent-run',
+    });
+    const worker = await new PiWorkerProcess({
+      executablePath: electronExecutable,
+      cliPath: join(packageRoot, 'dist', 'cli.js'),
+      cwd,
+      configDir,
+      sessionDir,
+      tools: ['read', 'grep', 'find', 'ls'],
+      additionalArgs: ['--extension', extension.extensionPath, '--no-session'],
+      env: extension.env,
+      sensitiveValues: extension.sensitiveValues,
+      commandTimeoutMs: 5_000,
+    }).start();
+    try {
+      await expect(worker.request({ type: 'get_state' })).resolves.toMatchObject({
+        type: 'response', command: 'get_state', success: true,
+      });
+      expect(worker.stderrDiagnostic).not.toContain('Failed to load extension');
+      await expect(worker.stop()).resolves.toMatchObject({ mode: 'stdin-close', code: 0 });
+    } finally {
+      await worker.stop().catch(() => undefined);
+      await extension.dispose();
+      await extensionHost.close();
+    }
+  }, 15_000);
 });