fix(coding): serialize agent server sleep restart

tests/unit/pi-agent-server-process-real.test.ts

@@ -133,6 +133,30 @@ describe('Pi Agent Server real process', () => {
     }
   }, 10_000);
 
+  it('restarts when start races with a graceful background stop', async () => {
+    const root = await mkdtemp(path.join(tmpdir(), 'makelore-pi-agent-server-restart-'));
+    roots.push(root);
+    const layout = await materializePackagedAgentServerLayout(root);
+    const server = new PiAgentServerProcess({
+      executablePath: electronExecutable,
+      ...layout,
+    });
+
+    try {
+      await server.start();
+      const firstProcessId = server.processId;
+      expect(firstProcessId).toBeTypeOf('number');
+
+      const stopping = server.stop();
+      const restarting = server.start();
+      await Promise.all([stopping, restarting]);
+      expect(server.processId).toBeTypeOf('number');
+      expect(server.processId).not.toBe(firstProcessId);
+    } finally {
+      await server.stop();
+    }
+  }, 20_000);
+
   it('hosts isolated Conversation threads in one long-lived process', async () => {
     const root = await mkdtemp(path.join(tmpdir(), 'makelore-pi-agent-server-'));
     roots.push(root);