fix: close and recreate macOS windows safely

tests/unit/agent-browser-core.test.ts

@@ -1742,6 +1742,67 @@ describe('AgentBrowserModule', () => {
     expect(adapter.resetPartitions).toEqual([agentBrowserPartition(projectPath)]);
   });
 
+  it.each(['close', 'replace-preview', 'switch-project'] as const)(
+    'waits for old preview cleanup and cancels stale opens when reopening after %s',
+    async (scenario) => {
+      const adapter = new FakeAdapter();
+      const preview = new FakePreviewDataSession();
+      adapter.onCreate = (view) => {
+        view.webContents.debugger.responders.set('Page.addScriptToEvaluateOnNewDocument', async () => ({
+          identifier: 'script-root',
+        }));
+      };
+      const module = new AgentBrowserModule(adapter, { previewDataSession: preview });
+      await module.open({
+        projectId: 'clock', projectPath, url: 'http://127.0.0.1:4173/', injectProjectData: true,
+      });
+      let finishCleanup!: () => void;
+      const cleanup = new Promise<void>((resolve) => { finishCleanup = resolve; });
+      const cleanupStarted = vi.fn(async () => await cleanup);
+      adapter.views[0].webContents.debugger.responders.set(
+        'Page.removeScriptToEvaluateOnNewDocument', cleanupStarted,
+      );
+      const superseded = scenario === 'close' ? undefined : module.open({
+        projectId: 'clock',
+        projectPath: scenario === 'switch-project' ? `${projectPath}-other` : projectPath,
+        url: 'http://localhost:3001/',
+      });
+      const supersededResult = superseded?.catch((error: unknown) => error);
+      if (superseded) await vi.waitFor(() => expect(cleanupStarted).toHaveBeenCalledOnce());
+
+      const closing = module.close();
+      await vi.waitFor(() => expect(cleanupStarted).toHaveBeenCalledOnce());
+      const reopening = module.open({
+        projectId: 'clock', projectPath, url: 'http://localhost:3002/',
+      });
+      await Promise.resolve();
+      expect(adapter.views).toHaveLength(1);
+
+      finishCleanup();
+      await expect(closing).resolves.toMatchObject({ state: 'closed' });
+      if (supersededResult) await expect(supersededResult).resolves.toMatchObject({ code: 'CLOSED' });
+      await expect(reopening).resolves.toMatchObject({
+        state: 'attached', generation: 2, url: 'http://localhost:3002/',
+      });
+      expect(adapter.views).toHaveLength(2);
+      expect(adapter.destroyed).toBe(1);
+      expect(adapter.views[1].webContents.destroyed).toBe(false);
+    },
+  );
+
+  it('cleans up a new view if its host window has already closed', async () => {
+    const adapter = new FakeAdapter();
+    vi.spyOn(adapter, 'mount').mockImplementation(() => { throw new Error('window-closed'); });
+    const module = new AgentBrowserModule(adapter);
+
+    await expect(module.open({
+      projectId: 'clock', projectPath, url: 'http://localhost:3001/',
+    })).rejects.toThrow('window-closed');
+    expect(adapter.destroyed).toBe(1);
+    expect(adapter.views[0].webContents.destroyed).toBe(true);
+    await expect(module.getSnapshot()).resolves.toMatchObject({ state: 'closed' });
+  });
+
   it('does not reopen a project partition until profile reset has finished', async () => {
     const adapter = new FakeAdapter();
     let finishReset: (() => void) | undefined;