fix(cli): allow closing debug console after auto-open via flicker

packages/cli/src/ui/AppContainer.tsx

@@ -1520,28 +1520,14 @@ Logging in with Google... Restarting Gemini CLI to continue.
       if (keyMatchers[Command.SHOW_ERROR_DETAILS](key)) {
         if (settings.merged.general.devtools) {
           void (async () => {
-            try {
-              const { startDevToolsServer } = await import(
-                '../utils/devtoolsService.js'
-              );
-              const { openBrowserSecurely, shouldLaunchBrowser } = await import(
-                '@google/gemini-cli-core'
-              );
-              const url = await startDevToolsServer(config);
-              if (shouldLaunchBrowser()) {
-                try {
-                  await openBrowserSecurely(url);
-                } catch (e) {
-                  setShowErrorDetails((prev) => !prev);
-                  debugLogger.warn('Failed to open browser securely:', e);
-                }
-              } else {
-                setShowErrorDetails((prev) => !prev);
-              }
-            } catch (e) {
-              setShowErrorDetails(true);
-              debugLogger.error('Failed to start DevTools server:', e);
-            }
+            const { toggleDevToolsPanel } = await import(
+              '../utils/devtoolsService.js'
+            );
+            await toggleDevToolsPanel(
+              config,
+              () => setShowErrorDetails((prev) => !prev),
+              () => setShowErrorDetails(true),
+            );
           })();
         } else {
           setShowErrorDetails((prev) => !prev);

packages/cli/src/utils/devtoolsService.test.ts

@@ -70,12 +70,20 @@ vi.mock('./activityLogger.js', () => ({
   },
 }));
 
+const mockShouldLaunchBrowser = vi.hoisted(() => vi.fn(() => true));
+const mockOpenBrowserSecurely = vi.hoisted(() =>
+  vi.fn(() => Promise.resolve()),
+);
+
 vi.mock('@google/gemini-cli-core', () => ({
   debugLogger: {
     log: vi.fn(),
     debug: vi.fn(),
     error: vi.fn(),
+    warn: vi.fn(),
   },
+  shouldLaunchBrowser: mockShouldLaunchBrowser,
+  openBrowserSecurely: mockOpenBrowserSecurely,
 }));
 
 vi.mock('ws', () => ({
@@ -92,6 +100,7 @@ vi.mock('gemini-cli-devtools', () => ({
 import {
   setupInitialActivityLogger,
   startDevToolsServer,
+  toggleDevToolsPanel,
   resetForTesting,
 } from './devtoolsService.js';
 
@@ -426,4 +435,86 @@ describe('devtoolsService', () => {
       expect(mockAddNetworkTransport).toHaveBeenCalledTimes(3);
     });
   });
+
+  describe('toggleDevToolsPanel', () => {
+    it('calls toggle when browser opens successfully', async () => {
+      const config = createMockConfig();
+      const toggle = vi.fn();
+      const setOpen = vi.fn();
+
+      mockShouldLaunchBrowser.mockReturnValue(true);
+      mockOpenBrowserSecurely.mockResolvedValue(undefined);
+      mockDevToolsInstance.start.mockResolvedValue('http://127.0.0.1:25417');
+      mockDevToolsInstance.getPort.mockReturnValue(25417);
+
+      const promise = toggleDevToolsPanel(config, toggle, setOpen);
+
+      await vi.waitFor(() => expect(MockWebSocket.instances.length).toBe(1));
+      MockWebSocket.instances[0].simulateError();
+
+      await promise;
+
+      expect(toggle).toHaveBeenCalledTimes(1);
+      expect(setOpen).not.toHaveBeenCalled();
+    });
+
+    it('calls toggle when browser fails to open', async () => {
+      const config = createMockConfig();
+      const toggle = vi.fn();
+      const setOpen = vi.fn();
+
+      mockShouldLaunchBrowser.mockReturnValue(true);
+      mockOpenBrowserSecurely.mockRejectedValue(new Error('no browser'));
+      mockDevToolsInstance.start.mockResolvedValue('http://127.0.0.1:25417');
+      mockDevToolsInstance.getPort.mockReturnValue(25417);
+
+      const promise = toggleDevToolsPanel(config, toggle, setOpen);
+
+      await vi.waitFor(() => expect(MockWebSocket.instances.length).toBe(1));
+      MockWebSocket.instances[0].simulateError();
+
+      await promise;
+
+      expect(toggle).toHaveBeenCalledTimes(1);
+      expect(setOpen).not.toHaveBeenCalled();
+    });
+
+    it('calls toggle when shouldLaunchBrowser returns false', async () => {
+      const config = createMockConfig();
+      const toggle = vi.fn();
+      const setOpen = vi.fn();
+
+      mockShouldLaunchBrowser.mockReturnValue(false);
+      mockDevToolsInstance.start.mockResolvedValue('http://127.0.0.1:25417');
+      mockDevToolsInstance.getPort.mockReturnValue(25417);
+
+      const promise = toggleDevToolsPanel(config, toggle, setOpen);
+
+      await vi.waitFor(() => expect(MockWebSocket.instances.length).toBe(1));
+      MockWebSocket.instances[0].simulateError();
+
+      await promise;
+
+      expect(toggle).toHaveBeenCalledTimes(1);
+      expect(setOpen).not.toHaveBeenCalled();
+    });
+
+    it('calls setOpen when DevTools server fails to start', async () => {
+      const config = createMockConfig();
+      const toggle = vi.fn();
+      const setOpen = vi.fn();
+
+      mockDevToolsInstance.start.mockRejectedValue(new Error('fail'));
+
+      const promise = toggleDevToolsPanel(config, toggle, setOpen);
+
+      await vi.waitFor(() => expect(MockWebSocket.instances.length).toBe(1));
+      MockWebSocket.instances[0].simulateError();
+
+      await promise;
+
+      expect(toggle).not.toHaveBeenCalled();
+      expect(setOpen).toHaveBeenCalledTimes(1);
+    });
+  });
 });

packages/cli/src/utils/devtoolsService.ts

@@ -210,6 +210,35 @@ async function startDevToolsServerImpl(config: Config): Promise<string> {
   return url;
 }
 
+/**
+ * Handles the F12 key toggle for the DevTools panel.
+ * Starts the DevTools server, attempts to open the browser,
+ * and always calls the toggle callback regardless of the outcome.
+ */
+export async function toggleDevToolsPanel(
+  config: Config,
+  toggle: () => void,
+  setOpen: () => void,
+): Promise<void> {
+  try {
+    const { openBrowserSecurely, shouldLaunchBrowser } = await import(
+      '@google/gemini-cli-core'
+    );
+    const url = await startDevToolsServer(config);
+    if (shouldLaunchBrowser()) {
+      try {
+        await openBrowserSecurely(url);
+      } catch (e) {
+        debugLogger.warn('Failed to open browser securely:', e);
+      }
+    }
+    toggle();
+  } catch (e) {
+    setOpen();
+    debugLogger.error('Failed to start DevTools server:', e);
+  }
+}
+
 /** Reset module-level state — test only. */
 export function resetForTesting() {
   promotionAttempts = 0;