feat(cli): defer devtools startup and integrate with F12

packages/cli/src/gemini.tsx

@@ -519,10 +519,10 @@ export async function main() {
     adminControlsListner.setConfig(config);
 
     if (config.isInteractive() && settings.merged.general.devtools) {
-      const { registerActivityLogger } = await import(
+      const { setupInitialActivityLogger } = await import(
         './utils/devtoolsService.js'
       );
-      await registerActivityLogger(config);
+      setupInitialActivityLogger(config);
     }
 
     // Register config for telemetry shutdown

packages/cli/src/ui/AppContainer.tsx

@@ -1492,7 +1492,37 @@ Logging in with Google... Restarting Gemini CLI to continue.
       }
 
       if (keyMatchers[Command.SHOW_ERROR_DETAILS](key)) {
-        setShowErrorDetails((prev) => !prev);
+        if (settings.merged.general.devtools) {
+          void (async () => {
+            try {
+              const { startDevToolsServer } = await import(
+                '../utils/devtoolsService.js'
+              );
+              const { openBrowserSecurely } = await import(
+                '@google/gemini-cli-core'
+              );
+              const url = await startDevToolsServer(config);
+              try {
+                await openBrowserSecurely(url);
+              } catch (e) {
+                setShowErrorDetails(true);
+                historyManager.addItem(
+                  {
+                    type: MessageType.INFO,
+                    text: `Failed to open browser. DevTools available at: ${url}`,
+                  },
+                  Date.now(),
+                );
+                debugLogger.warn('Failed to open browser securely:', e);
+              }
+            } catch (e) {
+              setShowErrorDetails(true);
+              debugLogger.error('Failed to start DevTools server:', e);
+            }
+          })();
+        } else {
+          setShowErrorDetails((prev) => !prev);
+        }
         return true;
       } else if (keyMatchers[Command.SUSPEND_APP](key)) {
         const undoMessage = isITerm2()
@@ -1619,6 +1649,8 @@ Logging in with Google... Restarting Gemini CLI to continue.
       lastOutputTimeRef,
       tabFocusTimeoutRef,
       handleWarning,
+      historyManager,
+      settings.merged.general.devtools,
     ],
   );
 

packages/cli/src/ui/hooks/slashCommandProcessor.ts

@@ -702,6 +702,7 @@ export const useSlashCommandProcessor = (
       setIsProcessing,
       setConfirmationRequest,
       setCustomDialog,
+      setPendingItem,
     ],
   );
 

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

@@ -0,0 +1,61 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach } from 'vitest';
+import { ActivityLogger, type NetworkLog } from './activityLogger.js';
+import type { ConsoleLogPayload } from '@google/gemini-cli-core';
+
+describe('ActivityLogger', () => {
+  let logger: ActivityLogger;
+
+  beforeEach(() => {
+    // Reset singleton instance if necessary or just get it
+    logger = ActivityLogger.getInstance();
+    // Manually reset buffers for testing
+    // @ts-expect-error - accessing private member for test
+    logger.networkBuffer = [];
+    // @ts-expect-error - accessing private member for test
+    logger.consoleBuffer = [];
+  });
+
+  it('buffers only the last 10 network requests', () => {
+    for (let i = 0; i < 15; i++) {
+      const log: NetworkLog = {
+        id: `req-${i}`,
+        timestamp: i,
+        method: 'GET',
+        url: 'http://example.com',
+        headers: {},
+      };
+      // @ts-expect-error - accessing private member for test
+      logger.safeEmitNetwork(log);
+    }
+
+    const logs = logger.getBufferedLogs();
+    expect(logs.network.length).toBe(10);
+    expect(logs.network[0].id).toBe('req-5');
+    expect(logs.network[9].id).toBe('req-14');
+  });
+
+  it('buffers only the last 10 console logs', () => {
+    for (let i = 0; i < 15; i++) {
+      const log: ConsoleLogPayload = { content: `log-${i}`, type: 'log' };
+      logger.logConsole(log);
+    }
+
+    const logs = logger.getBufferedLogs();
+    expect(logs.console.length).toBe(10);
+    expect(logs.console[0].content).toBe('log-5');
+    expect(logs.console[9].content).toBe('log-14');
+  });
+
+  it('clears buffers after retrieval', () => {
+    logger.logConsole({ content: 'test', type: 'log' });
+    logger.getBufferedLogs();
+    const logs = logger.getBufferedLogs();
+    expect(logs.console.length).toBe(0);
+  });
+});