feat: Add startup profiler to measure and record application initialization phases. (#13638)

packages/cli/src/core/initializer.ts

@@ -12,6 +12,7 @@ import {
   type Config,
   StartSessionEvent,
   logCliConfiguration,
+  startupProfiler,
 } from '@google/gemini-cli-core';
 import { type LoadedSettings } from '../config/settings.js';
 import { performInitialAuth } from './auth.js';
@@ -35,10 +36,12 @@ export async function initializeApp(
   config: Config,
   settings: LoadedSettings,
 ): Promise<InitializationResult> {
+  const authHandle = startupProfiler.start('authenticate');
   const authError = await performInitialAuth(
     config,
     settings.merged.security?.auth?.selectedType,
   );
+  authHandle?.end();
   const themeError = validateTheme(settings);
 
   const shouldOpenAuthDialog =