perf(cli): background IDE client to speed up initialization (#23603)

packages/cli/src/core/initializer.test.ts

@@ -105,6 +105,9 @@ describe('initializer', () => {
       mockSettings,
     );
 
+    // Wait for the background promise to resolve
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
     expect(result).toEqual({
       authError: null,
       accountSuspensionInfo: null,

packages/cli/src/core/initializer.ts

@@ -13,6 +13,7 @@ import {
   StartSessionEvent,
   logCliConfiguration,
   startupProfiler,
+  debugLogger,
 } from '@google/gemini-cli-core';
 import { type LoadedSettings } from '../config/settings.js';
 import { performInitialAuth } from './auth.js';
@@ -55,9 +56,18 @@ export async function initializeApp(
   );
 
   if (config.getIdeMode()) {
-    const ideClient = await IdeClient.getInstance();
-    await ideClient.connect();
-    logIdeConnection(config, new IdeConnectionEvent(IdeConnectionType.START));
+    IdeClient.getInstance()
+      .then(async (ideClient) => {
+        await ideClient.connect();
+        logIdeConnection(
+          config,
+          new IdeConnectionEvent(IdeConnectionType.START),
+        );
+      })
+      .catch((e) => {
+        // We log locally if IDE connection setup fails in the background.
+        debugLogger.error('Failed to initialize IDE client:', e);
+      });
   }
 
   return {