fix(cli): resolve environment loading and auth validation issues in ACP mode (#18025)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/cli/src/zed-integration/zedIntegration.ts

@@ -40,7 +40,7 @@ import { AcpFileSystemService } from './fileSystemService.js';
 import { Readable, Writable } from 'node:stream';
 import type { Content, Part, FunctionCall } from '@google/genai';
 import type { LoadedSettings } from '../config/settings.js';
-import { SettingScope } from '../config/settings.js';
+import { SettingScope, loadSettings } from '../config/settings.js';
 import * as fs from 'node:fs/promises';
 import * as path from 'node:path';
 import { z } from 'zod';
@@ -139,7 +139,11 @@ export class GeminiAgent {
     // Refresh auth with the requested method
     // This will reuse existing credentials if they're valid,
     // or perform new authentication if needed
-    await this.config.refreshAuth(method);
+    try {
+      await this.config.refreshAuth(method);
+    } catch (e) {
+      throw new acp.RequestError(getErrorStatus(e) || 401, getErrorMessage(e));
+    }
     this.settings.setValue(
       SettingScope.User,
       'security.auth.selectedType',
@@ -152,12 +156,47 @@ export class GeminiAgent {
     mcpServers,
   }: acp.NewSessionRequest): Promise<acp.NewSessionResponse> {
     const sessionId = randomUUID();
-    const config = await this.initializeSessionConfig(
+    const loadedSettings = loadSettings(cwd);
+    const config = await this.newSessionConfig(
       sessionId,
       cwd,
       mcpServers,
+      loadedSettings,
     );
 
+    const authType =
+      loadedSettings.merged.security.auth.selectedType || AuthType.USE_GEMINI;
+
+    let isAuthenticated = false;
+    let authErrorMessage = '';
+    try {
+      await config.refreshAuth(authType);
+      isAuthenticated = true;
+
+      // Extra validation for Gemini API key
+      const contentGeneratorConfig = config.getContentGeneratorConfig();
+      if (
+        authType === AuthType.USE_GEMINI &&
+        (!contentGeneratorConfig || !contentGeneratorConfig.apiKey)
+      ) {
+        isAuthenticated = false;
+        authErrorMessage = 'Gemini API key is missing or not configured.';
+      }
+    } catch (e) {
+      isAuthenticated = false;
+      authErrorMessage = getErrorMessage(e);
+      debugLogger.error(
+        `Authentication failed: ${e instanceof Error ? e.stack : e}`,
+      );
+    }
+
+    if (!isAuthenticated) {
+      throw new acp.RequestError(
+        401,
+        authErrorMessage || 'Authentication required.',
+      );
+    }
+
     if (this.clientCapabilities?.fs) {
       const acpFileSystemService = new AcpFileSystemService(
         this.connection,
@@ -168,6 +207,9 @@ export class GeminiAgent {
       config.setFileSystemService(acpFileSystemService);
     }
 
+    await config.initialize();
+    startupProfiler.flush(config);
+
     const geminiClient = config.getGeminiClient();
     const chat = await geminiClient.startChat();
     const session = new Session(sessionId, chat, config, this.connection);
@@ -264,8 +306,10 @@ export class GeminiAgent {
     sessionId: string,
     cwd: string,
     mcpServers: acp.McpServer[],
+    loadedSettings?: LoadedSettings,
   ): Promise<Config> {
-    const mergedMcpServers = { ...this.settings.merged.mcpServers };
+    const currentSettings = loadedSettings || this.settings;
+    const mergedMcpServers = { ...currentSettings.merged.mcpServers };
 
     for (const server of mcpServers) {
       if (
@@ -300,7 +344,10 @@ export class GeminiAgent {
       }
     }
 
-    const settings = { ...this.settings.merged, mcpServers: mergedMcpServers };
+    const settings = {
+      ...currentSettings.merged,
+      mcpServers: mergedMcpServers,
+    };
 
     const config = await loadCliConfig(settings, sessionId, this.argv, { cwd });
 
@@ -497,7 +544,10 @@ export class Session {
           return { stopReason: 'cancelled' };
         }
 
-        throw error;
+        throw new acp.RequestError(
+          getErrorStatus(error) || 500,
+          getErrorMessage(error),
+        );
       }
 
       if (functionCalls.length > 0) {