Fix: Preserve conversation history when changing auth methods via /auth (#5216)

Co-authored-by: Jacob Richman <jacob314@gmail.com>

packages/core/src/config/config.test.ts

@@ -184,6 +184,87 @@ describe('Server Config (config.ts)', () => {
       // Verify that fallback mode is reset
       expect(config.isInFallbackMode()).toBe(false);
     });
+
+    it('should preserve conversation history when refreshing auth', async () => {
+      const config = new Config(baseParams);
+      const authType = AuthType.USE_GEMINI;
+      const mockContentConfig = {
+        model: 'gemini-pro',
+        apiKey: 'test-key',
+      };
+
+      (createContentGeneratorConfig as Mock).mockReturnValue(mockContentConfig);
+
+      // Mock the existing client with some history
+      const mockExistingHistory = [
+        { role: 'user', parts: [{ text: 'Hello' }] },
+        { role: 'model', parts: [{ text: 'Hi there!' }] },
+        { role: 'user', parts: [{ text: 'How are you?' }] },
+      ];
+
+      const mockExistingClient = {
+        isInitialized: vi.fn().mockReturnValue(true),
+        getHistory: vi.fn().mockReturnValue(mockExistingHistory),
+      };
+
+      const mockNewClient = {
+        isInitialized: vi.fn().mockReturnValue(true),
+        getHistory: vi.fn().mockReturnValue([]),
+        setHistory: vi.fn(),
+        initialize: vi.fn().mockResolvedValue(undefined),
+      };
+
+      // Set the existing client
+      (
+        config as unknown as { geminiClient: typeof mockExistingClient }
+      ).geminiClient = mockExistingClient;
+      (GeminiClient as Mock).mockImplementation(() => mockNewClient);
+
+      await config.refreshAuth(authType);
+
+      // Verify that existing history was retrieved
+      expect(mockExistingClient.getHistory).toHaveBeenCalled();
+
+      // Verify that new client was created and initialized
+      expect(GeminiClient).toHaveBeenCalledWith(config);
+      expect(mockNewClient.initialize).toHaveBeenCalledWith(mockContentConfig);
+
+      // Verify that history was restored to the new client
+      expect(mockNewClient.setHistory).toHaveBeenCalledWith(
+        mockExistingHistory,
+      );
+    });
+
+    it('should handle case when no existing client is initialized', async () => {
+      const config = new Config(baseParams);
+      const authType = AuthType.USE_GEMINI;
+      const mockContentConfig = {
+        model: 'gemini-pro',
+        apiKey: 'test-key',
+      };
+
+      (createContentGeneratorConfig as Mock).mockReturnValue(mockContentConfig);
+
+      const mockNewClient = {
+        isInitialized: vi.fn().mockReturnValue(true),
+        getHistory: vi.fn().mockReturnValue([]),
+        setHistory: vi.fn(),
+        initialize: vi.fn().mockResolvedValue(undefined),
+      };
+
+      // No existing client
+      (config as unknown as { geminiClient: null }).geminiClient = null;
+      (GeminiClient as Mock).mockImplementation(() => mockNewClient);
+
+      await config.refreshAuth(authType);
+
+      // Verify that new client was created and initialized
+      expect(GeminiClient).toHaveBeenCalledWith(config);
+      expect(mockNewClient.initialize).toHaveBeenCalledWith(mockContentConfig);
+
+      // Verify that setHistory was not called since there was no existing history
+      expect(mockNewClient.setHistory).not.toHaveBeenCalled();
+    });
   });
 
   it('Config constructor should store userMemory correctly', () => {

packages/core/src/config/config.ts

@@ -47,6 +47,7 @@ import { ClearcutLogger } from '../telemetry/clearcut-logger/clearcut-logger.js'
 import { shouldAttemptBrowserLaunch } from '../utils/browser.js';
 import { MCPOAuthConfig } from '../mcp/oauth-provider.js';
 import { IdeClient } from '../ide/ide-client.js';
+import type { Content } from '@google/genai';
 
 // Re-export OAuth config type
 export type { MCPOAuthConfig };
@@ -332,13 +333,30 @@ export class Config {
   }
 
   async refreshAuth(authMethod: AuthType) {
-    this.contentGeneratorConfig = createContentGeneratorConfig(
+    // Save the current conversation history before creating a new client
+    let existingHistory: Content[] = [];
+    if (this.geminiClient && this.geminiClient.isInitialized()) {
+      existingHistory = this.geminiClient.getHistory();
+    }
+
+    // Create new content generator config
+    const newContentGeneratorConfig = createContentGeneratorConfig(
       this,
       authMethod,
     );
 
-    this.geminiClient = new GeminiClient(this);
-    await this.geminiClient.initialize(this.contentGeneratorConfig);
+    // Create and initialize new client in local variable first
+    const newGeminiClient = new GeminiClient(this);
+    await newGeminiClient.initialize(newContentGeneratorConfig);
+
+    // Only assign to instance properties after successful initialization
+    this.contentGeneratorConfig = newContentGeneratorConfig;
+    this.geminiClient = newGeminiClient;
+
+    // Restore the conversation history to the new client
+    if (existingHistory.length > 0) {
+      this.geminiClient.setHistory(existingHistory);
+    }
 
     // Reset the session flag since we're explicitly changing auth and using default model
     this.inFallbackMode = false;