feat(acp): add set models interface (#20991)

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

@@ -173,6 +173,8 @@ describe('GeminiAgent', () => {
       }),
       getApprovalMode: vi.fn().mockReturnValue('default'),
       isPlanEnabled: vi.fn().mockReturnValue(false),
+      getGemini31LaunchedSync: vi.fn().mockReturnValue(false),
+      getHasAccessToPreviewModel: vi.fn().mockReturnValue(false),
       getCheckpointingEnabled: vi.fn().mockReturnValue(false),
     } as unknown as Mocked<Awaited<ReturnType<typeof loadCliConfig>>>;
     mockSettings = {
@@ -304,6 +306,38 @@ describe('GeminiAgent', () => {
       ],
       currentModeId: 'default',
     });
+    expect(response.models).toEqual({
+      availableModels: expect.arrayContaining([
+        expect.objectContaining({
+          modelId: 'auto-gemini-2.5',
+          name: 'Auto (Gemini 2.5)',
+        }),
+      ]),
+      currentModelId: 'gemini-pro',
+    });
+  });
+
+  it('should include preview models when user has access', async () => {
+    mockConfig.getHasAccessToPreviewModel = vi.fn().mockReturnValue(true);
+    mockConfig.getGemini31LaunchedSync = vi.fn().mockReturnValue(true);
+
+    const response = await agent.newSession({
+      cwd: '/tmp',
+      mcpServers: [],
+    });
+
+    expect(response.models?.availableModels).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          modelId: 'auto-gemini-3',
+          name: expect.stringContaining('Auto'),
+        }),
+        expect.objectContaining({
+          modelId: 'gemini-3.1-pro-preview',
+          name: 'gemini-3.1-pro-preview',
+        }),
+      ]),
+    );
   });
 
   it('should return modes with plan mode when plan is enabled', async () => {
@@ -331,6 +365,15 @@ describe('GeminiAgent', () => {
       ],
       currentModeId: 'plan',
     });
+    expect(response.models).toEqual({
+      availableModels: expect.arrayContaining([
+        expect.objectContaining({
+          modelId: 'auto-gemini-2.5',
+          name: 'Auto (Gemini 2.5)',
+        }),
+      ]),
+      currentModelId: 'gemini-pro',
+    });
   });
 
   it('should fail session creation if Gemini API key is missing', async () => {
@@ -480,6 +523,32 @@ describe('GeminiAgent', () => {
       }),
     ).rejects.toThrow('Session not found: unknown');
   });
+
+  it('should delegate setModel to session (unstable)', async () => {
+    await agent.newSession({ cwd: '/tmp', mcpServers: [] });
+    const session = (
+      agent as unknown as { sessions: Map<string, Session> }
+    ).sessions.get('test-session-id');
+    if (!session) throw new Error('Session not found');
+    session.setModel = vi.fn().mockReturnValue({});
+
+    const result = await agent.unstable_setSessionModel({
+      sessionId: 'test-session-id',
+      modelId: 'gemini-2.0-pro-exp',
+    });
+
+    expect(session.setModel).toHaveBeenCalledWith('gemini-2.0-pro-exp');
+    expect(result).toEqual({});
+  });
+
+  it('should throw error when setting model on non-existent session (unstable)', async () => {
+    await expect(
+      agent.unstable_setSessionModel({
+        sessionId: 'unknown',
+        modelId: 'gemini-2.0-pro-exp',
+      }),
+    ).rejects.toThrow('Session not found: unknown');
+  });
 });
 
 describe('Session', () => {
@@ -528,6 +597,7 @@ describe('Session', () => {
       getDebugMode: vi.fn().mockReturnValue(false),
       getMessageBus: vi.fn().mockReturnValue(mockMessageBus),
       setApprovalMode: vi.fn(),
+      setModel: vi.fn(),
       isPlanEnabled: vi.fn().mockReturnValue(false),
       getCheckpointingEnabled: vi.fn().mockReturnValue(false),
       getGitService: vi.fn().mockResolvedValue({} as GitService),
@@ -1383,6 +1453,12 @@ describe('Session', () => {
       'Invalid or unavailable mode: invalid-mode',
     );
   });
+
+  it('should set model on config', () => {
+    session.setModel('gemini-2.0-flash-exp');
+    expect(mockConfig.setModel).toHaveBeenCalledWith('gemini-2.0-flash-exp');
+  });
+
   it('should handle unquoted commands from autocomplete (with empty leading parts)', async () => {
     // Mock handleCommand to verify it gets called
     const handleCommandSpy = vi