fix(core): restrict "System: Please continue" invalid stream retry to Gemini 2 models (#20897)

Author: SandyTao520

packages/core/src/core/client.test.ts

@@ -1892,11 +1892,16 @@ ${JSON.stringify(
       );
     });
 
-    it('should recursively call sendMessageStream with "Please continue." when InvalidStream event is received', async () => {
+    it('should recursively call sendMessageStream with "Please continue." when InvalidStream event is received for Gemini 2 models', async () => {
       vi.spyOn(client['config'], 'getContinueOnFailedApiCall').mockReturnValue(
         true,
       );
-      // Arrange
+      // Arrange - router must return a Gemini 2 model for retry to trigger
+      mockRouterService.route.mockResolvedValue({
+        model: 'gemini-2.0-flash',
+        reason: 'test',
+      });
+
       const mockStream1 = (async function* () {
         yield { type: GeminiEventType.InvalidStream };
       })();
@@ -1926,7 +1931,7 @@ ${JSON.stringify(
 
       // Assert
       expect(events).toEqual([
-        { type: GeminiEventType.ModelInfo, value: 'default-routed-model' },
+        { type: GeminiEventType.ModelInfo, value: 'gemini-2.0-flash' },
         { type: GeminiEventType.InvalidStream },
         { type: GeminiEventType.Content, value: 'Continued content' },
       ]);
@@ -1937,7 +1942,7 @@ ${JSON.stringify(
       // First call with original request
       expect(mockTurnRunFn).toHaveBeenNthCalledWith(
         1,
-        { model: 'default-routed-model', isChatModel: true },
+        { model: 'gemini-2.0-flash', isChatModel: true },
         initialRequest,
         expect.any(AbortSignal),
         undefined,
@@ -1946,7 +1951,7 @@ ${JSON.stringify(
       // Second call with "Please continue."
       expect(mockTurnRunFn).toHaveBeenNthCalledWith(
         2,
-        { model: 'default-routed-model', isChatModel: true },
+        { model: 'gemini-2.0-flash', isChatModel: true },
         [{ text: 'System: Please continue.' }],
         expect.any(AbortSignal),
         undefined,
@@ -1990,11 +1995,57 @@ ${JSON.stringify(
       expect(mockTurnRunFn).toHaveBeenCalledTimes(1);
     });
 
+    it('should not retry with "Please continue." when InvalidStream event is received for non-Gemini-2 models', async () => {
+      vi.spyOn(client['config'], 'getContinueOnFailedApiCall').mockReturnValue(
+        true,
+      );
+      // Arrange - router returns a non-Gemini-2 model
+      mockRouterService.route.mockResolvedValue({
+        model: 'gemini-3.0-pro',
+        reason: 'test',
+      });
+
+      const mockStream1 = (async function* () {
+        yield { type: GeminiEventType.InvalidStream };
+      })();
+
+      mockTurnRunFn.mockReturnValueOnce(mockStream1);
+
+      const mockChat: Partial<GeminiChat> = {
+        addHistory: vi.fn(),
+        setTools: vi.fn(),
+        getHistory: vi.fn().mockReturnValue([]),
+        getLastPromptTokenCount: vi.fn(),
+      };
+      client['chat'] = mockChat as GeminiChat;
+
+      const initialRequest = [{ text: 'Hi' }];
+      const promptId = 'prompt-id-invalid-stream-non-g2';
+      const signal = new AbortController().signal;
+
+      // Act
+      const stream = client.sendMessageStream(initialRequest, signal, promptId);
+      const events = await fromAsync(stream);
+
+      // Assert
+      expect(events).toEqual([
+        { type: GeminiEventType.ModelInfo, value: 'gemini-3.0-pro' },
+        { type: GeminiEventType.InvalidStream },
+      ]);
+
+      // Verify that turn.run was called only once (no retry)
+      expect(mockTurnRunFn).toHaveBeenCalledTimes(1);
+    });
+
     it('should stop recursing after one retry when InvalidStream events are repeatedly received', async () => {
       vi.spyOn(client['config'], 'getContinueOnFailedApiCall').mockReturnValue(
         true,
       );
-      // Arrange
+      // Arrange - router must return a Gemini 2 model for retry to trigger
+      mockRouterService.route.mockResolvedValue({
+        model: 'gemini-2.0-flash',
+        reason: 'test',
+      });
       // Always return a new invalid stream
       mockTurnRunFn.mockImplementation(() =>
         (async function* () {
@@ -2025,7 +2076,7 @@ ${JSON.stringify(
         events
           .filter((e) => e.type === GeminiEventType.ModelInfo)
           .map((e) => e.value),
-      ).toEqual(['default-routed-model']);
+      ).toEqual(['gemini-2.0-flash']);
 
       // Verify that turn.run was called twice
       expect(mockTurnRunFn).toHaveBeenCalledTimes(2);

packages/core/src/core/client.ts

@@ -60,7 +60,7 @@ import {
   applyModelSelection,
   createAvailabilityContextProvider,
 } from '../availability/policyHelpers.js';
-import { resolveModel } from '../config/models.js';
+import { resolveModel, isGemini2Model } from '../config/models.js';
 import type { RetryAvailabilityContext } from '../utils/retry.js';
 import { partToString } from '../utils/partUtils.js';
 import { coreEvents, CoreEvent } from '../utils/events.js';
@@ -725,7 +725,10 @@ export class GeminiClient {
     }
 
     if (isInvalidStream) {
-      if (this.config.getContinueOnFailedApiCall()) {
+      if (
+        this.config.getContinueOnFailedApiCall() &&
+        isGemini2Model(modelToUse)
+      ) {
         if (isInvalidStreamRetry) {
           logContentRetryFailure(
             this.config,