Show model in history (#13034)

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

@@ -254,6 +254,7 @@ describe('Gemini Client (client.ts)', () => {
       getSkipNextSpeakerCheck: vi.fn().mockReturnValue(false),
       getUseSmartEdit: vi.fn().mockReturnValue(false),
       getUseModelRouter: vi.fn().mockReturnValue(false),
+      getShowModelInfoInChat: vi.fn().mockReturnValue(false),
       getContinueOnFailedApiCall: vi.fn(),
       getProjectRoot: vi.fn().mockReturnValue('/test/project/root'),
       storage: {
@@ -1488,6 +1489,7 @@ ${JSON.stringify(
 
       // Assert
       expect(events).toEqual([
+        { type: GeminiEventType.ModelInfo, value: 'default-routed-model' },
         { type: GeminiEventType.InvalidStream },
         { type: GeminiEventType.Content, value: 'Continued content' },
       ]);
@@ -1539,7 +1541,10 @@ ${JSON.stringify(
       const events = await fromAsync(stream);
 
       // Assert
-      expect(events).toEqual([{ type: GeminiEventType.InvalidStream }]);
+      expect(events).toEqual([
+        { type: GeminiEventType.ModelInfo, value: 'default-routed-model' },
+        { type: GeminiEventType.InvalidStream },
+      ]);
 
       // Verify that turn.run was called only once
       expect(mockTurnRunFn).toHaveBeenCalledTimes(1);
@@ -1573,10 +1578,12 @@ ${JSON.stringify(
       const events = await fromAsync(stream);
 
       // Assert
-      // We expect 2 InvalidStream events (original + 1 retry)
-      expect(events.length).toBe(2);
+      // We expect 3 events (model_info + original + 1 retry)
+      expect(events.length).toBe(3);
       expect(
-        events.every((e) => e.type === GeminiEventType.InvalidStream),
+        events
+          .filter((e) => e.type !== GeminiEventType.ModelInfo)
+          .every((e) => e.type === GeminiEventType.InvalidStream),
       ).toBe(true);
 
       // Verify that turn.run was called twice

packages/core/src/core/client.ts

@@ -521,6 +521,7 @@ export class GeminiClient {
       modelToUse = decision.model;
       // Lock the model for the rest of the sequence
       this.currentSequenceModel = modelToUse;
+      yield { type: GeminiEventType.ModelInfo, value: modelToUse };
     }
 
     const resultStream = turn.run(modelToUse, request, linkedSignal);

packages/core/src/core/turn.ts

@@ -62,6 +62,7 @@ export enum GeminiEventType {
   Retry = 'retry',
   ContextWindowWillOverflow = 'context_window_will_overflow',
   InvalidStream = 'invalid_stream',
+  ModelInfo = 'model_info',
 }
 
 export type ServerGeminiRetryEvent = {
@@ -80,6 +81,11 @@ export type ServerGeminiInvalidStreamEvent = {
   type: GeminiEventType.InvalidStream;
 };
 
+export type ServerGeminiModelInfoEvent = {
+  type: GeminiEventType.ModelInfo;
+  value: string;
+};
+
 export interface StructuredError {
   message: string;
   status?: number;
@@ -212,7 +218,8 @@ export type ServerGeminiStreamEvent =
   | ServerGeminiUserCancelledEvent
   | ServerGeminiRetryEvent
   | ServerGeminiContextWindowWillOverflowEvent
-  | ServerGeminiInvalidStreamEvent;
+  | ServerGeminiInvalidStreamEvent
+  | ServerGeminiModelInfoEvent;
 
 // A turn manages the agentic loop turn within the server context.
 export class Turn {