fix: setModel failure

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

@@ -755,7 +755,7 @@ describe('setApprovalMode with folder trust', () => {
       const logModelSwitchSpy = vi.spyOn(config['logger']!, 'logModelSwitch');
 
       // Change the model
-      config.setModel('qwen-vl-max-latest', {
+      await config.setModel('qwen-vl-max-latest', {
         reason: 'vision_auto_switch',
         context: 'Test model switch',
       });
@@ -785,7 +785,7 @@ describe('setApprovalMode with folder trust', () => {
       const logModelSwitchSpy = vi.spyOn(config['logger']!, 'logModelSwitch');
 
       // Set the same model
-      config.setModel('qwen3-coder-plus');
+      await config.setModel('qwen3-coder-plus');
 
       // Verify that logModelSwitch was not called
       expect(logModelSwitchSpy).not.toHaveBeenCalled();
@@ -807,7 +807,7 @@ describe('setApprovalMode with folder trust', () => {
       const logModelSwitchSpy = vi.spyOn(config['logger']!, 'logModelSwitch');
 
       // Change the model without options
-      config.setModel('qwen-vl-max-latest');
+      await config.setModel('qwen-vl-max-latest');
 
       // Verify that logModelSwitch was called with default reason
       expect(logModelSwitchSpy).toHaveBeenCalledWith({

packages/core/src/config/config.ts

@@ -528,13 +528,13 @@ export class Config {
     return this.contentGeneratorConfig?.model || this.model;
   }
 
-  setModel(
+  async setModel(
     newModel: string,
     options?: {
       reason?: ModelSwitchEvent['reason'];
       context?: string;
     },
-  ): void {
+  ): Promise<void> {
     const oldModel = this.getModel();
 
     if (this.contentGeneratorConfig) {
@@ -559,13 +559,16 @@ export class Config {
     // Reinitialize chat with updated configuration while preserving history
     const geminiClient = this.getGeminiClient();
     if (geminiClient && geminiClient.isInitialized()) {
-      // Use async operation but don't await to avoid blocking
-      geminiClient.reinitialize().catch((error) => {
+      // Now await the reinitialize operation to ensure completion
+      try {
+        await geminiClient.reinitialize();
+      } catch (error) {
         console.error(
           'Failed to reinitialize chat with updated config:',
           error,
         );
-      });
+        throw error; // Re-throw to let callers handle the error
+      }
     }
   }
 

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

@@ -41,7 +41,7 @@ describe('Flash Model Fallback Configuration', () => {
   // with the fallback mechanism. This will be necessary we introduce more
   // intelligent model routing.
   describe('setModel', () => {
-    it('should only mark as switched if contentGeneratorConfig exists', () => {
+    it('should only mark as switched if contentGeneratorConfig exists', async () => {
       // Create config without initializing contentGeneratorConfig
       const newConfig = new Config({
         sessionId: 'test-session-2',
@@ -52,15 +52,15 @@ describe('Flash Model Fallback Configuration', () => {
       });
 
       // Should not crash when contentGeneratorConfig is undefined
-      newConfig.setModel(DEFAULT_GEMINI_FLASH_MODEL);
+      await newConfig.setModel(DEFAULT_GEMINI_FLASH_MODEL);
       expect(newConfig.isInFallbackMode()).toBe(false);
     });
   });
 
   describe('getModel', () => {
-    it('should return contentGeneratorConfig model if available', () => {
+    it('should return contentGeneratorConfig model if available', async () => {
       // Simulate initialized content generator config
-      config.setModel(DEFAULT_GEMINI_FLASH_MODEL);
+      await config.setModel(DEFAULT_GEMINI_FLASH_MODEL);
       expect(config.getModel()).toBe(DEFAULT_GEMINI_FLASH_MODEL);
     });
 
@@ -88,8 +88,8 @@ describe('Flash Model Fallback Configuration', () => {
       expect(config.isInFallbackMode()).toBe(false);
     });
 
-    it('should persist switched state throughout session', () => {
-      config.setModel(DEFAULT_GEMINI_FLASH_MODEL);
+    it('should persist switched state throughout session', async () => {
+      await config.setModel(DEFAULT_GEMINI_FLASH_MODEL);
       // Setting state for fallback mode as is expected of clients
       config.setFallbackMode(true);
       expect(config.isInFallbackMode()).toBe(true);

packages/core/src/core/client.ts

@@ -1053,7 +1053,7 @@ export class GeminiClient {
           error,
         );
         if (accepted !== false && accepted !== null) {
-          this.config.setModel(fallbackModel);
+          await this.config.setModel(fallbackModel);
           this.config.setFallbackMode(true);
           return fallbackModel;
         }

packages/core/src/core/geminiChat.ts

@@ -224,7 +224,7 @@ export class GeminiChat {
           error,
         );
         if (accepted !== false && accepted !== null) {
-          this.config.setModel(fallbackModel);
+          await this.config.setModel(fallbackModel);
           this.config.setFallbackMode(true);
           return fallbackModel;
         }

packages/core/src/subagents/subagent.test.ts

@@ -72,6 +72,19 @@ async function createMockConfig(
   } as unknown as ToolRegistry;
 
   vi.spyOn(config, 'getToolRegistry').mockReturnValue(mockToolRegistry);
+
+  // Mock getContentGeneratorConfig to return a valid config
+  vi.spyOn(config, 'getContentGeneratorConfig').mockReturnValue({
+    model: DEFAULT_GEMINI_MODEL,
+    authType: AuthType.USE_GEMINI,
+  });
+
+  // Mock setModel method
+  vi.spyOn(config, 'setModel').mockResolvedValue();
+
+  // Mock getSessionId method
+  vi.spyOn(config, 'getSessionId').mockReturnValue('test-session');
+
   return { config, toolRegistry: mockToolRegistry };
 }
 

packages/core/src/subagents/subagent.ts

@@ -826,7 +826,7 @@ export class SubAgentScope {
       );
 
       if (this.modelConfig.model) {
-        this.runtimeContext.setModel(this.modelConfig.model);
+        await this.runtimeContext.setModel(this.modelConfig.model);
       }
 
       return new GeminiChat(