feat(ai): 完成 DeepSeek 大模型官方 API 接入、双模调用、高可用平滑降级与管理后台连通性测试

backend/test/modules/ai/chat.test.ts

@@ -160,6 +160,24 @@ describe('T36: 名片 AI 顾问对话 (modules/ai chat)', () => {
       expect(result.shouldCollectLead).toBe(true);
       expect(/[\u4e00-\u9fff]/.test(result.reply)).toBe(true);
     });
+
+    it('当 DeepSeekService 已配置时优先调用大模型，失败时平滑降级', async () => {
+      const mockDeepSeek = {
+        isConfigured: jest.fn().mockReturnValue(true),
+        chatCompletion: jest.fn().mockResolvedValue('这是 DeepSeek 大模型生成的拟人顾问回复'),
+      };
+      service.deepSeekService = mockDeepSeek as any;
+
+      const res = await service.ask(userAsk('你们都有什么服务？'));
+      expect(res.reply).toBe('这是 DeepSeek 大模型生成的拟人顾问回复');
+      expect(mockDeepSeek.chatCompletion).toHaveBeenCalled();
+
+      // 测试异常平滑降级
+      mockDeepSeek.chatCompletion.mockRejectedValue(new Error('Network error'));
+      const fallbackRes = await service.ask(userAsk('你好', { locale: 'zh-CN' }));
+      expect(fallbackRes.reply).toBeTruthy();
+      expect(fallbackRes.reply).toContain('智能顾问');
+    });
   });
 
   describe('3. OpenAiChatController /open/ai/chat', () => {