feat: support course-specific Qwen endpoints

src/ai/agent.service.ts

@@ -66,6 +66,7 @@ export class AgentService {
       provider: setting.provider as AiProvider,
       model: setting.model,
       apiKey: this.credentialService.decrypt(setting.encryptedApiKey),
+      endpointUrl: setting.endpointUrl,
       json: true,
       system: this.systemPrompt(),
       messages: [{

src/ai/ai-provider.service.spec.ts

@@ -10,7 +10,7 @@ describe('AiProviderService', () => {
     jest.restoreAllMocks();
   });
 
-  it('calls the Qwen OpenAI-compatible chat endpoint', async () => {
+  it('prefers the course Qwen endpoint over the server default', async () => {
     const fetchMock = jest.fn().mockResolvedValue({
       ok: true,
       status: 200,
@@ -20,20 +20,21 @@ describe('AiProviderService', () => {
       }),
     });
     global.fetch = fetchMock as typeof fetch;
-    const config = { get: jest.fn().mockReturnValue('https://example.test/compatible-mode/v1') } as unknown as ConfigService;
+    const config = { get: jest.fn().mockReturnValue('https://server-default.test/compatible-mode/v1') } as unknown as ConfigService;
     const service = new AiProviderService(config);
 
     const result = await service.complete({
       provider: 'QWEN',
       model: 'qwen3.7-plus',
       apiKey: 'qwen-secret',
+      endpointUrl: 'https://course-endpoint.test/compatible-mode/v1',
       system: 'system prompt',
       messages: [{ role: 'user', content: 'hello' }],
       json: true,
     });
 
     expect(result.content).toBe('{"ok":true}');
-    expect(fetchMock).toHaveBeenCalledWith('https://example.test/compatible-mode/v1/chat/completions', expect.objectContaining({
+    expect(fetchMock).toHaveBeenCalledWith('https://course-endpoint.test/compatible-mode/v1/chat/completions', expect.objectContaining({
       method: 'POST',
       headers: expect.objectContaining({ Authorization: 'Bearer qwen-secret' }),
     }));

src/ai/ai-provider.service.ts

@@ -7,6 +7,7 @@ type CompletionInput = {
   provider: AiProvider;
   model: string;
   apiKey: string;
+  endpointUrl?: string | null;
   system: string;
   messages: Array<{ role: 'user' | 'assistant'; content: string }>;
   json?: boolean;
@@ -105,7 +106,7 @@ export class AiProviderService {
   }
 
   private async qwen(input: CompletionInput): Promise<AiCompletionResult> {
-    const configuredUrl = this.configService.get<string>('QWEN_API_BASE_URL')?.trim();
+    const configuredUrl = input.endpointUrl?.trim() || this.configService.get<string>('QWEN_API_BASE_URL')?.trim();
     const normalizedUrl = configuredUrl?.replace(/\/+$/, '');
     const endpoint = normalizedUrl
       ? `${normalizedUrl}${normalizedUrl.endsWith('/chat/completions') ? '' : '/chat/completions'}`

src/ai/dto/update-course-ai-setting.dto.ts

@@ -14,6 +14,11 @@ export class UpdateCourseAiSettingDto {
   @MaxLength(120)
   model: string;
 
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  endpointUrl?: string;
+
   @IsOptional()
   @IsString()
   @MaxLength(500)