fix(agent): serialize retrieval trace responses

ai_knowledge_base_v2/apps/admin-web/src/services/api.ts

@@ -46,13 +46,25 @@ async function request<T>(path: string, init: RequestInit = {}): Promise<T> {
   const token = getToken();
   if (token) headers.set("Authorization", `Bearer ${token}`);
   const response = await fetch(`${API_BASE}${path}`, { ...init, headers });
-  const body = (await response.json()) as ApiResponse<T> & { detail?: string };
+  const body = await readApiResponse<T>(response);
   if (!response.ok || body.code !== 0) {
     throw new Error(body.detail || body.message || `${response.status} ${response.statusText}`);
   }
   return body.data;
 }
 
+async function readApiResponse<T>(response: Response): Promise<ApiResponse<T> & { detail?: string }> {
+  const text = await response.text();
+  if (!text.trim()) {
+    throw new Error(response.ok ? "接口返回为空" : `服务暂时不可用（${response.status}）`);
+  }
+  try {
+    return JSON.parse(text) as ApiResponse<T> & { detail?: string };
+  } catch {
+    throw new Error(response.ok ? "接口返回格式不正确" : `服务暂时不可用（${response.status}）`);
+  }
+}
+
 async function download(path: string, filename: string) {
   const headers = new Headers();
   const token = getToken();
@@ -73,7 +85,7 @@ async function upload<T>(path: string, formData: FormData): Promise<T> {
   const token = getToken();
   if (token) headers.set("Authorization", `Bearer ${token}`);
   const response = await fetch(`${API_BASE}${path}`, { method: "POST", body: formData, headers });
-  const body = (await response.json()) as ApiResponse<T> & { detail?: string };
+  const body = await readApiResponse<T>(response);
   if (!response.ok || body.code !== 0) {
     throw new Error(body.message || body.detail || `${response.status} ${response.statusText}`);
   }