feat: expand platform management, admin controls, and learning workflows

frontend/src/lib/api.ts

@@ -2,6 +2,12 @@ export const API_BASE =
   process.env.NEXT_PUBLIC_API_BASE ??
   (process.env.NODE_ENV === "development" ? "http://localhost:8080" : "/admin139");
 
+function uiText(zhText: string, enText: string): string {
+  if (typeof window === "undefined") return enText;
+  const lang = window.localStorage.getItem("csp.ui.language");
+  return lang === "zh" ? zhText : enText;
+}
+
 type ApiEnvelope<T> =
   | { ok: true; data?: T; [k: string]: unknown }
   | { ok: false; error?: string; [k: string]: unknown };
@@ -17,11 +23,45 @@ export async function apiFetch<T>(
     headers.set("Content-Type", "application/json");
   }
 
-  const resp = await fetch(`${API_BASE}${path}`, {
-    ...init,
-    headers,
-    cache: "no-store",
-  });
+  const method = (init?.method ?? "GET").toUpperCase();
+  const retryable = method === "GET" || method === "HEAD";
+
+  let resp: Response;
+  try {
+    resp = await fetch(`${API_BASE}${path}`, {
+      ...init,
+      headers,
+      cache: "no-store",
+    });
+  } catch (err) {
+    if (!retryable) {
+      throw new Error(
+        uiText(
+          `网络请求失败，请检查后端服务或代理连接（${err instanceof Error ? err.message : String(err)}）`,
+          `Network request failed. Please check backend/proxy connectivity (${err instanceof Error ? err.message : String(err)}).`
+        )
+      );
+    }
+    await new Promise((resolve) => setTimeout(resolve, 400));
+    try {
+      resp = await fetch(`${API_BASE}${path}`, {
+        ...init,
+        headers,
+        cache: "no-store",
+      });
+    } catch (retryErr) {
+      throw new Error(
+        uiText(
+          `网络请求失败，请检查后端服务或代理连接（${
+            retryErr instanceof Error ? retryErr.message : String(retryErr)
+          }）`,
+          `Network request failed. Please check backend/proxy connectivity (${
+            retryErr instanceof Error ? retryErr.message : String(retryErr)
+          }).`
+        )
+      );
+    }
+  }
 
   const text = await resp.text();
   let payload: unknown = null;