's'

app/api/vip/check-by-user/route.ts

@@ -15,6 +15,8 @@ type PayjsVipResult = {
   email?: string;
 };
 
+const inflightUserChecks = new Map<string, Promise<PayjsVipResult | null>>();
+
 async function fetchPayjsVipWithRetry(
   url: string,
   timeoutMs: number,
@@ -51,6 +53,12 @@ async function checkVipFromPayjsapi(
   request: NextRequest,
   userId: string
 ): Promise<PayjsVipResult | null> {
+  const existed = inflightUserChecks.get(userId);
+  if (existed) {
+    return existed;
+  }
+
+  const task = (async () => {
   try {
     const apiUrl = resolvePayApiUrl(request);
     const url = `${apiUrl}/nomadvip/check_vip?user_id=${encodeURIComponent(
@@ -95,6 +103,14 @@ async function checkVipFromPayjsapi(
     );
     return null;
   }
+  })();
+
+  inflightUserChecks.set(userId, task);
+  try {
+    return await task;
+  } finally {
+    inflightUserChecks.delete(userId);
+  }
 }
 
 export async function POST(request: NextRequest) {