테블릿 로딩 이슈 수정

frontend/src/utils/upbitWsBroker.ts

@@ -64,6 +64,12 @@ function listenerCount(): number {
   return listeners.size;
 }
 
+function mayOpenSocket(): boolean {
+  if (listenerCount() === 0) return false;
+  if (typeof document !== 'undefined' && document.visibilityState === 'hidden') return false;
+  return true;
+}
+
 function cancelPendingDisconnect(): void {
   if (disconnectTimer) {
     clearTimeout(disconnectTimer);
@@ -134,7 +140,7 @@ function dispatch(text: string): void {
 }
 
 function scheduleReconnect(): void {
-  if (listenerCount() === 0) return;
+  if (!mayOpenSocket()) return;
   if (reconnectTimer) return;
   const delay = Math.min(RECONNECT_BASE * 2 ** retryCount, RECONNECT_MAX);
   retryCount += 1;
@@ -236,6 +242,17 @@ export function subscribeUpbitWsConnection(listener: ConnectionListener): () =>
   return () => connectionListeners.delete(listener);
 }
 
+if (typeof document !== 'undefined') {
+  document.addEventListener('visibilitychange', () => {
+    if (document.visibilityState === 'hidden') {
+      cancelPendingConnect();
+      if (listenerCount() === 0) teardownSocket();
+      return;
+    }
+    if (mayOpenSocket()) scheduleConnect();
+  });
+}
+
 /**
  * 업비트 WS 채널 구독 (참조 카운트). codes 가 비어 있으면 구독하지 않음.
  */