Changes before error encountered

Co-authored-by: pdf114514 <57948770+pdf114514@users.noreply.github.com>
Agent-Logs-Url: https://github.com/pdf114514/CarReservation/sessions/a42d4e36-a3cf-4ff7-b1cb-f076e601b1b8

frontend/src/hooks/useWebSocket.js

@@ -5,8 +5,9 @@ const WS_BASE = (() => {
   const loc = window.location;
   const proto = loc.protocol === 'https:' ? 'wss:' : 'ws:';
   // Use the same origin as the page; in development the Vite dev server
-  // proxies /ws to the backend, and in production nginx does the same.
-  return `${proto}//${loc.host}/ws`;
+  // proxies /api/ws to the backend, and in production nginx does the same
+  // via the existing location /api/ block (no extra nginx config needed).
+  return `${proto}//${loc.host}/api/ws`;
 })();
 
 const RECONNECT_DELAYS = [1000, 2000, 4000, 8000, 15000, 30000]; // ms
@@ -71,11 +72,30 @@ export default function useWebSocket(onMessage) {
   }, []);
 
   useEffect(() => {
+    // Reset on each mount so that React StrictMode's simulated unmount/remount
+    // does not leave unmountedRef permanently true and block reconnection.
+    unmountedRef.current = false;
     connect();
     return () => {
       unmountedRef.current = true;
       clearTimeout(retryTimerRef.current);
-      wsRef.current?.close();
+      const ws = wsRef.current;
+      if (ws) {
+        // Null out all handlers first to prevent any reconnect attempts.
+        ws.onopen = null;
+        ws.onclose = null;
+        ws.onerror = null;
+        ws.onmessage = null;
+        if (ws.readyState === WebSocket.CONNECTING) {
+          // Closing a CONNECTING socket triggers the browser warning
+          // "WebSocket is closed before the connection is established".
+          // Instead, schedule a close as soon as it opens so the server
+          // isn't left with a permanently idle connection.
+          ws.onopen = () => ws.close();
+        } else if (ws.readyState === WebSocket.OPEN) {
+          ws.close();
+        }
+      }
     };
   }, [connect]);