Attempt to handle false "ended" events with mkv files in Chrome due to blob bug

public/app.js

@@ -13,6 +13,13 @@
   let driftInterval = null;
   let serverState = { playing: false, position: 0, speed: 1 };
 
+  // Reconnection state
+  let reconnectAttempts = 0;
+  let reconnectTimer = null;
+  let isReconnecting = false;
+  let messageQueue = []; // queued messages while disconnected
+  let roomFileInfo = null; // cached file info for the room
+
   // User colors for chat
   const userColors = [
     "#3ea6ff", "#ff7043", "#66bb6a", "#ab47bc",
@@ -106,11 +113,27 @@
 
   // --- WebSocket ---
   function connect() {
+    if (reconnectTimer) {
+      clearTimeout(reconnectTimer);
+      reconnectTimer = null;
+    }
+
     const protocol = location.protocol === "https:" ? "wss:" : "ws:";
     ws = new WebSocket(`${protocol}//${location.host}/ws`);
 
     ws.addEventListener("open", () => {
       console.log("WebSocket connected");
+      reconnectAttempts = 0;
+
+      // If we were in a room, auto-rejoin
+      if (isReconnecting && roomCode && username) {
+        console.log("Auto-rejoining room", roomCode);
+        ws.send(JSON.stringify({
+          type: "rejoin_room",
+          username,
+          code: roomCode,
+        }));
+      }
     });
 
     ws.addEventListener("message", (e) => {
@@ -120,9 +143,10 @@
 
     ws.addEventListener("close", () => {
       console.log("WebSocket disconnected");
-      // Attempt reconnect after 2s if in room
       if (roomCode) {
-        setTimeout(() => connect(), 2000);
+        isReconnecting = true;
+        showConnectionStatus("reconnecting");
+        scheduleReconnect();
       }
     });
 
@@ -131,9 +155,54 @@
     });
   }
 
+  function scheduleReconnect() {
+    // Exponential backoff: 1s, 2s, 4s, 8s, capped at 10s
+    const delay = Math.min(1000 * Math.pow(2, reconnectAttempts), 10000);
+    reconnectAttempts++;
+    console.log(`Reconnecting in ${delay}ms (attempt ${reconnectAttempts})`);
+    reconnectTimer = setTimeout(() => connect(), delay);
+  }
+
   function send(data) {
     if (ws && ws.readyState === WebSocket.OPEN) {
       ws.send(JSON.stringify(data));
+    } else if (roomCode) {
+      // Queue messages while disconnected
+      if (data.type === "sync") {
+        // Only keep the latest sync message (stale syncs are useless)
+        const idx = messageQueue.findIndex((m) => m.type === "sync");
+        if (idx >= 0) messageQueue[idx] = data;
+        else messageQueue.push(data);
+      } else {
+        messageQueue.push(data);
+      }
+    }
+  }
+
+  function flushMessageQueue() {
+    if (!ws || ws.readyState !== WebSocket.OPEN) return;
+    const queue = messageQueue.splice(0);
+    for (const msg of queue) {
+      ws.send(JSON.stringify(msg));
+    }
+  }
+
+  // --- Connection Status Indicator ---
+  function showConnectionStatus(status) {
+    const banner = $("connection-status");
+    if (!banner) return;
+
+    if (status === "reconnecting") {
+      banner.textContent = "⚡ Reconnecting...";
+      banner.className = "connection-status reconnecting";
+    } else if (status === "reconnected") {
+      banner.textContent = "✓ Reconnected";
+      banner.className = "connection-status reconnected";
+      setTimeout(() => {
+        banner.className = "connection-status hidden";
+      }, 3000);
+    } else {
+      banner.className = "connection-status hidden";
     }
   }
 
@@ -142,6 +211,7 @@
     switch (msg.type) {
       case "room_created":
         roomCode = msg.code;
+        roomFileInfo = msg.fileInfo;
         enterRoom(msg);
         break;
 
@@ -151,6 +221,7 @@
 
       case "room_joined":
         roomCode = msg.code;
+        roomFileInfo = msg.fileInfo;
         fileCheckModal.classList.add("hidden");
         enterRoom(msg);
         // Apply initial state
@@ -163,11 +234,29 @@
         }
         break;
 
+      case "room_rejoined":
+        // Seamless reconnection — sync to server state
+        isReconnecting = false;
+        showConnectionStatus("reconnected");
+        updateUsers(msg.users);
+        if (msg.state) {
+          applySync(msg.state);
+        }
+        addSystemMessage("Reconnected");
+        startDriftCorrection();
+        flushMessageQueue();
+        break;
+
       case "user_joined":
         updateUsers(msg.users);
         addSystemMessage(`${msg.username} joined`);
         break;
 
+      case "user_rejoined":
+        updateUsers(msg.users);
+        addSystemMessage(`${msg.username} reconnected`);
+        break;
+
       case "user_left":
         updateUsers(msg.users);
         addSystemMessage(`${msg.username} left`);
@@ -187,6 +276,13 @@
         break;
 
       case "error":
+        // If room no longer exists on rejoin, go back to lobby
+        if (isReconnecting) {
+          isReconnecting = false;
+          showConnectionStatus("hidden");
+          roomCode = "";
+          showView(lobbyView);
+        }
         showError(msg.message);
         break;
     }
@@ -202,14 +298,83 @@
     // Load local file into video player
     const file = localFile || joinFile;
     if (file) {
-      const url = URL.createObjectURL(file);
-      videoPlayer.src = url;
+      loadVideoSource(file);
     }
 
+    // --- Handle false "ended" events (Chromium MKV blob bug) ---
+    // Chrome can't properly index MKV containers loaded via blob URLs.
+    // After ~30s it may jump to the end and fire "ended" even though
+    // the video isn't actually over. Recovery: reload the blob and seek.
+    let recoveryAttempts = 0;
+    const MAX_RECOVERY_ATTEMPTS = 5;
+
+    videoPlayer.addEventListener("ended", () => {
+      const duration = videoPlayer.duration || 0;
+      // Only attempt recovery if we have server state showing we're not near the end
+      if (duration > 0 && lastServerState.position < duration - 5 && recoveryAttempts < MAX_RECOVERY_ATTEMPTS) {
+        recoveryAttempts++;
+        console.log(`[MKV-RECOVERY] False ended detected. Server pos=${lastServerState.position.toFixed(1)}, duration=${duration.toFixed(1)}. Reloading source (attempt ${recoveryAttempts}/${MAX_RECOVERY_ATTEMPTS})`);
+        
+        const targetPos = lastServerState.position;
+        const wasPlaying = lastServerState.playing;
+        const currentFile = localFile || joinFile;
+        
+        if (currentFile) {
+          // Reload the video with a fresh blob URL
+          loadVideoSource(currentFile, targetPos, wasPlaying);
+        }
+      }
+    });
+
+    // Reset recovery counter when video plays successfully for a while
+    let recoveryResetTimer = null;
+    videoPlayer.addEventListener("timeupdate", () => {
+      if (recoveryAttempts > 0) {
+        clearTimeout(recoveryResetTimer);
+        recoveryResetTimer = setTimeout(() => {
+          recoveryAttempts = 0;
+        }, 10000); // Reset after 10s of successful playback
+      }
+    });
+
+    // --- Resync on tab focus (handles background tab throttling) ---
+    document.addEventListener("visibilitychange", () => {
+      if (!document.hidden && roomCode && ws && ws.readyState === WebSocket.OPEN) {
+        console.log("[SYNC] Tab became visible, requesting state resync");
+        send({ type: "request_state" });
+      }
+    });
+
     // Start drift correction
     startDriftCorrection();
   }
 
+  // --- Video Source Loading ---
+  let currentBlobUrl = null;
+  let lastServerState = { playing: false, position: 0, speed: 1 };
+
+  function loadVideoSource(file, seekTo, shouldPlay) {
+    // Revoke old blob URL to free memory
+    if (currentBlobUrl) {
+      URL.revokeObjectURL(currentBlobUrl);
+    }
+    currentBlobUrl = URL.createObjectURL(file);
+    videoPlayer.src = currentBlobUrl;
+
+    if (seekTo !== undefined) {
+      videoPlayer.addEventListener("loadedmetadata", function onMeta() {
+        videoPlayer.removeEventListener("loadedmetadata", onMeta);
+        videoPlayer.currentTime = seekTo;
+        if (shouldPlay) {
+          videoPlayer.play().then(() => {
+            videoWrapper.classList.add("playing");
+            updatePlayPauseIcon();
+          }).catch(() => {});
+        }
+      });
+    }
+  }
+
   // --- File Check Modal ---
   let pendingRoomFileInfo = null;
 
@@ -291,6 +456,11 @@
   function applySync(data) {
     ignoreSync = true;
 
+    // Track latest server state for recovery
+    if (data.position !== undefined) lastServerState.position = data.position;
+    if (data.playing !== undefined) lastServerState.playing = data.playing;
+    if (data.speed !== undefined) lastServerState.speed = data.speed;
+
     if (data.speed !== undefined && videoPlayer.playbackRate !== data.speed) {
       videoPlayer.playbackRate = data.speed;
       speedSelect.value = String(data.speed);
@@ -305,16 +475,24 @@
 
     if (data.playing !== undefined) {
       if (data.playing && videoPlayer.paused) {
-        videoPlayer.play().catch(() => {});
-        videoWrapper.classList.add("playing");
+        videoPlayer.play().then(() => {
+          videoWrapper.classList.add("playing");
+          updatePlayPauseIcon();
+        }).catch(() => {
+          videoWrapper.classList.remove("playing");
+          updatePlayPauseIcon();
+        });
       } else if (!data.playing && !videoPlayer.paused) {
         videoPlayer.pause();
         videoWrapper.classList.remove("playing");
+        updatePlayPauseIcon();
+      } else {
+        updatePlayPauseIcon();
       }
+    } else {
+      updatePlayPauseIcon();
     }
 
-    updatePlayPauseIcon();
-
     // Clear ignore flag after a short delay
     clearTimeout(syncTimeout);
     syncTimeout = setTimeout(() => {
@@ -488,16 +666,26 @@
 
   // --- Room: Leave ---
   leaveRoomBtn.addEventListener("click", () => {
-    if (ws) ws.close();
+    // Intentional leave — clear roomCode before closing so we don't auto-reconnect
+    const code = roomCode;
     roomCode = "";
+    isReconnecting = false;
+    if (reconnectTimer) {
+      clearTimeout(reconnectTimer);
+      reconnectTimer = null;
+    }
+    if (ws) ws.close();
     localFile = null;
     joinFile = null;
+    roomFileInfo = null;
+    messageQueue = [];
     if (driftInterval) clearInterval(driftInterval);
     videoPlayer.src = "";
     chatMessages.innerHTML = '<div class="chat-welcome" id="chat-welcome"><p>Welcome to the room! 👋</p></div>';
     createFileInfo.classList.add("hidden");
     createFileInput.value = "";
     createRoomBtn.disabled = true;
+    showConnectionStatus("hidden");
     showView(lobbyView);
   });
 
@@ -507,15 +695,11 @@
     if (videoPlayer.paused) {
       videoPlayer.play().catch(() => {});
       videoWrapper.classList.add("playing");
-      if (!ignoreSync) {
-        send({ type: "sync", action: "play", position: videoPlayer.currentTime });
-      }
+      send({ type: "sync", action: "play", position: videoPlayer.currentTime });
     } else {
       videoPlayer.pause();
       videoWrapper.classList.remove("playing");
-      if (!ignoreSync) {
-        send({ type: "sync", action: "pause", position: videoPlayer.currentTime });
-      }
+      send({ type: "sync", action: "pause", position: videoPlayer.currentTime });
     }
     updatePlayPauseIcon();
   }
@@ -565,9 +749,7 @@
     const time = (seekBar.value / 1000) * videoPlayer.duration;
     videoPlayer.currentTime = time;
     isSeeking = false;
-    if (!ignoreSync) {
-      send({ type: "sync", action: "seek", position: time });
-    }
+    send({ type: "sync", action: "seek", position: time });
   });
 
   // Volume
@@ -588,9 +770,7 @@
   speedSelect.addEventListener("change", () => {
     const speed = parseFloat(speedSelect.value);
     videoPlayer.playbackRate = speed;
-    if (!ignoreSync) {
-      send({ type: "sync", action: "speed", speed });
-    }
+    send({ type: "sync", action: "speed", speed });
   });
 
   // Fullscreen

public/index.html

@@ -95,6 +95,8 @@
   <!-- ===== ROOM VIEW ===== -->
   <div id="room" class="view">
     <div class="room-layout">
+      <!-- Connection Status Banner -->
+      <div id="connection-status" class="connection-status hidden"></div>
       <!-- Video Area -->
       <div class="video-area">
         <div class="video-topbar">

public/style.css

@@ -1,5 +1,7 @@
 /* ===== Reset & Base ===== */
-*, *::before, *::after {
+*,
+*::before,
+*::after {
   box-sizing: border-box;
   margin: 0;
   padding: 0;
@@ -25,12 +27,13 @@
   --radius: 8px;
   --radius-lg: 12px;
   --radius-xl: 16px;
-  --shadow: 0 4px 24px rgba(0,0,0,0.4);
+  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
   --transition: 0.2s ease;
   --font: 'Roboto', -apple-system, BlinkMacSystemFont, sans-serif;
 }
 
-html, body {
+html,
+body {
   height: 100%;
   font-family: var(--font);
   background: var(--bg-primary);
@@ -39,33 +42,45 @@ html, body {
   -webkit-font-smoothing: antialiased;
 }
 
-input, button, select {
+input,
+button,
+select {
   font-family: var(--font);
   font-size: inherit;
 }
 
-.hidden { display: none !important; }
+.hidden {
+  display: none !important;
+}
 
 .view {
   display: none;
   height: 100vh;
 }
-.view.active { display: flex; }
+
+.view.active {
+  display: flex;
+}
 
 /* ===== LOBBY ===== */
 #lobby {
   align-items: center;
   justify-content: center;
   background:
-    radial-gradient(ellipse at 20% 50%, rgba(62,166,255,0.06) 0%, transparent 50%),
-    radial-gradient(ellipse at 80% 50%, rgba(62,166,255,0.04) 0%, transparent 50%),
+    radial-gradient(ellipse at 20% 50%, rgba(62, 166, 255, 0.06) 0%, transparent 50%),
+    radial-gradient(ellipse at 80% 50%, rgba(62, 166, 255, 0.04) 0%, transparent 50%),
     var(--bg-primary);
   animation: lobbyBg 20s ease-in-out infinite alternate;
 }
 
 @keyframes lobbyBg {
-  0% { background-position: 0% 50%; }
-  100% { background-position: 100% 50%; }
+  0% {
+    background-position: 0% 50%;
+  }
+
+  100% {
+    background-position: 100% 50%;
+  }
 }
 
 .lobby-container {
@@ -86,8 +101,15 @@ input, button, select {
 }
 
 @keyframes logoPulse {
-  0%, 100% { transform: scale(1); }
-  50% { transform: scale(1.05); }
+
+  0%,
+  100% {
+    transform: scale(1);
+  }
+
+  50% {
+    transform: scale(1.05);
+  }
 }
 
 .lobby-brand h1 {
@@ -319,14 +341,21 @@ input, button, select {
   border-radius: var(--radius);
   font-size: 0.9rem;
   font-weight: 500;
-  box-shadow: 0 4px 20px rgba(255,78,69,0.3);
+  box-shadow: 0 4px 20px rgba(255, 78, 69, 0.3);
   z-index: 1000;
   animation: toastIn 0.3s ease;
 }
 
 @keyframes toastIn {
-  from { opacity: 0; transform: translateX(-50%) translateY(20px); }
-  to { opacity: 1; transform: translateX(-50%) translateY(0); }
+  from {
+    opacity: 0;
+    transform: translateX(-50%) translateY(20px);
+  }
+
+  to {
+    opacity: 1;
+    transform: translateX(-50%) translateY(0);
+  }
 }
 
 /* ===== FILE CHECK MODAL ===== */
@@ -342,7 +371,7 @@ input, button, select {
 .modal-backdrop {
   position: absolute;
   inset: 0;
-  background: rgba(0,0,0,0.7);
+  background: rgba(0, 0, 0, 0.7);
   backdrop-filter: blur(4px);
 }
 
@@ -359,8 +388,15 @@ input, button, select {
 }
 
 @keyframes modalIn {
-  from { opacity: 0; transform: scale(0.95); }
-  to { opacity: 1; transform: scale(1); }
+  from {
+    opacity: 0;
+    transform: scale(0.95);
+  }
+
+  to {
+    opacity: 1;
+    transform: scale(1);
+  }
 }
 
 .modal-content h2 {
@@ -406,7 +442,7 @@ input, button, select {
   margin-top: 10px;
 }
 
-.file-info-card .row > div {
+.file-info-card .row>div {
   flex: 1;
 }
 
@@ -419,14 +455,14 @@ input, button, select {
 }
 
 .file-match-status.match {
-  background: rgba(46,204,113,0.1);
-  border: 1px solid rgba(46,204,113,0.3);
+  background: rgba(46, 204, 113, 0.1);
+  border: 1px solid rgba(46, 204, 113, 0.3);
   color: var(--success);
 }
 
 .file-match-status.mismatch {
-  background: rgba(255,78,69,0.1);
-  border: 1px solid rgba(255,78,69,0.3);
+  background: rgba(255, 78, 69, 0.1);
+  border: 1px solid rgba(255, 78, 69, 0.3);
   color: var(--danger);
 }
 
@@ -441,12 +477,70 @@ input, button, select {
   flex: 1;
 }
 
-/* ===== ROOM VIEW ===== */
 .room-layout {
   display: flex;
   width: 100%;
   height: 100vh;
   overflow: hidden;
+  position: relative;
+}
+
+/* Connection Status Banner */
+.connection-status {
+  position: absolute;
+  top: 52px;
+  left: 50%;
+  transform: translateX(-50%);
+  z-index: 100;
+  padding: 8px 20px;
+  border-radius: 20px;
+  font-size: 0.8rem;
+  font-weight: 600;
+  letter-spacing: 0.3px;
+  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
+  animation: statusIn 0.3s ease;
+  transition: opacity 0.5s ease;
+}
+
+.connection-status.reconnecting {
+  background: rgba(243, 156, 18, 0.15);
+  border: 1px solid rgba(243, 156, 18, 0.4);
+  color: var(--warning);
+  animation: statusIn 0.3s ease, statusPulse 2s ease-in-out infinite;
+}
+
+.connection-status.reconnected {
+  background: rgba(46, 204, 113, 0.15);
+  border: 1px solid rgba(46, 204, 113, 0.4);
+  color: var(--success);
+}
+
+.connection-status.hidden {
+  display: none !important;
+}
+
+@keyframes statusIn {
+  from {
+    opacity: 0;
+    transform: translateX(-50%) translateY(-10px);
+  }
+
+  to {
+    opacity: 1;
+    transform: translateX(-50%) translateY(0);
+  }
+}
+
+@keyframes statusPulse {
+
+  0%,
+  100% {
+    opacity: 1;
+  }
+
+  50% {
+    opacity: 0.7;
+  }
 }
 
 /* Video Area */
@@ -572,7 +666,7 @@ input, button, select {
 }
 
 .big-play-btn:hover svg circle {
-  fill: rgba(0,0,0,0.75);
+  fill: rgba(0, 0, 0, 0.75);
 }
 
 /* Controls bar */
@@ -581,7 +675,7 @@ input, button, select {
   bottom: 0;
   left: 0;
   right: 0;
-  background: linear-gradient(transparent, rgba(0,0,0,0.85));
+  background: linear-gradient(transparent, rgba(0, 0, 0, 0.85));
   padding: 20px 12px 10px;
   opacity: 0;
   transition: opacity 0.3s ease;
@@ -602,7 +696,7 @@ input, button, select {
   appearance: none;
   width: 100%;
   height: 4px;
-  background: rgba(255,255,255,0.2);
+  background: rgba(255, 255, 255, 0.2);
   border-radius: 2px;
   outline: none;
   cursor: pointer;
@@ -620,7 +714,7 @@ input, button, select {
   background: var(--accent);
   border-radius: 50%;
   cursor: pointer;
-  box-shadow: 0 0 4px rgba(0,0,0,0.3);
+  box-shadow: 0 0 4px rgba(0, 0, 0, 0.3);
   transition: transform 0.15s ease;
 }
 
@@ -664,7 +758,7 @@ input, button, select {
 }
 
 .ctrl-btn:hover {
-  background: rgba(255,255,255,0.1);
+  background: rgba(255, 255, 255, 0.1);
 }
 
 .volume-control {
@@ -678,7 +772,7 @@ input, button, select {
   appearance: none;
   width: 70px;
   height: 3px;
-  background: rgba(255,255,255,0.3);
+  background: rgba(255, 255, 255, 0.3);
   border-radius: 2px;
   outline: none;
   cursor: pointer;
@@ -712,14 +806,14 @@ input, button, select {
 
 .time-display {
   font-size: 0.8rem;
-  color: rgba(255,255,255,0.8);
+  color: rgba(255, 255, 255, 0.8);
   font-variant-numeric: tabular-nums;
   margin-left: 4px;
 }
 
 .speed-select {
   background: none;
-  border: 1px solid rgba(255,255,255,0.2);
+  border: 1px solid rgba(255, 255, 255, 0.2);
   color: white;
   padding: 4px 8px;
   border-radius: 4px;
@@ -773,8 +867,15 @@ input, button, select {
 }
 
 @keyframes dotPulse {
-  0%, 100% { opacity: 1; }
-  50% { opacity: 0.5; }
+
+  0%,
+  100% {
+    opacity: 1;
+  }
+
+  50% {
+    opacity: 0.5;
+  }
 }
 
 .users-list {
@@ -845,8 +946,15 @@ input, button, select {
 }
 
 @keyframes msgIn {
-  from { opacity: 0; transform: translateY(4px); }
-  to { opacity: 1; transform: translateY(0); }
+  from {
+    opacity: 0;
+    transform: translateY(4px);
+  }
+
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
 }
 
 .chat-msg .msg-author {
@@ -955,4 +1063,4 @@ input, button, select {
   .file-badge {
     display: none;
   }
-}
+}

server.ts

@@ -27,6 +27,7 @@ interface ChatMessage {
 
 // --- Room Management ---
 const rooms = new Map<string, RoomState>();
+const pendingDisconnects = new Map<string, ReturnType<typeof setTimeout>>(); // key: "roomCode:username"
 
 function generateRoomCode(): string {
   const chars = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"; // no ambiguous chars
@@ -348,6 +349,64 @@ const server = Bun.serve<WSData>({
           );
           break;
         }
+
+        case "rejoin_room": {
+          const username = (msg.username || "").trim();
+          const code = (msg.code || "").trim().toUpperCase();
+          if (!username || !code) {
+            ws.send(JSON.stringify({ type: "error", message: "Username and room code required" }));
+            return;
+          }
+
+          const room = rooms.get(code);
+          if (!room) {
+            ws.send(JSON.stringify({ type: "error", message: "Room no longer exists" }));
+            return;
+          }
+
+          // Cancel any pending disconnect timer for this user
+          const disconnectKey = `${code}:${username}`;
+          const pendingTimer = pendingDisconnects.get(disconnectKey);
+          if (pendingTimer) {
+            clearTimeout(pendingTimer);
+            pendingDisconnects.delete(disconnectKey);
+            console.log(`[Room ${code}] ${username} reconnected (cancelled disconnect timer)`);
+          }
+
+          // Swap in the new WebSocket
+          ws.data.username = username;
+          ws.data.roomCode = code;
+          room.users.set(username, ws as unknown as WebSocket);
+
+          // Send full current state to the reconnected client
+          ws.send(
+            JSON.stringify({
+              type: "room_rejoined",
+              code,
+              fileInfo: room.fileInfo,
+              users: getUserList(room),
+              state: {
+                playing: room.playing,
+                position: getCurrentPosition(room),
+                speed: room.speed,
+              },
+              chatHistory: room.chatHistory.slice(-50),
+            })
+          );
+
+          // Notify others that user is back
+          broadcastToRoom(
+            room,
+            {
+              type: "user_rejoined",
+              username,
+              users: getUserList(room),
+            },
+            ws as unknown as WebSocket
+          );
+          console.log(`[Room ${code}] ${username} rejoined`);
+          break;
+        }
       }
     },
 
@@ -358,19 +417,35 @@ const server = Bun.serve<WSData>({
       const room = rooms.get(roomCode);
       if (!room) return;
 
-      room.users.delete(username);
-      console.log(`[Room ${roomCode}] ${username} left`);
+      // Don't remove immediately — give a 30s grace period for reconnection
+      const disconnectKey = `${roomCode}:${username}`;
+      console.log(`[Room ${roomCode}] ${username} disconnected (waiting 30s for reconnect)`);
 
-      if (room.users.size === 0) {
-        rooms.delete(roomCode);
-        console.log(`[Room ${roomCode}] Deleted (empty)`);
-      } else {
-        broadcastToRoom(room, {
-          type: "user_left",
-          username,
-          users: getUserList(room),
-        });
-      }
+      const timer = setTimeout(() => {
+        pendingDisconnects.delete(disconnectKey);
+        const currentRoom = rooms.get(roomCode);
+        if (!currentRoom) return;
+
+        // Only remove if the stored WS is still the old one (not swapped by rejoin)
+        const currentWs = currentRoom.users.get(username);
+        if (currentWs === (ws as unknown as WebSocket)) {
+          currentRoom.users.delete(username);
+          console.log(`[Room ${roomCode}] ${username} removed (grace period expired)`);
+
+          if (currentRoom.users.size === 0) {
+            rooms.delete(roomCode);
+            console.log(`[Room ${roomCode}] Deleted (empty)`);
+          } else {
+            broadcastToRoom(currentRoom, {
+              type: "user_left",
+              username,
+              users: getUserList(currentRoom),
+            });
+          }
+        }
+      }, 30_000);
+
+      pendingDisconnects.set(disconnectKey, timer);
     },
   },
 });