diff --git a/extension/background.js b/extension/background.js
index 25e555a..e25a77c 100644
--- a/extension/background.js
+++ b/extension/background.js
@@ -1,4 +1,4 @@
-import { EVENTS, PROTOCOL_VERSION, OFFICIAL_SERVER_URL, OFFICIAL_SERVER_TOKEN, APP_VERSION, EPISODE_LOBBY_TIMEOUT } from './shared/constants.js';
+import { EVENTS, PROTOCOL_VERSION, OFFICIAL_SERVER_URL, OFFICIAL_SERVER_TOKEN, APP_VERSION, EPISODE_LOBBY_TIMEOUT, FORCE_SYNC_TIMEOUT } from './shared/constants.js';
 
 // --- State Management ---
 let socket = null;
@@ -849,7 +849,7 @@ function executeEpisodeLobby() {
 
     isForceSyncInitiator = true;
     forceSyncAcks.clear();
-    const deadline = Date.now() + 8500;
+    const deadline = Date.now() + FORCE_SYNC_TIMEOUT;
     const timestamp = Date.now();
     updateLastAction(EVENTS.FORCE_SYNC_PREPARE, 'You', timestamp);
     lastActionState.targetTime = 0.0;
@@ -869,7 +869,7 @@ function executeEpisodeLobby() {
             addLog('Force Sync (Episode): Timeout waiting for ACKs, executing anyway...', 'warn');
             executeForceSync();
         }
-    }, 8500);
+    }, FORCE_SYNC_TIMEOUT);
 }
 
 function checkEpisodeLobbyCompletion() {
@@ -1149,7 +1149,7 @@ async function handleAsyncMessage(message, sender, sendResponse) {
             if (message.action === EVENTS.FORCE_SYNC_PREPARE) {
                 isForceSyncInitiator = true;
                 forceSyncAcks.clear();
-                const deadline = Date.now() + 8500;
+                const deadline = Date.now() + FORCE_SYNC_TIMEOUT;
                 chrome.storage.session.set({ 
                     isForceSyncInitiator: true, 
                     forceSyncAcks: [], 
@@ -1164,7 +1164,7 @@ async function handleAsyncMessage(message, sender, sendResponse) {
                         addLog('Force Sync: Timeout waiting for ACKs, executing anyway...', 'warn');
                         executeForceSync();
                     }
-                }, 8500);
+                }, FORCE_SYNC_TIMEOUT);
             }
             addToHistory(message.action, 'You');
             emit(message.action, { ...message.payload, peerId });
diff --git a/extension/popup.js b/extension/popup.js
index fdbad03..b6e1561 100644
--- a/extension/popup.js
+++ b/extension/popup.js
@@ -57,6 +57,7 @@ let joinBtnTimeout = null;
 let forceSyncResetTimer = null;
 let popupIntervals = [];
 let populateTabsToken = null;
+let errorToken = 0;
 let forceSyncDone = false;
 
 // --- Initialization ---
@@ -838,6 +839,7 @@ function showToast(message, type = 'info', duration = 3000) {
 
 function showError(msg) {
     if (!elements.roomError) return;
+    const currentToken = ++errorToken;
     elements.roomError.textContent = msg;
     elements.roomError.style.display = 'block';
     elements.roomId.style.borderColor = 'var(--error)';
@@ -846,6 +848,7 @@ function showError(msg) {
     showToast(msg, 'error', 5000);
 
     setTimeout(() => {
+        if (currentToken !== errorToken) return;
         if (elements.roomError) elements.roomError.style.display = 'none';
         elements.roomId.style.borderColor = '';
         elements.password.style.borderColor = '';
diff --git a/server/index.js b/server/index.js
index f7e8ab5..a31e1f7 100644
--- a/server/index.js
+++ b/server/index.js
@@ -480,30 +480,30 @@ io.on('connection', (socket) => {
         }
     });
 
-        socket.on(EVENTS.EVENT_ACK, (data) => {
-            if (!checkEventRate(socket.id)) {
-                log('SECURITY', `Event rate limit exceeded for socket (ACK): ${socket.id}`);
-                socket.disconnect(true);
-                return;
-            }
-            if (!data || typeof data !== 'object') return;
-            if (typeof data.targetId !== 'string') return;
-            if (data.actionTimestamp !== undefined && (typeof data.actionTimestamp !== 'number' || !Number.isFinite(data.actionTimestamp))) return;
-            
-            const senderMapping = socketToRoom.get(socket.id);
-            const targetSocketId = peerToSocket.get(data.targetId);
-            const targetMapping = targetSocketId ? socketToRoom.get(targetSocketId) : null;
+    socket.on(EVENTS.EVENT_ACK, (data) => {
+        if (!checkEventRate(socket.id)) {
+            log('SECURITY', `Event rate limit exceeded for socket (ACK): ${socket.id}`);
+            socket.disconnect(true);
+            return;
+        }
+        if (!data || typeof data !== 'object') return;
+        if (typeof data.targetId !== 'string') return;
+        if (data.actionTimestamp !== undefined && (typeof data.actionTimestamp !== 'number' || !Number.isFinite(data.actionTimestamp))) return;
+        
+        const senderMapping = socketToRoom.get(socket.id);
+        const targetSocketId = peerToSocket.get(data.targetId);
+        const targetMapping = targetSocketId ? socketToRoom.get(targetSocketId) : null;
 
-            // Security: Only relay ACK if both peers are in the same room
-            if (senderMapping && targetMapping && senderMapping.roomId === targetMapping.roomId) {
-                io.to(targetSocketId).emit(EVENTS.EVENT_ACK, { 
-                    senderId: senderMapping.peerId,
-                    actionTimestamp: data.actionTimestamp
-                });
-            } else {
-                log('SECURITY', `Blocked cross-room ACK attempt from ${socket.id} to ${data.targetId}`);
-            }
-        });
+        // Security: Only relay ACK if both peers are in the same room
+        if (senderMapping && targetMapping && senderMapping.roomId === targetMapping.roomId) {
+            io.to(targetSocketId).emit(EVENTS.EVENT_ACK, { 
+                senderId: senderMapping.peerId,
+                actionTimestamp: data.actionTimestamp
+            });
+        } else {
+            log('SECURITY', `Blocked cross-room ACK attempt from ${socket.id} to ${data.targetId}`);
+        }
+    });
 
     socket.on('disconnect', () => {
         eventCounts.delete(socket.id);
diff --git a/shared/constants.js b/shared/constants.js
index 3714cca..78cc09e 100644
--- a/shared/constants.js
+++ b/shared/constants.js
@@ -40,5 +40,5 @@ export const EVENTS = {
 };
 
 export const HEARTBEAT_INTERVAL = 15000; // 15s
-export const FORCE_SYNC_TIMEOUT = 5000; // 5s timeout for ACKs
+export const FORCE_SYNC_TIMEOUT = 8500; // 8.5s timeout for force sync ACKs (must be > content.js poll timeout of 8s)
 export const EPISODE_LOBBY_TIMEOUT = 60000; // 60s timeout for episode lobby