feat: implement one-click auto-join and self-closing bridge with countdown

extension/background.js

@@ -596,6 +596,7 @@ chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
             useCustomServer: !!useCustomServer,
             serverUrl: serverUrl || ''
         }, () => {
+            broadcastConnectionStatus('connecting');
             if (socket && socket.readyState === WebSocket.OPEN && isNamespaceJoined) {
                 // FORCE TRANSITION: Emit Join Room directly if already connected
                 getSettings().then(settings => {
@@ -612,7 +613,9 @@ chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
             } else {
                 connect();
             }
+            sendResponse({ status: 'ok' });
         });
+        return true; // Keep channel open for async getSettings
     } else if (message.type === 'REGENERATE_ID') {
         const newId = self.crypto.randomUUID().substring(0, 8);
         chrome.storage.local.set({ peerId: newId }, () => {

extension/popup.js

@@ -286,6 +286,15 @@ function applyConnectionStatus(status) {
 
     elements.connText.textContent = connected ? 'Connected' : (connecting ? 'Connecting...' : (failed ? 'Failed' : 'Disconnected'));
     elements.retryBtn.style.display = failed ? 'block' : 'none';
+
+    // Update Join Button during auto-transition
+    if (connecting) {
+        elements.joinBtn.disabled = true;
+        elements.joinBtn.textContent = 'Connecting...';
+    } else if (!connected) {
+        elements.joinBtn.disabled = false;
+        elements.joinBtn.textContent = 'Join Room';
+    }
 }
 
 function updateHistory(history) {