Add queued sending for Codex App drafts

Also include WebSocket heartbeat handling to keep idle connections healthy.

server.js

@@ -4942,6 +4942,7 @@ const server = http.createServer((req, res) => {
 
 // === WebSocket Server ===
 const wss = new WebSocketServer({ noServer: true });
+const WS_HEARTBEAT_INTERVAL_MS = 30000;
 
 server.on('upgrade', (req, socket, head) => {
   let pathname = '';
@@ -4978,8 +4979,14 @@ wss.on('connection', (ws, req) => {
   let authToken = null;
   const wsId = crypto.randomBytes(4).toString('hex'); // short id for log correlation
   const wsConnectTime = new Date().toISOString();
+  ws.isAlive = true;
+  ws._ccWebId = wsId;
   plog('INFO', 'ws_connect', { wsId });
 
+  ws.on('pong', () => {
+    ws.isAlive = true;
+  });
+
   ws.on('message', (raw) => {
     let msg;
     try {
@@ -5120,6 +5127,26 @@ wss.on('connection', (ws, req) => {
   });
 });
 
+// WebSocket 心跳：避免反向代理因空闲连接关闭 /ws。
+const wsHeartbeatTimer = setInterval(() => {
+  for (const client of wss.clients) {
+    if (client.isAlive === false) {
+      client.terminate();
+      continue;
+    }
+    client.isAlive = false;
+    if (client.readyState === 1) {
+      try {
+        client.ping();
+      } catch (err) {
+        plog('WARN', 'ws_ping_failed', { wsId: client._ccWebId || null, error: err.message });
+        client.terminate();
+      }
+    }
+  }
+}, WS_HEARTBEAT_INTERVAL_MS);
+if (typeof wsHeartbeatTimer.unref === 'function') wsHeartbeatTimer.unref();
+
 // === Notify Config Handlers ===
 function handleSaveNotifyConfig(ws, newConfig) {
   if (!newConfig || !newConfig.provider) {