Recover presence connections after temporary database failures

src/client/presence.ts

@@ -1,21 +1,29 @@
 import { io, type Socket } from 'socket.io-client';
 import type { GameSessionAuth } from '../shared/p2p-types.js';
+import { PRESENCE_RETRY_MS } from '../../constants/presence.js';
 
 export function createPresence(counter: HTMLElement) {
   let socket: Socket | undefined, sessionId = '';
+  let retry: ReturnType<typeof setTimeout> | undefined;
   const unknown = () => { counter.textContent = '접속 확인 중'; };
-  window.addEventListener('pagehide', () => { socket?.disconnect(); unknown(); });
+  window.addEventListener('pagehide', () => { clearTimeout(retry); socket?.disconnect(); unknown(); });
   window.addEventListener('pageshow', () => { socket?.connect(); });
   return {
     connect(auth: GameSessionAuth) {
       if (socket && sessionId === auth.gameSessionId) { socket.connect(); return; }
-      socket?.removeAllListeners(); socket?.disconnect(); unknown();
+      clearTimeout(retry); socket?.removeAllListeners(); socket?.disconnect(); unknown();
       sessionId = auth.gameSessionId;
       socket = io('/presence', { auth: { gameSessionId: auth.gameSessionId, token: auth.token }, forceNew: true, autoConnect: false });
       socket.on('presence:count', (count: unknown) => {
         if (Number.isSafeInteger(count) && (count as number) >= 0) counter.textContent = `접속 ${count}명`;
       });
-      socket.on('disconnect', unknown); socket.on('connect_error', unknown);
+      socket.on('connect', () => clearTimeout(retry));
+      socket.on('disconnect', unknown);
+      socket.on('connect_error', error => {
+        unknown(); clearTimeout(retry);
+        // Middleware errors do not trigger Socket.IO's transport reconnection loop.
+        if (error.message !== 'INVALID_SESSION') retry = setTimeout(() => socket?.connect(), PRESENCE_RETRY_MS);
+      });
       socket.connect();
     },
   };

src/server/presence.ts

@@ -1,5 +1,5 @@
 import type { Server } from 'socket.io';
-import type { GameSessionStore } from './game-session-store.js';
+import { ApiError, type GameSessionStore } from './game-session-store.js';
 import { PRESENCE_AUTH_REFRESH_MS } from '../../constants/presence.js';
 
 // The application is deployed as one process, as is the ranked match service.
@@ -15,7 +15,7 @@ export function registerPresence(io: Server, sessions: GameSessionStore) {
     void sessions.get({ gameSessionId, token }).then(session => {
       socket.data.playerId = session.playerId ?? session.gameSessionId;
       next();
-    }, () => next(new Error('INVALID_SESSION')));
+    }, error => next(new Error(error instanceof ApiError && error.statusCode === 401 ? 'INVALID_SESSION' : 'PRESENCE_UNAVAILABLE')));
   });
   namespace.on('connection', socket => {
     const before = count; publish();
@@ -25,7 +25,10 @@ export function registerPresence(io: Server, sessions: GameSessionStore) {
       if (checking) return;
       checking = true;
       const { gameSessionId, token } = socket.handshake.auth;
-      void sessions.get({ gameSessionId, token }).catch(() => socket.disconnect(true)).finally(() => { checking = false; });
+      void sessions.get({ gameSessionId, token }).catch(error => {
+        if (error instanceof ApiError && error.statusCode === 401) socket.disconnect(true);
+        else socket.conn.close(); // Transport closure permits Socket.IO to reconnect after a transient outage.
+      }).finally(() => { checking = false; });
     }, PRESENCE_AUTH_REFRESH_MS);
     timer.unref();
     socket.on('disconnect', () => { clearInterval(timer); publish(); });