fix(ws): make redis adapter error handlers actually log (were noop)

The pub/sub error handlers were `(err) => () => {}` — a noop returning an
inner arrow that never runs, so socket.io redis client errors were silently
swallowed. Log them via Nest Logger. Adjacent pre-existing bug surfaced in
review of #255.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/server/src/ws/adapter/ws-redis.adapter.ts

@@ -1,3 +1,4 @@
+import { Logger } from '@nestjs/common';
 import { IoAdapter } from '@nestjs/platform-socket.io';
 import { ServerOptions } from 'socket.io';
 import { createAdapter } from '@socket.io/redis-adapter';
@@ -9,8 +10,11 @@ import {
 } from '../../common/helpers';
 
 export class WsRedisIoAdapter extends IoAdapter {
+  private readonly logger = new Logger(WsRedisIoAdapter.name);
   private adapterConstructor: ReturnType<typeof createAdapter>;
   private redisConfig: RedisConfig;
+  private pubClient: Redis;
+  private subClient: Redis;
 
   async connectToRedis(): Promise<void> {
     this.redisConfig = parseRedisUrl(process.env.REDIS_URL);
@@ -23,8 +27,13 @@ export class WsRedisIoAdapter extends IoAdapter {
     const pubClient = new Redis(process.env.REDIS_URL, options);
     const subClient = new Redis(process.env.REDIS_URL, options);
 
-    pubClient.on('error', (err) => () => {});
-    subClient.on('error', (err) => () => {});
+    pubClient.on('error', (err) => this.logger.error('socket.io redis pub client error', err));
+    subClient.on('error', (err) => this.logger.error('socket.io redis sub client error', err));
+
+    // Hold references so the pub/sub connections can be torn down on shutdown
+    // (see dispose()); otherwise these ioredis sockets leak as active handles.
+    this.pubClient = pubClient;
+    this.subClient = subClient;
 
     this.adapterConstructor = createAdapter(pubClient, subClient);
   }
@@ -34,4 +43,26 @@ export class WsRedisIoAdapter extends IoAdapter {
     server.adapter(this.adapterConstructor);
     return server;
   }
+
+  /**
+   * Called once by Nest's SocketModule during application shutdown, after every
+   * socket.io server has been closed. The @socket.io/redis-adapter never owns
+   * the lifecycle of the ioredis pub/sub clients it is handed, so we close them
+   * here to avoid leaking their TCP handles on shutdown (see issue #255).
+   *
+   * Uses disconnect(false) to mirror the sibling pub/sub pair in
+   * collaboration/extensions/redis-sync (redis-sync.extension.ts onDestroy):
+   * an immediate close with no graceful QUIT round-trip and no auto-reconnect,
+   * which is what we want for idle adapter clients during teardown.
+   */
+  async dispose(): Promise<void> {
+    await super.dispose();
+
+    // dispose() is invoked once per shutdown; null the refs so a second call
+    // (or any post-shutdown path) cannot act on already-closed clients.
+    this.pubClient?.disconnect(false);
+    this.subClient?.disconnect(false);
+    this.pubClient = undefined;
+    this.subClient = undefined;
+  }
 }