Websocket Implementation

This is a production-ready WebSocket setup using Socket.IO with Redis pub/sub for horizontal scaling. It covers authentication middleware, room-based messaging, connection management, and includes both server and client implementations plus a React hook. The code handles reconnection logic, message queuing when offline, and provides monitoring endpoints for tracking active connections. What I like here is the scaling guidance table that tells you exactly when to add Redis (10K+ connections) versus staying single-server. It's opinionated about real concerns like rate limiting and not storing unlimited messages in memory, which saves you from learning those lessons the hard way in production.