Socket.io+Edge Runtime

Socket.io is built upon the Engine.io protocol, which fundamentally requires a persistent Node.js environment to maintain the heartbeat of a WebSocket connection. Edge Runtimes, such as those provided by Vercel or Cloudflare, are built on the V8 engine with a limited set of Web Standard APIs. They lack the net, tls, and http modules that Socket.io depends on for low-level socket handling.

Furthermore, Edge functions are designed to be stateless and short-lived. A WebSocket connection requires a stateful, long-lived process to track client IDs and manage rooms. Since Edge functions scale to zero and have strict execution time limits, they cannot maintain the persistent TCP connection required for the Socket.io handshake and subsequent event emission. Attempting to run the server-side library in this environment will result in immediate runtime errors regarding missing modules.