How to Integrate Mirror and SocketIO in Unity — A Hybrid Multiplayer Architecture

If you've built multiplayer in Unity, you've probably hit this question at some point: "Do I use Mirror, or do I use a backend with Socket.IO?" The answer most tutorials give you is pick one. But they're solving different problems — and using both is not only possible, it's the right architecture for most production multiplayer games. This guide covers exactly how to integrate socketio-unity with Mirror — what each system owns, where the boundary is, and how to implement the integration without