Connection managers and broadcasting

A WebSocket handler knows about one socket: its own. The moment something outside that handler needs to send to it, whether a background worker that finished an escalation, a support agent joining the conversation, or an admin broadcast, you need a place where open sockets are kept and looked up. That place is a connection manager, and it is a small class: a dictionary from a key to a set of sockets, with connect, disconnect, and send_to methods.

The second problem arrives when you run two replicas. A socket lives in exactly one process, so a manager in process A cannot send to a socket held by process B. Redis pub/sub is the fix: every process subscribes to a channel, a send becomes a publish, and each process forwards the message to whichever sockets it holds.