I don’t worry about that. I just don’t need the channel’s logic
I googled through the forum and was hoping that may be something changed 
According to the code it is just a hardcoded event name. So actually I believe it is a limitation for some reason to give an interface to interact only via channels but then the question is why 
def ws_info(%Broadcast{event: "disconnect"}, state) do
{:shutdown, state}
end
disconnect is of course the only hard-coded message, but you can listen for others on the socket (not channel) PID by subscribing it to what it needs.
Literally just that, subscribe to a pubsub topic then handle such messages, though I’m unsure how to setup such a receive in a socket (if there is no good API then one really should be PR’d in to handle arbitrary unhandled messages to the socket PID).
You might try running <YourApp>.Endpoint.subscribe("<some_topic>") from within the connect/2 callback. Supposedly, it would run inside the process handling the socket. Then you would be able to broadcast to all socket processes subscribed to "<some_topic>" with <YourApp>.Endpoint.broadcast("<some_topic>", some_event, some_msg) and see where it gets you. If phoenix’s socket is just a handler module for cowboy, you might be able to use cowboy’s callbacks to handle incoming messages, which IIRC is websocket_info, which seems to be forwarded to handler’s ws_info in phoenix v1.3 and to handle_info in phoenix master.
if there is no good API then one really should be PR’d in to handle arbitrary unhandled messages to the socket PID
It seems like handle_info has been added as a possible callback to phoenix.socket in v1.4. But in v1.3 the messages are simply ignored unless you pack them in a {:socket_push, _, _encoded_payload} tuple.
I tried to subscribe in connect but yeah for some reason it returns :ok but nothing happens.
1.4 is not released yet, so it is better to wait I think before using it in production.
Yes, I do. I saw somewhere a comment that connect is a transport layer and it is not possible to automatically subscribe.