One idea for having custom error handling would be to do a regular HTTP request using fetch instead of relying on the socket connect. You could do your regular authentication/authorization checks and then return any response you like. On success, you’d respond with a short-lived signed Phoenix.Token that you use for the socket connect. Therefore, when connecting, you can verify the token and skip the other checks. With that approach, the only case where the connect would fail (other than an attacker deliberately messing with tokens) is a network error.
