ConstReadonlyClose: "close"The socket closed; handler receives code and reason.
ReadonlyError: "error"A transport error occurred; handler receives an Error.
ReadonlyMessage: "message"A validated ServerMessage arrived.
ReadonlyOpen: "open"The socket opened successfully.
ReadonlyReconnecting: "reconnecting"A reconnect attempt started; handler receives the attempt number.
ReadonlyTerminated: "terminated"The transport gave up permanently — either a non-retryable close code
(e.g. auth failure / expired token) or reconnect exhaustion. No further
reconnects will be attempted. Handler receives code and reason.
Events emitted by a Transport (see TransportEvents for handler signatures).