Client events (client.on)

client.on(event, handler) returns an unsubscribe function.

Event	Payload	When it fires
`connected`	`undefined`	After `connect()` succeeds.
`disconnected`	`{ reason?: string }`	After the socket closes.
`reconnecting`	`{ attempt: number; delayMs: number }`	Before sleeping for backoff.
`stateChange`	`{ state: ConnectionState }`	Whenever the connection state machine moves.
`message`	`CachePuppyEnvelope`	For every decoded envelope from the transport.
`topicPresence`	`{ topic: string; clientCount: number }`	When presence-derived occupancy changes for a subscribed topic.
`error`	`Error`	Protocol issues, transport failures surfaced as `Error`, etc.

Prefer topicPresence and the topic helpers when you only care about occupancy. Subscribe to message when you are building lower-level tooling.