Returns a single channel's occupancy and (on request) counts. Channels exist implicitly — a channel appears when the first connection subscribes and vanishes when the last one leaves — so this endpoint reports state, not existence: an unknown or never-used name returns 200 with `occupied: false`, never 404. Attributes to include. Repeatable. Requesting `member_count` for a non-presence channel, or `connection_count` when the app's connection-counting flag is off, returns a validation error (400). Distinct members (presence channels only; requires include=member_count). Connections currently subscribed to this channel (requires include=connection_count and the app's connection-counting flag). Channel-scoped — distinct from the app-wide peak connections metric. Whether at least one client is subscribed.