Durable, transactional key/value storage scoped to this object.

Accepts a socket as hibernatable.

Unlike ws.accept(), this tells the runtime it need not pin the Durable Object to memory while the connection is open: the object may be evicted and its constructor re-run when the next message arrives. That is why RealtimeBackplaneObjectCore keeps no membership in a field — getWebSockets is the only state that survives.

Returns every currently connected socket.

Survives hibernation, which is what makes it usable as the sole source of truth for broadcast membership.