Function local_workspace_key 

pub fn local_workspace_key() -> Option<PresenceKey>

The scope this process should publish its presence under — the workspace it collaborates in, or None when it has no workspace. Read from local_cluster_id, the same value the routing address is built from, so the two cannot drift apart.

None when the workspace is the nil uuid: that value addresses nobody (CrdtRoute::is_addressable rejects it — an unminted workspace would otherwise make every unconfigured machine share one workspace). Fail closed.