localFabric

Whether this peer's own end of the fabric carrying this room can carry frames now.

Session-scoped, never device-scoped: a peer in two rooms over two fabrics has two independent values and neither speaks for the other. A room over a bonded CompositeSeam reports FabricAvailability.Unavailable only when every woven ply is down.

FabricAvailability.Unknown means the fabric has no live path observer. Treat it as "kuilt cannot tell", never as either answer — and expect it: it is the value every fabric but a path-observing one reports, so it is the common case rather than an error.

This is the authoritative, replay-safe level. Being a StateFlow, a late collector immediately reads the current value and so cannot miss a drop, where MembershipEvent.LocalFabricLost / MembershipEvent.LocalFabricRestored on events are only notifications that it moved.

The level is never staler than an edge — so it never claims the fabric is up while an emitted MembershipEvent.LocalFabricLost says otherwise. It can, however, be ahead of the edge you are handling: events are buffered, so under a rapid flap (Available → Unavailable → Available) a handler may read Available while processing the LocalFabricLost, with the matching LocalFabricRestored still queued behind it. Treat the edges as idempotent notifications and this level as authoritative; do not assert that the level matches the edge in hand (#1712).

Deliberately has no interface default. An implementation that silently inherited Unknown would be claiming it cannot tell, when a Room implementation — a fake above all — is exactly the thing that can.