Major rewrite of relay federation replacing virtual participants with
a clean router model:
1. Global rooms: [[global_rooms]] in TOML config declares rooms that
are bridged across federation. Each relay is a router + local SFU.
2. Room events: RoomManager emits LocalJoin/LocalLeave via broadcast
channel when rooms transition between empty and non-empty.
3. GlobalRoomActive/Inactive signals: relays announce when they have
local participants in global rooms. Peers track active state and
forward media accordingly. Announcements propagate for multi-hop.
4. Media forwarding: separated from SFU loop. Local participant sends
via mpsc channel → egress task → forward_to_peers() → room-hash
tagged datagrams to active peer links. Inbound datagrams delivered
to local participants + forwarded to other active peers (multi-hop).
5. Loop prevention: don't forward back to source relay.
6. Room name hashing: is_global_room() checks both plain name and
hash (clients hash room names for SNI privacy).
Removed: ParticipantSender::Federation, federated_participants, virtual
participant join/leave, periodic room polling. Rooms now only contain
local participants.
Signaling tested: 3-relay chain (A→B←C) correctly propagates
GlobalRoomActive through B to both A and C. Media forwarding plumbing
in place but needs final debugging.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
b00db5dfdc