The broadcast alone wasn't reaching the first client because its
recv loop hadn't started yet when the second client registered.
Now the relay sends PresenceList directly to the new client (right
after RegisterPresenceAck) AND broadcasts to all others.
This guarantees every client gets the full user list:
- New client: via direct send (queued before recv loop starts)
- Existing clients: via broadcast
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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