When a party re-subscribes (e.g., Android reconnects), the old gRPC stream's
defer Unsubscribe() was accidentally removing the NEW subscription from the
subscribers map, causing the party to miss session_started events.
Fix:
- Subscribe() now returns the channel to the caller
- Unsubscribe() now takes the channel and only removes if it matches
- This prevents older streams from removing newer subscriptions
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
hailin
549b21f298
