Problem: Participants joining early only got incomplete participant list
from other_parties (only those who had joined), causing partyIndex mismatch.
Solution:
- Add parties field to SessionInfo (from validateInviteCode response)
- Pass parties to joinSession call from frontend
- Backend joinSession uses params.parties (complete list) instead of
result.other_parties (incomplete list)
- Add debug logging to track participant list state
Now all participants have the complete parties list with correct partyIndex.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>