DoMatchingInternal calls IMatchingPairUpService.TryPairAsync, then maps:
- null result → 3002 RETRY (empty node_server_url, no battle_id)
- IsAiFallback → 3011 AI_BATTLE_MATCHING_SUCCEEDED
- IsOwner → 3007 SUCCEEDED_OWNER (cache pickup)
- joiner → 3004 SUCCEEDED
BuildForRankBattleAsync's InvalidOperationException (typically "no deck
for format") surfaces as 3001 ILLEGAL so the client shows the
matchmaking-error dialog rather than retrying.
card_master_id is a placeholder (0) per the per-battle card-master
split deferral. AI-fallback timing is covered by InProcessPairUp unit
tests; controller tests focus on the wire mapping (3002, 3004, 3007).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>