gamer147
c789d836f1
feat(engine-ambient): delete static fallbacks; add MultiInstanceEngineTests
Step 8 (final) of multi-instancing migration. All per-battle statics now
require a BattleAmbient scope — unwrapped writes throw InvalidOperationException
(fail-fast forcing function). MultiInstanceEngineTests proves correctness:
two parallel battles resolve independently, N=4/8/16 stress matches sequential
baseline, GameMgr.GetIns throws without scope.
Migration complete. EngineSessionGate gone. Suite fully green.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>