Battle formulas: action values as stat formulas, costs from stat pools, MP gauge for party members, action schema

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/BattleStatsBridge.cs

@@ -0,0 +1,42 @@
+namespace Cthangover.Mods.BattleFormulas
+{
+    using System.Linq;
+    using Cthangover.Core.Battle;
+    using Cthangover.Core.Events;
+    using Cthangover.Mods.Stats;
+
+    /// <summary>
+    /// The moment a battle starts: formula actions are (re)registered, the party's bound
+    /// stats are synced (a member may have joined in the same dialog that started the
+    /// fight), and enemies whose templates carry stats data (<c>Stats</c>,
+    /// <c>Archetype</c> or <c>Traits</c>) get their battle attributes from their sheets. An
+    /// enemy without stats data keeps its template's numbers, so old content fights as before.
+    /// </summary>
+    public static class BattleStatsBridge
+    {
+        /// <summary>
+        /// The battle route is about to load: the battle scene builds its sides and HUD from
+        /// the attributes right after this, so they get their stats now.
+        /// </summary>
+        public static void OnRouteActivating(SceneRouteActivatingEvent evt)
+        {
+            if (evt?.LogicalName == "Battle")
+                OnBattleStarted(null);
+        }
+
+        /// <summary>
+        /// Handler of <see cref="BattleStartedEvent"/> (also run on the route activation);
+        /// every step is idempotent, so running twice changes nothing.
+        /// </summary>
+        public static void OnBattleStarted(BattleStartedEvent evt)
+        {
+            FormulaActions.Refresh();
+            StatSync.SyncRoster();
+            foreach (var enemy in BattleRequest.Current?.EnemiesCards?.Where(e => e != null) ?? Enumerable.Empty<Core.Characters.Character>())
+            {
+                if (StatsService.Participates(enemy.ID))
+                    StatBindings.Apply(StatsService.Sheet(enemy.ID), enemy.Attributes);
+            }
+        }
+    }
+}