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/FormulaActions.cs

@@ -0,0 +1,47 @@
+namespace Cthangover.Mods.BattleFormulas
+{
+    using System.Collections.Generic;
+    using System.Linq;
+    using Cthangover.Core.Battle.Actions;
+    using Cthangover.Core.Characters;
+    using Cthangover.Core.Mods.Resolvers;
+    using Cthangover.Core.Utils;
+
+    /// <summary>
+    /// Finds the action entities that carry a <c>Formula=</c> value and registers a
+    /// <see cref="FormulaActionExecutor"/> for each as a global battle executor. Runs when
+    /// mod resources are ready and again as every battle starts, so an action added in an
+    /// editor or by a freshly loaded mod is playable in the next battle.
+    /// <para/>
+    /// The hub keys executors by action id and replaces on re-registration, so a reload
+    /// simply re-points the ids at this assembly's executors.
+    /// </summary>
+    public static class FormulaActions
+    {
+        private const string FormulaPrefix = "Formula=";
+
+        private static object snapshot;
+
+        /// <summary>The ids of the loaded formula actions.</summary>
+        public static List<string> Ids()
+            => Entities.Collect<ActionCharacterInfo>().Values
+                .Where(IsFormulaAction).Select(a => a.ID).OrderBy(id => id, System.StringComparer.Ordinal).ToList();
+
+        /// <summary>Whether an action entity is driven by a formula.</summary>
+        public static bool IsFormulaAction(ActionCharacterInfo info)
+            => info?.Values != null && info.Values.Any(v => v != null && v.StartsWith(FormulaPrefix, System.StringComparison.OrdinalIgnoreCase));
+
+        /// <summary>Registers an executor per formula action (only when the data snapshot changed).</summary>
+        public static void Refresh()
+        {
+            var current = Entities.Collect<ActionCharacterInfo>();
+            if (ReferenceEquals(current, snapshot))
+                return;
+            snapshot = current;
+            var ids = Ids();
+            foreach (var id in ids)
+                ActionExecutorHub.Instance.RegisterGlobal(new FormulaActionExecutor(id));
+            GameLogger.Log("BATTLE", $"battle formulas: {ids.Count} formula action(s) registered");
+        }
+    }
+}