Targeted item actions (action/heal), item.add scenario action, inventory cell Decorate; mod cover

src/HealItemAction.cs

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+using System;
+using Cthangover.Core.Items;
+using Cthangover.Core.Settings;
+
+namespace Cthangover.Mods.Items
+{
+    /// <summary>
+    /// Restores health of the chosen party member (<c>"ItemAction": "action/heal"</c>).
+    /// The amount is item data, not code: the item's <c>"heal"</c> key (an extra JSON
+    /// key, so it lands in <see cref="IItem.Properties"/>), which lets one action serve
+    /// a mushroom and an elixir alike. Health never rises above its base value, and a
+    /// fallen character (health 0) is not revived — that is a different effect.
+    /// The party member's attributes are the very objects the battle uses, so a heal
+    /// in the inventory during a battle shows on the battle widgets at once.
+    /// </summary>
+    public class HealItemAction : ITargetedItemAction
+    {
+        /// <summary>Item property with the amount of health restored.</summary>
+        public const string HealProperty = "heal";
+
+        /// <summary>Action id referenced by item definitions.</summary>
+        public string ID => "action/heal";
+
+        /// <summary>Healing always needs a target; without one nothing happens.</summary>
+        public bool UseAction(IItem item) => false;
+
+        /// <summary>
+        /// Adds the item's <c>heal</c> amount to the target's health, capped at the
+        /// base value. Returns <c>false</c> (item not spent) for a missing target, a
+        /// non-positive amount, a fallen target or one already at full health.
+        /// </summary>
+        public bool UseOn(IItem item, CharacterInfoData target)
+        {
+            var health = target?.Attributes?.Health;
+            var amount = item?.Properties?.GetInt(HealProperty) ?? 0;
+            if (health == null || amount <= 0 || health.Value <= 0 || health.Value >= health.BaseValue)
+                return false;
+
+            health.Value = Math.Min(health.BaseValue, health.Value + amount);
+            return true;
+        }
+    }
+}