draft options working; spells won't cast though

Assets/_Project/Scripts/Gameplay/SpellSlot.cs

@@ -0,0 +1,63 @@
+// Assets/_Project/Scripts/Gameplay/SpellSlot.cs
+using System;
+using Unity.Netcode;
+using TD.Core;
+
+namespace TD.Gameplay
+{
+    /// <summary>
+    /// One granted builder spell in a <see cref="PlayerSpellLoadout"/>. Replicated as part of
+    /// a <see cref="NetworkList{T}"/>; the entry's index in that list IS the hotkey slot
+    /// (grant order == key order), so no separate slot index field is needed.
+    /// </summary>
+    /// <remarks>
+    /// <b>One struct, not parallel lists.</b> <see cref="Kind"/> is set once at grant time;
+    /// <see cref="CooldownEndServerTime"/> is rewritten on every cast. <c>NetworkList{T}</c>'s
+    /// indexer setter (<c>spells[i] = newValue</c>) short-circuits the write when
+    /// <c>Equals</c> on the old value returns true (see <see cref="BuildJob"/> for the
+    /// documented case that first surfaced this). Comparing only <see cref="Kind"/> would mean
+    /// a cooldown update — same Kind, new CooldownEndServerTime — never actually replicates.
+    /// <see cref="Equals"/> therefore compares every field.
+    /// </remarks>
+    [Serializable]
+    public struct SpellSlot : INetworkSerializable, IEquatable<SpellSlot>
+    {
+        /// <summary>Which spell occupies this slot. Fixed for the slot's lifetime.</summary>
+        public BuilderSpellKind Kind;
+
+        /// <summary>
+        /// <c>NetworkManager.ServerTime.Time</c> at which this slot is next ready to cast.
+        /// 0 (or any value &lt;= current server time) means ready now.
+        /// </summary>
+        public double CooldownEndServerTime;
+
+        public static SpellSlot CreateReady(BuilderSpellKind kind)
+        {
+            return new SpellSlot { Kind = kind, CooldownEndServerTime = 0d };
+        }
+
+        // ----- INetworkSerializable ---------------------------------------
+
+        public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
+        {
+            byte kindByte = (byte)Kind;
+            serializer.SerializeValue(ref kindByte);
+            Kind = (BuilderSpellKind)kindByte;
+
+            serializer.SerializeValue(ref CooldownEndServerTime);
+        }
+
+        // ----- IEquatable -------------------------------------------------
+        //
+        // Full-field comparison — see remarks above. Without this, cooldown writes
+        // (Kind unchanged, only CooldownEndServerTime updated) would be silently dropped
+        // by NetworkList's indexer setter.
+
+        public bool Equals(SpellSlot other) =>
+            Kind == other.Kind && CooldownEndServerTime == other.CooldownEndServerTime;
+
+        public override bool Equals(object obj) => obj is SpellSlot other && Equals(other);
+
+        public override int GetHashCode() => (int)Kind;
+    }
+}