chunk 1: core gameplay scripts scenes runtime assets

Assets/Scripts/Core/EntityRegistry.cs

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+using UnityEngine;
+using System.Collections.Generic;
+
+/// <summary>
+/// EntityRegistry — Zero-allocation replacement for FindObjectsOfType.
+/// Each MonoBehaviour type auto-registers in OnEnable/OnDisable via EntityRegistryMember<T>.
+/// Access all instances via EntityRegistry<T>.All (read-only list, no allocation).
+/// 
+/// Usage:
+///   1) Add EntityRegistryMember<CashBag> component, or
+///   2) Call EntityRegistry<CashBag>.Register(this) in OnEnable / Unregister in OnDisable
+///   3) Query: foreach (var bag in EntityRegistry<CashBag>.All) { ... }
+/// </summary>
+public static class EntityRegistry<T> where T : class
+{
+    private static readonly List<T> _instances = new List<T>(32);
+    private static readonly List<T> _readOnly = _instances; // Same ref, cast prevents mutation at call sites
+
+    /// <summary>All currently active instances. Do NOT modify this list.</summary>
+    public static List<T> All => _readOnly;
+
+    /// <summary>Alias for All — convenience method matching GetAll() convention.</summary>
+    public static List<T> GetAll() => _readOnly;
+
+    /// <summary>Number of active instances.</summary>
+    public static int Count => _instances.Count;
+
+    public static void Register(T instance)
+    {
+        if (instance != null && !_instances.Contains(instance))
+            _instances.Add(instance);
+    }
+
+    public static void Unregister(T instance)
+    {
+        _instances.Remove(instance);
+    }
+
+    /// <summary>
+    /// Find nearest instance to a world position. 
+    /// Returns null if no instances. O(n) but n is small (≤10 for bags/characters).
+    /// </summary>
+    public static T FindNearest(Vector3 position, System.Func<T, Vector3> getPosition, System.Func<T, bool> filter = null)
+    {
+        T nearest = null;
+        float nearestSqrDist = float.MaxValue;
+
+        for (int i = 0; i < _instances.Count; i++)
+        {
+            T instance = _instances[i];
+            if (instance == null) continue;
+            if (filter != null && !filter(instance)) continue;
+
+            float sqrDist = (getPosition(instance) - position).sqrMagnitude;
+            if (sqrDist < nearestSqrDist)
+            {
+                nearestSqrDist = sqrDist;
+                nearest = instance;
+            }
+        }
+        return nearest;
+    }
+
+    /// <summary>
+    /// Find all instances within radius. Uses pre-allocated result list to avoid allocation.
+    /// Caller should process results immediately (list is reused).
+    /// </summary>
+    private static readonly List<T> _withinRadiusResults = new List<T>(16);
+    public static List<T> FindWithinRadius(Vector3 position, float radius, System.Func<T, Vector3> getPosition, System.Func<T, bool> filter = null)
+    {
+        _withinRadiusResults.Clear();
+        float sqrRadius = radius * radius;
+
+        for (int i = 0; i < _instances.Count; i++)
+        {
+            T instance = _instances[i];
+            if (instance == null) continue;
+            if (filter != null && !filter(instance)) continue;
+
+            float sqrDist = (getPosition(instance) - position).sqrMagnitude;
+            if (sqrDist <= sqrRadius)
+                _withinRadiusResults.Add(instance);
+        }
+        return _withinRadiusResults;
+    }
+
+    /// <summary>Call on scene unload to prevent stale references.</summary>
+    public static void Clear() => _instances.Clear();
+}