Fix entry into existing frost caves

Source/World/FrostCaveInterior.cs

@@ -0,0 +1,104 @@
+using System.Collections.Generic;
+using HarmonyLib;
+using UnityEngine;
+
+namespace PraetorisClient
+{
+    // LocationProxy reconstructs the non-networked gateway from today's prefab.
+    // An existing dungeon still uses its saved generator and room transforms.
+    internal sealed class FrostCaveInterior : MonoBehaviour
+    {
+        private readonly List<ZDO> _objects = new List<ZDO>();
+        private Location _location = null!;
+        private float _nextCheck;
+
+        internal void Initialize(Location location)
+        {
+            _location = location;
+            Update();
+        }
+
+        private void Update()
+        {
+            if (_location == null || ZDOMan.instance == null || Time.unscaledTime < _nextCheck)
+            {
+                return;
+            }
+
+            _nextCheck = Time.unscaledTime + 1f;
+            DungeonGenerator generator = _location.m_generator;
+            Transform interior = _location.m_interiorTransform;
+            if (generator == null || interior == null || !generator.transform.IsChildOf(interior))
+            {
+                Destroy(this);
+                return;
+            }
+
+            int prefabHash = Utils.GetPrefabName(generator.gameObject).GetStableHashCode();
+            Vector3 expectedPosition = generator.transform.position;
+            _objects.Clear();
+            ZDOMan.instance.FindSectorObjects(ZoneSystem.GetZone(expectedPosition),
+                new SimulationDistance(0, 0, classic: true), _objects);
+
+            ZDO? savedGenerator = null;
+            foreach (ZDO candidate in _objects)
+            {
+                if (candidate.GetPrefab() != prefabHash ||
+                    Mathf.Abs(candidate.GetPosition().y - expectedPosition.y) > 1f)
+                {
+                    continue;
+                }
+
+                if (savedGenerator != null)
+                {
+                    PraetorisClientPlugin.Log.LogWarning("Frost cave interior has multiple saved dungeon generators; leaving its transform unchanged.");
+                    Destroy(this);
+                    return;
+                }
+
+                savedGenerator = candidate;
+            }
+
+            // On a remote client the generator ZDO may arrive after the proxy.
+            if (savedGenerator == null)
+            {
+                return;
+            }
+
+            Vector3 savedPosition = savedGenerator.GetPosition();
+            Quaternion savedRotation = savedGenerator.GetRotation();
+            if (Vector3.Distance(expectedPosition, savedPosition) > 0.01f ||
+                Quaternion.Angle(generator.transform.rotation, savedRotation) > 0.01f)
+            {
+                Quaternion correction = savedRotation * Quaternion.Inverse(generator.transform.rotation);
+                interior.rotation = correction * interior.rotation;
+                interior.position += savedPosition - generator.transform.position;
+                PraetorisClientPlugin.Log.LogInfo("Aligned frost cave interior with saved dungeon: " +
+                    expectedPosition + " -> " + savedPosition + ".");
+            }
+
+            Destroy(this);
+        }
+    }
+
+    [HarmonyPatch(typeof(LocationProxy), "SpawnLocation")]
+    internal static class FrostCaveInteriorSpawnPatch
+    {
+        [HarmonyPostfix]
+        private static void Postfix(LocationProxy __instance, bool __result)
+        {
+            if (!__result || __instance.m_instance == null)
+            {
+                return;
+            }
+
+            Location location = __instance.m_instance.GetComponent<Location>();
+            if (location == null || Utils.GetPrefabName(location.gameObject) != "MountainCave02")
+            {
+                return;
+            }
+
+            location.gameObject.AddComponent<FrostCaveInterior>().Initialize(location);
+        }
+    }
+}