Reapply "OBT1.1.0 Merge branch 'dev_pte' into dev"

This reverts commit 046483b9da.

Barotrauma/BarotraumaShared/SharedSource/Map/Gap.cs

@@ -10,13 +10,71 @@ using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using System.Xml.Linq;
 
 namespace Barotrauma
 {
+    /// <summary>
+    /// Thread-safe wrapper for Gap list operations.
+    /// Uses copy-on-write pattern for lock-free reads.
+    /// </summary>
+    internal class ThreadSafeGapList : IEnumerable<Gap>
+    {
+        private volatile List<Gap> _list = new List<Gap>();
+        private readonly object _writeLock = new object();
+
+        public int Count => _list.Count;
+
+        public void Add(Gap gap)
+        {
+            lock (_writeLock)
+            {
+                var newList = new List<Gap>(_list) { gap };
+                Interlocked.Exchange(ref _list, newList);
+            }
+        }
+
+        public bool Remove(Gap gap)
+        {
+            lock (_writeLock)
+            {
+                var newList = new List<Gap>(_list);
+                bool removed = newList.Remove(gap);
+                if (removed)
+                {
+                    Interlocked.Exchange(ref _list, newList);
+                }
+                return removed;
+            }
+        }
+
+        public void Clear()
+        {
+            Interlocked.Exchange(ref _list, new List<Gap>());
+        }
+
+        public bool Contains(Gap gap) => _list.Contains(gap);
+
+        public Gap this[int index] => _list[index];
+
+        public IEnumerator<Gap> GetEnumerator() => _list.GetEnumerator();
+        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() => GetEnumerator();
+
+        // LINQ-friendly methods
+        public List<Gap> ToList() => new List<Gap>(_list);
+        public Gap FirstOrDefault(Func<Gap, bool> predicate) => _list.FirstOrDefault(predicate);
+        public Gap Find(Predicate<Gap> predicate) => _list.Find(predicate);
+        public List<Gap> FindAll(Predicate<Gap> predicate) => _list.FindAll(predicate);
+        public IEnumerable<Gap> Where(Func<Gap, bool> predicate) => _list.Where(predicate);
+        public bool Any() => _list.Any();
+        public bool Any(Func<Gap, bool> predicate) => _list.Any(predicate);
+        public IOrderedEnumerable<Gap> OrderBy<TKey>(Func<Gap, TKey> keySelector) => _list.OrderBy(keySelector);
+    }
+
     partial class Gap : MapEntity, ISerializableEntity
     {
-        public static List<Gap> GapList = new List<Gap>();
+        public static ThreadSafeGapList GapList = new ThreadSafeGapList();
 
         const float MaxFlowForce = 500.0f;