perf(context)!: release retired fibers and bound diagnostic history

Runtime/Context/ShrinkCtx.cs

@@ -14,6 +14,7 @@ namespace ShrinkContext
     public sealed class ShrinkCtx
     {
         private readonly List<ShrinkEffectHandle> _effects = new();
+        private bool _disposing;
         private readonly Dictionary<string, string>? _isolateOverlay;
         private Dictionary<string, IReadOnlyDictionary<string, object?>>? _interceptOverlay;
 
@@ -81,6 +82,13 @@ namespace ShrinkContext
 
         internal void Attach(ShrinkEffectHandle handle) => _effects.Add(handle);
 
+        internal void Detach(ShrinkEffectHandle handle)
+        {
+            // During parent teardown the reverse traversal owns removal.
+            if (!_disposing)
+                _effects.Remove(handle);
+        }
+
         /// <summary>
         /// 前向已在外部执行完毕的效应：仅登记逆操作（供桥接适配器把既有 API 的"注册/注销"对包装为可逆效应）。
         /// </summary>
@@ -98,9 +106,14 @@ namespace ShrinkContext
         /// <summary>按 LIFO 顺序执行本上下文注册的全部逆操作。</summary>
         public async UniTask DisposeAsync()
         {
-            for (var i = _effects.Count - 1; i >= 0; i--)
-                await _effects[i].DisposeAsync();
-            _effects.Clear();
+            _disposing = true;
+            try
+            {
+                for (var i = _effects.Count - 1; i >= 0; i--)
+                    await _effects[i].DisposeAsync();
+                _effects.Clear();
+            }
+            finally { _disposing = false; }
         }
 
         // ---------------- 余效应（论文 3.2 / 算法 2） ----------------