diff --git a/src/AcDream.Core/Items/ItemRepository.cs b/src/AcDream.Core/Items/ItemRepository.cs
index 6ffcc85c..5543c958 100644
--- a/src/AcDream.Core/Items/ItemRepository.cs
+++ b/src/AcDream.Core/Items/ItemRepository.cs
@@ -61,6 +61,11 @@ public sealed class ItemRepository
     /// <summary>Fires when an item's properties are updated (typically after Appraise).</summary>
     public event Action<ItemInstance>? ItemPropertiesUpdated;
 
+    /// <summary>PropertyInt.UiEffects (ACE enum value 18) — the icon effect bitfield;
+    /// the typed mirror <see cref="UpdateIntProperty"/> maintains on
+    /// <see cref="ItemInstance.Effects"/>.</summary>
+    public const uint UiEffectsPropertyId = 18u;
+
     public int ItemCount => _items.Count;
     public int ContainerCount => _containers.Count;
 
@@ -187,9 +192,6 @@ public sealed class ItemRepository
         return true;
     }
 
-    /// <summary>PropertyInt.UiEffects (ACE enum value 18) — the icon effect bitfield.</summary>
-    public const uint UiEffectsPropertyId = 18u;
-
     /// <summary>
     /// Apply a single PropertyInt update (from PublicUpdatePropertyInt 0x02CE) to an
     /// item: store it in the bundle and, for known typed ints, mirror to the typed
diff --git a/tests/AcDream.Core.Tests/Items/ItemRepositoryTests.cs b/tests/AcDream.Core.Tests/Items/ItemRepositoryTests.cs
index 5b39b932..0ee2631d 100644
--- a/tests/AcDream.Core.Tests/Items/ItemRepositoryTests.cs
+++ b/tests/AcDream.Core.Tests/Items/ItemRepositoryTests.cs
@@ -158,10 +158,10 @@ public sealed class ItemRepositoryTests
         repo.AddOrUpdate(new ItemInstance { ObjectId = 0x500000ABu });
         ItemInstance? fired = null;
         repo.ItemPropertiesUpdated += i => fired = i;
-        bool ok = repo.UpdateIntProperty(0x500000ABu, 18u, value: 0x9);   // 18 = UiEffects
+        bool ok = repo.UpdateIntProperty(0x500000ABu, ItemRepository.UiEffectsPropertyId, value: 0x9);
         Assert.True(ok);
         Assert.Equal(0x9u, repo.GetItem(0x500000ABu)!.Effects);
-        Assert.Equal(0x9, repo.GetItem(0x500000ABu)!.Properties.Ints[18u]);
+        Assert.Equal(0x9, repo.GetItem(0x500000ABu)!.Properties.Ints[ItemRepository.UiEffectsPropertyId]);
         Assert.NotNull(fired);
     }