feat(ui): drive toolbar use state from selection

Port the retail selected-object availability predicate into Core and project it through the shared interaction owner. The imported hand now follows canonical selection/object notices, keeps weapon and targeted-tool activation on the existing wield/use cursor paths, and ghosts empty or explicitly unusable selections per the connected UX requirement.

Co-authored-by: Codex <codex@openai.com>

src/AcDream.App/UI/ItemInteractionController.cs

@@ -496,6 +496,23 @@ public sealed class ItemInteractionController : IDisposable
         return true;
     }
 
+    /// <summary>
+    /// Projects retail <c>gmToolbarUI::HandleSelectionChanged @ 0x004BF380</c>
+    /// from the live selected object's public description. This is deliberately
+    /// a read-only query; activation still flows through <see cref="ActivateItem"/>.
+    /// </summary>
+    public bool IsToolbarUseEnabled(uint selectedObjectId)
+    {
+        if (selectedObjectId == 0
+            || _objects.Get(selectedObjectId) is not { } item)
+            return false;
+
+        return ItemInteractionPolicy.IsToolbarUseEnabled(
+            item.Type,
+            item.CombatUse ?? 0,
+            item.Useability ?? ItemUseability.Undef);
+    }
+
     public bool ActivateItem(uint itemGuid)
     {
         if (itemGuid == 0) return false;

src/AcDream.App/UI/Layout/ToolbarController.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using AcDream.Core.Combat;
 using AcDream.Core.Items;
 using AcDream.Core.Net.Messages;
+using AcDream.Core.Selection;
 
 namespace AcDream.App.UI.Layout;
 
@@ -73,6 +74,7 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
     private readonly ItemInteractionController? _itemInteraction;
     private readonly Action<uint>? _selectItem;
     private readonly Func<uint> _selectedObjectId;
+    private readonly SelectionState? _selection;
     private readonly Func<uint>? _playerGuid;
     private readonly Action<uint, uint, int>? _sendPutItemInContainer;
     private uint _ammoObjectId;
@@ -106,6 +108,7 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
         Action? toggleCombat = null,
         Action<uint>? selectItem = null,
         Func<uint>? selectedObjectId = null,
+        SelectionState? selection = null,
         Func<uint>? playerGuid = null,
         Action<uint, uint, int>? sendPutItemInContainer = null,
         UiDatFont? ammoFont = null,
@@ -125,6 +128,7 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
         _sendRemoveShortcut = sendRemoveShortcut;
         _selectItem = selectItem;
         _selectedObjectId = selectedObjectId ?? (() => 0u);
+        _selection = selection;
         _playerGuid = playerGuid;
         _sendPutItemInContainer = sendPutItemInContainer;
 
@@ -196,6 +200,8 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
         // Wire live combat-mode changes if a CombatState was provided.
         if (_combatState is not null)
             _combatState.CombatModeChanged += SetCombatMode;
+        if (_selection is not null)
+            _selection.Changed += OnSelectionChanged;
 
         // D.5.4: the table now holds ALL objects (creatures, NPCs, etc.), so filter
         // to our 18 shortcut guids — else every creature spawn in a busy zone
@@ -206,6 +212,7 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
         repo.ObjectMoved   += OnRepositoryObjectMoved;
         repo.Cleared       += OnRepositoryCleared;
         RefreshAmmo();
+        RefreshUseButton();
     }
 
     private void OnRepositoryObjectChanged(ClientObject obj)
@@ -214,6 +221,8 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
             RefreshAmmo();
         if (IsShortcutGuid(obj.ObjectId))
             Populate();
+        if (obj.ObjectId == _selectedObjectId())
+            RefreshUseButton();
     }
 
     private void OnRepositoryObjectMoved(ClientObjectMove move)
@@ -234,6 +243,23 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
     {
         RefreshAmmo();
         Populate();
+        RefreshUseButton();
+    }
+
+    private void OnSelectionChanged(SelectionTransition _)
+        => RefreshUseButton();
+
+    private void RefreshUseButton()
+    {
+        if (_useButton is null)
+            return;
+
+        // Retail normally leaves state 1 active when selectedID == 0 so the
+        // click can enter generic TARGET_MODE_USE. acdream intentionally
+        // ghosts that empty state per the connected UX requirement; every
+        // selected-object classification below is the exact retail predicate.
+        _useButton.Enabled =
+            _itemInteraction?.IsToolbarUseEnabled(_selectedObjectId()) == true;
     }
 
     private bool IsAmmoRelated(ClientObject obj)
@@ -330,6 +356,7 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
         Action? toggleCombat = null,
         Action<uint>? selectItem = null,
         Func<uint>? selectedObjectId = null,
+        SelectionState? selection = null,
         Func<uint>? playerGuid = null,
         Action<uint, uint, int>? sendPutItemInContainer = null,
         UiDatFont? ammoFont = null,
@@ -338,7 +365,7 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
         var c = new ToolbarController(layout, repo, shortcuts, iconIds, useItem, combatState,
                                       regularDigits, ghostedDigits, emptyDigits, itemInteraction,
                                       sendAddShortcut, sendRemoveShortcut, toggleCombat, selectItem,
-                                      selectedObjectId, playerGuid, sendPutItemInContainer, ammoFont,
+                                      selectedObjectId, selection, playerGuid, sendPutItemInContainer, ammoFont,
                                       dragIconIds);
         c.Populate();
         return c;
@@ -736,6 +763,8 @@ public sealed class ToolbarController : IItemListDragHandler, IRetainedPanelCont
 
         if (_combatState is not null)
             _combatState.CombatModeChanged -= SetCombatMode;
+        if (_selection is not null)
+            _selection.Changed -= OnSelectionChanged;
         _repo.ObjectAdded   -= OnRepositoryObjectChanged;
         _repo.ObjectUpdated -= OnRepositoryObjectChanged;
         _repo.ObjectRemoved -= OnRepositoryObjectChanged;

src/AcDream.App/UI/RetailUiRuntime.cs

@@ -689,6 +689,7 @@ public sealed class RetailUiRuntime : IDisposable
             toggleCombat: b.ToggleCombat,
             selectItem: guid => b.Selection.Select(guid, SelectionChangeSource.Toolbar),
             selectedObjectId: () => b.Selection.SelectedObjectId ?? 0u,
+            selection: b.Selection,
             playerGuid: b.PlayerGuid,
             sendPutItemInContainer: b.SendPutItemInContainer,
             ammoFont: _bindings.Assets.DefaultFont,

src/AcDream.Core/Items/ItemInteractionPolicy.cs

@@ -151,6 +151,22 @@ public static class ItemInteractionPolicy
     private static readonly EquipMask BodyLocations = (EquipMask)0x00007E00u;
     private static readonly EquipMask ClothingLocations = (EquipMask)0x080001FFu;
     private static readonly EquipMask HeldLocations = (EquipMask)0x7C0F8000u;
+    private const ItemType ToolbarEquipmentTypes =
+        ItemType.Armor | ItemType.Clothing | ItemType.Jewelry;
+
+    /// <summary>
+    /// Exact selected-object predicate used by retail's toolbar hand.
+    /// <c>gmToolbarUI::HandleSelectionChanged @ 0x004BF380</c> leaves the
+    /// button active for combat-use objects, armor/clothing/jewelry, or an
+    /// <c>ItemUses</c> value whose <c>USEABLE_NO</c> bit is clear.
+    /// </summary>
+    public static bool IsToolbarUseEnabled(
+        ItemType type,
+        byte combatUse,
+        uint useability)
+        => combatUse != 0
+            || (type & ToolbarEquipmentTypes) != 0
+            || (useability & ItemUseability.No) == 0;
 
     public static ItemPrimaryUseResult DetermineUseResult(
         in ItemPolicyObject item,