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>

tests/AcDream.App.Tests/UI/Layout/ToolbarControllerTests.cs

@@ -5,6 +5,7 @@ using AcDream.App.UI.Layout;
 using AcDream.Core.Combat;
 using AcDream.Core.Items;
 using AcDream.Core.Net.Messages;
+using AcDream.Core.Selection;
 using Xunit;
 
 namespace AcDream.App.Tests.UI.Layout;
@@ -515,6 +516,123 @@ public class ToolbarControllerTests
         Assert.Equal(InteractionModeKind.Examine, interaction.InteractionState.Current.Kind);
     }
 
+    [Fact]
+    public void UseButton_tracksEmptyUnusableAndTargetedSelection()
+    {
+        const uint player = 0x50000001u;
+        const uint pack = 0x50000002u;
+        const uint component = 0x50000003u;
+        const uint healthKit = 0x50000004u;
+        var (layout, _, _) = FakeToolbar();
+        var repo = new ClientObjectTable();
+        repo.AddOrUpdate(new ClientObject { ObjectId = player, Type = ItemType.Creature });
+        repo.AddOrUpdate(new ClientObject { ObjectId = pack, Type = ItemType.Container });
+        repo.MoveItem(pack, player, 0);
+        repo.AddOrUpdate(new ClientObject
+        {
+            ObjectId = component,
+            Type = ItemType.SpellComponents,
+            Useability = ItemUseability.No,
+        });
+        repo.MoveItem(component, pack, 0);
+        repo.AddOrUpdate(new ClientObject
+        {
+            ObjectId = healthKit,
+            Type = ItemType.Misc,
+            Useability = 0x00220008u,
+            TargetType = (uint)ItemType.Creature,
+        });
+        repo.MoveItem(healthKit, pack, 1);
+
+        var selection = new SelectionState();
+        using var interaction = new ItemInteractionController(
+            repo,
+            () => player,
+            sendUse: null,
+            sendUseWithTarget: null,
+            sendWield: null,
+            sendDrop: null);
+        using var controller = ToolbarController.Bind(
+            layout,
+            repo,
+            () => Array.Empty<ShortcutEntry>(),
+            iconIds: (_, _, _, _, _) => 0u,
+            useItem: _ => { },
+            itemInteraction: interaction,
+            selectedObjectId: () => selection.SelectedObjectId ?? 0u,
+            selection: selection);
+        var use = Assert.IsType<UiButton>(layout.FindElement(UseButtonId));
+
+        Assert.False(use.Enabled);
+        Assert.Equal("Ghosted", use.ActiveState);
+        use.OnEvent(new UiEvent(0u, use, UiEventType.Click));
+        Assert.Equal(InteractionModeKind.None, interaction.InteractionState.Current.Kind);
+
+        selection.Select(component, SelectionChangeSource.Inventory);
+        Assert.False(use.Enabled);
+        Assert.Equal("Ghosted", use.ActiveState);
+
+        selection.Select(healthKit, SelectionChangeSource.Inventory);
+        Assert.True(use.Enabled);
+        Assert.Equal("Normal", use.ActiveState);
+        use.OnEvent(new UiEvent(0u, use, UiEventType.Click));
+        Assert.Equal(
+            InteractionModeKind.UseItemOnTarget,
+            interaction.InteractionState.Current.Kind);
+
+        selection.Clear(SelectionChangeSource.Inventory);
+        Assert.False(use.Enabled);
+        Assert.Equal("Ghosted", use.ActiveState);
+    }
+
+    [Fact]
+    public void UseButton_selectedCombatItem_routesExistingWieldPath()
+    {
+        const uint player = 0x50000001u;
+        const uint pack = 0x50000002u;
+        const uint sword = 0x50000003u;
+        var (layout, _, _) = FakeToolbar();
+        var repo = new ClientObjectTable();
+        repo.AddOrUpdate(new ClientObject { ObjectId = player, Type = ItemType.Creature });
+        repo.AddOrUpdate(new ClientObject { ObjectId = pack, Type = ItemType.Container });
+        repo.MoveItem(pack, player, 0);
+        repo.AddOrUpdate(new ClientObject
+        {
+            ObjectId = sword,
+            Type = ItemType.MeleeWeapon,
+            CombatUse = 1,
+            Useability = ItemUseability.No,
+            ValidLocations = EquipMask.MeleeWeapon,
+        });
+        repo.MoveItem(sword, pack, 0);
+
+        var selection = new SelectionState();
+        selection.Select(sword, SelectionChangeSource.Inventory);
+        var wields = new List<(uint Item, uint Location)>();
+        using var interaction = new ItemInteractionController(
+            repo,
+            () => player,
+            sendUse: null,
+            sendUseWithTarget: null,
+            sendWield: (item, location) => wields.Add((item, location)),
+            sendDrop: null);
+        using var controller = ToolbarController.Bind(
+            layout,
+            repo,
+            () => Array.Empty<ShortcutEntry>(),
+            iconIds: (_, _, _, _, _) => 0u,
+            useItem: _ => { },
+            itemInteraction: interaction,
+            selectedObjectId: () => selection.SelectedObjectId ?? 0u,
+            selection: selection);
+        var use = Assert.IsType<UiButton>(layout.FindElement(UseButtonId));
+
+        Assert.True(use.Enabled);
+        use.OnEvent(new UiEvent(0u, use, UiEventType.Click));
+
+        Assert.Equal(new[] { (sword, (uint)EquipMask.MeleeWeapon) }, wields);
+    }
+
     // ── C1: combat-mode indicator tests ─────────────────────────────────────
 
     [Fact]

tests/AcDream.Core.Tests/Items/ItemInteractionPolicyTests.cs

@@ -7,6 +7,28 @@ public sealed class ItemInteractionPolicyTests
     private const uint Player = 0x50000001u;
     private const uint GroundContainer = 0x70000001u;
 
+    [Fact]
+    public void ToolbarUseEnabled_matchesRetailSelectionPredicate()
+    {
+        Assert.True(ItemInteractionPolicy.IsToolbarUseEnabled(
+            ItemType.MeleeWeapon,
+            combatUse: 1,
+            useability: ItemUseability.No));
+        Assert.True(ItemInteractionPolicy.IsToolbarUseEnabled(
+            ItemType.Armor | ItemType.Clothing,
+            combatUse: 0,
+            useability: ItemUseability.No));
+        Assert.True(ItemInteractionPolicy.IsToolbarUseEnabled(
+            ItemType.Misc,
+            combatUse: 0,
+            useability: 0x00220008u));
+
+        Assert.False(ItemInteractionPolicy.IsToolbarUseEnabled(
+            ItemType.SpellComponents,
+            combatUse: 0,
+            useability: ItemUseability.No));
+    }
+
     [Fact]
     public void DetermineUseResult_looseItemAndComponentPack_matchRetailPickupBranch()
     {