From 89d82e1b76c53f7e89c7b72ce86bb0361cd7f809 Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Wed, 13 May 2026 17:59:08 +0200
Subject: [PATCH] feat(B.4b): GameWindow wires Select/Use handlers via
 WorldPicker
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Closes #57. Adds three OnInputAction switch cases (SelectLeft,
SelectDblLeft, UseSelected) and three private helpers
(PickAndStoreSelection, UseCurrentSelection, SendUse). Single-click
selects but does not Use; double-click selects + Uses; R hotkey
sends Use on the existing _selectedGuid. ImGui mouse-capture
filtering already happens in InputDispatcher — no new guard needed.

Diagnostic lines emitted for log grep:
  [B.4b] pick guid=0x{guid:X8} name={label}
  [B.4b] use  guid=0x{guid:X8} seq={seq}

Also adds a one-line doc comment on _selectedGuid clarifying its
dual-purpose role (combat Q-cycle + interaction click), per the Task 3
review.

Build green; tests 1046/1054 (8 pre-existing-baseline fails
unchanged). Switch-case behavior verified at runtime via the Holtburg
inn doorway visual test (per spec §Testing → Runtime verification).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 src/AcDream.App/Rendering/GameWindow.cs | 74 +++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 6d2da3f..6124b01 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -783,6 +783,7 @@ public sealed class GameWindow : IDisposable
     /// fields when a 0xF625 ObjDescEvent arrives carrying only updated visuals.
     /// </summary>
     private readonly Dictionary<uint, AcDream.Core.Net.WorldSession.EntitySpawn> _lastSpawnByGuid = new();
+    // Current selection: written by Q-cycle (combat) and LMB click (interact); cleared on entity despawn.
     private uint? _selectedGuid;
     private readonly record struct LiveEntityInfo(
         string? Name,
@@ -8629,6 +8630,18 @@ public sealed class GameWindow : IDisposable
                 SendLiveCombatAttack(AcDream.Core.Combat.CombatAttackAction.High);
                 break;
 
+            case AcDream.UI.Abstractions.Input.InputAction.SelectLeft:
+                PickAndStoreSelection(useImmediately: false);
+                break;
+
+            case AcDream.UI.Abstractions.Input.InputAction.SelectDblLeft:
+                PickAndStoreSelection(useImmediately: true);
+                break;
+
+            case AcDream.UI.Abstractions.Input.InputAction.UseSelected:
+                UseCurrentSelection();
+                break;
+
             case AcDream.UI.Abstractions.Input.InputAction.EscapeKey:
                 if (_cameraController?.IsFlyMode == true)
                     _cameraController.ToggleFly();  // exit fly, release cursor
@@ -8703,6 +8716,67 @@ public sealed class GameWindow : IDisposable
         return SelectClosestCombatTarget(showToast: false);
     }
 
+    // ============================================================
+    // Phase B.4b — outbound Use handler. Wires three input actions
+    // (LMB click select, LMB-double-click select+use, R hotkey
+    // use-selected) through WorldPicker into InteractRequests.BuildUse.
+    // The inbound reply (SetState 0xF74B) lands via L.2g slice 1.
+    // ============================================================
+
+    private void PickAndStoreSelection(bool useImmediately)
+    {
+        if (_cameraController is null || _window is null) return;
+
+        var camera = _cameraController.Active;
+        var (origin, direction) = AcDream.Core.Selection.WorldPicker.BuildRay(
+            mouseX: _lastMouseX, mouseY: _lastMouseY,
+            viewportW: _window.Size.X, viewportH: _window.Size.Y,
+            view: camera.View, projection: camera.Projection);
+
+        if (direction.LengthSquared() < 1e-6f) return;  // degenerate ray
+
+        var picked = AcDream.Core.Selection.WorldPicker.Pick(
+            origin, direction,
+            _entitiesByServerGuid.Values,
+            skipServerGuid: _playerServerGuid,
+            maxDistance: 50f);
+
+        if (picked is uint guid)
+        {
+            _selectedGuid = guid;
+            string label = DescribeLiveEntity(guid);
+            Console.WriteLine($"[B.4b] pick guid=0x{guid:X8} name={label}");
+            _debugVm?.AddToast($"Selected: {label}");
+            if (useImmediately) SendUse(guid);
+        }
+        else
+        {
+            _debugVm?.AddToast("Nothing to select");
+        }
+    }
+
+    private void UseCurrentSelection()
+    {
+        if (_selectedGuid is uint sel)
+            SendUse(sel);
+        else
+            _debugVm?.AddToast("Nothing selected");
+    }
+
+    private void SendUse(uint guid)
+    {
+        if (_liveSession is null
+            || _liveSession.CurrentState != AcDream.Core.Net.WorldSession.State.InWorld)
+        {
+            _debugVm?.AddToast("Not in world");
+            return;
+        }
+        var seq  = _liveSession.NextGameActionSequence();
+        var body = AcDream.Core.Net.Messages.InteractRequests.BuildUse(seq, guid);
+        _liveSession.SendGameAction(body);
+        Console.WriteLine($"[B.4b] use guid=0x{guid:X8} seq={seq}");
+    }
+
     private uint? SelectClosestCombatTarget(bool showToast)
     {
         if (!_entitiesByServerGuid.TryGetValue(_playerServerGuid, out var playerEntity))