Fix stop reset, piece selection visuals, add trajectory preview and menu button

Bugfixes:
- Stop now fully rebuilds piece visuals (fixes destroyed pieces not
  reappearing and lingering cargo indicators)
- Piece stock buttons use explicit selected/unselected styling instead
  of ambiguous toggle behavior (teal bg + bright border when selected)
- Color dots next to stock buttons match piece colors

Features:
- Clicking a placed piece highlights its start/end cells with piece color
- Back-to-menu button ("← Menu") in top-left returns to level selector
  with fade transition
- DetailPanel shows "Pion" name and has styled remove button

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Scripts/Main.cs

@@ -133,14 +133,35 @@ public partial class Main : Node2D
 		uiRoot.MouseFilter = Control.MouseFilterEnum.Ignore;
 		_uiLayer.AddChild(uiRoot);
 
-		// Level title (top-left)
+		// Level title bar (top-left)
+		var titleBar = new HBoxContainer();
+		titleBar.SetAnchorsPreset(Control.LayoutPreset.TopLeft);
+		titleBar.OffsetLeft = 12;
+		titleBar.OffsetTop = 8;
+		titleBar.AddThemeConstantOverride("separation", 12);
+
+		var backButton = new Button { Text = "← Menu", CustomMinimumSize = new Vector2(70, 28) };
+		backButton.AddThemeFontSizeOverride("font_size", 11);
+		var backStyle = new StyleBoxFlat
+		{
+			BgColor = new Color("#2A2A2E"),
+			BorderColor = new Color("#444448"),
+			BorderWidthBottom = 1, BorderWidthTop = 1, BorderWidthLeft = 1, BorderWidthRight = 1,
+			CornerRadiusTopLeft = 4, CornerRadiusTopRight = 4,
+			CornerRadiusBottomLeft = 4, CornerRadiusBottomRight = 4,
+			ContentMarginLeft = 8, ContentMarginRight = 8,
+			ContentMarginTop = 2, ContentMarginBottom = 2
+		};
+		backButton.AddThemeStyleboxOverride("normal", backStyle);
+		backButton.Pressed += OnBackToMenu;
+		titleBar.AddChild(backButton);
+
 		_levelTitle = new Label { Text = "CHESSISTICS" };
-		_levelTitle.SetAnchorsPreset(Control.LayoutPreset.TopLeft);
-		_levelTitle.OffsetLeft = 16;
-		_levelTitle.OffsetTop = 12;
 		_levelTitle.AddThemeFontSizeOverride("font_size", 20);
 		_levelTitle.MouseFilter = Control.MouseFilterEnum.Ignore;
-		uiRoot.AddChild(_levelTitle);
+		titleBar.AddChild(_levelTitle);
+
+		uiRoot.AddChild(titleBar);
 
 		// --- Side Panel (anchored to right edge) ---
 		_sidePanel = new PanelContainer();
@@ -268,12 +289,23 @@ public partial class Main : Node2D
 		var snap = _sim.GetSnapshot();
 		if (snap.Phase != SimPhase.Edit) return;
 
+		_boardView.ClearHighlights();
+
 		var coords = new Coords(col, row);
 		var piece = snap.Pieces.FirstOrDefault(p => p.StartCell == coords || p.EndCell == coords);
 		if (piece != null)
+		{
 			_detailPanel.ShowPiece(piece);
+
+			// Highlight start and end cells to show trajectory
+			var pieceColor = PieceView.GetPieceColor(piece.Kind);
+			var highlightColor = new Color(pieceColor, 0.3f);
+			_boardView.HighlightCells([piece.StartCell, piece.EndCell], highlightColor);
+		}
 		else
+		{
 			_detailPanel.Hide();
+		}
 	}
 
 	// --- Level Management ---
@@ -491,13 +523,32 @@ public partial class Main : Node2D
 		_running = false;
 		_simTimer.Stop();
 		_sim.ProcessCommand(new StopSimulationCommand());
-		_eventAnimator.ResetPiecePositions(_sim.GetSnapshot());
+
+		// Full visual rebuild: clear everything and recreate from snapshot
+		_eventAnimator.ClearAll();
+		var snap = _sim.GetSnapshot();
+		foreach (var ps in snap.Pieces)
+		{
+			var pieceView = new PieceView();
+			pieceView.Setup(ps.Id, ps.Kind, ps.StartCell, ps.EndCell, _boardView);
+			_boardView.AddChild(pieceView);
+
+			var color = PieceView.GetPieceColor(ps.Kind);
+			var trajectView = new TrajectView();
+			trajectView.Setup(ps.Id,
+				_boardView.CoordsToPixel(ps.StartCell),
+				_boardView.CoordsToPixel(ps.EndCell),
+				color);
+			_boardView.AddChild(trajectView);
+
+			_eventAnimator.RegisterPiece(ps.Id, pieceView, trajectView);
+		}
+
 		_controlBar.UpdateForPhase(SimPhase.Edit);
 		_controlBar.ResetTurn();
 		_metricsOverlay.Hide();
-		_inputMapper.SetSnapshot(_sim.GetSnapshot());
+		_inputMapper.SetSnapshot(snap);
 
-		// Reset objective panel
 		if (_currentLevel != null)
 			_objectivePanel.Setup(_currentLevel.Demands);
 	}
@@ -550,4 +601,18 @@ public partial class Main : Node2D
 		else
 			ShowLevelSelect();
 	}
+
+	private void OnBackToMenu()
+	{
+		SfxManager.Instance?.PlayClick();
+		_running = false;
+		_simTimer.Stop();
+		_eventAnimator.ClearAll();
+
+		FadeOut(0.2f, () =>
+		{
+			ShowLevelSelect();
+			FadeIn(0.3f);
+		});
+	}
 }

Scripts/UI/DetailPanel.cs

@@ -1,5 +1,6 @@
 using Godot;
 using Chessistics.Engine.Model;
+using Chessistics.Scripts.Pieces;
 
 namespace Chessistics.Scripts.UI;
 
@@ -14,17 +15,41 @@ public partial class DetailPanel : PanelContainer
 
     public override void _Ready()
     {
+        var style = new StyleBoxFlat
+        {
+            BgColor = new Color(0.14f, 0.14f, 0.16f, 0.95f),
+            BorderColor = new Color("#444448"),
+            BorderWidthTop = 1,
+            CornerRadiusTopLeft = 4, CornerRadiusTopRight = 4,
+            ContentMarginLeft = 12, ContentMarginRight = 12,
+            ContentMarginTop = 8, ContentMarginBottom = 8
+        };
+        AddThemeStyleboxOverride("panel", style);
+
         var vbox = new VBoxContainer();
+        vbox.AddThemeConstantOverride("separation", 4);
 
         var title = new Label { Text = "DETAIL" };
-        title.AddThemeFontSizeOverride("font_size", 14);
+        title.AddThemeFontSizeOverride("font_size", 13);
+        title.AddThemeColorOverride("font_color", new Color("#B8942A"));
         vbox.AddChild(title);
 
         _infoLabel = new Label { Text = "" };
         _infoLabel.AddThemeFontSizeOverride("font_size", 11);
+        _infoLabel.AddThemeColorOverride("font_color", new Color("#CCCCCC"));
         vbox.AddChild(_infoLabel);
 
-        _removeButton = new Button { Text = "Retirer" };
+        _removeButton = new Button { Text = "Retirer", CustomMinimumSize = new Vector2(80, 26) };
+        _removeButton.AddThemeFontSizeOverride("font_size", 11);
+        var btnStyle = new StyleBoxFlat
+        {
+            BgColor = new Color("#5A2A2A"),
+            CornerRadiusTopLeft = 4, CornerRadiusTopRight = 4,
+            CornerRadiusBottomLeft = 4, CornerRadiusBottomRight = 4,
+            ContentMarginLeft = 8, ContentMarginRight = 8,
+            ContentMarginTop = 2, ContentMarginBottom = 2
+        };
+        _removeButton.AddThemeStyleboxOverride("normal", btnStyle);
         _removeButton.Pressed += () => EmitSignal(SignalName.RemoveRequested, _currentPieceId);
         vbox.AddChild(_removeButton);
 
@@ -37,6 +62,7 @@ public partial class DetailPanel : PanelContainer
         _currentPieceId = piece.Id;
         var kindName = piece.Kind switch
         {
+            PieceKind.Pawn => "Pion",
             PieceKind.Rook => "Tour II",
             PieceKind.Bishop => "Fou II",
             PieceKind.Knight => "Cavalier",

Scripts/UI/PieceStockPanel.cs

@@ -2,6 +2,7 @@ using Godot;
 using System;
 using System.Collections.Generic;
 using Chessistics.Engine.Model;
+using Chessistics.Scripts.Pieces;
 
 namespace Chessistics.Scripts.UI;
 
@@ -15,6 +16,13 @@ public partial class PieceStockPanel : VBoxContainer
 
     public PieceKind? SelectedKind => _selectedKind;
 
+    private static readonly Color NormalBg = new("#2A2A2E");
+    private static readonly Color SelectedBg = new("#3D6B8E");
+    private static readonly Color HoverBg = new("#353538");
+    private static readonly Color DisabledBg = new("#1E1E20");
+    private static readonly Color BorderNormal = new("#444448");
+    private static readonly Color BorderSelected = new("#5A9ECC");
+
     public void Setup(IReadOnlyList<PieceStock> stock)
     {
         foreach (var child in GetChildren())
@@ -24,7 +32,7 @@ public partial class PieceStockPanel : VBoxContainer
 
         var title = new Label { Text = "PIECES" };
         title.AddThemeFontSizeOverride("font_size", 16);
-        title.AddThemeColorOverride("font_color", new Color("#FFD700"));
+        title.AddThemeColorOverride("font_color", new Color("#B8942A"));
         AddChild(title);
 
         AddChild(new HSeparator());
@@ -32,16 +40,31 @@ public partial class PieceStockPanel : VBoxContainer
         foreach (var entry in stock)
         {
             var hbox = new HBoxContainer();
+            hbox.AddThemeConstantOverride("separation", 8);
+
+            // Color dot matching piece color
+            var dot = new ColorRect
+            {
+                CustomMinimumSize = new Vector2(10, 10),
+                Size = new Vector2(10, 10),
+                Color = PieceView.GetPieceColor(entry.Kind),
+                MouseFilter = Control.MouseFilterEnum.Ignore
+            };
+            var dotCenter = new CenterContainer { CustomMinimumSize = new Vector2(14, 32) };
+            dotCenter.AddChild(dot);
+            hbox.AddChild(dotCenter);
 
             var button = new Button
             {
                 Text = GetPieceName(entry.Kind),
                 CustomMinimumSize = new Vector2(120, 32),
-                ToggleMode = true
+                ToggleMode = false // We manage selection state ourselves
             };
+            ApplyButtonStyle(button, false);
 
             var countLabel = new Label { Text = $"x{entry.Count}" };
-            countLabel.AddThemeFontSizeOverride("font_size", 14);
+            countLabel.AddThemeFontSizeOverride("font_size", 13);
+            countLabel.AddThemeColorOverride("font_color", new Color("#999999"));
 
             var kind = entry.Kind;
             button.Pressed += () => OnPieceButtonPressed(kind);
@@ -72,11 +95,45 @@ public partial class PieceStockPanel : VBoxContainer
     {
         foreach (var (k, (button, _, remaining)) in _entries)
         {
-            button.ButtonPressed = k == _selectedKind;
+            bool selected = k == _selectedKind;
             button.Disabled = remaining <= 0;
+            ApplyButtonStyle(button, selected);
         }
     }
 
+    private static void ApplyButtonStyle(Button button, bool selected)
+    {
+        var bg = selected ? SelectedBg : NormalBg;
+        var border = selected ? BorderSelected : BorderNormal;
+
+        var normal = MakeStyle(bg, border);
+        var hover = MakeStyle(selected ? SelectedBg.Lightened(0.1f) : HoverBg, border);
+        var disabled = MakeStyle(DisabledBg, new Color("#2A2A2E"));
+
+        button.AddThemeStyleboxOverride("normal", normal);
+        button.AddThemeStyleboxOverride("hover", hover);
+        button.AddThemeStyleboxOverride("pressed", MakeStyle(bg.Darkened(0.15f), border));
+        button.AddThemeStyleboxOverride("disabled", disabled);
+        button.AddThemeFontSizeOverride("font_size", 12);
+        button.AddThemeColorOverride("font_color", selected ? Colors.White : new Color("#CCCCCC"));
+        button.AddThemeColorOverride("font_disabled_color", new Color("#555555"));
+    }
+
+    private static StyleBoxFlat MakeStyle(Color bg, Color border)
+    {
+        return new StyleBoxFlat
+        {
+            BgColor = bg,
+            BorderColor = border,
+            BorderWidthBottom = 1, BorderWidthTop = 1,
+            BorderWidthLeft = 1, BorderWidthRight = 1,
+            CornerRadiusTopLeft = 4, CornerRadiusTopRight = 4,
+            CornerRadiusBottomLeft = 4, CornerRadiusBottomRight = 4,
+            ContentMarginLeft = 8, ContentMarginRight = 8,
+            ContentMarginTop = 4, ContentMarginBottom = 4
+        };
+    }
+
     public void UpdateCount(PieceKind kind, int remaining)
     {
         if (!_entries.TryGetValue(kind, out var entry)) return;