Add object identity fields with on-canvas info display

src/OpenApparatus.Studio/ViewModels/MainWindowViewModel.cs

@@ -333,6 +333,13 @@ partial void OnEditModeChanged(EditModeKind value)
     public bool IsObjectsMode => EditMode == EditModeKind.Object;
     public bool IsLayoutMode => EditMode == EditModeKind.Layout;
 
+    /// <summary>When true (Object mode only), the editor draws each object's
+    /// identity fields — GlobalID, TypeID, CustomID, Name — as small text
+    /// beside its icon. Toggled from the Object-types panel.</summary>
+    [ObservableProperty] bool _showItemInfo;
+
+    partial void OnShowItemInfoChanged(bool value) => EditVersion++;
+
     /// <summary>Whether the keyboard-shortcut help overlay is showing. F1
     /// toggles, Esc dismisses (handled in MainWindow code-behind).</summary>
     [ObservableProperty] bool _isShortcutOverlayVisible;
@@ -573,6 +580,28 @@ public void OnEditedObjectType()
         EditVersion++;
     }
 
+    /// <summary>Next default <see cref="RoomObject.GlobalId"/> — the largest
+    /// numeric GlobalId already in use plus one (0 when none parse). Non-numeric
+    /// user-edited ids are ignored; uniqueness is not enforced.</summary>
+    int NextGlobalId()
+    {
+        int next = 0;
+        foreach (var o in _objects)
+            if (int.TryParse(o.GlobalId, out int v) && v >= next) next = v + 1;
+        return next;
+    }
+
+    /// <summary>Next default <see cref="RoomObject.TypeId"/> for objects of
+    /// <paramref name="slot"/> — the largest numeric TypeId among same-slot
+    /// objects plus one (0 when none parse).</summary>
+    int NextTypeId(int slot)
+    {
+        int next = 0;
+        foreach (var o in _objects)
+            if (o.Slot == slot && int.TryParse(o.TypeId, out int v) && v >= next) next = v + 1;
+        return next;
+    }
+
     /// <summary>Sub-cell side length in metres at the current subdivision.</summary>
     public float SubCellSize => TileSize / System.Math.Max(1, GridSubdivision);
 
@@ -628,12 +657,18 @@ public void PlaceObjectAtSelectedSubCell(int slot)
             }
         }
         PushUndo();
+        string globalId = NextGlobalId().ToString();
+        string typeId = NextTypeId(slot).ToString();
         var obj = new RoomObject
         {
             OwningRoomId = roomId,
             Slot = slot,
             Position = new System.Numerics.Vector3(center2.X, DefaultObjectY, center2.Y),
             Rotation = 0f,
+            GlobalId = globalId,
+            TypeId = typeId,
+            CustomId = $"{globalId}_{typeId}",
+            Name = $"{typeForPlacement.Name}_{globalId}_{typeId}",
         };
         _objects.Add(obj);
         SelectedObjectIndex = _objects.Count - 1;
@@ -1719,6 +1754,10 @@ public ProjectFile ToProjectFile()
                 OwningRoomId = o.OwningRoomId,
                 X = o.Position.X, Y = o.Position.Y, Z = o.Position.Z,
                 Rotation = o.Rotation,
+                GlobalId = o.GlobalId,
+                TypeId = o.TypeId,
+                CustomId = o.CustomId,
+                Name = o.Name,
             }).ToList();
         return f;
 
@@ -1825,14 +1864,41 @@ public void RestoreFromProjectFile(ProjectFile f)
         _objects.Clear();
         if (f.Objects is not null)
         {
+            // Identity fields were added after the first releases. Files
+            // saved before then carry null/empty ids — backfill sequential
+            // defaults so older apparatus stay usable and consistent.
+            int backfillGlobal = 0;
+            var backfillType = new Dictionary<int, int>();
             foreach (var o in f.Objects)
+            {
+                string globalId = o.GlobalId ?? "";
+                string typeId = o.TypeId ?? "";
+                string customId = o.CustomId ?? "";
+                string name = o.Name ?? "";
+                if (globalId.Length == 0 && typeId.Length == 0 &&
+                    customId.Length == 0 && name.Length == 0)
+                {
+                    int gid = backfillGlobal++;
+                    backfillType.TryGetValue(o.Slot, out int tid);
+                    backfillType[o.Slot] = tid + 1;
+                    globalId = gid.ToString();
+                    typeId = tid.ToString();
+                    customId = $"{globalId}_{typeId}";
+                    var t = GetObjectType(o.Slot);
+                    name = $"{t?.Name ?? "Object"}_{globalId}_{typeId}";
+                }
                 _objects.Add(new RoomObject
                 {
                     Slot = o.Slot,
                     OwningRoomId = o.OwningRoomId,
                     Position = new System.Numerics.Vector3(o.X, o.Y, o.Z),
                     Rotation = o.Rotation,
+                    GlobalId = globalId,
+                    TypeId = typeId,
+                    CustomId = customId,
+                    Name = name,
                 });
+            }
         }
 
         // Camera.

src/OpenApparatus.Studio/Views/GridEditorView.cs

@@ -1153,7 +1153,7 @@ void DrawSide(OpenApparatus.Topology.Adjacency a, bool isRoomA,
         // Object icons — drawn last so they sit on top of room labels in
         // Objects mode. In Floor / Ceiling mode they still render, dimmed,
         // so the user always sees what's been placed.
-        DrawObjects(ctx, vm, origin, tileSize);
+        DrawObjects(ctx, vm, origin, tileSize, typeface);
 
         // Constraint zones (door annular wedges, object exclusion discs) and
         // violator rings — drawn before the measurement labels so the labels
@@ -2002,10 +2002,31 @@ public static void DrawAngleLabel(
         ctx.DrawText(fmt, new Point(rect.X + padX, rect.Y + padY));
     }
 
-    static void DrawObjects(DrawingContext ctx, MainWindowViewModel vm, Point origin, double tileSize)
+    static void DrawObjects(DrawingContext ctx, MainWindowViewModel vm, Point origin, double tileSize, Typeface typeface)
     {
         if (vm.Objects.Count == 0) return;
         bool dim = !vm.IsObjectsMode;
+        bool showInfo = vm.ShowItemInfo && vm.IsObjectsMode;
+
+        // Overlap detection for the info labels: a value is "overlapping" when
+        // it appears on more than one object. TypeID is scoped per type (the
+        // 0,1,2… sequence restarts for each object type); the rest are global.
+        Dictionary<string, int>? globalIdCounts = null, customIdCounts = null, nameCounts = null;
+        Dictionary<(int, string), int>? typeIdCounts = null;
+        if (showInfo)
+        {
+            globalIdCounts = new(); customIdCounts = new(); nameCounts = new();
+            typeIdCounts = new();
+            foreach (var o in vm.Objects)
+            {
+                globalIdCounts[o.GlobalId] = globalIdCounts.GetValueOrDefault(o.GlobalId) + 1;
+                customIdCounts[o.CustomId] = customIdCounts.GetValueOrDefault(o.CustomId) + 1;
+                nameCounts[o.Name] = nameCounts.GetValueOrDefault(o.Name) + 1;
+                var tk = (o.Slot, o.TypeId);
+                typeIdCounts[tk] = typeIdCounts.GetValueOrDefault(tk) + 1;
+            }
+        }
+
         for (int i = 0; i < vm.Objects.Count; i++)
         {
             var o = vm.Objects[i];
@@ -2036,6 +2057,56 @@ static void DrawObjects(DrawingContext ctx, MainWindowViewModel vm, Point origin
                     },
                     screen, iconR + 5, iconR + 5);
             }
+
+            if (showInfo)
+            {
+                var lines = new (string Text, bool Overlap)[]
+                {
+                    ($"G: {o.GlobalId}", globalIdCounts![o.GlobalId] > 1),
+                    ($"T: {o.TypeId}",  typeIdCounts![(o.Slot, o.TypeId)] > 1),
+                    (o.CustomId,        customIdCounts![o.CustomId] > 1),
+                    (o.Name,            nameCounts![o.Name] > 1),
+                };
+                DrawObjectInfoLabel(ctx, typeface, lines,
+                    new Point(screen.X + iconR + 4, screen.Y));
+            }
+        }
+    }
+
+    /// <summary>Renders an object's identity fields as a small stacked label.
+    /// Each line is green by default, red when its value overlaps another
+    /// object. A faint backing panel keeps the text legible over the grid.</summary>
+    static void DrawObjectInfoLabel(
+        DrawingContext ctx, Typeface typeface, (string Text, bool Overlap)[] lines, Point anchor)
+    {
+        const double fontSize = 9.0;
+        var ok = new SolidColorBrush(Color.FromRgb(0x2E, 0x7D, 0x32));
+        var bad = new SolidColorBrush(Color.FromRgb(0xC8, 0x28, 0x28));
+
+        var fmts = new FormattedText[lines.Length];
+        double maxW = 0, totalH = 0;
+        for (int i = 0; i < lines.Length; i++)
+        {
+            fmts[i] = new FormattedText(lines[i].Text,
+                System.Globalization.CultureInfo.InvariantCulture, FlowDirection.LeftToRight,
+                typeface, fontSize, lines[i].Overlap ? bad : ok);
+            maxW = System.Math.Max(maxW, fmts[i].Width);
+            totalH += fmts[i].Height;
+        }
+        const double padX = 3.0, padY = 2.0;
+        // Centre the panel vertically on the object's icon.
+        var panel = new Rect(
+            anchor.X, anchor.Y - totalH * 0.5 - padY,
+            maxW + padX * 2, totalH + padY * 2);
+        ctx.DrawRectangle(
+            new SolidColorBrush(Color.FromArgb(225, 250, 250, 250)),
+            new Pen(new SolidColorBrush(Color.FromArgb(225, 200, 200, 205)), 0.8),
+            panel, 2, 2);
+        double y = panel.Y + padY;
+        for (int i = 0; i < fmts.Length; i++)
+        {
+            ctx.DrawText(fmts[i], new Point(panel.X + padX, y));
+            y += fmts[i].Height;
         }
     }
 

src/OpenApparatus.Studio/Views/ObjectTypesPanel.axaml.cs

@@ -75,6 +75,22 @@ void Rebuild()
         for (int i = 0; i < _vm.ObjectTypes.Count; i++)
             Body.Children.Add(TypeRow(i, _vm.ObjectTypes[i]));
 
+        // Item-info toggle — draws each object's GlobalID / TypeID / CustomID /
+        // Name beside its icon on the canvas. Overlapping values render red.
+        var infoToggle = new CheckBox
+        {
+            Content = "Show item info",
+            IsChecked = _vm.ShowItemInfo,
+            Margin = new Thickness(0, 10, 0, 0),
+        };
+        ToolTip.SetTip(infoToggle,
+            "Display each object's IDs and name beside it. Overlapping values are red.");
+        infoToggle.IsCheckedChanged += (_, _) =>
+        {
+            if (_vm is not null) _vm.ShowItemInfo = infoToggle.IsChecked == true;
+        };
+        Body.Children.Add(infoToggle);
+
         var addBtn = new Button
         {
             Content = "+ Add type",

src/OpenApparatus.Studio/Views/RoomEditorPanel.axaml.cs

@@ -511,6 +511,16 @@ void AddObjectEditorControls(StackPanel host, int idx)
             Margin = new Thickness(0, 0, 0, 6),
         });
 
+        // Identity fields — all user-editable, none uniqueness-enforced.
+        host.Children.Add(BuildObjectTextRow("Global ID", sel.GlobalId,
+            v => MutateSelectedObject(o => o.GlobalId = v)));
+        host.Children.Add(BuildObjectTextRow("Type ID", sel.TypeId,
+            v => MutateSelectedObject(o => o.TypeId = v)));
+        host.Children.Add(BuildObjectTextRow("Custom ID", sel.CustomId,
+            v => MutateSelectedObject(o => o.CustomId = v)));
+        host.Children.Add(BuildObjectTextRow("Name", sel.Name,
+            v => MutateSelectedObject(o => o.Name = v)));
+
         // Position — single horizontal row with X/Y/Z side-by-side, each
         // labelled in its axis colour (Unity / Blender / Houdini convention:
         // red X, green Y, blue Z). Reads as one transform unit instead of
@@ -568,6 +578,45 @@ void MutateSelectedObject(System.Action<RoomObject> change)
         _vm!.OnEditedSelectedObject();
     }
 
+    /// <summary>A labelled single-line text editor for an object identity
+    /// field. Commits on LostFocus / Enter only — committing per keystroke
+    /// would bump EditVersion and rebuild the panel mid-edit.</summary>
+    Control BuildObjectTextRow(string label, string value, System.Action<string> commit)
+    {
+        var holder = new StackPanel { Margin = new Thickness(0, 0, 0, 6) };
+        holder.Children.Add(new TextBlock
+        {
+            Text = label,
+            FontSize = 11,
+            Foreground = TextSecondary,
+            Margin = new Thickness(0, 0, 0, 2),
+        });
+        var box = new TextBox
+        {
+            Text = value,
+            HorizontalAlignment = HorizontalAlignment.Stretch,
+        };
+        string lastCommitted = value;
+        void Commit()
+        {
+            var t = box.Text ?? string.Empty;
+            if (t == lastCommitted) return;
+            lastCommitted = t;
+            commit(t);
+        }
+        box.LostFocus += (_, _) => Commit();
+        box.KeyDown += (_, e) =>
+        {
+            if (e.Key == Avalonia.Input.Key.Enter)
+            {
+                Commit();
+                e.Handled = true;
+            }
+        };
+        holder.Children.Add(box);
+        return holder;
+    }
+
     Control TypeRow(int index, ObjectType type)
     {
         // 30×30 swatch button — clicking opens the shape/color picker.