Inspector: keep field editing usable, clarify editable fields

Split the inspector's revision into a list revision and a detail
revision. The periodic refresh now only bumps the list revision, and only
when the entity count actually changes, so the field-editor TextBox in the
details pane is no longer recreated (losing focus) twice a second while you
type. Stats and the performance tab update as plain text every frame
without rebuilding widgets.

Editable fields now render with a background, border and padding so they
read as inputs; read-only values and enum hints are muted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/MrGameEng.UI/EcsInspector.cs

@@ -42,7 +42,7 @@ public readonly record struct PerfSnapshot(
 /// store's entities grouped by archetype, reflects a selected entity's components and fields,
 /// writes simple field edits back, and (when a renderer is supplied) picks entities under the
 /// cursor and reports frame metrics. Holds no Myra state, so its logic is unit-testable without a
-/// GPU. UI lazily rebuilds when <see cref="Revision"/> changes.
+/// GPU. UI lazily rebuilds when <see cref="ListRevision"/> or <see cref="DetailRevision"/> change.
 /// </summary>
 public sealed class EcsInspector
 {
@@ -70,8 +70,14 @@ public sealed class EcsInspector
     /// <summary>True while the inspector panel is open.</summary>
     public bool IsOpen { get; private set; }
 
-    /// <summary>Increments on every change the UI should rebuild for (open/select/edit/refresh).</summary>
+    /// <summary>Increments when the entity/archetype lists or tab state need a UI rebuild.</summary>
-    public int Revision { get; private set; }
+    public int ListRevision { get; private set; }
+
+    /// <summary>
+    /// Increments when the selected entity's field view needs a UI rebuild. Kept separate from
+    /// <see cref="ListRevision"/> so the periodic refresh never recreates a field editor mid-edit.
+    /// </summary>
+    public int DetailRevision { get; private set; }
 
     /// <summary>The active tab.</summary>
     public InspectorTab ActiveTab { get; private set; }
@@ -93,21 +99,22 @@ public sealed class EcsInspector
     {
         IsOpen = !IsOpen;
         _dirty = true;
-        Bump();
+        BumpList();
+        BumpDetail();
     }
 
     /// <summary>Switches the active tab.</summary>
     public void SetTab(InspectorTab tab)
     {
         ActiveTab = tab;
-        Bump();
+        BumpList();
     }
 
     /// <summary>Arms (or disarms) world-pick mode.</summary>
     public void ArmPick(bool armed = true)
     {
         PickArmed = armed;
-        Bump();
+        BumpList();
     }
 
     /// <summary>Sets the archetype filter and refreshes the list.</summary>
@@ -115,7 +122,7 @@ public sealed class EcsInspector
     {
         Search = search ?? "";
         _dirty = true;
-        Bump();
+        BumpList();
     }
 
     /// <summary>Selects an archetype group by index; clears the entity selection.</summary>
@@ -123,14 +130,16 @@ public sealed class EcsInspector
     {
         SelectedArchetype = index;
         SelectedEntityId = -1;
-        Bump();
+        BumpList();
+        BumpDetail();
     }
 
     /// <summary>Selects an entity by runtime id.</summary>
     public void SelectEntity(int entityId)
     {
         SelectedEntityId = entityId;
-        Bump();
+        BumpList();
+        BumpDetail();
     }
 
     /// <summary>
@@ -145,11 +154,24 @@ public sealed class EcsInspector
         }
 
         _refreshTimer += deltaSeconds;
-        if (_refreshTimer >= 0.5f)
+        if (_refreshTimer < 0.5f)
         {
+            return;
+        }
+
         _refreshTimer = 0f;
+        // Only rebuild the lists when entities were actually added or removed — never on a plain
+        // tick, so a field editor in the details pane is not destroyed while it has focus.
+        var count = 0;
+        foreach (var _ in _store.Entities)
+        {
+            count++;
+        }
+
+        if (count != _entityCount)
+        {
             _dirty = true;
-            Bump();
+            BumpList();
         }
     }
 
@@ -231,7 +253,7 @@ public sealed class EcsInspector
 
             // Adding an existing component type replaces it with the edited value.
             AddComponentMethod.MakeGenericMethod(componentType).Invoke(entity, [boxed]);
-            Bump();
+            BumpDetail();
             return true;
         }
 
@@ -281,7 +303,8 @@ public sealed class EcsInspector
         {
             SelectedEntityId = best;
             PickArmed = false;
-            Bump();
+            BumpList();
+            BumpDetail();
         }
 
         return best;
@@ -345,7 +368,9 @@ public sealed class EcsInspector
     private static object BoxedValue(EntityComponent component) => component.Value;
 #pragma warning restore CS0618
 
-    private void Bump() => Revision++;
+    private void BumpList() => ListRevision++;
+
+    private void BumpDetail() => DetailRevision++;
 
     private void RebuildIfNeeded()
     {

src/MrGameEng.UI/EcsInspectorUi.cs

@@ -12,7 +12,7 @@ namespace MrGameEng.Inspector;
 /// Entities/Performance tabs and arms world-pick; the Entities tab shows archetypes → entities →
 /// the selected entity's components and editable fields; the Performance tab shows renderer
 /// timings. A thin border tracks the selected entity in the world each frame. Rebuilds lazily on
-/// <see cref="EcsInspector.Revision"/> changes.
+/// <see cref="EcsInspector.ListRevision"/>/<see cref="EcsInspector.DetailRevision"/> changes.
 /// </summary>
 internal sealed class EcsInspectorUi
 {
@@ -33,7 +33,8 @@ internal sealed class EcsInspectorUi
     private readonly Panel _highlight;
     private readonly VerticalStackPanel _panel;
 
-    private int _lastRevision = -1;
+    private int _lastListRevision = -1;
+    private int _lastDetailRevision = -1;
 
     public EcsInspectorUi(EcsInspector inspector, Renderer2D renderer)
     {
@@ -91,10 +92,24 @@ internal sealed class EcsInspectorUi
             return;
         }
 
-        if (_inspector.Revision != _lastRevision)
+        // Stats and perf are cheap text updates — refresh every frame so they stay live.
+        var perf = _inspector.Performance();
+        UpdateStats(perf);
+        if (_inspector.ActiveTab == InspectorTab.Performance)
         {
-            _lastRevision = _inspector.Revision;
+            UpdatePerf(perf);
-            Rebuild();
+        }
+
+        if (_inspector.ListRevision != _lastListRevision)
+        {
+            _lastListRevision = _inspector.ListRevision;
+            RebuildLists();
+        }
+
+        if (_inspector.DetailRevision != _lastDetailRevision)
+        {
+            _lastDetailRevision = _inspector.DetailRevision;
+            RebuildDetails();
         }
 
         UpdateHighlight();
@@ -116,25 +131,28 @@ internal sealed class EcsInspectorUi
         return section;
     }
 
-    private void Rebuild()
+    private void RebuildLists()
     {
         var entitiesTab = _inspector.ActiveTab == InspectorTab.Entities;
         _entitiesSection.Visible = entitiesTab;
         _perf.Visible = !entitiesTab;
         _pickLabel.Text = _inspector.PickArmed ? "Pick*" : "Pick";
 
-        var perf = _inspector.Performance();
-        _stats.Text =
-            $"entities {perf.Entities} | archetypes {perf.Archetypes} | {perf.Fps} FPS"
-            + (_inspector.PickArmed ? " | click an entity…" : "");
-
         if (entitiesTab)
         {
             RebuildArchetypes();
             RebuildEntities();
-            RebuildDetails();
         }
-        else
+    }
+
+    private void UpdateStats(in PerfSnapshot perf)
+    {
+        _stats.Text =
+            $"entities {perf.Entities} | archetypes {perf.Archetypes} | {perf.Fps} FPS"
+            + (_inspector.PickArmed ? " | click an entity…" : "");
+    }
+
+    private void UpdatePerf(in PerfSnapshot perf)
     {
         _perf.Text =
             $"FPS         {perf.Fps}\n"
@@ -147,7 +165,6 @@ internal sealed class EcsInspectorUi
             + $"sprites     {perf.SubmittedSprites} drawn, {perf.CulledSprites} culled\n"
             + $"entities    {perf.Entities}";
     }
-    }
 
     private void RebuildArchetypes()
     {
@@ -209,16 +226,31 @@ internal sealed class EcsInspectorUi
 
     private Widget BuildFieldRow(Type componentType, FieldRow field)
     {
-        var row = new HorizontalStackPanel { Spacing = 6 };
+        var row = new HorizontalStackPanel { Spacing = 8 };
-        row.Widgets.Add(new Label { Text = field.Name, Width = 150 });
+        row.Widgets.Add(
+            new Label
+            {
+                Text = field.Name,
+                Width = 140,
+                TextColor = new Color(170, 178, 190),
+            }
+        );
 
         if (!field.Editable)
         {
-            row.Widgets.Add(new Label { Text = field.Value });
+            row.Widgets.Add(new Label { Text = field.Value, TextColor = new Color(150, 156, 168) });
             return row;
         }
 
-        var editor = new TextBox { Text = field.Value, Width = 220 };
+        var editor = new TextBox
+        {
+            Text = field.Value,
+            Width = 150,
+            Padding = new Thickness(4, 2),
+            Background = new SolidBrush(new Color(28, 33, 42)),
+            Border = new SolidBrush(new Color(70, 82, 100)),
+            BorderThickness = new Thickness(1),
+        };
         var entityId = _inspector.SelectedEntityId;
         editor.KeyDown += (_, args) =>
         {
@@ -230,7 +262,13 @@ internal sealed class EcsInspectorUi
         row.Widgets.Add(editor);
         if (field.Kind == FieldKind.Enum && field.EnumOptions is { Length: > 0 })
         {
-            row.Widgets.Add(new Label { Text = "(" + string.Join("/", field.EnumOptions) + ")" });
+            row.Widgets.Add(
+                new Label
+                {
+                    Text = string.Join(" / ", field.EnumOptions),
+                    TextColor = new Color(120, 128, 140),
+                }
+            );
         }
 
         return row;