fix(ui): keep closed etch-only parts selectable

OpenNest.WinForms.Tests/EtchVisibilityTests.cs

@@ -1,5 +1,6 @@
 using System.Drawing;
 using System.Drawing.Drawing2D;
+using System.Reflection;
 using OpenNest.CNC;
 using OpenNest.Controls;
 using OpenNest.Geometry;
@@ -39,6 +40,36 @@ public class EtchVisibilityTests
                 Assert.Equal(0, layout.Path.PointCount);
         }, TimeSpan.FromMinutes(1), "Panned etch test timed out.");
 
+    [Fact]
+    public void EtchOnlyPart_RemainsSelectableAndHoverableWithoutCutMaterial()
+        => StaTestThread.Run(() =>
+        {
+            var program = new CNC.Program();
+            AddSquare(program, 100, LayerType.Scribe);
+            var part = new Part(new Drawing("etch-only", program));
+            using var view = new PannedView();
+            view.Plate.Parts.Add(part);
+            var layout = Assert.Single(view.LayoutParts);
+            Assert.Equal(0, layout.Path.PointCount);
+            Assert.True(layout.EtchPath.PointCount > 0);
+
+            Assert.Same(layout, view.Selection.GetPartAtGraphPoint(new PointF(110, 110)));
+            Assert.Null(view.Selection.GetPartAtGraphPoint(new PointF(50, 50)));
+            Assert.Contains(layout, view.Selection.GetPartsFromWindow(
+                new RectangleF(105, 105, 10, 10), SelectionType.Intersect));
+            Assert.Contains(layout, view.Selection.GetPartsFromWindow(
+                new RectangleF(95, 95, 30, 30), SelectionType.Contains));
+
+            typeof(PlateView).GetField("hoverPending", BindingFlags.Instance | BindingFlags.NonPublic)!
+                .SetValue(view, true);
+            typeof(PlateView).GetField("hoverPoint", BindingFlags.Instance | BindingFlags.NonPublic)!
+                .SetValue(view, new Point(15, 15));
+            typeof(PlateView).GetMethod("HoverCheck", BindingFlags.Instance | BindingFlags.NonPublic)!
+                .Invoke(view, null);
+            Assert.Same(layout, typeof(PlateView).GetField("hoveredPart",
+                BindingFlags.Instance | BindingFlags.NonPublic)!.GetValue(view));
+        }, TimeSpan.FromMinutes(1), "Etch selection test timed out.");
+
     private static void AddSquare(CNC.Program program, double origin, LayerType layer)
     {
         program.MoveTo(origin, origin);

OpenNest/Controls/PlateView.cs

@@ -816,7 +816,8 @@ namespace OpenNest.Controls
 
             for (var i = parts.Count - 1; i >= 0; --i)
             {
-                if (parts[i].Path.GetBounds().Contains(graphPt) && parts[i].Path.IsVisible(graphPt))
+                var path = parts[i].SelectionPath;
+                if (path?.GetBounds().Contains(graphPt) == true && path.IsVisible(graphPt))
                 {
                     hitPart = parts[i];
                     break;

OpenNest/Controls/SelectionManager.cs

@@ -208,7 +208,7 @@ namespace OpenNest.Controls
             var parts = view.LayoutParts;
             for (var i = parts.Count - 1; i >= 0; --i)
             {
-                if (parts[i].Path.IsVisible(pt))
+                if (parts[i].SelectionPath?.IsVisible(pt) == true)
                     return parts[i];
             }
             return null;
@@ -230,10 +230,12 @@ namespace OpenNest.Controls
                 for (var i = 0; i < parts.Count; ++i)
                 {
                     var part = parts[i];
-                    var region = new Region(part.Path);
+                    var path = part.SelectionPath;
+                    if (path == null)
+                        continue;
+                    using var region = new Region(path);
                     if (region.IsVisible(rect))
                         list.Add(part);
-                    region.Dispose();
                 }
             }
             else
@@ -241,8 +243,8 @@ namespace OpenNest.Controls
                 for (var i = 0; i < parts.Count; ++i)
                 {
                     var part = parts[i];
-                    var bounds = part.Path.GetBounds();
-                    if (rect.Contains(bounds))
+                    var path = part.SelectionPath;
+                    if (path != null && rect.Contains(path.GetBounds()))
                         list.Add(part);
                 }
             }

OpenNest/LayoutPart.cs

@@ -60,6 +60,10 @@ namespace OpenNest
 
         public GraphicsPath EtchPath { get; private set; }
 
+        // Etch-only parts have no material path, but their visible closed mark must
+        // remain hit-testable without treating scribe geometry as a cut or fill.
+        internal GraphicsPath SelectionPath => Path?.PointCount > 0 ? Path : EtchPath;
+
         internal RectangleF DisplayBounds { get; private set; }
 
         public Color Color

docs/nesting-view-colors.md

@@ -23,7 +23,9 @@ custom or saved fill colors; open a saved nest before applying Workshop to recol
 
 In plate views and drawing thumbnails, scribe/etch motions have a separate stroke
 from material cuts. A closed etched circle or lettering does not make a hole in
-the displayed part fill. Selection changes the part highlight, not the etch color.
+the displayed part fill. An etch-only part remains selectable by its closed
+mark in the plate view; etch lines still do not become cut material. Selection
+changes the part highlight, not the etch color.
 Lead-in/out strokes keep their existing orange-red appearance. Preview placements
 show etches too. A cut coincident with an etch is drawn over the etch, so it is not
 hidden by the mark.