fix(cutting): exclude scribes from downstream pierce targets

OpenNest.Engine/CuttingPlanning/PreferredContourEntries.cs

@@ -89,11 +89,13 @@ internal static class PreferredContourEntries
     /// first non-rapid motion (lead-in when present — that is where the next rapid must
     /// arrive), which reflects native rounding and clamping of a nominal entry.
     /// </summary>
-    private static Vector Pierce(PreparedContours prepared, ContourChoice choice, CancellationToken token)
+    internal static Vector Pierce(PreparedContours prepared, ContourChoice choice, CancellationToken token)
     {
         var program = prepared.EmitCandidateForValidation(choice);
         var execution = ExecutionMotionReader.Read(program, Vector.Zero, null, token);
-        var first = execution.Motions.First(m => !m.Rapid);
+        // The diagnostic emission includes the part's scribes before the selected contour.
+        // Those marks are not the downstream cut's pierce.
+        var first = execution.Motions.First(m => !m.Rapid && m.Layer != LayerType.Scribe);
         return first.Start ?? first.End;
     }
 }

OpenNest.Tests/CuttingPlanning/PreferredContourEntriesTests.cs

@@ -201,6 +201,24 @@ public class PreferredContourEntriesTests
         Assert.All(proposal.HoleChoices, c => Assert.NotEqual(3, c.ContourOrdinal)); // never the perimeter
     }
 
+    [Fact]
+    public void ScribesDoNotBecomeTheDownstreamPierceTarget()
+    {
+        var clean = RectHolesProgram((3, 3, 5, 5), (7, 3, 9, 5));
+        var centres = new[] { new Vector(4, 4), new Vector(8, 4), new Vector(5, 5) };
+        var prepared = PreparedContours.Capture(clean, ExplicitContourTests.Parameters());
+        var entry = prepared.Entry(2, 2, new Vector(10, 4));
+        var baseline = PreferredContourEntries.TryPlan(prepared, entry, new[] { 0, 1 },
+            centres, Arrival, _ => new(ContourFeasibilityStatus.Clear, null));
+        clean.MoveTo(-20, -20);
+        clean.Codes.Add(new LinearMove(-19, -19) { Layer = LayerType.Scribe });
+        var marked = PreparedContours.Capture(clean, ExplicitContourTests.Parameters());
+        var actual = PreferredContourEntries.TryPlan(marked, marked.Entry(2, 2, new Vector(10, 4)),
+            new[] { 0, 1 }, centres, Arrival, _ => new(ContourFeasibilityStatus.Clear, null));
+        Assert.True(actual.IsPreferred, actual.Reason);
+        Assert.Equal(baseline.HoleChoices.Select(c => c.Point), actual.HoleChoices.Select(c => c.Point));
+    }
+
     [Fact]
     public void ChainingIsDeterministic()
     {