Fix false self-intersection warnings at rounded contour joints

OpenNest.Core/CNC/CuttingPlanning/LeadMaterialSnapshot.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Threading;
 using OpenNest.Diagnostics;
 using OpenNest.Geometry;
+using OpenNest.Math;
 
 namespace OpenNest.CNC.CuttingPlanning;
 
@@ -66,11 +67,14 @@ public sealed class LeadMaterialSnapshot
                             var b = rings[s][j];
                             var contacts = a.Contacts(b, out var overlap);
                             var adjacent = r == s && (j == i + 1 || (i == 0 && j == rings[r].Length - 1));
+                            // Native contacts at rounded arc/line joints can drift from the
+                            // authored endpoint. Use the shared geometry tolerance only to
+                            // recognize that joint; overlaps and other contacts still refuse.
                             if (overlap || contacts.Any(p => !adjacent
-                                || !(p.DistanceTo(a.End) <= PostVerificationGeometry.Epsilon
-                                    && p.DistanceTo(b.Start) <= PostVerificationGeometry.Epsilon)
-                                && !(p.DistanceTo(a.Start) <= PostVerificationGeometry.Epsilon
-                                    && p.DistanceTo(b.End) <= PostVerificationGeometry.Epsilon)))
+                                || !(p.DistanceTo(a.End) <= Tolerance.Epsilon
+                                    && p.DistanceTo(b.Start) <= Tolerance.Epsilon)
+                                && !(p.DistanceTo(a.Start) <= Tolerance.Epsilon
+                                    && p.DistanceTo(b.End) <= Tolerance.Epsilon)))
                                 throw new ArgumentException($"Material boundaries overlap, touch or self-intersect ({r}:{i}, {s}:{j}, overlap={overlap}).");
                         }
             var outer = -1;

OpenNest.Tests/CuttingPlanning/LeadMaterialSnapshotTests.cs

@@ -0,0 +1,82 @@
+using OpenNest.CNC;
+using OpenNest.CNC.CuttingPlanning;
+using OpenNest.Geometry;
+
+namespace OpenNest.Tests.CuttingPlanning;
+
+public class LeadMaterialSnapshotTests
+{
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public void RoundedCornerContact_RoundingAtAdjacentEndpointIsAccepted(bool atSeam)
+    {
+        // Rounded imported corner: its native tangent contact falls 1.52e-8
+        // from the authored arc/line joint. Exercise both consecutive and seam adjacency.
+        var program = new Program();
+        var start = new Vector(120.509177, 14.879559);
+        program.MoveTo(start);
+        program.Codes.Add(new ArcMove(new Vector(120.5, 14.9375),
+            new Vector(120.6875000024, 14.9374999848), RotationType.CW));
+        program.LineTo(120.5, 28.5625);
+        program.Codes.Add(new ArcMove(new Vector(120.6875, 28.75),
+            new Vector(120.6875, 28.5625), RotationType.CW));
+        program.LineTo(127.6875, 28.75);
+        program.Codes.Add(new ArcMove(new Vector(127.875, 28.5625),
+            new Vector(127.6875, 28.5625), RotationType.CW));
+        program.LineTo(127.875, 14.9375);
+        program.Codes.Add(new ArcMove(new Vector(127.6875, 14.75),
+            new Vector(127.6875, 14.9375), RotationType.CW));
+        program.LineTo(120.6875, 14.75);
+        program.Codes.Add(new ArcMove(start,
+            new Vector(120.6874999967, 14.9375000024), RotationType.CW));
+        if (atSeam)
+        {
+            var first = program.Codes[1];
+            program.Codes.RemoveAt(1);
+            program.Codes.Add(first);
+            program.Codes[0] = new RapidMove(120.5, 14.9375);
+        }
+
+        var material = LeadMaterialSnapshot.Capture(program, Vector.Zero);
+
+        Assert.True(material.IsComplete, material.Reason);
+    }
+
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public void CrossingOrRetracedBoundary_RemainsRejected(bool retraced)
+    {
+        var program = new Program();
+        program.MoveTo(0, 0);
+        program.LineTo(8, 8);
+        if (retraced)
+        {
+            program.LineTo(4, 4);
+            program.LineTo(0, 8);
+        }
+        else
+        {
+            program.LineTo(0, 8);
+            program.LineTo(8, 0);
+        }
+        program.LineTo(0, 0);
+
+        var material = LeadMaterialSnapshot.Capture(program, Vector.Zero);
+
+        Assert.False(material.IsComplete);
+        Assert.Contains("Material boundaries", material.Reason);
+    }
+
+    [Fact]
+    public void SeparateTouchingHoles_RemainRejected()
+    {
+        var part = BestEffortCuttingPlanTests.TouchingContours();
+
+        var material = LeadMaterialSnapshot.Capture(part.BaseDrawing.Program, Vector.Zero);
+
+        Assert.False(material.IsComplete);
+        Assert.Contains("Material boundaries", material.Reason);
+    }
+}

docs/cutting-planner.md

@@ -53,6 +53,13 @@ does not visit a globally shared descendant twice; it never changes the fixed pa
 
 ## Cutting dependencies
 
+Nominal material validation recognizes contacts at shared endpoints of adjacent
+contour segments using `OpenNest.Math.Tolerance.Epsilon` (0.00001 model units).
+This avoids false self-intersection warnings from rounding at arc/line joints,
+including the contour seam. Overlapping segments and contacts away from those
+joints or between separate contours still fail validation. Contour closure and
+the underlying native intersection queries retain their existing tolerances.
+
 Capture builds whole-part prerequisites from owned values, and both the search and
 the final replay enforce them: