perf(fill): remove discarded extents pitch geometry

OpenNest.Engine/Fill/FillExtents.cs

@@ -117,29 +117,32 @@ namespace OpenNest.Engine.Fill
         {
             var column = new List<Part> { (Part)pair.Part1.Clone(), (Part)pair.Part2.Clone() };
 
-            // Find geometry-aware copy distance for the pair vertically.
-            var boundary1 = new PartBoundary(pair.Part1, halfSpacing);
-            var boundary2 = new PartBoundary(pair.Part2, halfSpacing);
-
-            // Compute vertical copy distance using bounding boxes as starting point,
-            // then slide down to find true geometry distance.
             var pairHeight = pair.Bbox.Width;
-            var testOffset = new Vector(0, pairHeight);
+            var copyDistance = pairHeight + partSpacing;
 
-            // Create test parts for slide distance measurement.
-            var testPart1 = pair.Part1.CloneAtOffset(testOffset);
-            var testPart2 = pair.Part2.CloneAtOffset(testOffset);
+            // For finite valid geometry and nonnegative spacing, the legacy helper returns
+            // pairHeight + partSpacing on negative/no-hit slides. Otherwise minSlide >= 0,
+            // so Max(pairHeight - minSlide, pairHeight + partSpacing) is the same pitch.
+            // Public callers do not validate spacing; retain legacy work/behavior outside
+            // that domain rather than changing its results or exceptions.
+            if (!double.IsFinite(partSpacing) || partSpacing < 0 || !double.IsFinite(pairHeight))
+            {
+                var boundary1 = new PartBoundary(pair.Part1, halfSpacing);
+                var boundary2 = new PartBoundary(pair.Part2, halfSpacing);
+                var testOffset = new Vector(0, pairHeight);
+                var testPart1 = pair.Part1.CloneAtOffset(testOffset);
+                var testPart2 = pair.Part2.CloneAtOffset(testOffset);
 
-            // Find minimum distance from test pair sliding down toward original pair.
-            var copyDistance = FindVerticalCopyDistance(
-                pair.Part1,
-                pair.Part2,
-                testPart1,
-                testPart2,
-                boundary1,
-                boundary2,
-                pairHeight
-            );
+                copyDistance = FindVerticalCopyDistance(
+                    pair.Part1,
+                    pair.Part2,
+                    testPart1,
+                    testPart2,
+                    boundary1,
+                    boundary2,
+                    pairHeight
+                );
+            }
 
             if (copyDistance <= 0)
                 return column;

OpenNest.Engine/Fill/PartBoundary.cs

@@ -23,6 +23,7 @@ namespace OpenNest.Engine.Fill
 
         public PartBoundary(Part part, double spacing)
         {
+            PerfCounters.CountPartBoundaryPreparation();
             var entities = ConvertProgram
                 .ToGeometry(part.Program)
                 .Where(e => e.Layer == SpecialLayers.Cut)