feat: add EdgeStartSequencer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

OpenNest.Engine/Sequencing/EdgeStartSequencer.cs

@@ -0,0 +1,36 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenNest.Engine.Sequencing
+{
+    public class EdgeStartSequencer : IPartSequencer
+    {
+        public List<SequencedPart> Sequence(IReadOnlyList<Part> parts, Plate plate)
+        {
+            // Plate(width, length) stores Size with Width/Length swapped internally.
+            // Reconstruct the logical plate box using the BoundingBox origin and the
+            // corrected extents: Size.Length = X-extent, Size.Width = Y-extent.
+            var origin = plate.BoundingBox(false);
+            var plateBox = new OpenNest.Geometry.Box(
+                origin.X, origin.Y,
+                plate.Size.Length,
+                plate.Size.Width);
+
+            return parts
+                .OrderBy(p => MinEdgeDistance(p.BoundingBox.Center, plateBox))
+                .ThenBy(p => p.Location.X)
+                .Select(p => new SequencedPart { Part = p })
+                .ToList();
+        }
+
+        private static double MinEdgeDistance(OpenNest.Geometry.Vector center, OpenNest.Geometry.Box plateBox)
+        {
+            var distLeft   = center.X - plateBox.Left;
+            var distRight  = plateBox.Right - center.X;
+            var distBottom = center.Y - plateBox.Bottom;
+            var distTop    = plateBox.Top - center.Y;
+
+            return System.Math.Min(System.Math.Min(distLeft, distRight), System.Math.Min(distBottom, distTop));
+        }
+    }
+}

OpenNest.Tests/Sequencing/EdgeStartSequencerTests.cs

@@ -0,0 +1,31 @@
+using System.Collections.Generic;
+using OpenNest.CNC;
+using OpenNest.Engine.Sequencing;
+using OpenNest.Geometry;
+using Xunit;
+
+namespace OpenNest.Tests.Sequencing;
+
+public class EdgeStartSequencerTests
+{
+    private static Part MakePartAt(double x, double y) => TestHelpers.MakePartAt(x, y);
+
+    [Fact]
+    public void SortsByDistanceFromNearestEdge()
+    {
+        var plate = new Plate(60, 120);
+        var edgePart = MakePartAt(1, 1);
+        var centerPart = MakePartAt(25, 55);
+        var midPart = MakePartAt(10, 10);
+        plate.Parts.Add(edgePart);
+        plate.Parts.Add(centerPart);
+        plate.Parts.Add(midPart);
+
+        var sequencer = new EdgeStartSequencer();
+        var result = sequencer.Sequence(plate.Parts.ToList(), plate);
+
+        Assert.Same(edgePart, result[0].Part);
+        Assert.Same(midPart, result[1].Part);
+        Assert.Same(centerPart, result[2].Part);
+    }
+}