refactor: extract CollectPoints from FindBestRotation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Core/Geometry/Entity.cs

@@ -247,7 +247,7 @@ namespace OpenNest.Geometry
 
     public static class EntityExtensions
     {
-        public static BoundingRectangleResult FindBestRotation(this List<Entity> entities, double startAngle = 0, double endAngle = Angle.TwoPI)
+        public static List<Vector> CollectPoints(this IEnumerable<Entity> entities)
         {
             var points = new List<Vector>();
 
@@ -286,17 +286,35 @@ namespace OpenNest.Geometry
 
                     case EntityType.Shape:
                         var shape = (Shape)entity;
-                        var subResult = shape.Entities.FindBestRotation(startAngle, endAngle);
+                        points.AddRange(shape.Entities.CollectPoints());
-                        return subResult;
+                        break;
                 }
             }
 
+            return points;
+        }
+
+        public static BoundingRectangleResult FindBestRotation(this List<Entity> entities, double startAngle = 0, double endAngle = Angle.TwoPI)
+        {
+            // Check for Shape entity first (recursive case returns early)
+            foreach (var entity in entities)
+            {
+                if (entity.Type == EntityType.Shape)
+                {
+                    var shape = (Shape)entity;
+                    var subResult = shape.Entities.FindBestRotation(startAngle, endAngle);
+                    return subResult;
+                }
+            }
+
+            var points = entities.CollectPoints();
+
             if (points.Count == 0)
                 return new BoundingRectangleResult(startAngle, 0, 0);
 
             var hull = ConvexHull.Compute(points);
 
-            bool constrained = !startAngle.IsEqualTo(0) || !endAngle.IsEqualTo(Angle.TwoPI);
+            var constrained = !startAngle.IsEqualTo(0) || !endAngle.IsEqualTo(Angle.TwoPI);
 
             return constrained
                 ? RotatingCalipers.MinimumBoundingRectangle(hull, startAngle, endAngle)

OpenNest.Tests/CutOffGeometryTests.cs

@@ -321,6 +321,21 @@ public class CutOffGeometryTests
         Assert.Equal(6, cutoff.Drawing.Program.Codes.Count);
     }
 
+    [Fact]
+    public void CollectPoints_LinesAndArcs_ReturnsAllPoints()
+    {
+        var entities = new List<Entity>
+        {
+            new Line(new Vector(0, 0), new Vector(10, 0)),
+            new Arc(new Vector(5, 5), 5, 0, System.Math.PI)
+        };
+
+        var points = entities.CollectPoints();
+
+        // Line: 2 points. Arc: 2 endpoints + 4 cardinals = 6. Total = 8.
+        Assert.Equal(8, points.Count);
+    }
+
     [Fact]
     public void ShapeProfile_SelectsLargestShapeAsPerimeter()
     {