fix(io): deduplicate circles and full-circle arcs during DXF import

Duplicate circle entities at the same location inflated pierce counts
and cut pricing (e.g. SULLYS-035 showed 9 pierces instead of 8).

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

OpenNest.Core/Geometry/Arc.cs

@@ -93,6 +93,9 @@ namespace OpenNest.Geometry
             }
         }
 
+        public bool IsFullCircle() =>
+            SweepAngle() >= Angle.TwoPI - Tolerance.Epsilon;
+
         /// <summary>
         /// Angle in radians between start and end angles.
         /// </summary>

OpenNest.Core/Geometry/GeometryOptimizer.cs

@@ -17,6 +17,38 @@ namespace OpenNest.Geometry
                 (list, item, i) => list.GetCollinearLines(item, i),
                 (Line a, Line b, out Line joined) => TryJoinLines(a, b, out joined));
 
+        public static void Deduplicate(IList<Circle> circles)
+        {
+            for (var i = circles.Count - 1; i >= 1; i--)
+            {
+                for (var j = i - 1; j >= 0; j--)
+                {
+                    if (circles[i].Center.DistanceTo(circles[j].Center) <= Tolerance.Epsilon
+                        && circles[i].Radius.IsEqualTo(circles[j].Radius))
+                    {
+                        circles.RemoveAt(i);
+                        break;
+                    }
+                }
+            }
+        }
+
+        public static void Deduplicate(IList<Circle> circles, IList<Arc> arcs)
+        {
+            for (var i = circles.Count - 1; i >= 0; i--)
+            {
+                for (var j = arcs.Count - 1; j >= 0; j--)
+                {
+                    if (arcs[j].Center.DistanceTo(circles[i].Center) <= Tolerance.Epsilon
+                        && arcs[j].Radius.IsEqualTo(circles[i].Radius)
+                        && arcs[j].IsFullCircle())
+                    {
+                        arcs.RemoveAt(j);
+                    }
+                }
+            }
+        }
+
         private delegate bool TryJoin<T>(T a, T b, out T joined);
 
         private static void MergePass<T>(IList<T> items,

OpenNest.IO/CadImporter.cs

@@ -27,6 +27,7 @@ namespace OpenNest.IO
             var dxf = Dxf.Import(path);
 
             RemoveDuplicateArcs(dxf.Entities);
+            RemoveZeroSweepArcs(dxf.Entities);
 
             var bends = new List<Bend>();
             if (options.DetectBends && dxf.Document != null)
@@ -141,6 +142,12 @@ namespace OpenNest.IO
             return drawing;
         }
 
+        internal static void RemoveZeroSweepArcs(List<Entity> entities)
+        {
+            entities.RemoveAll(e =>
+                e is Arc arc && arc.StartAngle.IsEqualTo(arc.EndAngle, Tolerance.ChainTolerance));
+        }
+
         internal static void RemoveDuplicateArcs(List<Entity> entities)
         {
             var circles = entities.OfType<Circle>().ToList();

OpenNest.IO/Dxf.cs

@@ -133,6 +133,7 @@ namespace OpenNest.IO
             var entities = new List<Entity>();
             var lines = new List<Line>();
             var arcs = new List<Arc>();
+            var circles = new List<Circle>();
 
             foreach (var entity in doc.Entities)
             {
@@ -150,7 +151,7 @@ namespace OpenNest.IO
                         break;
 
                     case ACadSharp.Entities.Circle circle:
-                        entities.Add(circle.ToOpenNest());
+                        circles.Add(circle.ToOpenNest());
                         break;
 
                     case ACadSharp.Entities.Spline spline:
@@ -181,7 +182,10 @@ namespace OpenNest.IO
 
             GeometryOptimizer.Optimize(lines);
             GeometryOptimizer.Optimize(arcs);
+            GeometryOptimizer.Deduplicate(circles);
+            GeometryOptimizer.Deduplicate(circles, arcs);
 
+            entities.AddRange(circles);
             entities.AddRange(lines);
             entities.AddRange(arcs);