refactor: merge DxfImporter and DxfExporter into single static Dxf class

Consolidated two stateless classes into one unified API: Dxf.Import(),
Dxf.GetGeometry(), Dxf.ExportPlate(), Dxf.ExportProgram(). Export
state moved into a private ExportContext. Removed bool+out pattern
from GetGeometry in favor of returning empty list on failure.

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

OpenNest.Api/NestRunner.cs

@@ -25,14 +25,13 @@ public static class NestRunner
 
         // 1. Import DXFs → Drawings
         var drawings = new List<Drawing>();
-        var importer = new DxfImporter();
-
         foreach (var part in request.Parts)
         {
             if (!File.Exists(part.DxfPath))
                 throw new FileNotFoundException($"DXF file not found: {part.DxfPath}", part.DxfPath);
 
-            if (!importer.GetGeometry(part.DxfPath, out var geometry) || geometry.Count == 0)
+            var geometry = Dxf.GetGeometry(part.DxfPath);
+            if (geometry.Count == 0)
                 throw new InvalidOperationException($"Failed to import DXF: {part.DxfPath}");
 
             var normalized = ShapeProfile.NormalizeEntities(geometry);

OpenNest.Console/Program.cs

@@ -241,17 +241,11 @@ static class NestConsole
 
     static Drawing ImportDxf(string path)
     {
-        var importer = new DxfImporter();
-
-        if (!importer.GetGeometry(path, out var geometry))
-        {
-            Console.Error.WriteLine($"Error: failed to read DXF file: {path}");
-            return null;
-        }
+        var geometry = Dxf.GetGeometry(path);
 
         if (geometry.Count == 0)
         {
-            Console.Error.WriteLine($"Error: no geometry found in DXF file: {path}");
+            Console.Error.WriteLine($"Error: failed to read DXF file or no geometry found: {path}");
             return null;
         }
 

OpenNest.IO/Dxf.cs

@@ -0,0 +1,378 @@
+using ACadSharp;
+using ACadSharp.IO;
+using CSMath;
+using OpenNest.CNC;
+using OpenNest.Geometry;
+using OpenNest.Math;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+
+namespace OpenNest.IO
+{
+    using AcadArc = ACadSharp.Entities.Arc;
+    using AcadCircle = ACadSharp.Entities.Circle;
+    using AcadLine = ACadSharp.Entities.Line;
+    using Layer = ACadSharp.Tables.Layer;
+
+    public static class Dxf
+    {
+        #region Import
+
+        /// <summary>
+        /// Imports a DXF file, returning both converted entities and the raw CadDocument
+        /// for bend detection. The CadDocument is NOT disposed — caller can use it for
+        /// additional analysis (e.g., MText extraction for bend notes).
+        /// </summary>
+        public static DxfImportResult Import(string path)
+        {
+            using var reader = new DxfReader(path);
+            var doc = reader.Read();
+
+            return new DxfImportResult
+            {
+                Entities = ConvertEntities(doc),
+                Document = doc
+            };
+        }
+
+        public static List<Entity> GetGeometry(string path)
+        {
+            try
+            {
+                using var reader = new DxfReader(path);
+                var doc = reader.Read();
+                return ConvertEntities(doc);
+            }
+            catch (Exception ex)
+            {
+                Debug.WriteLine(ex.Message);
+                return new List<Entity>();
+            }
+        }
+
+        public static List<Entity> GetGeometry(Stream stream)
+        {
+            try
+            {
+                using var reader = new DxfReader(stream);
+                var doc = reader.Read();
+                return ConvertEntities(doc);
+            }
+            catch (Exception ex)
+            {
+                Debug.WriteLine(ex.Message);
+                return new List<Entity>();
+            }
+        }
+
+        #endregion
+
+        #region Export
+
+        public static void ExportProgram(Program program, string path)
+        {
+            using var stream = File.Create(path);
+            ExportProgram(program, stream);
+        }
+
+        public static void ExportProgram(Program program, Stream stream)
+        {
+            var ctx = new ExportContext();
+            ctx.AddProgram(program);
+
+            using var writer = new DxfWriter(stream, ctx.Document, false);
+            writer.Write();
+        }
+
+        public static void ExportPlate(Plate plate, string path)
+        {
+            using var stream = File.Create(path);
+            ExportPlate(plate, stream);
+        }
+
+        public static void ExportPlate(Plate plate, Stream stream)
+        {
+            var ctx = new ExportContext();
+            ctx.AddPlateOutline(plate);
+
+            foreach (var part in plate.Parts)
+            {
+                var endpt = part.Location.ToAcadXYZ();
+                ctx.AddLine(ctx.CurPos, endpt, ctx.RapidLayer);
+                ctx.CurPos = part.Location.ToAcadXYZ();
+                ctx.AddProgram(part.Program);
+            }
+
+            using var writer = new DxfWriter(stream, ctx.Document, false);
+            writer.Write();
+        }
+
+        #endregion
+
+        #region Private
+
+        private static List<Entity> ConvertEntities(CadDocument doc)
+        {
+            var entities = new List<Entity>();
+            var lines = new List<Line>();
+            var arcs = new List<Arc>();
+
+            foreach (var entity in doc.Entities)
+            {
+                if (IsNonCutLayer(entity.Layer?.Name))
+                    continue;
+
+                switch (entity)
+                {
+                    case ACadSharp.Entities.Line line:
+                        lines.Add(line.ToOpenNest());
+                        break;
+
+                    case ACadSharp.Entities.Arc arc:
+                        arcs.Add(arc.ToOpenNest());
+                        break;
+
+                    case ACadSharp.Entities.Circle circle:
+                        entities.Add(circle.ToOpenNest());
+                        break;
+
+                    case ACadSharp.Entities.Spline spline:
+                        foreach (var e in spline.ToOpenNest())
+                        {
+                            if (e is Line l) lines.Add(l);
+                            else if (e is Arc a) arcs.Add(a);
+                        }
+                        break;
+
+                    case ACadSharp.Entities.LwPolyline lwPolyline:
+                        lines.AddRange(lwPolyline.ToOpenNest());
+                        break;
+
+                    case ACadSharp.Entities.Polyline polyline:
+                        lines.AddRange(polyline.ToOpenNest());
+                        break;
+
+                    case ACadSharp.Entities.Ellipse ellipse:
+                        foreach (var e in ellipse.ToOpenNest())
+                        {
+                            if (e is Line l) lines.Add(l);
+                            else if (e is Arc a) arcs.Add(a);
+                        }
+                        break;
+                }
+            }
+
+            GeometryOptimizer.Optimize(lines);
+            GeometryOptimizer.Optimize(arcs);
+
+            entities.AddRange(lines);
+            entities.AddRange(arcs);
+
+            return entities;
+        }
+
+        private static bool IsNonCutLayer(string layerName)
+        {
+            return string.Equals(layerName, "BEND", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(layerName, "ETCH", StringComparison.OrdinalIgnoreCase);
+        }
+
+        private class ExportContext
+        {
+            public CadDocument Document { get; }
+            public XYZ CurPos { get; set; }
+            public Layer CutLayer { get; }
+            public Layer RapidLayer { get; }
+            public Layer PlateLayer { get; }
+
+            private Mode mode;
+
+            public ExportContext()
+            {
+                Document = new CadDocument();
+
+                CutLayer = new Layer("Cut") { Color = new Color(1) };
+                RapidLayer = new Layer("Rapid") { Color = new Color(5) };
+                PlateLayer = new Layer("Plate") { Color = new Color(4) };
+
+                Document.Layers.Add(CutLayer);
+                Document.Layers.Add(RapidLayer);
+                Document.Layers.Add(PlateLayer);
+            }
+
+            public void AddLine(XYZ start, XYZ end, Layer layer)
+            {
+                var ln = new AcadLine
+                {
+                    StartPoint = start,
+                    EndPoint = end,
+                    Layer = layer
+                };
+                Document.Entities.Add(ln);
+            }
+
+            public void AddPlateOutline(Plate plate)
+            {
+                XYZ pt1, pt2, pt3, pt4;
+
+                switch (plate.Quadrant)
+                {
+                    case 1:
+                        pt1 = new XYZ(0, 0, 0);
+                        pt2 = new XYZ(0, plate.Size.Width, 0);
+                        pt3 = new XYZ(plate.Size.Length, plate.Size.Width, 0);
+                        pt4 = new XYZ(plate.Size.Length, 0, 0);
+                        break;
+
+                    case 2:
+                        pt1 = new XYZ(0, 0, 0);
+                        pt2 = new XYZ(0, plate.Size.Width, 0);
+                        pt3 = new XYZ(-plate.Size.Length, plate.Size.Width, 0);
+                        pt4 = new XYZ(-plate.Size.Length, 0, 0);
+                        break;
+
+                    case 3:
+                        pt1 = new XYZ(0, 0, 0);
+                        pt2 = new XYZ(0, -plate.Size.Width, 0);
+                        pt3 = new XYZ(-plate.Size.Length, -plate.Size.Width, 0);
+                        pt4 = new XYZ(-plate.Size.Length, 0, 0);
+                        break;
+
+                    case 4:
+                        pt1 = new XYZ(0, 0, 0);
+                        pt2 = new XYZ(0, -plate.Size.Width, 0);
+                        pt3 = new XYZ(plate.Size.Length, -plate.Size.Width, 0);
+                        pt4 = new XYZ(plate.Size.Length, 0, 0);
+                        break;
+
+                    default:
+                        return;
+                }
+
+                AddLine(pt1, pt2, PlateLayer);
+                AddLine(pt2, pt3, PlateLayer);
+                AddLine(pt3, pt4, PlateLayer);
+                AddLine(pt4, pt1, PlateLayer);
+
+                var m1 = new XYZ(pt1.X + plate.EdgeSpacing.Left, pt1.Y + plate.EdgeSpacing.Bottom, 0);
+                var m2 = new XYZ(m1.X, pt2.Y - plate.EdgeSpacing.Top, 0);
+                var m3 = new XYZ(pt3.X - plate.EdgeSpacing.Right, m2.Y, 0);
+                var m4 = new XYZ(m3.X, m1.Y, 0);
+
+                AddLine(m1, m2, PlateLayer);
+                AddLine(m2, m3, PlateLayer);
+                AddLine(m3, m4, PlateLayer);
+                AddLine(m4, m1, PlateLayer);
+            }
+
+            public void AddProgram(Program program)
+            {
+                mode = program.Mode;
+
+                for (var i = 0; i < program.Length; ++i)
+                {
+                    var code = program[i];
+
+                    switch (code.Type)
+                    {
+                        case CodeType.ArcMove:
+                            AddArcMove((ArcMove)code);
+                            break;
+
+                        case CodeType.LinearMove:
+                            AddLinearMove((LinearMove)code);
+                            break;
+
+                        case CodeType.RapidMove:
+                            AddRapidMove((RapidMove)code);
+                            break;
+
+                        case CodeType.SubProgramCall:
+                            var tmpmode = mode;
+                            AddProgram(((SubProgramCall)code).Program);
+                            mode = tmpmode;
+                            break;
+                    }
+                }
+            }
+
+            private void AddLinearMove(LinearMove line)
+            {
+                var pt = line.EndPoint.ToAcadXYZ();
+
+                if (mode == Mode.Incremental)
+                    pt = new XYZ(pt.X + CurPos.X, pt.Y + CurPos.Y, 0);
+
+                AddLine(CurPos, pt, CutLayer);
+                CurPos = pt;
+            }
+
+            private void AddRapidMove(RapidMove rapid)
+            {
+                var pt = rapid.EndPoint.ToAcadXYZ();
+
+                if (mode == Mode.Incremental)
+                    pt = new XYZ(pt.X + CurPos.X, pt.Y + CurPos.Y, 0);
+
+                AddLine(CurPos, pt, RapidLayer);
+                CurPos = pt;
+            }
+
+            private void AddArcMove(ArcMove arc)
+            {
+                var center = arc.CenterPoint.ToAcadXYZ();
+                var endpt = arc.EndPoint.ToAcadXYZ();
+
+                if (mode == Mode.Incremental)
+                {
+                    endpt = new XYZ(endpt.X + CurPos.X, endpt.Y + CurPos.Y, 0);
+                    center = new XYZ(center.X + CurPos.X, center.Y + CurPos.Y, 0);
+                }
+
+                var startAngle = System.Math.Atan2(
+                    CurPos.Y - center.Y,
+                    CurPos.X - center.X);
+
+                var endAngle = System.Math.Atan2(
+                    endpt.Y - center.Y,
+                    endpt.X - center.X);
+
+                if (arc.Rotation == RotationType.CW)
+                    Generic.Swap(ref startAngle, ref endAngle);
+
+                var dx = endpt.X - center.X;
+                var dy = endpt.Y - center.Y;
+                var radius = System.Math.Sqrt(dx * dx + dy * dy);
+
+                if (startAngle.IsEqualTo(endAngle))
+                {
+                    var circle = new AcadCircle
+                    {
+                        Center = center,
+                        Radius = radius,
+                        Layer = CutLayer
+                    };
+                    Document.Entities.Add(circle);
+                }
+                else
+                {
+                    var acadArc = new AcadArc
+                    {
+                        Center = center,
+                        Radius = radius,
+                        StartAngle = startAngle,
+                        EndAngle = endAngle,
+                        Layer = CutLayer
+                    };
+                    Document.Entities.Add(acadArc);
+                }
+
+                CurPos = endpt;
+            }
+        }
+
+        #endregion
+    }
+}

OpenNest.IO/DxfExporter.cs

@@ -1,297 +0,0 @@
-using ACadSharp;
-using ACadSharp.IO;
-using CSMath;
-using OpenNest.CNC;
-using OpenNest.Math;
-using System.Diagnostics;
-using System.IO;
-
-namespace OpenNest.IO
-{
-    using AcadArc = ACadSharp.Entities.Arc;
-    using AcadCircle = ACadSharp.Entities.Circle;
-    using AcadLine = ACadSharp.Entities.Line;
-    using Layer = ACadSharp.Tables.Layer;
-
-    public class DxfExporter
-    {
-        private CadDocument doc;
-        private XYZ curpos;
-        private Mode mode;
-        private readonly Layer cutLayer;
-        private readonly Layer rapidLayer;
-        private readonly Layer plateLayer;
-
-        public DxfExporter()
-        {
-            doc = new CadDocument();
-
-            cutLayer = new Layer("Cut");
-            cutLayer.Color = new Color(1);
-
-            rapidLayer = new Layer("Rapid");
-            rapidLayer.Color = new Color(5);
-
-            plateLayer = new Layer("Plate");
-            plateLayer.Color = new Color(4);
-        }
-
-        public void ExportProgram(Program program, Stream stream)
-        {
-            doc = new CadDocument();
-            EnsureLayers();
-            AddProgram(program);
-            using (var writer = new DxfWriter(stream, doc, false))
-            {
-                writer.Write();
-            }
-        }
-
-        public bool ExportProgram(Program program, string path)
-        {
-            Stream stream = null;
-            var success = false;
-
-            try
-            {
-                stream = File.Create(path);
-                ExportProgram(program, stream);
-                success = true;
-            }
-            catch
-            {
-                Debug.Fail("DxfExporter.ExportProgram failed to write program to file: " + path);
-            }
-            finally
-            {
-                if (stream != null)
-                    stream.Close();
-            }
-
-            return success;
-        }
-
-        public void ExportPlate(Plate plate, Stream stream)
-        {
-            doc = new CadDocument();
-            EnsureLayers();
-            AddPlateOutline(plate);
-
-            foreach (var part in plate.Parts)
-            {
-                var endpt = part.Location.ToAcadXYZ();
-                AddLine(curpos, endpt, rapidLayer);
-                curpos = part.Location.ToAcadXYZ();
-                AddProgram(part.Program);
-            }
-
-            using (var writer = new DxfWriter(stream, doc, false))
-            {
-                writer.Write();
-            }
-        }
-
-        public bool ExportPlate(Plate plate, string path)
-        {
-            Stream stream = null;
-            var success = false;
-
-            try
-            {
-                stream = File.Create(path);
-                ExportPlate(plate, stream);
-                success = true;
-            }
-            catch
-            {
-                Debug.Fail("DxfExporter.ExportPlate failed to write plate to file: " + path);
-            }
-            finally
-            {
-                if (stream != null)
-                    stream.Close();
-            }
-
-            return success;
-        }
-
-        private void EnsureLayers()
-        {
-            doc.Layers.Add(cutLayer);
-            doc.Layers.Add(rapidLayer);
-            doc.Layers.Add(plateLayer);
-        }
-
-        private void AddLine(XYZ start, XYZ end, Layer layer)
-        {
-            var ln = new AcadLine();
-            ln.StartPoint = start;
-            ln.EndPoint = end;
-            ln.Layer = layer;
-            doc.Entities.Add(ln);
-        }
-
-        private void AddPlateOutline(Plate plate)
-        {
-            XYZ pt1;
-            XYZ pt2;
-            XYZ pt3;
-            XYZ pt4;
-
-            switch (plate.Quadrant)
-            {
-                case 1:
-                    pt1 = new XYZ(0, 0, 0);
-                    pt2 = new XYZ(0, plate.Size.Width, 0);
-                    pt3 = new XYZ(plate.Size.Length, plate.Size.Width, 0);
-                    pt4 = new XYZ(plate.Size.Length, 0, 0);
-                    break;
-
-                case 2:
-                    pt1 = new XYZ(0, 0, 0);
-                    pt2 = new XYZ(0, plate.Size.Width, 0);
-                    pt3 = new XYZ(-plate.Size.Length, plate.Size.Width, 0);
-                    pt4 = new XYZ(-plate.Size.Length, 0, 0);
-                    break;
-
-                case 3:
-                    pt1 = new XYZ(0, 0, 0);
-                    pt2 = new XYZ(0, -plate.Size.Width, 0);
-                    pt3 = new XYZ(-plate.Size.Length, -plate.Size.Width, 0);
-                    pt4 = new XYZ(-plate.Size.Length, 0, 0);
-                    break;
-
-                case 4:
-                    pt1 = new XYZ(0, 0, 0);
-                    pt2 = new XYZ(0, -plate.Size.Width, 0);
-                    pt3 = new XYZ(plate.Size.Length, -plate.Size.Width, 0);
-                    pt4 = new XYZ(plate.Size.Length, 0, 0);
-                    break;
-
-                default:
-                    return;
-            }
-
-            AddLine(pt1, pt2, plateLayer);
-            AddLine(pt2, pt3, plateLayer);
-            AddLine(pt3, pt4, plateLayer);
-            AddLine(pt4, pt1, plateLayer);
-
-            var m1 = new XYZ(pt1.X + plate.EdgeSpacing.Left, pt1.Y + plate.EdgeSpacing.Bottom, 0);
-            var m2 = new XYZ(m1.X, pt2.Y - plate.EdgeSpacing.Top, 0);
-            var m3 = new XYZ(pt3.X - plate.EdgeSpacing.Right, m2.Y, 0);
-            var m4 = new XYZ(m3.X, m1.Y, 0);
-
-            AddLine(m1, m2, plateLayer);
-            AddLine(m2, m3, plateLayer);
-            AddLine(m3, m4, plateLayer);
-            AddLine(m4, m1, plateLayer);
-        }
-
-        private void AddProgram(Program program)
-        {
-            mode = program.Mode;
-
-            for (var i = 0; i < program.Length; ++i)
-            {
-                var code = program[i];
-
-                switch (code.Type)
-                {
-                    case CodeType.ArcMove:
-                        var arc = (ArcMove)code;
-                        AddArcMove(arc);
-                        break;
-
-                    case CodeType.LinearMove:
-                        var line = (LinearMove)code;
-                        AddLinearMove(line);
-                        break;
-
-                    case CodeType.RapidMove:
-                        var rapid = (RapidMove)code;
-                        AddRapidMove(rapid);
-                        break;
-
-                    case CodeType.SubProgramCall:
-                        var tmpmode = mode;
-                        var subpgm = (CNC.SubProgramCall)code;
-                        AddProgram(subpgm.Program);
-                        mode = tmpmode;
-                        break;
-                }
-            }
-        }
-
-        private void AddLinearMove(LinearMove line)
-        {
-            var pt = line.EndPoint.ToAcadXYZ();
-
-            if (mode == Mode.Incremental)
-                pt = new XYZ(pt.X + curpos.X, pt.Y + curpos.Y, 0);
-
-            AddLine(curpos, pt, cutLayer);
-            curpos = pt;
-        }
-
-        private void AddRapidMove(RapidMove rapid)
-        {
-            var pt = rapid.EndPoint.ToAcadXYZ();
-
-            if (mode == Mode.Incremental)
-                pt = new XYZ(pt.X + curpos.X, pt.Y + curpos.Y, 0);
-
-            AddLine(curpos, pt, rapidLayer);
-            curpos = pt;
-        }
-
-        private void AddArcMove(ArcMove arc)
-        {
-            var center = arc.CenterPoint.ToAcadXYZ();
-            var endpt = arc.EndPoint.ToAcadXYZ();
-
-            if (mode == Mode.Incremental)
-            {
-                endpt = new XYZ(endpt.X + curpos.X, endpt.Y + curpos.Y, 0);
-                center = new XYZ(center.X + curpos.X, center.Y + curpos.Y, 0);
-            }
-
-            var startAngle = System.Math.Atan2(
-                curpos.Y - center.Y,
-                curpos.X - center.X);
-
-            var endAngle = System.Math.Atan2(
-                endpt.Y - center.Y,
-                endpt.X - center.X);
-
-            if (arc.Rotation == OpenNest.RotationType.CW)
-                Generic.Swap(ref startAngle, ref endAngle);
-
-            var dx = endpt.X - center.X;
-            var dy = endpt.Y - center.Y;
-
-            var radius = System.Math.Sqrt(dx * dx + dy * dy);
-
-            if (startAngle.IsEqualTo(endAngle))
-            {
-                var circle = new AcadCircle();
-                circle.Center = center;
-                circle.Radius = radius;
-                circle.Layer = cutLayer;
-                doc.Entities.Add(circle);
-            }
-            else
-            {
-                var arc2 = new AcadArc();
-                arc2.Center = center;
-                arc2.Radius = radius;
-                arc2.StartAngle = startAngle;
-                arc2.EndAngle = endAngle;
-                arc2.Layer = cutLayer;
-                doc.Entities.Add(arc2);
-            }
-
-            curpos = endpt;
-        }
-    }
-}

OpenNest.IO/DxfImporter.cs

@@ -1,155 +0,0 @@
-using ACadSharp;
-using ACadSharp.IO;
-using OpenNest.Geometry;
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.IO;
-
-namespace OpenNest.IO
-{
-    public class DxfImporter
-    {
-        public int SplinePrecision { get; set; }
-
-        public DxfImporter()
-        {
-        }
-
-        private List<Entity> GetGeometry(CadDocument doc)
-        {
-            var entities = new List<Entity>();
-            var lines = new List<Line>();
-            var arcs = new List<Arc>();
-
-            foreach (var entity in doc.Entities)
-            {
-                // Skip bend/etch entities — bends are converted to Bend objects
-                // separately via bend detection, and etch marks are generated from
-                // bends during DXF export. Neither should be treated as cut geometry.
-                if (IsNonCutLayer(entity.Layer?.Name))
-                    continue;
-
-                switch (entity)
-                {
-                    case ACadSharp.Entities.Line line:
-                        lines.Add(line.ToOpenNest());
-                        break;
-
-                    case ACadSharp.Entities.Arc arc:
-                        arcs.Add(arc.ToOpenNest());
-                        break;
-
-                    case ACadSharp.Entities.Circle circle:
-                        entities.Add(circle.ToOpenNest());
-                        break;
-
-                    case ACadSharp.Entities.Spline spline:
-                        foreach (var e in spline.ToOpenNest(SplinePrecision))
-                        {
-                            if (e is Line l) lines.Add(l);
-                            else if (e is Arc a) arcs.Add(a);
-                        }
-                        break;
-
-                    case ACadSharp.Entities.LwPolyline lwPolyline:
-                        lines.AddRange(lwPolyline.ToOpenNest());
-                        break;
-
-                    case ACadSharp.Entities.Polyline polyline:
-                        lines.AddRange(polyline.ToOpenNest());
-                        break;
-
-                    case ACadSharp.Entities.Ellipse ellipse:
-                        foreach (var e in ellipse.ToOpenNest())
-                        {
-                            if (e is Line l) lines.Add(l);
-                            else if (e is Arc a) arcs.Add(a);
-                        }
-                        break;
-                }
-            }
-
-            GeometryOptimizer.Optimize(lines);
-            GeometryOptimizer.Optimize(arcs);
-
-            entities.AddRange(lines);
-            entities.AddRange(arcs);
-
-            return entities;
-        }
-
-        /// <summary>
-        /// Imports a DXF file, returning both converted entities and the raw CadDocument
-        /// for bend detection. The CadDocument is NOT disposed — caller can use it for
-        /// additional analysis (e.g., MText extraction for bend notes).
-        /// </summary>
-        public DxfImportResult Import(string path)
-        {
-            using var reader = new DxfReader(path);
-            var doc = reader.Read();
-            var entities = GetGeometry(doc);
-
-            return new DxfImportResult
-            {
-                Entities = entities,
-                Document = doc
-            };
-        }
-
-        public bool GetGeometry(Stream stream, out List<Entity> geometry)
-        {
-            var success = false;
-
-            try
-            {
-                using (var reader = new DxfReader(stream))
-                {
-                    var doc = reader.Read();
-                    geometry = GetGeometry(doc);
-                    success = true;
-                }
-            }
-            catch (Exception ex)
-            {
-                Debug.WriteLine(ex.Message);
-                geometry = new List<Entity>();
-            }
-            finally
-            {
-                if (stream != null)
-                    stream.Close();
-            }
-
-            return success;
-        }
-
-        public bool GetGeometry(string path, out List<Entity> geometry)
-        {
-            var success = false;
-
-            try
-            {
-                using (var reader = new DxfReader(path))
-                {
-                    var doc = reader.Read();
-                    geometry = GetGeometry(doc);
-                    success = true;
-                }
-            }
-            catch (Exception ex)
-            {
-                Debug.WriteLine(ex.Message);
-                geometry = new List<Entity>();
-            }
-
-            return success;
-        }
-
-        private static bool IsNonCutLayer(string layerName)
-        {
-            return string.Equals(layerName, "BEND", System.StringComparison.OrdinalIgnoreCase)
-                || string.Equals(layerName, "ETCH", System.StringComparison.OrdinalIgnoreCase);
-        }
-    }
-}

OpenNest.IO/Extensions.cs

@@ -57,7 +57,7 @@ namespace OpenNest.IO
             return result;
         }
 
-        public static List<Geometry.Entity> ToOpenNest(this Spline spline, int precision)
+        public static List<Geometry.Entity> ToOpenNest(this Spline spline)
         {
             var layer = spline.Layer.ToOpenNest();
             var color = spline.ResolveColor();
@@ -67,7 +67,7 @@ namespace OpenNest.IO
             List<XYZ> curvePoints;
             try
             {
-                curvePoints = spline.PolygonalVertexes(precision > 0 ? precision : 200);
+                curvePoints = spline.PolygonalVertexes(200);
             }
             catch (Exception ex)
             {

OpenNest.Mcp/Tools/InputTools.cs

@@ -96,13 +96,10 @@ namespace OpenNest.Mcp.Tools
             if (!File.Exists(path))
                 return $"Error: file not found: {path}";
 
-            var importer = new DxfImporter();
-
-            if (!importer.GetGeometry(path, out var geometry))
-                return "Error: failed to read DXF file";
+            var geometry = Dxf.GetGeometry(path);
 
             if (geometry.Count == 0)
-                return "Error: no geometry found in DXF file";
+                return "Error: failed to read DXF file or no geometry found";
 
             var normalized = ShapeProfile.NormalizeEntities(geometry);
             var pgm = ConvertGeometry.ToProgram(normalized);

OpenNest.Tests/Api/NestRunnerTests.cs

@@ -70,8 +70,7 @@ public class NestRunnerTests
         var pgm = ConvertGeometry.ToProgram(shape);
         var path = Path.Combine(Path.GetTempPath(), $"test-{Guid.NewGuid()}.dxf");
 
-        var exporter = new DxfExporter();
-        exporter.ExportProgram(pgm, path);
+        Dxf.ExportProgram(pgm, path);
 
         return path;
     }

OpenNest.Tests/Bending/SolidWorksBendDetectorTests.cs

@@ -35,8 +35,7 @@ public class SolidWorksBendDetectorTests
         var path = Path.Combine(AppContext.BaseDirectory, "Bending", "TestData", "4526 A14 PT11 Test.dxf");
         Assert.True(File.Exists(path), $"Test DXF not found: {path}");
 
-        var importer = new OpenNest.IO.DxfImporter { SplinePrecision = 200 };
-        var result = importer.Import(path);
+        var result = OpenNest.IO.Dxf.Import(path);
 
         // EllipseConverter now produces arcs directly during import,
         // so the imported entities should contain Arc instances from the ellipses
@@ -61,8 +60,7 @@ public class SolidWorksBendDetectorTests
         var path = Path.Combine(AppContext.BaseDirectory, "Bending", "TestData", "4526 A14 PT11.dxf");
         Assert.True(File.Exists(path), $"Test DXF not found: {path}");
 
-        var importer = new OpenNest.IO.DxfImporter();
-        var result = importer.Import(path);
+        var result = OpenNest.IO.Dxf.Import(path);
 
         // The DXF has 2 trimmed ellipses forming an oblong slot.
         // Trimmed ellipses must not generate a closing chord line.

OpenNest.Tests/BestFit/BestFitOverlapTests.cs

@@ -32,8 +32,7 @@ public class BestFitOverlapTests
         if (!File.Exists(DxfPath))
             return null;
 
-        var importer = new DxfImporter();
-        importer.GetGeometry(DxfPath, out var geometry);
+        var geometry = Dxf.GetGeometry(DxfPath);
         var pgm = ConvertGeometry.ToProgram(geometry);
         return new Drawing("PT16", pgm);
     }

OpenNest.Tests/Engine/EngineOverlapTests.cs

@@ -20,8 +20,7 @@ public class EngineOverlapTests
         if (!System.IO.File.Exists(DxfPath))
             return null;
 
-        var importer = new DxfImporter();
-        importer.GetGeometry(DxfPath, out var geometry);
+        var geometry = Dxf.GetGeometry(DxfPath);
         var pgm = ConvertGeometry.ToProgram(geometry);
         return new Drawing("PT15", pgm);
     }

OpenNest.Tests/Geometry/EllipseConverterTests.cs

@@ -228,8 +228,7 @@ public class EllipseConverterTests
             using (var writer = new ACadSharp.IO.DxfWriter(stream, doc, false))
                 writer.Write();
 
-            var importer = new OpenNest.IO.DxfImporter { SplinePrecision = 200 };
-            var result = importer.Import(tempPath);
+            var result = OpenNest.IO.Dxf.Import(tempPath);
 
             var arcCount = result.Entities.Count(e => e is Arc);
             var lineCount = result.Entities.Count(e => e is Line);

OpenNest.Tests/Geometry/GeometrySimplifierTests.cs

@@ -138,8 +138,7 @@ public class GeometrySimplifierTests
         if (!File.Exists(path))
             return; // skip if file not available
 
-        var importer = new DxfImporter();
-        var result = importer.Import(path);
+        var result = Dxf.Import(path);
         var shapes = ShapeBuilder.GetShapes(result.Entities);
 
         var simplifier = new GeometrySimplifier { Tolerance = 0.004 };

OpenNest.Tests/IO/DxfRoundtripTests.cs

@@ -11,17 +11,14 @@ public class DxfRoundtripTests
     private static List<Entity> ExportAndReimport(List<Entity> geometry)
     {
         var program = ConvertGeometry.ToProgram(geometry);
-        var exporter = new DxfExporter();
-        var importer = new DxfImporter();
-
         using var exportStream = new MemoryStream();
-        exporter.ExportProgram(program, exportStream);
+        Dxf.ExportProgram(program, exportStream);
         var bytes = exportStream.ToArray();
 
         var importStream = new MemoryStream(bytes);
-        var success = importer.GetGeometry(importStream, out var reimported);
+        var reimported = Dxf.GetGeometry(importStream);
 
-        Assert.True(success, "Failed to re-import exported DXF");
+        Assert.NotEmpty(reimported);
         return reimported;
     }
 

OpenNest.Tests/Splitting/DrawingSplitterTests.cs

@@ -369,8 +369,7 @@ public class DrawingSplitterTests
             var writer = new OpenNest.IO.SplitDxfWriter();
             writer.Write(tempPath, results[0]);
 
-            var reimporter = new OpenNest.IO.DxfImporter();
-            var reimportResult = reimporter.Import(tempPath);
+            var reimportResult = OpenNest.IO.Dxf.Import(tempPath);
 
             var afterArcs = reimportResult.Entities.OfType<Arc>().Count();
             var afterCircles = reimportResult.Entities.OfType<Circle>().Count();

OpenNest.Tests/Splitting/SplitDxfWriterEtchLayerTests.cs

@@ -185,8 +185,7 @@ public class SplitDxfWriterEtchLayerTests
                 writer.Write(tempPath, splitDrawing);
 
                 // Re-import via DxfImporter (same path as CadConverterForm)
-                var importer = new DxfImporter();
-                var result = importer.Import(tempPath);
+                var result = Dxf.Import(tempPath);
 
                 // ETCH entities should be filtered during import (like BEND)
                 var etchEntities = result.Entities

OpenNest.Tests/Strategies/StrategyOverlapTests.cs

@@ -23,8 +23,7 @@ public class StrategyOverlapTests
         if (!System.IO.File.Exists(DxfPath))
             return null;
 
-        var importer = new DxfImporter();
-        importer.GetGeometry(DxfPath, out var geometry);
+        var geometry = Dxf.GetGeometry(DxfPath);
         var pgm = ConvertGeometry.ToProgram(geometry);
         return new Drawing("PT15", pgm);
     }

OpenNest.Training/Program.cs

@@ -104,7 +104,6 @@ int RunDataCollection(string dir, string dbPath, string saveDir, double s, strin
     if (backfilled > 0)
         Console.WriteLine($"Backfilled PerimeterToAreaRatio for {backfilled} existing parts");
 
-    var importer = new DxfImporter();
     var colorIndex = 0;
     var processed = 0;
     var skippedGeometry = 0;
@@ -129,7 +128,8 @@ int RunDataCollection(string dir, string dbPath, string saveDir, double s, strin
                 continue;
             }
 
-            if (!importer.GetGeometry(file, out var entities))
+            var entities = Dxf.GetGeometry(file);
+            if (entities.Count == 0)
             {
                 Console.WriteLine(" - SKIP (no geometry)");
                 skippedGeometry++;

OpenNest/Controls/DrawingListBox.cs

@@ -125,6 +125,10 @@ namespace OpenNest.Controls
                 pt.Y += 18;
                 e.Graphics.DrawString(text3, Font, detailBrush, pt);
             }
+
+            using var separatorPen = new Pen(Color.LightGray);
+            var separatorY = e.Bounds.Bottom - 1;
+            e.Graphics.DrawLine(separatorPen, e.Bounds.X, separatorY, e.Bounds.Right, separatorY);
         }
 
         protected override void OnMouseMove(MouseEventArgs e)

OpenNest/Forms/BomImportForm.cs

@@ -382,7 +382,6 @@ namespace OpenNest.Forms
             }
 
             var jobName = txtJobName.Text.Trim();
-            var importer = new DxfImporter();
             var nestsCreated = 0;
             var importErrors = new List<string>();
 
@@ -416,7 +415,7 @@ namespace OpenNest.Forms
 
                     try
                     {
-                        var result = importer.Import(part.DxfPath);
+                        var result = Dxf.Import(part.DxfPath);
 
                         var drawingName = Path.GetFileNameWithoutExtension(part.DxfPath);
                         var drawing = new Drawing(drawingName);

OpenNest/Forms/CadConverterForm.cs

@@ -74,9 +74,7 @@ namespace OpenNest.Forms
         {
             try
             {
-                var importer = new DxfImporter();
-                importer.SplinePrecision = Settings.Default.ImportSplinePrecision;
-                var result = importer.Import(file);
+                var result = Dxf.Import(file);
 
                 if (result.Entities.Count == 0)
                     return;
@@ -384,9 +382,7 @@ namespace OpenNest.Forms
                 newItems.Add(splitPath);
 
                 // Re-import geometry but keep bends from the split drawing
-                var importer = new DxfImporter();
-                importer.SplinePrecision = Settings.Default.ImportSplinePrecision;
-                var result = importer.Import(splitPath);
+                var result = Dxf.Import(splitPath);
 
                 var splitItem = new FileListItem
                 {

OpenNest/Forms/EditNestForm.cs

@@ -259,6 +259,11 @@ namespace OpenNest.Forms
 
         public void UpdateDrawingList()
         {
+            var topIndex = drawingListBox1.TopIndex;
+            var selected = drawingListBox1.SelectedItem;
+
+            drawingListBox1.BeginUpdate();
+
             drawingListBox1.Items.Clear();
 
             foreach (var dwg in Nest.Drawings.OrderBy(d => d.Name).ToList())
@@ -268,6 +273,14 @@ namespace OpenNest.Forms
 
                 drawingListBox1.Items.Add(dwg);
             }
+
+            if (selected != null && drawingListBox1.Items.Contains(selected))
+                drawingListBox1.SelectedItem = selected;
+
+            if (topIndex < drawingListBox1.Items.Count)
+                drawingListBox1.TopIndex = topIndex;
+
+            drawingListBox1.EndUpdate();
         }
 
         public void Save()
@@ -349,9 +362,8 @@ namespace OpenNest.Forms
             {
                 if (dlg.FilterIndex == 1)
                 {
-                    var exporter = new DxfExporter();
-                    var success = exporter.ExportPlate(PlateView.Plate, dlg.FileName);
-                    return success;
+                    Dxf.ExportPlate(PlateView.Plate, dlg.FileName);
+                    return true;
                 }
                 else if (dlg.FilterIndex == 2)
                 {
@@ -527,8 +539,7 @@ namespace OpenNest.Forms
             var plate = PlateView.Plate;
             var name = string.Format("{0}-P{1}.dxf", Nest.Name, PlateManager.CurrentIndex + 1);
             var path = Path.Combine(Path.GetTempPath(), name);
-            var exporter = new DxfExporter();
-            exporter.ExportPlate(plate, path);
+            Dxf.ExportPlate(plate, path);
 
             Process.Start(path);
         }
@@ -886,7 +897,6 @@ namespace OpenNest.Forms
 
         private void PlateManager_PlateListChanged(object sender, EventArgs e)
         {
-            tabControl1.SelectedIndex = 0;
             UpdatePlateList();
             UpdatePlateHeader();
             UpdateRemovePlateButton();
@@ -935,9 +945,20 @@ namespace OpenNest.Forms
             drawingListBox1.Invoke(new MethodInvoker(() =>
             {
                 if (hideNestedButton.Checked)
-                    UpdateDrawingList();
-                else
-                    drawingListBox1.Refresh();
+                {
+                    drawingListBox1.BeginUpdate();
+
+                    for (var i = drawingListBox1.Items.Count - 1; i >= 0; i--)
+                    {
+                        var dwg = (Drawing)drawingListBox1.Items[i];
+                        if (dwg.Quantity.Required > 0 && dwg.Quantity.Remaining == 0)
+                            drawingListBox1.Items.RemoveAt(i);
+                    }
+
+                    drawingListBox1.EndUpdate();
+                }
+
+                drawingListBox1.Invalidate();
             }));
         }
 

OpenNest/Forms/OptionsForm.Designer.cs

@@ -33,11 +33,9 @@
             this.label1 = new System.Windows.Forms.Label();
             this.toolTip1 = new System.Windows.Forms.ToolTip(this.components);
             this.numericUpDown1 = new OpenNest.Controls.NumericUpDown();
-            this.label2 = new System.Windows.Forms.Label();
             this.tableLayoutPanel1 = new System.Windows.Forms.TableLayoutPanel();
             this.textBox1 = new System.Windows.Forms.TextBox();
             this.label3 = new System.Windows.Forms.Label();
-            this.numericUpDown2 = new OpenNest.Controls.NumericUpDown();
             this.button1 = new System.Windows.Forms.Button();
             this.saveButton = new System.Windows.Forms.Button();
             this.cancelButton = new System.Windows.Forms.Button();
@@ -46,7 +44,6 @@
             this.strategyGroupBox = new System.Windows.Forms.GroupBox();
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
             this.tableLayoutPanel1.SuspendLayout();
-            ((System.ComponentModel.ISupportInitialize)(this.numericUpDown2)).BeginInit();
             this.bottomPanel1.SuspendLayout();
             this.SuspendLayout();
             // 
@@ -87,17 +84,7 @@
             this.numericUpDown1.Suffix = "";
             this.numericUpDown1.TabIndex = 4;
             this.toolTip1.SetToolTip(this.numericUpDown1, "The amount to round the plate size up.");
-            // 
-            // label2
-            // 
-            this.label2.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
-            this.label2.AutoSize = true;
-            this.label2.Location = new System.Drawing.Point(3, 92);
-            this.label2.Name = "label2";
-            this.label2.Size = new System.Drawing.Size(145, 16);
-            this.label2.TabIndex = 5;
-            this.label2.Text = "Import spline precision:\r\n";
-            // 
+            //
             // tableLayoutPanel1
             // 
             this.tableLayoutPanel1.ColumnCount = 4;
@@ -107,19 +94,16 @@
             this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Absolute, 100F));
             this.tableLayoutPanel1.Controls.Add(this.label1, 0, 1);
             this.tableLayoutPanel1.Controls.Add(this.textBox1, 1, 0);
-            this.tableLayoutPanel1.Controls.Add(this.label2, 0, 2);
             this.tableLayoutPanel1.Controls.Add(this.label3, 0, 0);
-            this.tableLayoutPanel1.Controls.Add(this.checkBox1, 0, 3);
-            this.tableLayoutPanel1.Controls.Add(this.numericUpDown2, 1, 2);
+            this.tableLayoutPanel1.Controls.Add(this.checkBox1, 0, 2);
             this.tableLayoutPanel1.Controls.Add(this.numericUpDown1, 1, 1);
             this.tableLayoutPanel1.Controls.Add(this.button1, 3, 0);
             this.tableLayoutPanel1.Location = new System.Drawing.Point(12, 12);
             this.tableLayoutPanel1.Name = "tableLayoutPanel1";
-            this.tableLayoutPanel1.RowCount = 4;
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
-            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 25F));
+            this.tableLayoutPanel1.RowCount = 3;
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 33.33F));
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 33.33F));
+            this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 33.34F));
             this.tableLayoutPanel1.Size = new System.Drawing.Size(684, 160);
             this.tableLayoutPanel1.TabIndex = 0;
             // 
@@ -141,31 +125,7 @@
             this.label3.Size = new System.Drawing.Size(145, 16);
             this.label3.TabIndex = 0;
             this.label3.Text = "Nest Template Path:";
-            // 
-            // numericUpDown2
-            // 
-            this.numericUpDown2.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
-            this.numericUpDown2.Location = new System.Drawing.Point(154, 89);
-            this.numericUpDown2.Maximum = new decimal(new int[] {
-            360,
-            0,
-            0,
-            0});
-            this.numericUpDown2.Minimum = new decimal(new int[] {
-            3,
-            0,
-            0,
-            0});
-            this.numericUpDown2.Name = "numericUpDown2";
-            this.numericUpDown2.Size = new System.Drawing.Size(130, 22);
-            this.numericUpDown2.Suffix = "";
-            this.numericUpDown2.TabIndex = 6;
-            this.numericUpDown2.Value = new decimal(new int[] {
-            200,
-            0,
-            0,
-            0});
-            // 
+            //
             // button1
             // 
             this.button1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
@@ -259,7 +219,6 @@
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).EndInit();
             this.tableLayoutPanel1.ResumeLayout(false);
             this.tableLayoutPanel1.PerformLayout();
-            ((System.ComponentModel.ISupportInitialize)(this.numericUpDown2)).EndInit();
             this.bottomPanel1.ResumeLayout(false);
             this.ResumeLayout(false);
 
@@ -273,8 +232,6 @@
         private System.Windows.Forms.Label label1;
         private Controls.NumericUpDown numericUpDown1;
         private System.Windows.Forms.ToolTip toolTip1;
-        private System.Windows.Forms.Label label2;
-        private Controls.NumericUpDown numericUpDown2;
         private Controls.BottomPanel bottomPanel1;
         private System.Windows.Forms.TableLayoutPanel tableLayoutPanel1;
         private System.Windows.Forms.TextBox textBox1;

OpenNest/Forms/OptionsForm.cs

@@ -67,7 +67,6 @@ namespace OpenNest.Forms
             textBox1.Text = Settings.Default.NestTemplatePath;
             checkBox1.Checked = Settings.Default.CreateNewNestOnOpen;
             numericUpDown1.Value = (decimal)Settings.Default.AutoSizePlateFactor;
-            numericUpDown2.Value = (decimal)Settings.Default.ImportSplinePrecision;
 
             var disabledNames = ParseDisabledStrategies(Settings.Default.DisabledStrategies);
             foreach (DataGridViewRow row in strategyGrid.Rows)
@@ -79,7 +78,6 @@ namespace OpenNest.Forms
             Settings.Default.NestTemplatePath = textBox1.Text;
             Settings.Default.CreateNewNestOnOpen = checkBox1.Checked;
             Settings.Default.AutoSizePlateFactor = (double)numericUpDown1.Value;
-            Settings.Default.ImportSplinePrecision = (int)numericUpDown2.Value;
 
             var disabledNames = new List<string>();
             foreach (DataGridViewRow row in strategyGrid.Rows)

OpenNest/Properties/Settings.Designer.cs

@@ -118,19 +118,7 @@ namespace OpenNest.Properties {
                 this["NestNumber"] = value;
             }
         }
-        
-        [global::System.Configuration.UserScopedSettingAttribute()]
-        [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
-        [global::System.Configuration.DefaultSettingValueAttribute("200")]
-        public int ImportSplinePrecision {
-            get {
-                return ((int)(this["ImportSplinePrecision"]));
-            }
-            set {
-                this["ImportSplinePrecision"] = value;
-            }
-        }
-        
+
         [global::System.Configuration.UserScopedSettingAttribute()]
         [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
         [global::System.Configuration.DefaultSettingValueAttribute("Inches")]

OpenNest/Properties/Settings.settings

@@ -26,9 +26,6 @@
     <Setting Name="NestNumber" Type="System.Int32" Scope="User">
       <Value Profile="(Default)">1</Value>
     </Setting>
-    <Setting Name="ImportSplinePrecision" Type="System.Int32" Scope="User">
-      <Value Profile="(Default)">200</Value>
-    </Setting>
     <Setting Name="DefaultUnit" Type="OpenNest.Units" Scope="User">
       <Value Profile="(Default)">Inches</Value>
     </Setting>

OpenNest/app.config

@@ -32,9 +32,6 @@
       <setting name="NestNumber" serializeAs="String">
         <value>1</value>
       </setting>
-      <setting name="ImportSplinePrecision" serializeAs="String">
-        <value>200</value>
-      </setting>
       <setting name="DefaultUnit" serializeAs="String">
         <value>Inches</value>
       </setting>