feat(ui): render DXF text annotations in CAD converter preview

Extract MText and TextEntity from the CadDocument during DXF import
and render them in the EntityView. Handles text alignment (left/center/
right via InsertPoint vs AlignmentPoint) and replaces AutoCAD control
codes (%%p → ±, %%d → °, %%c → ⌀). MText formatting codes are
stripped before display.

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

OpenNest.Console/Program.cs

@@ -41,7 +41,6 @@ static class NestConsole
             }
         }
 
-        using var log = SetUpLog(options);
         var nest = LoadOrCreateNest(options);
 
         if (nest == null)
@@ -68,10 +67,6 @@ static class NestConsole
 
         var overlapCount = CheckOverlaps(plate, options);
 
-        // Flush and close the log before printing results.
-        Trace.Flush();
-        log?.Dispose();
-
         PrintResults(success, plate, elapsed);
         Save(nest, options);
         PostProcess(nest, options);
@@ -112,9 +107,6 @@ static class NestConsole
                 case "--no-save":
                     o.NoSave = true;
                     break;
-                case "--no-log":
-                    o.NoLog = true;
-                    break;
                 case "--keep-parts":
                     o.KeepParts = true;
                     break;
@@ -153,28 +145,14 @@ static class NestConsole
         return o;
     }
 
-    static StreamWriter SetUpLog(Options options)
-    {
-        if (options.NoLog)
-            return null;
-
-        var baseDir = Path.GetDirectoryName(options.InputFiles[0]);
-        var logDir = Path.Combine(baseDir, "test-harness-logs");
-        Directory.CreateDirectory(logDir);
-        var logFile = Path.Combine(logDir, $"debug-{DateTime.Now:yyyyMMdd-HHmmss}.log");
-        var writer = new StreamWriter(logFile) { AutoFlush = true };
-        Trace.Listeners.Add(new TextWriterTraceListener(writer));
-        Console.WriteLine($"Debug log: {logFile}");
-        return writer;
-    }
-
     static Nest LoadOrCreateNest(Options options)
     {
         var nestFile = options.InputFiles.FirstOrDefault(f =>
             f.EndsWith(NestFormat.FileExtension, StringComparison.OrdinalIgnoreCase)
             || f.EndsWith(".zip", StringComparison.OrdinalIgnoreCase));
         var dxfFiles = options.InputFiles.Where(f =>
-            f.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase)).ToList();
+            f.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase) ||
+            f.EndsWith(".dwg", StringComparison.OrdinalIgnoreCase)).ToList();
 
         // If we have a nest file, load it and optionally add DXFs.
         if (nestFile != null)
@@ -210,7 +188,7 @@ static class NestConsole
         // DXF-only mode: create a fresh nest.
         if (dxfFiles.Count == 0)
         {
-            Console.Error.WriteLine("Error: no nest (.nest) or DXF (.dxf) files specified");
+            Console.Error.WriteLine("Error: no nest (.nest) or CAD (.dxf/.dwg) files specified");
             return null;
         }
 
@@ -484,7 +462,7 @@ static class NestConsole
         Console.Error.WriteLine("Usage: OpenNest.Console <input-files...> [options]");
         Console.Error.WriteLine();
         Console.Error.WriteLine("Arguments:");
-        Console.Error.WriteLine("  input-files            One or more .nest nest files or .dxf drawing files");
+        Console.Error.WriteLine("  input-files            One or more .nest nest files or .dxf/.dwg drawing files");
         Console.Error.WriteLine();
         Console.Error.WriteLine("Modes:");
         Console.Error.WriteLine("  <nest.nest>             Load nest and fill (existing behavior)");
@@ -503,7 +481,6 @@ static class NestConsole
         Console.Error.WriteLine("  --keep-parts           Don't clear existing parts before filling");
         Console.Error.WriteLine("  --check-overlaps       Run overlap detection after fill (exit code 1 if found)");
         Console.Error.WriteLine("  --no-save              Skip saving output file");
-        Console.Error.WriteLine("  --no-log               Skip writing debug log file");
         Console.Error.WriteLine("  --post <name>          Run a post processor after nesting");
         Console.Error.WriteLine("  --post-output <path>   Output file for post processor (default: <input>.cnc)");
         Console.Error.WriteLine("  --posts-dir <path>     Directory containing post processor DLLs (default: Posts/)");
@@ -522,7 +499,6 @@ static class NestConsole
         public Size? PlateSize;
         public bool CheckOverlaps;
         public bool NoSave;
-        public bool NoLog;
         public bool KeepParts;
         public bool AutoNest;
         public string TemplateFile;

OpenNest.Core/CNC/CuttingStrategy/ContourCuttingStrategy.cs

@@ -305,9 +305,6 @@ namespace OpenNest.CNC.CuttingStrategy
                 subPgm.Codes.AddRange(leadIn.Generate(relativePoint, normal, winding));
                 var reindexed = relativeShape.ReindexAt(relativePoint, relativeCircle);
 
-                if (Parameters.TabsEnabled && Parameters.TabConfig != null)
-                    reindexed = TrimShapeForTab(reindexed, relativePoint, Parameters.TabConfig.Size);
-
                 subPgm.Codes.AddRange(ConvertShapeToMoves(reindexed, relativePoint));
                 subPgm.Codes.AddRange(leadOut.Generate(relativePoint, normal, winding));
                 subPgm.Mode = Mode.Incremental;
@@ -331,7 +328,7 @@ namespace OpenNest.CNC.CuttingStrategy
 
             var reindexedShape = shape.ReindexAt(point, entity);
 
-            if (Parameters.TabsEnabled && Parameters.TabConfig != null)
+            if (Parameters.TabsEnabled && Parameters.TabConfig != null && contourType == ContourType.External)
                 reindexedShape = TrimShapeForTab(reindexedShape, point, Parameters.TabConfig.Size);
 
             program.Codes.AddRange(ConvertShapeToMoves(reindexedShape, point));

OpenNest.Core/CNC/Program.cs

@@ -128,6 +128,12 @@ namespace OpenNest.CNC
             {
                 var code = Codes[i];
 
+                if (code is SubProgramCall subpgm)
+                {
+                    subpgm.Offset = new Geometry.Vector(
+                        subpgm.Offset.X + x, subpgm.Offset.Y + y);
+                }
+
                 if (code is Motion == false)
                     continue;
 
@@ -150,6 +156,12 @@ namespace OpenNest.CNC
             {
                 var code = Codes[i];
 
+                if (code is SubProgramCall subpgm)
+                {
+                    subpgm.Offset = new Geometry.Vector(
+                        subpgm.Offset.X + voffset.X, subpgm.Offset.Y + voffset.Y);
+                }
+
                 if (code is Motion == false)
                     continue;
 

OpenNest.Core/CNC/RapidEnumerator.cs

@@ -0,0 +1,80 @@
+using OpenNest.Geometry;
+using System.Collections.Generic;
+
+namespace OpenNest.CNC
+{
+    public static class RapidEnumerator
+    {
+        public readonly record struct Segment(Vector From, Vector To);
+
+        public static List<Segment> Enumerate(Program pgm, Vector basePos, Vector startPos)
+        {
+            var results = new List<Segment>();
+
+            // Draw the rapid from the previous tool position to the program's first
+            // pierce point. This also primes pos so the interior walk interprets
+            // Incremental deltas from the correct absolute location (basePos), which
+            // matters for raw pre-lead-in programs that are emitted Incremental.
+            var firstPierce = FirstPiercePoint(pgm, basePos);
+            results.Add(new Segment(startPos, firstPierce));
+
+            var pos = firstPierce;
+            Walk(pgm, basePos, ref pos, skipFirst: true, results);
+            return results;
+        }
+
+        private static Vector FirstPiercePoint(Program pgm, Vector basePos)
+        {
+            for (var i = 0; i < pgm.Length; i++)
+            {
+                if (pgm[i] is SubProgramCall call && call.Program != null)
+                    return FirstPiercePoint(call.Program, basePos + call.Offset);
+
+                if (pgm[i] is Motion motion)
+                    return motion.EndPoint + basePos;
+            }
+            return basePos;
+        }
+
+        private static void Walk(Program pgm, Vector basePos, ref Vector pos, bool skipFirst, List<Segment> results)
+        {
+            var skipped = !skipFirst;
+
+            for (var i = 0; i < pgm.Length; ++i)
+            {
+                var code = pgm[i];
+
+                if (code is SubProgramCall { Program: { } program } call)
+                {
+                    var holeBase = basePos + call.Offset;
+                    var firstPierce = FirstPiercePoint(program, holeBase);
+
+                    if (!skipped)
+                        skipped = true;
+                    else
+                        results.Add(new Segment(pos, firstPierce));
+
+                    var subPos = holeBase;
+                    Walk(program, holeBase, ref subPos, skipFirst: true, results);
+                    pos = subPos;
+                }
+                else if (code is Motion motion)
+                {
+                    var endpt = pgm.Mode == Mode.Incremental
+                        ? motion.EndPoint + pos
+                        : motion.EndPoint + basePos;
+
+                    if (code.Type == CodeType.RapidMove)
+                    {
+                        if (!skipped)
+                            skipped = true;
+                        else
+                            results.Add(new Segment(pos, endpt));
+                    }
+
+                    pos = endpt;
+                }
+            }
+        }
+    }
+}

OpenNest.Core/CanonicalAngle.cs

@@ -0,0 +1,78 @@
+using OpenNest.Converters;
+using OpenNest.Geometry;
+using System.Linq;
+
+namespace OpenNest
+{
+    /// <summary>
+    /// Computes the rotation that maps a drawing to its canonical (MBR-axis-aligned) frame.
+    /// Lives in OpenNest.Core so Drawing.Program setter can invoke it directly without
+    /// a circular dependency on OpenNest.Engine.
+    /// </summary>
+    public static class CanonicalAngle
+    {
+        /// <summary>Angles with |v| below this (radians) are snapped to 0.</summary>
+        public const double SnapToZero = 0.001;
+
+        /// <summary>
+        /// Derives the canonical angle from a pre-computed MBR. Used both by Compute (which
+        /// computes the MBR itself) and by PartClassifier (which already has one). Single formula
+        /// across both callers.
+        /// </summary>
+        public static double FromMbr(BoundingRectangleResult mbr)
+        {
+            if (mbr.Area <= OpenNest.Math.Tolerance.Epsilon)
+                return 0.0;
+
+            // The MBR edge angle can represent any of four equivalent orientations
+            // (edge-i, edge-i + π/2, edge-i + π, edge-i - π/2) depending on which hull
+            // edge the algorithm happened to pick. Normalize -mbr.Angle to the
+            // representative in [-π/4, π/4] so snap-to-zero works for inputs near
+            // ANY of the equivalent orientations.
+            var angle = -mbr.Angle;
+            const double halfPi = System.Math.PI / 2.0;
+            angle -= halfPi * System.Math.Round(angle / halfPi);
+
+            if (System.Math.Abs(angle) < SnapToZero)
+                return 0.0;
+
+            return angle;
+        }
+
+        public static double Compute(Drawing drawing)
+        {
+            if (drawing?.Program == null)
+                return 0.0;
+
+            var entities = ConvertProgram.ToGeometry(drawing.Program)
+                .Where(e => e.Layer != SpecialLayers.Rapid);
+
+            var shapes = ShapeBuilder.GetShapes(entities);
+            if (shapes.Count == 0)
+                return 0.0;
+
+            var perimeter = shapes[0];
+            var perimeterArea = perimeter.Area();
+            for (var i = 1; i < shapes.Count; i++)
+            {
+                var area = shapes[i].Area();
+                if (area > perimeterArea)
+                {
+                    perimeter = shapes[i];
+                    perimeterArea = area;
+                }
+            }
+
+            var polygon = perimeter.ToPolygonWithTolerance(0.1);
+            if (polygon == null || polygon.Vertices.Count < 3)
+                return 0.0;
+
+            var hull = ConvexHull.Compute(polygon.Vertices);
+            if (hull.Vertices.Count < 3)
+                return 0.0;
+
+            var mbr = RotatingCalipers.MinimumBoundingRectangle(hull);
+            return FromMbr(mbr);
+        }
+    }
+}

OpenNest.Core/Converters/ConvertGeometry.cs

@@ -1,5 +1,6 @@
 using OpenNest.CNC;
 using OpenNest.Geometry;
+using OpenNest.Math;
 using System.Collections.Generic;
 
 namespace OpenNest.Converters
@@ -81,12 +82,21 @@ namespace OpenNest.Converters
             var startpt = arc.StartPoint();
             var endpt = arc.EndPoint();
 
-            if (startpt != lastpt)
+            if (startpt.DistanceTo(lastpt) > Tolerance.ChainTolerance)
                 pgm.MoveTo(startpt);
 
             lastpt = endpt;
 
-            pgm.ArcTo(endpt, arc.Center, arc.IsReversed ? RotationType.CW : RotationType.CCW);
+            var sweep = System.Math.Abs(arc.SweepAngle());
+            if (sweep < Tolerance.Epsilon || sweep.IsEqualTo(Angle.TwoPI))
+            {
+                pgm.LineTo(endpt);
+            }
+            else
+            {
+                pgm.ArcTo(endpt, arc.Center, arc.IsReversed ? RotationType.CW : RotationType.CCW);
+            }
+
             return lastpt;
         }
 
@@ -94,7 +104,7 @@ namespace OpenNest.Converters
         {
             var startpt = new Vector(circle.Center.X + circle.Radius, circle.Center.Y);
 
-            if (startpt != lastpt)
+            if (startpt.DistanceTo(lastpt) > Tolerance.ChainTolerance)
                 pgm.MoveTo(startpt);
 
             pgm.ArcTo(startpt, circle.Center, circle.Rotation);
@@ -105,7 +115,7 @@ namespace OpenNest.Converters
 
         private static Vector AddLine(Program pgm, Vector lastpt, Line line)
         {
-            if (line.StartPoint != lastpt)
+            if (line.StartPoint.DistanceTo(lastpt) > Tolerance.ChainTolerance)
                 pgm.MoveTo(line.StartPoint);
 
             var move = new LinearMove(line.EndPoint);

OpenNest.Core/Drawing.cs

@@ -16,7 +16,7 @@ namespace OpenNest
         private static int nextColorIndex;
         private Program program;
 
-        public static readonly Color[] PartColors = new Color[]
+        public static Color[] PartColors = new Color[]
         {
             Color.FromArgb(205, 92, 92),    // Indian Red
             Color.FromArgb(148, 103, 189),  // Medium Purple
@@ -54,9 +54,9 @@ namespace OpenNest
             Id = Interlocked.Increment(ref nextId);
             Name = name;
             Material = new Material();
-            Program = pgm;
             Constraints = new NestConstraints();
             Source = new SourceInfo();
+            Program = pgm;
         }
 
         public int Id { get; }
@@ -78,9 +78,29 @@ namespace OpenNest
             {
                 program = value;
                 UpdateArea();
+                RecomputeCanonicalAngle();
             }
         }
 
+        /// <summary>
+        /// Recomputes and stores the canonical angle from the current Program.
+        /// Callers that mutate Program in place (rather than reassigning it) must invoke this explicitly.
+        /// Cut-off drawings are left with Angle=0.
+        /// </summary>
+        public void RecomputeCanonicalAngle()
+        {
+            if (Source == null)
+                Source = new SourceInfo();
+
+            if (program == null || IsCutOff)
+            {
+                Source.Angle = 0.0;
+                return;
+            }
+
+            Source.Angle = CanonicalAngle.Compute(this);
+        }
+
         public Color Color { get; set; }
 
         public bool IsCutOff { get; set; }
@@ -163,5 +183,15 @@ namespace OpenNest
         /// Offset distances to the original location.
         /// </summary>
         public Vector Offset { get; set; }
+
+        /// <summary>
+        /// Rotation (radians) that maps the source program geometry to its canonical
+        /// (MBR-axis-aligned) frame. Populated automatically by the <see cref="Drawing.Program"/>
+        /// setter via <see cref="CanonicalAngle.Compute"/>. A value of 0 means the drawing is
+        /// already canonical or <see cref="Drawing.IsCutOff"/> is true. Callers that mutate
+        /// <see cref="Drawing.Program"/> in place must invoke
+        /// <see cref="Drawing.RecomputeCanonicalAngle"/> to refresh.
+        /// </summary>
+        public double Angle { get; set; }
     }
 }

OpenNest.Core/Geometry/Arc.cs

@@ -404,26 +404,29 @@ namespace OpenNest.Geometry
                 maxY = startpt.Y;
             }
 
-            var angle1 = StartAngle;
-            var angle2 = EndAngle;
+            var sweep = SweepAngle();
+            if (sweep > Tolerance.Epsilon)
+            {
+                var angle1 = StartAngle;
+                var angle2 = EndAngle;
 
-            // switch the angle to counter clockwise.
-            if (IsReversed)
-                Generic.Swap(ref angle1, ref angle2);
+                if (IsReversed)
+                    Generic.Swap(ref angle1, ref angle2);
 
-            if (Angle.IsBetweenRad(Angle.HalfPI, angle1, angle2))
-                maxY = Center.Y + Radius;
+                if (Angle.IsBetweenRad(Angle.HalfPI, angle1, angle2))
+                    maxY = Center.Y + Radius;
 
-            if (Angle.IsBetweenRad(System.Math.PI, angle1, angle2))
-                minX = Center.X - Radius;
+                if (Angle.IsBetweenRad(System.Math.PI, angle1, angle2))
+                    minX = Center.X - Radius;
 
-            const double oneHalfPI = System.Math.PI * 1.5;
+                const double oneHalfPI = System.Math.PI * 1.5;
 
-            if (Angle.IsBetweenRad(oneHalfPI, angle1, angle2))
-                minY = Center.Y - Radius;
+                if (Angle.IsBetweenRad(oneHalfPI, angle1, angle2))
+                    minY = Center.Y - Radius;
 
-            if (Angle.IsBetweenRad(Angle.TwoPI, angle1, angle2))
-                maxX = Center.X + Radius;
+                if (Angle.IsBetweenRad(Angle.TwoPI, angle1, angle2))
+                    maxX = Center.X + Radius;
+            }
 
             boundingBox.X = minX;
             boundingBox.Y = minY;

OpenNest.Core/Geometry/Box.cs

@@ -1,8 +1,9 @@
-using OpenNest.Math;
+using System;
+using OpenNest.Math;
 
 namespace OpenNest.Geometry
 {
-    public class Box
+    public class Box : IComparable<Box>
     {
         public static readonly Box Empty = new Box();
 
@@ -214,5 +215,19 @@ namespace OpenNest.Geometry
         {
             return string.Format("[Box: X={0}, Y={1}, Width={2}, Length={3}]", X, Y, Width, Length);
         }
+
+        public int CompareTo(Box other)
+        {
+            var cmp = Width.CompareTo(other.Width);
+            return cmp != 0 ? cmp : Length.CompareTo(other.Length);
+        }
+
+        public static bool operator >(Box a, Box b) => a.CompareTo(b) > 0;
+
+        public static bool operator <(Box a, Box b) => a.CompareTo(b) < 0;
+
+        public static bool operator >=(Box a, Box b) => a.CompareTo(b) >= 0;
+
+        public static bool operator <=(Box a, Box b) => a.CompareTo(b) <= 0;
     }
 }

OpenNest.Core/Geometry/EllipseConverter.cs

@@ -173,7 +173,11 @@ namespace OpenNest.Geometry
 
             if (maxDev <= tolerance)
             {
-                results.Add(CreateArc(arcCenter, radius, center, semiMajor, semiMinor, rotation, t0, t1));
+                var arc = CreateArc(arcCenter, radius, center, semiMajor, semiMinor, rotation, t0, t1);
+                if (arc.SweepAngle() < Tolerance.Epsilon)
+                    results.Add(new Line(p0, p1));
+                else
+                    results.Add(arc);
             }
             else
             {

OpenNest.Core/Geometry/ShapeBuilder.cs

@@ -1,12 +1,13 @@
 using OpenNest.Math;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 
 namespace OpenNest.Geometry
 {
     public static class ShapeBuilder
     {
-        public static List<Shape> GetShapes(IEnumerable<Entity> entities)
+        public static List<Shape> GetShapes(IEnumerable<Entity> entities, double? weldTolerance = null)
         {
             var lines = new List<Line>();
             var arcs = new List<Arc>();
@@ -57,6 +58,9 @@ namespace OpenNest.Geometry
             entityList.AddRange(lines);
             entityList.AddRange(arcs);
 
+            if (weldTolerance.HasValue)
+                WeldEndpoints(entityList, weldTolerance.Value);
+
             while (entityList.Count > 0)
             {
                 var next = entityList[0];
@@ -107,6 +111,93 @@ namespace OpenNest.Geometry
             return shapes;
         }
 
+        public static void WeldEndpoints(List<Entity> entities, double tolerance)
+        {
+            var endpointGroups = new List<List<(Entity entity, bool isStart, Vector point)>>();
+
+            foreach (var entity in entities)
+            {
+                var (start, end) = GetEndpoints(entity);
+                if (!start.IsValid() || !end.IsValid())
+                    continue;
+
+                AddToGroup(endpointGroups, entity, true, start, tolerance);
+                AddToGroup(endpointGroups, entity, false, end, tolerance);
+            }
+
+            foreach (var group in endpointGroups)
+            {
+                if (group.Count <= 1)
+                    continue;
+
+                var avgX = group.Average(g => g.point.X);
+                var avgY = group.Average(g => g.point.Y);
+                var weldedPoint = new Vector(avgX, avgY);
+
+                foreach (var (entity, isStart, _) in group)
+                    ApplyWeld(entity, isStart, weldedPoint);
+            }
+        }
+
+        private static void AddToGroup(
+            List<List<(Entity entity, bool isStart, Vector point)>> groups,
+            Entity entity, bool isStart, Vector point, double tolerance)
+        {
+            foreach (var group in groups)
+            {
+                if (group[0].point.DistanceTo(point) <= tolerance)
+                {
+                    group.Add((entity, isStart, point));
+                    return;
+                }
+            }
+
+            groups.Add(new List<(Entity, bool, Vector)> { (entity, isStart, point) });
+        }
+
+        private static (Vector start, Vector end) GetEndpoints(Entity entity)
+        {
+            switch (entity.Type)
+            {
+                case EntityType.Arc:
+                    var arc = (Arc)entity;
+                    return (arc.StartPoint(), arc.EndPoint());
+
+                case EntityType.Line:
+                    var line = (Line)entity;
+                    return (line.StartPoint, line.EndPoint);
+
+                default:
+                    return (Vector.Invalid, Vector.Invalid);
+            }
+        }
+
+        private static void ApplyWeld(Entity entity, bool isStart, Vector weldedPoint)
+        {
+            switch (entity.Type)
+            {
+                case EntityType.Line:
+                    var line = (Line)entity;
+                    if (isStart)
+                        line.StartPoint = weldedPoint;
+                    else
+                        line.EndPoint = weldedPoint;
+                    break;
+
+                case EntityType.Arc:
+                    var arc = (Arc)entity;
+                    var deltaX = weldedPoint.X - arc.Center.X;
+                    var deltaY = weldedPoint.Y - arc.Center.Y;
+                    var angle = System.Math.Atan2(deltaY, deltaX);
+
+                    if (isStart)
+                        arc.StartAngle = angle;
+                    else
+                        arc.EndAngle = angle;
+                    break;
+            }
+        }
+
         internal static Entity GetConnected(Vector pt, IEnumerable<Entity> geometry)
         {
             var tol = Tolerance.ChainTolerance;

OpenNest.Core/IMaterialProvidingPostProcessor.cs

@@ -0,0 +1,9 @@
+using System.Collections.Generic;
+
+namespace OpenNest
+{
+    public interface IMaterialProvidingPostProcessor
+    {
+        IEnumerable<string> GetMaterialNames();
+    }
+}

OpenNest.Core/IPostProcessorNestAware.cs

@@ -0,0 +1,7 @@
+namespace OpenNest
+{
+    public interface IPostProcessorNestAware
+    {
+        void PrepareForNest(Nest nest);
+    }
+}

OpenNest.Core/Math/Fraction.cs

@@ -3,7 +3,7 @@ using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
 
-namespace OpenNest.IO.Bom
+namespace OpenNest.Math
 {
     public static class Fraction
     {

OpenNest.Core/Shapes/CircleShape.cs

@@ -7,6 +7,8 @@ namespace OpenNest.Shapes
     {
         public double Diameter { get; set; }
 
+        public override string GenerateName() => $"Circle {Dim(Diameter)} Dia";
+
         public override void SetPreviewDefaults()
         {
             Diameter = 8;

OpenNest.Core/Shapes/IsoscelesTriangleShape.cs

@@ -8,6 +8,8 @@ namespace OpenNest.Shapes
         public double Base { get; set; }
         public double Height { get; set; }
 
+        public override string GenerateName() => $"Isosceles Triangle {Dim(Base)}x{Dim(Height)}";
+
         public override void SetPreviewDefaults()
         {
             Base = 8;

OpenNest.Core/Shapes/LShape.cs

@@ -10,6 +10,8 @@ namespace OpenNest.Shapes
         public double LegWidth { get; set; }
         public double LegHeight { get; set; }
 
+        public override string GenerateName() => $"L {Dim(Width)}x{Dim(Height)}";
+
         public override void SetPreviewDefaults()
         {
             Width = 8;

OpenNest.Core/Shapes/NgonShape.cs

@@ -3,33 +3,40 @@ using System.Collections.Generic;
 
 namespace OpenNest.Shapes
 {
-    public class OctagonShape : ShapeDefinition
+    public class NgonShape : ShapeDefinition
     {
+        public int Sides { get; set; }
         public double Width { get; set; }
 
+        public override string GenerateName() => $"{Sides}-Sided Polygon {Dim(Width)}";
+
         public override void SetPreviewDefaults()
         {
+            Sides = 8;
             Width = 8;
         }
 
         public override Drawing GetDrawing()
         {
+            var n = Sides < 3 ? 3 : Sides;
             var center = Width / 2.0;
-            var circumRadius = Width / (2.0 * System.Math.Cos(System.Math.PI / 8.0));
+            var circumRadius = Width / (2.0 * System.Math.Cos(System.Math.PI / n));
+            var step = 2.0 * System.Math.PI / n;
+            var start = System.Math.PI / n;
 
-            var vertices = new Vector[8];
-            for (var i = 0; i < 8; i++)
+            var vertices = new Vector[n];
+            for (var i = 0; i < n; i++)
             {
-                var angle = System.Math.PI / 8.0 + i * System.Math.PI / 4.0;
+                var angle = start + i * step;
                 vertices[i] = new Vector(
                     center + circumRadius * System.Math.Cos(angle),
                     center + circumRadius * System.Math.Sin(angle));
             }
 
             var entities = new List<Entity>();
-            for (var i = 0; i < 8; i++)
+            for (var i = 0; i < n; i++)
             {
-                var next = (i + 1) % 8;
+                var next = (i + 1) % n;
                 entities.Add(new Line(vertices[i], vertices[next]));
             }
 

OpenNest.Core/Shapes/PipeFlangeShape.cs

@@ -13,6 +13,14 @@ namespace OpenNest.Shapes
         public double PipeClearance { get; set; }
         public bool Blind { get; set; }
 
+        public override string GenerateName()
+        {
+            var name = $"Pipe Flange {Dim(OD)} OD";
+            if (!string.IsNullOrEmpty(PipeSize))
+                name += $" {PipeSize} Pipe";
+            return name;
+        }
+
         public override void SetPreviewDefaults()
         {
             OD = 7.5;

OpenNest.Core/Shapes/RectangleShape.cs

@@ -8,6 +8,8 @@ namespace OpenNest.Shapes
         public double Length { get; set; }
         public double Width { get; set; }
 
+        public override string GenerateName() => $"Rectangle {Dim(Length)}x{Dim(Width)}";
+
         public override void SetPreviewDefaults()
         {
             Length = 12;

OpenNest.Core/Shapes/RightTriangleShape.cs

@@ -8,6 +8,8 @@ namespace OpenNest.Shapes
         public double Width { get; set; }
         public double Height { get; set; }
 
+        public override string GenerateName() => $"Right Triangle {Dim(Width)}x{Dim(Height)}";
+
         public override void SetPreviewDefaults()
         {
             Width = 8;

OpenNest.Core/Shapes/RingShape.cs

@@ -8,6 +8,8 @@ namespace OpenNest.Shapes
         public double OuterDiameter { get; set; }
         public double InnerDiameter { get; set; }
 
+        public override string GenerateName() => $"Ring {Dim(OuterDiameter)}x{Dim(InnerDiameter)}";
+
         public override void SetPreviewDefaults()
         {
             OuterDiameter = 10;

OpenNest.Core/Shapes/RoundedRectangleShape.cs

@@ -10,6 +10,8 @@ namespace OpenNest.Shapes
         public double Width { get; set; }
         public double Radius { get; set; }
 
+        public override string GenerateName() => $"Rounded Rectangle {Dim(Length)}x{Dim(Width)} R{Dim(Radius)}";
+
         public override void SetPreviewDefaults()
         {
             Length = 12;

OpenNest.Core/Shapes/ShapeDefinition.cs

@@ -26,6 +26,14 @@ namespace OpenNest.Shapes
 
         public abstract Drawing GetDrawing();
 
+        public virtual string GenerateName()
+        {
+            var typeName = GetType().Name;
+            return typeName.EndsWith("Shape")
+                ? typeName.Substring(0, typeName.Length - 5)
+                : typeName;
+        }
+
         public virtual void SetPreviewDefaults() { }
 
         public static List<T> LoadFromJson<T>(string path) where T : ShapeDefinition
@@ -34,6 +42,8 @@ namespace OpenNest.Shapes
             return JsonSerializer.Deserialize<List<T>>(json, JsonOptions);
         }
 
+        protected static string Dim(double value) => value.ToString("0.###");
+
         protected Drawing CreateDrawing(List<Entity> entities)
         {
             var pgm = ConvertGeometry.ToProgram(entities);

OpenNest.Core/Shapes/TShape.cs

@@ -10,6 +10,8 @@ namespace OpenNest.Shapes
         public double StemWidth { get; set; }
         public double BarHeight { get; set; }
 
+        public override string GenerateName() => $"T {Dim(Width)}x{Dim(Height)}";
+
         public override void SetPreviewDefaults()
         {
             Width = 10;

OpenNest.Core/Shapes/TrapezoidShape.cs

@@ -9,6 +9,8 @@ namespace OpenNest.Shapes
         public double BottomWidth { get; set; }
         public double Height { get; set; }
 
+        public override string GenerateName() => $"Trapezoid {Dim(TopWidth)}x{Dim(BottomWidth)}x{Dim(Height)}";
+
         public override void SetPreviewDefaults()
         {
             TopWidth = 6;

OpenNest.Engine/BestFit/BestFitCache.cs

@@ -24,6 +24,9 @@ namespace OpenNest.Engine.BestFit
             if (_cache.TryGetValue(key, out var cached))
                 return cached;
 
+            // Operate on the canonical frame so cached pair positions are orientation-invariant.
+            var canonical = CanonicalFrame.AsCanonicalCopy(drawing);
+
             IPairEvaluator evaluator = null;
             ISlideComputer slideComputer = null;
 
@@ -31,7 +34,7 @@ namespace OpenNest.Engine.BestFit
             {
                 if (CreateEvaluator != null)
                 {
-                    try { evaluator = CreateEvaluator(drawing, spacing); }
+                    try { evaluator = CreateEvaluator(canonical, spacing); }
                     catch { /* fall back to default evaluator */ }
                 }
 
@@ -42,7 +45,7 @@ namespace OpenNest.Engine.BestFit
                 }
 
                 var finder = new BestFitFinder(plateWidth, plateHeight, evaluator, slideComputer);
-                var results = finder.FindBestFits(drawing, spacing, StepSize);
+                var results = finder.FindBestFits(canonical, spacing, StepSize);
 
                 _cache.TryAdd(key, results);
                 return results;
@@ -86,9 +89,12 @@ namespace OpenNest.Engine.BestFit
 
             try
             {
+                // Operate on the canonical frame so cached pair positions are orientation-invariant.
+                var canonical = CanonicalFrame.AsCanonicalCopy(drawing);
+
                 if (CreateEvaluator != null)
                 {
-                    try { evaluator = CreateEvaluator(drawing, spacing); }
+                    try { evaluator = CreateEvaluator(canonical, spacing); }
                     catch { /* fall back to default evaluator */ }
                 }
 
@@ -100,7 +106,7 @@ namespace OpenNest.Engine.BestFit
 
                 // Compute candidates and evaluate once with the largest plate.
                 var finder = new BestFitFinder(maxWidth, maxHeight, evaluator, slideComputer);
-                var baseResults = finder.FindBestFits(drawing, spacing, StepSize);
+                var baseResults = finder.FindBestFits(canonical, spacing, StepSize);
 
                 // Cache a filtered copy for each plate size.
                 foreach (var size in needed)

OpenNest.Engine/BestFit/NfpSlideStrategy.cs

@@ -1,18 +1,10 @@
 using OpenNest.Geometry;
-using OpenNest.Math;
 using System.Collections.Generic;
-using System.IO;
 
 namespace OpenNest.Engine.BestFit
 {
     public class NfpSlideStrategy : IBestFitStrategy
     {
-        private static readonly string LogPath = Path.Combine(
-            System.Environment.GetFolderPath(System.Environment.SpecialFolder.Desktop),
-            "nfp-slide-debug.log");
-
-        private static readonly object LogLock = new object();
-
         private readonly double _part2Rotation;
         private readonly Polygon _stationaryPerimeter;
         private readonly Polygon _stationaryHull;
@@ -46,12 +38,6 @@ namespace OpenNest.Engine.BestFit
 
             var hull = ConvexHull.Compute(result.Polygon.Vertices);
 
-            Log($"=== Create: drawing={drawing.Name}, rotation={Angle.ToDegrees(part2Rotation):F1}deg ===");
-            Log($"  Perimeter: {result.Polygon.Vertices.Count} verts, bounds={FormatBounds(result.Polygon)}");
-            Log($"  Hull: {hull.Vertices.Count} verts, bounds={FormatBounds(hull)}");
-            Log($"  Correction: ({result.Correction.X:F4}, {result.Correction.Y:F4})");
-            Log($"  ProgramBBox: {drawing.Program.BoundingBox()}");
-
             return new NfpSlideStrategy(part2Rotation, type, description,
                 result.Polygon, hull, result.Correction);
         }
@@ -63,40 +49,17 @@ namespace OpenNest.Engine.BestFit
             if (stepSize <= 0)
                 return candidates;
 
-            Log($"--- GenerateCandidates: drawing={drawing.Name}, part2Rot={Angle.ToDegrees(_part2Rotation):F1}deg, spacing={spacing}, stepSize={stepSize} ---");
-
-            // Orbiting polygon: same shape rotated to Part2's angle.
             var orbitingPerimeter = PolygonHelper.RotatePolygon(_stationaryPerimeter, _part2Rotation, reNormalize: true);
             var orbitingPoly = ConvexHull.Compute(orbitingPerimeter.Vertices);
 
-            Log($"  Stationary hull: {_stationaryHull.Vertices.Count} verts, bounds={FormatBounds(_stationaryHull)}");
-            Log($"  Orbiting perimeter (rotated): {orbitingPerimeter.Vertices.Count} verts, bounds={FormatBounds(orbitingPerimeter)}");
-            Log($"  Orbiting hull: {orbitingPoly.Vertices.Count} verts, bounds={FormatBounds(orbitingPoly)}");
-
             var nfp = NoFitPolygon.ComputeConvex(_stationaryHull, orbitingPoly);
 
             if (nfp == null || nfp.Vertices.Count < 3)
-            {
-                Log($"  NFP failed or degenerate (verts={nfp?.Vertices.Count ?? 0})");
                 return candidates;
-            }
 
             var verts = nfp.Vertices;
             var vertCount = nfp.IsClosed() ? verts.Count - 1 : verts.Count;
 
-            Log($"  NFP: {verts.Count} verts (closed={nfp.IsClosed()}, walking {vertCount}), bounds={FormatBounds(nfp)}");
-            Log($"  Correction: ({_correction.X:F4}, {_correction.Y:F4})");
-
-            // Log NFP vertices
-            for (var v = 0; v < vertCount; v++)
-                Log($"    NFP vert[{v}]: ({verts[v].X:F4}, {verts[v].Y:F4}) -> corrected: ({verts[v].X - _correction.X:F4}, {verts[v].Y - _correction.Y:F4})");
-
-            // Compare with what RotationSlideStrategy would produce
-            var part1 = Part.CreateAtOrigin(drawing);
-            var part2 = Part.CreateAtOrigin(drawing, _part2Rotation);
-            Log($"  Part1 (rot=0): loc=({part1.Location.X:F4}, {part1.Location.Y:F4}), bbox={part1.BoundingBox}");
-            Log($"  Part2 (rot={Angle.ToDegrees(_part2Rotation):F1}): loc=({part2.Location.X:F4}, {part2.Location.Y:F4}), bbox={part2.BoundingBox}");
-
             var testNumber = 0;
 
             for (var i = 0; i < vertCount; i++)
@@ -125,20 +88,6 @@ namespace OpenNest.Engine.BestFit
                 }
             }
 
-            // Log overlap check for vertex candidates (first few)
-            var checkCount = System.Math.Min(vertCount, 8);
-            for (var c = 0; c < checkCount; c++)
-            {
-                var cand = candidates[c];
-                var p2 = Part.CreateAtOrigin(drawing, cand.Part2Rotation);
-                p2.Location = cand.Part2Offset;
-                var overlaps = part1.Intersects(p2, out _);
-                Log($"  Candidate[{c}]: offset=({cand.Part2Offset.X:F4}, {cand.Part2Offset.Y:F4}), overlaps={overlaps}");
-            }
-
-            Log($"  Total candidates: {candidates.Count}");
-            Log("");
-
             return candidates;
         }
 
@@ -160,20 +109,5 @@ namespace OpenNest.Engine.BestFit
                 Spacing = spacing
             };
         }
-
-        private static string FormatBounds(Polygon polygon)
-        {
-            polygon.UpdateBounds();
-            var bb = polygon.BoundingBox;
-            return $"[({bb.Left:F4}, {bb.Bottom:F4})-({bb.Right:F4}, {bb.Top:F4}), {bb.Width:F2}x{bb.Length:F2}]";
-        }
-
-        private static void Log(string message)
-        {
-            lock (LogLock)
-            {
-                File.AppendAllText(LogPath, message + "\n");
-            }
-        }
     }
 }

OpenNest.Engine/CanonicalFrame.cs

@@ -0,0 +1,76 @@
+using OpenNest.CNC;
+using OpenNest.Geometry;
+using OpenNest.Math;
+using System.Collections.Generic;
+
+namespace OpenNest.Engine
+{
+    /// <summary>
+    /// Produces transient canonical (MBR-axis-aligned) copies of drawings for engine consumption
+    /// and un-rotates placed parts back to the drawing's original frame.
+    /// </summary>
+    public static class CanonicalFrame
+    {
+        /// <summary>
+        /// Returns a new Drawing whose Program geometry is rotated to the canonical frame.
+        /// The source drawing is not mutated.
+        /// </summary>
+        public static Drawing AsCanonicalCopy(Drawing drawing)
+        {
+            if (drawing == null)
+                return null;
+
+            var angle = drawing.Source?.Angle ?? 0.0;
+
+            // Clone program (never mutate the source).
+            var pgm = (drawing.Program.Clone() as OpenNest.CNC.Program)
+                      ?? new OpenNest.CNC.Program();
+
+            if (!Tolerance.IsEqualTo(angle, 0))
+                pgm.Rotate(angle, pgm.BoundingBox().Center);
+
+            var copy = new Drawing(drawing.Name ?? string.Empty, pgm)
+            {
+                Color = drawing.Color,
+                Constraints = drawing.Constraints,
+                Material = drawing.Material,
+                Priority = drawing.Priority,
+                Customer = drawing.Customer,
+                IsCutOff = drawing.IsCutOff,
+                Source = new SourceInfo
+                {
+                    Path = drawing.Source?.Path,
+                    Offset = drawing.Source?.Offset ?? new Vector(0, 0),
+                    Angle = 0.0,
+                },
+            };
+            return copy;
+        }
+
+        /// <summary>
+        /// Composes the source drawing's canonical angle onto each placed part so the
+        /// returned list is in the drawing's original (visible) frame.
+        ///
+        /// Derivation: let sourceAngle = S (rotation mapping source -> canonical).
+        /// Canonical part at rotation R shows visible orientation R.
+        /// Source part at rotation R' shows visible orientation R' + (-S), because the
+        /// source geometry is already rotated by -S relative to canonical.
+        /// Setting equal gives R' = R + S, so we ADD sourceAngle to each placed part.
+        ///
+        /// Rotation is performed around the part's Location so its placement position is preserved;
+        /// only the orientation composes.
+        /// </summary>
+        public static List<Part> FromCanonical(List<Part> placed, double sourceAngle)
+        {
+            if (placed == null || placed.Count == 0)
+                return placed;
+            if (Tolerance.IsEqualTo(sourceAngle, 0))
+                return placed;
+
+            foreach (var p in placed)
+                p.Rotate(sourceAngle, p.Location);
+
+            return placed;
+        }
+    }
+}

OpenNest.Engine/DefaultNestEngine.cs

@@ -47,14 +47,29 @@ namespace OpenNest
             PhaseResults.Clear();
             AngleResults.Clear();
 
-            // Fast path: for very small quantities, skip the full strategy pipeline.
-            if (item.Quantity > 0 && item.Quantity <= 2)
+            // Replace the item's Drawing with a canonical copy for the duration of this fill.
+            // All internal methods see canonical geometry; this wrapper un-canonicalizes the final result.
+            var sourceAngle = item.Drawing?.Source?.Angle ?? 0.0;
+            var originalDrawing = item.Drawing;
+            var canonicalItem = new NestItem
             {
-                var fast = TryFillSmallQuantity(item, workArea);
-                if (fast != null && fast.Count >= item.Quantity)
+                Drawing = CanonicalFrame.AsCanonicalCopy(item.Drawing),
+                Quantity = item.Quantity,
+                Priority = item.Priority,
+                RotationStart = item.RotationStart,
+                RotationEnd = item.RotationEnd,
+                StepAngle = item.StepAngle,
+            };
+
+            // Fast path for qty 1-2.
+            if (canonicalItem.Quantity > 0 && canonicalItem.Quantity <= 2)
+            {
+                var fast = TryFillSmallQuantity(canonicalItem, workArea);
+                if (fast != null && fast.Count >= canonicalItem.Quantity)
                 {
-                    Debug.WriteLine($"[Fill] Fast path: placed {fast.Count} parts for qty={item.Quantity}");
+                    Debug.WriteLine($"[Fill] Fast path: placed {fast.Count} parts for qty={canonicalItem.Quantity}");
                     WinnerPhase = NestPhase.Pairs;
+                    fast = RebindAndUnCanonicalize(fast, originalDrawing, sourceAngle);
                     ReportProgress(progress, new ProgressReport
                     {
                         Phase = WinnerPhase,
@@ -68,32 +83,30 @@ namespace OpenNest
                 }
             }
 
-            // For low quantities, shrink the work area in both dimensions to avoid
-            // running expensive strategies against the full plate.
             var effectiveWorkArea = workArea;
-            if (item.Quantity > 0)
+            if (canonicalItem.Quantity > 0)
             {
-                effectiveWorkArea = ShrinkWorkArea(item, workArea, Plate.PartSpacing);
-
+                effectiveWorkArea = ShrinkWorkArea(canonicalItem, workArea, Plate.PartSpacing);
                 if (effectiveWorkArea != workArea)
-                    Debug.WriteLine($"[Fill] Low-qty shrink: {item.Quantity} requested, " +
+                    Debug.WriteLine($"[Fill] Low-qty shrink: {canonicalItem.Quantity} requested, " +
                         $"from {workArea.Width:F1}x{workArea.Length:F1} " +
                         $"to {effectiveWorkArea.Width:F1}x{effectiveWorkArea.Length:F1}");
             }
 
-            var best = RunFillPipeline(item, effectiveWorkArea, progress, token);
+            var best = RunFillPipeline(canonicalItem, effectiveWorkArea, progress, token);
 
-            // Fallback: if the reduced area didn't yield enough, retry with full area.
-            if (item.Quantity > 0 && best.Count < item.Quantity && effectiveWorkArea != workArea)
+            if (canonicalItem.Quantity > 0 && best.Count < canonicalItem.Quantity && effectiveWorkArea != workArea)
             {
-                Debug.WriteLine($"[Fill] Low-qty fallback: got {best.Count}, need {item.Quantity}, retrying full area");
+                Debug.WriteLine($"[Fill] Low-qty fallback: got {best.Count}, need {canonicalItem.Quantity}, retrying full area");
                 PhaseResults.Clear();
                 AngleResults.Clear();
-                best = RunFillPipeline(item, workArea, progress, token);
+                best = RunFillPipeline(canonicalItem, workArea, progress, token);
             }
 
-            if (item.Quantity > 0 && best.Count > item.Quantity)
-                best = ShrinkFiller.TrimToCount(best, item.Quantity, TrimAxis);
+            if (canonicalItem.Quantity > 0 && best.Count > canonicalItem.Quantity)
+                best = ShrinkFiller.TrimToCount(best, canonicalItem.Quantity, TrimAxis);
+
+            best = RebindAndUnCanonicalize(best, originalDrawing, sourceAngle);
 
             ReportProgress(progress, new ProgressReport
             {
@@ -108,6 +121,31 @@ namespace OpenNest
             return best;
         }
 
+        /// <summary>
+        /// Single exit point for canonical -> source frame conversion. Rebinds every Part to the
+        /// original Drawing (so consumers see the user's drawing identity, not the transient canonical copy)
+        /// and composes sourceAngle onto each Part's rotation via CanonicalFrame.FromCanonical.
+        /// </summary>
+        private static List<Part> RebindAndUnCanonicalize(List<Part> parts, Drawing original, double sourceAngle)
+        {
+            if (parts == null || parts.Count == 0)
+                return parts;
+
+            for (var i = 0; i < parts.Count; i++)
+            {
+                var p = parts[i];
+                // Rebind to `original` while preserving world pose. CreateAtOrigin rotates
+                // at the origin (keeping bbox at world (0,0)) then we offset to match p's bbox.
+                var rebound = Part.CreateAtOrigin(original, p.Rotation);
+                var delta = p.BoundingBox.Location - rebound.BoundingBox.Location;
+                rebound.Offset(delta);
+                rebound.UpdateBounds();
+                parts[i] = rebound;
+            }
+
+            return CanonicalFrame.FromCanonical(parts, sourceAngle);
+        }
+
         /// <summary>
         /// Fast path for qty 1-2: place a single part or a best-fit pair
         /// without running the full strategy pipeline.
@@ -139,6 +177,10 @@ namespace OpenNest
             var bestFits = BestFitCache.GetOrCompute(
                 drawing, Plate.Size.Length, Plate.Size.Width, Plate.PartSpacing);
 
+            // Build pair candidates with a canonical drawing so their geometry matches
+            // the coordinate frame of the cached fit results.
+            var canonicalDrawing = CanonicalFrame.AsCanonicalCopy(drawing);
+
             List<Part> bestPlacement = null;
 
             foreach (var fit in bestFits)
@@ -152,7 +194,7 @@ namespace OpenNest
                 if (fit.LongestSide > System.Math.Max(workArea.Width, workArea.Length) + Tolerance.Epsilon)
                     continue;
 
-                var landscape = fit.BuildParts(drawing);
+                var landscape = fit.BuildParts(canonicalDrawing);
                 var portrait = RotatePair90(landscape);
 
                 var lFits = TryOffsetToWorkArea(landscape, workArea);
@@ -174,6 +216,8 @@ namespace OpenNest
                     bestPlacement = candidate;
             }
 
+            // Parts are returned in canonical frame, bound to the canonical drawing.
+            // The outer Fill wrapper (Task 7) rebinds to `drawing` and composes sourceAngle onto rotation.
             return bestPlacement;
         }
 

OpenNest.Engine/Fill/FillLinear.cs

@@ -61,92 +61,91 @@ namespace OpenNest.Engine.Fill
                 : NestDirection.Horizontal;
         }
 
-        /// <summary>
-        /// Computes the slide distance for the push algorithm, returning the
-        /// geometry-aware copy distance along the given axis.
-        /// </summary>
-        private double ComputeCopyDistance(double bboxDim, double slideDistance)
-        {
-            if (slideDistance >= double.MaxValue || slideDistance < 0)
-                return bboxDim + PartSpacing;
-
-            // The geometry-aware slide can produce a copy distance smaller than
-            // the part itself when inflated corner/arc vertices interact spuriously.
-            // Clamp to bboxDim + PartSpacing to prevent bounding box overlap.
-            return System.Math.Max(bboxDim - slideDistance, bboxDim + PartSpacing);
-        }
-
         /// <summary>
         /// Finds the geometry-aware copy distance between two identical parts along an axis.
-        /// Both parts are inflated by half-spacing for symmetric spacing.
+        /// Uses native Line/Arc entities (inflated by half-spacing) so curves are handled
+        /// exactly without polygon sampling error.
         /// </summary>
-        private double FindCopyDistance(Part partA, NestDirection direction, PartBoundary boundary)
+        private double FindCopyDistance(Part partA, NestDirection direction)
         {
             var bboxDim = GetDimension(partA.BoundingBox, direction);
             var pushDir = GetPushDirection(direction);
+            var startOffset = bboxDim + PartSpacing + Tolerance.Epsilon;
+            var offset = MakeOffset(direction, startOffset);
 
-            var locationBOffset = MakeOffset(direction, bboxDim);
+            var stationaryEntities = PartGeometry.GetOffsetPerimeterEntities(partA, HalfSpacing);
+            var movingEntities = PartGeometry.GetOffsetPerimeterEntities(
+                partA.CloneAtOffset(offset), HalfSpacing);
 
-            // Use the most efficient array-based overload to avoid all allocations.
             var slideDistance = SpatialQuery.DirectionalDistance(
-                boundary.GetEdges(pushDir), partA.Location + locationBOffset,
-                boundary.GetEdges(SpatialQuery.OppositeDirection(pushDir)), partA.Location,
-                pushDir);
+                movingEntities, stationaryEntities, pushDir);
 
-            return ComputeCopyDistance(bboxDim, slideDistance);
+            if (slideDistance >= double.MaxValue || slideDistance < 0)
+                return bboxDim + PartSpacing;
+
+            return startOffset - slideDistance;
         }
 
         /// <summary>
         /// Finds the geometry-aware copy distance between two identical patterns along an axis.
-        /// Checks every pair of parts across adjacent patterns so that multi-part
-        /// patterns (e.g. interlocking pairs) maintain spacing between ALL parts.
-        /// Both sides are inflated by half-spacing for symmetric spacing.
+        /// Checks every pair of parts across adjacent pattern copies so multi-part patterns
+        /// (e.g. interlocking pairs) maintain spacing between ALL parts. Uses native entity
+        /// geometry inflated by half-spacing — same primitive the Compactor uses — so arcs
+        /// are exact and no bbox clamp is needed.
         /// </summary>
-        private double FindPatternCopyDistance(Pattern patternA, NestDirection direction, PartBoundary[] boundaries)
+        private double FindPatternCopyDistance(Pattern patternA, NestDirection direction)
         {
-            if (patternA.Parts.Count <= 1)
-                return FindSinglePartPatternCopyDistance(patternA, direction, boundaries[0]);
+            if (patternA.Parts.Count == 1)
+                return FindCopyDistance(patternA.Parts[0], direction);
 
             var bboxDim = GetDimension(patternA.BoundingBox, direction);
             var pushDir = GetPushDirection(direction);
             var opposite = SpatialQuery.OppositeDirection(pushDir);
+            var dirVec = SpatialQuery.DirectionToOffset(pushDir, 1.0);
 
             // bboxDim already spans max(upper) - min(lower) across all parts,
             // so the start offset just needs to push beyond that plus spacing.
             var startOffset = bboxDim + PartSpacing + Tolerance.Epsilon;
             var offset = MakeOffset(direction, startOffset);
 
-            var maxCopyDistance = FindMaxPairDistance(
-                patternA.Parts, boundaries, offset, pushDir, opposite, startOffset);
+            var parts = patternA.Parts;
+            var stationaryBoxes = new Box[parts.Count];
+            var movingBoxes = new Box[parts.Count];
+            var stationaryEntities = new List<Entity>[parts.Count];
+            var movingEntities = new List<Entity>[parts.Count];
 
-            // The copy distance must be at least bboxDim + PartSpacing to prevent
-            // bounding box overlap. Cross-pair slides can underestimate when the
-            // circumscribed polygon boundary overshoots the true arc, creating
-            // spurious contacts between diagonal parts in adjacent copies.
-            return System.Math.Max(maxCopyDistance, bboxDim + PartSpacing);
-        }
+            for (var i = 0; i < parts.Count; i++)
+            {
+                stationaryBoxes[i] = parts[i].BoundingBox;
+                movingBoxes[i] = stationaryBoxes[i].Translate(offset);
+            }
 
-        /// <summary>
-        /// Tests every pair of parts across adjacent pattern copies and returns the
-        /// maximum copy distance found. Returns 0 if no valid slide was found.
-        /// </summary>
-        private static double FindMaxPairDistance(
-            List<Part> parts, PartBoundary[] boundaries, Vector offset,
-            PushDirection pushDir, PushDirection opposite, double startOffset)
-        {
             var maxCopyDistance = 0.0;
 
             for (var j = 0; j < parts.Count; j++)
             {
-                var movingEdges = boundaries[j].GetEdges(pushDir);
-                var locationB = parts[j].Location + offset;
+                var movingBox = movingBoxes[j];
 
                 for (var i = 0; i < parts.Count; i++)
                 {
+                    var stationaryBox = stationaryBoxes[i];
+
+                    // Skip if stationary is already ahead of moving in the push direction
+                    // (sliding forward would take them further apart).
+                    if (SpatialQuery.DirectionalGap(movingBox, stationaryBox, opposite) > 0)
+                        continue;
+
+                    // Skip if bboxes can't overlap along the axis perpendicular to the push.
+                    if (!SpatialQuery.PerpendicularOverlap(movingBox, stationaryBox, dirVec))
+                        continue;
+
+                    stationaryEntities[i] ??= PartGeometry.GetOffsetPerimeterEntities(
+                        parts[i], HalfSpacing);
+                    movingEntities[j] ??= PartGeometry.GetOffsetPerimeterEntities(
+                        parts[j].CloneAtOffset(offset), HalfSpacing);
+
                     var slideDistance = SpatialQuery.DirectionalDistance(
-                        movingEdges, locationB,
-                        boundaries[i].GetEdges(opposite), parts[i].Location,
-                        pushDir);
+                        movingEntities[j], stationaryEntities[i], pushDir);
 
                     if (slideDistance >= double.MaxValue || slideDistance < 0)
                         continue;
@@ -161,86 +160,15 @@ namespace OpenNest.Engine.Fill
             return maxCopyDistance;
         }
 
-        /// <summary>
-        /// Fast path for single-part patterns — no cross-part conflicts possible.
-        /// </summary>
-        private double FindSinglePartPatternCopyDistance(Pattern patternA, NestDirection direction, PartBoundary boundary)
-        {
-            var template = patternA.Parts[0];
-            return FindCopyDistance(template, direction, boundary);
-        }
-
-        /// <summary>
-        /// Gets offset boundary lines for all parts in a pattern using a shared boundary.
-        /// </summary>
-        private static List<Line> GetPatternLines(Pattern pattern, PartBoundary boundary, PushDirection direction)
-        {
-            var lines = new List<Line>();
-
-            foreach (var part in pattern.Parts)
-                lines.AddRange(boundary.GetLines(part.Location, direction));
-
-            return lines;
-        }
-
-        /// <summary>
-        /// Gets boundary lines for all parts in a pattern, with an additional
-        /// location offset applied. Avoids cloning the pattern.
-        /// </summary>
-        private static List<Line> GetOffsetPatternLines(Pattern pattern, Vector offset, PartBoundary boundary, PushDirection direction)
-        {
-            var lines = new List<Line>();
-
-            foreach (var part in pattern.Parts)
-                lines.AddRange(boundary.GetLines(part.Location + offset, direction));
-
-            return lines;
-        }
-
-        /// <summary>
-        /// Creates boundaries for all parts in a pattern. Parts that share the same
-        /// program geometry (same drawing and rotation) reuse the same boundary instance.
-        /// </summary>
-        private PartBoundary[] CreateBoundaries(Pattern pattern)
-        {
-            var boundaries = new PartBoundary[pattern.Parts.Count];
-            var cache = new List<(Drawing drawing, double rotation, PartBoundary boundary)>();
-
-            for (var i = 0; i < pattern.Parts.Count; i++)
-            {
-                var part = pattern.Parts[i];
-                PartBoundary found = null;
-
-                foreach (var entry in cache)
-                {
-                    if (entry.drawing == part.BaseDrawing && entry.rotation.IsEqualTo(part.Rotation))
-                    {
-                        found = entry.boundary;
-                        break;
-                    }
-                }
-
-                if (found == null)
-                {
-                    found = new PartBoundary(part, HalfSpacing);
-                    cache.Add((part.BaseDrawing, part.Rotation, found));
-                }
-
-                boundaries[i] = found;
-            }
-
-            return boundaries;
-        }
-
         /// <summary>
         /// Tiles a pattern along the given axis, returning the cloned parts
         /// (does not include the original pattern's parts). For multi-part
         /// patterns, also adds individual parts from the next incomplete copy
         /// that still fit within the work area.
         /// </summary>
-        private List<Part> TilePattern(Pattern basePattern, NestDirection direction, PartBoundary[] boundaries)
+        private List<Part> TilePattern(Pattern basePattern, NestDirection direction)
         {
-            var copyDistance = FindPatternCopyDistance(basePattern, direction, boundaries);
+            var copyDistance = FindPatternCopyDistance(basePattern, direction);
 
             if (copyDistance <= 0)
                 return new List<Part>();
@@ -394,11 +322,10 @@ namespace OpenNest.Engine.Fill
         private List<Part> FillGrid(Pattern pattern, NestDirection direction)
         {
             var perpAxis = PerpendicularAxis(direction);
-            var boundaries = CreateBoundaries(pattern);
 
             // Step 1: Tile along primary axis
             var row = new List<Part>(pattern.Parts);
-            row.AddRange(TilePattern(pattern, direction, boundaries));
+            row.AddRange(TilePattern(pattern, direction));
 
             if (pattern.Parts.Count > 1 && HasOverlappingParts(row, out var a1, out var b1))
             {
@@ -410,7 +337,7 @@ namespace OpenNest.Engine.Fill
             // If primary tiling didn't produce copies, just tile along perpendicular
             if (row.Count <= pattern.Parts.Count)
             {
-                row.AddRange(TilePattern(pattern, perpAxis, boundaries));
+                row.AddRange(TilePattern(pattern, perpAxis));
 
                 if (pattern.Parts.Count > 1 && HasOverlappingParts(row, out var a2, out var b2))
                 {
@@ -427,9 +354,8 @@ namespace OpenNest.Engine.Fill
             rowPattern.Parts.AddRange(row);
             rowPattern.UpdateBounds();
 
-            var rowBoundaries = CreateBoundaries(rowPattern);
             var gridResult = new List<Part>(rowPattern.Parts);
-            gridResult.AddRange(TilePattern(rowPattern, perpAxis, rowBoundaries));
+            gridResult.AddRange(TilePattern(rowPattern, perpAxis));
 
             if (HasOverlappingParts(gridResult, out var a3, out var b3))
             {
@@ -481,9 +407,8 @@ namespace OpenNest.Engine.Fill
                 return seed;
 
             var template = seed.Parts[0];
-            var boundary = new PartBoundary(template, HalfSpacing);
 
-            var copyDistance = FindCopyDistance(template, direction, boundary);
+            var copyDistance = FindCopyDistance(template, direction);
 
             if (copyDistance <= 0)
                 return seed;

OpenNest.Engine/ML/FeatureExtractor.cs

@@ -27,7 +27,10 @@ namespace OpenNest.Engine.ML
     {
         public static PartFeatures Extract(Drawing drawing)
         {
-            var entities = OpenNest.Converters.ConvertProgram.ToGeometry(drawing.Program)
+            // Normalize to canonical frame so features are invariant to import orientation.
+            var canonical = CanonicalFrame.AsCanonicalCopy(drawing);
+
+            var entities = OpenNest.Converters.ConvertProgram.ToGeometry(canonical.Program)
                 .Where(e => e.Layer != SpecialLayers.Rapid)
                 .ToList();
 
@@ -45,18 +48,18 @@ namespace OpenNest.Engine.ML
 
             var features = new PartFeatures
             {
-                Area = drawing.Area,
-                Convexity = drawing.Area / (hullArea > 0 ? hullArea : 1.0),
+                Area = canonical.Area,
+                Convexity = canonical.Area / (hullArea > 0 ? hullArea : 1.0),
                 AspectRatio = bb.Length / (bb.Width > 0 ? bb.Width : 1.0),
-                BoundingBoxFill = drawing.Area / (bb.Area() > 0 ? bb.Area() : 1.0),
+                BoundingBoxFill = canonical.Area / (bb.Area() > 0 ? bb.Area() : 1.0),
                 VertexCount = polygon.Vertices.Count,
                 Bitmask = GenerateBitmask(polygon, 32)
             };
 
             // Circularity = 4 * PI * Area / Perimeter^2
             var perimeterLen = polygon.Perimeter();
-            features.Circularity = (4 * System.Math.PI * drawing.Area) / (perimeterLen * perimeterLen);
-            features.PerimeterToAreaRatio = drawing.Area > 0 ? perimeterLen / drawing.Area : 0;
+            features.Circularity = (4 * System.Math.PI * canonical.Area) / (perimeterLen * perimeterLen);
+            features.PerimeterToAreaRatio = canonical.Area > 0 ? perimeterLen / canonical.Area : 0;
 
             return features;
         }

OpenNest.Engine/NestEngineBase.cs

@@ -334,6 +334,12 @@ namespace OpenNest
                 var bestFits = BestFitCache.GetOrCompute(
                     item.Drawing, Plate.Size.Length, Plate.Size.Width, Plate.PartSpacing);
 
+                // BestFitCache stores pair coordinates in canonical frame. Build candidates
+                // from a canonical drawing copy so geometry and coords share a frame; rebind
+                // + un-rotate winning pair to the original drawing's frame before returning.
+                var canonicalDrawing = CanonicalFrame.AsCanonicalCopy(item.Drawing);
+                var sourceAngle = item.Drawing?.Source?.Angle ?? 0.0;
+
                 List<Part> bestPlacement = null;
                 Box bestTarget = null;
 
@@ -342,7 +348,7 @@ namespace OpenNest
                     if (!fit.Keep)
                         continue;
 
-                    var parts = fit.BuildParts(item.Drawing);
+                    var parts = fit.BuildParts(canonicalDrawing);
                     var pairBbox = ((IEnumerable<IBoundable>)parts).GetBoundingBox();
                     var pairW = pairBbox.Width;
                     var pairL = pairBbox.Length;
@@ -374,6 +380,10 @@ namespace OpenNest
 
                 if (bestPlacement == null) continue;
 
+                // Rebind to the original drawing and compose sourceAngle onto rotation so the
+                // final placed parts sit in the user's visible frame.
+                bestPlacement = RebindPairToOriginal(bestPlacement, item.Drawing, sourceAngle);
+
                 result.AddRange(bestPlacement);
                 item.Quantity = 0;
 
@@ -388,6 +398,30 @@ namespace OpenNest
             return result;
         }
 
+        /// <summary>
+        /// Rebinds each canonical-frame Part in the pair to the original Drawing at its current
+        /// world pose, then composes sourceAngle onto each via CanonicalFrame.FromCanonical so
+        /// the returned list is in the original drawing's visible frame. Mirrors
+        /// DefaultNestEngine.RebindAndUnCanonicalize.
+        /// </summary>
+        private static List<Part> RebindPairToOriginal(List<Part> parts, Drawing original, double sourceAngle)
+        {
+            if (parts == null || parts.Count == 0)
+                return parts;
+
+            for (var i = 0; i < parts.Count; i++)
+            {
+                var p = parts[i];
+                var rebound = Part.CreateAtOrigin(original, p.Rotation);
+                var delta = p.BoundingBox.Location - rebound.BoundingBox.Location;
+                rebound.Offset(delta);
+                rebound.UpdateBounds();
+                parts[i] = rebound;
+            }
+
+            return CanonicalFrame.FromCanonical(parts, sourceAngle);
+        }
+
         /// <summary>
         /// Determines whether a drawing should use grid-fill (true) or bin-pack (false).
         /// Low-quantity items whose total area is a small fraction of the plate are

OpenNest.Engine/PartClassifier.cs

@@ -64,8 +64,8 @@ namespace OpenNest.Engine
             var mbrArea = mbr.Area;
             var mbrPerimeter = 2 * (mbr.Width + mbr.Height);
 
-            // Store primary angle (negated to align MBR with axes, same as RotationAnalysis).
-            result.PrimaryAngle = -mbr.Angle;
+            // Share the single angle formula with CanonicalAngle (no duplicate MBR compute).
+            result.PrimaryAngle = CanonicalAngle.FromMbr(mbr);
 
             // Drawing perimeter for circularity and perimeter ratio.
             var drawingPerimeter = polygon.Perimeter();

OpenNest.Engine/Strategies/FillContext.cs

@@ -15,7 +15,7 @@ namespace OpenNest.Engine.Strategies
         public int PlateNumber { get; init; }
         public CancellationToken Token { get; init; }
         public IProgress<NestProgress> Progress { get; init; }
-        public FillPolicy Policy { get; init; }
+        public FillPolicy Policy { get; init; } = new FillPolicy(new DefaultFillComparer());
         public int MaxQuantity { get; init; }
         public PartType PartType { get; set; }
 

OpenNest.IO/Bom/BomAnalyzer.cs

@@ -42,6 +42,11 @@ namespace OpenNest.IO.Bom
                     var nameWithoutExt = Path.GetFileNameWithoutExtension(file);
                     dxfFiles[nameWithoutExt] = file;
                 }
+                foreach (var file in Directory.GetFiles(dxfFolder, "*.dwg"))
+                {
+                    var nameWithoutExt = Path.GetFileNameWithoutExtension(file);
+                    dxfFiles.TryAdd(nameWithoutExt, file);
+                }
             }
 
             // Partition items into: skipped, unmatched, or matched (grouped)
@@ -57,8 +62,8 @@ namespace OpenNest.IO.Bom
 
                 var lookupName = item.FileName;
 
-                // Strip .dxf extension if the BOM includes it
-                if (lookupName.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase))
+                if (lookupName.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase)
+                    || lookupName.EndsWith(".dwg", StringComparison.OrdinalIgnoreCase))
                     lookupName = Path.GetFileNameWithoutExtension(lookupName);
 
                 if (!folderExists)

OpenNest.IO/CadImportResult.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using ACadSharp;
 using OpenNest.Bending;
 using OpenNest.Geometry;
 
@@ -38,5 +39,11 @@ namespace OpenNest.IO
         /// Default drawing name (filename without extension, unless overridden).
         /// </summary>
         public string Name { get; set; }
+
+        /// <summary>
+        /// The raw CAD document from the source file. Available for callers
+        /// that need access to non-geometry entities (e.g., text annotations).
+        /// </summary>
+        public CadDocument Document { get; set; }
     }
 }

OpenNest.IO/CadImporter.cs

@@ -5,6 +5,7 @@ using OpenNest.Bending;
 using OpenNest.Converters;
 using OpenNest.Geometry;
 using OpenNest.IO.Bending;
+using OpenNest.Math;
 
 namespace OpenNest.IO
 {
@@ -25,6 +26,8 @@ namespace OpenNest.IO
 
             var dxf = Dxf.Import(path);
 
+            RemoveDuplicateArcs(dxf.Entities);
+
             var bends = new List<Bend>();
             if (options.DetectBends && dxf.Document != null)
             {
@@ -44,6 +47,7 @@ namespace OpenNest.IO
                 Bounds = dxf.Entities.GetBoundingBox(),
                 SourcePath = path,
                 Name = options.Name ?? Path.GetFileNameWithoutExtension(path),
+                Document = dxf.Document,
             };
         }
 
@@ -136,5 +140,33 @@ namespace OpenNest.IO
 
             return drawing;
         }
+
+        internal static void RemoveDuplicateArcs(List<Entity> entities)
+        {
+            var circles = entities.OfType<Circle>().ToList();
+            var arcs = entities.OfType<Arc>().ToList();
+            var arcsToRemove = new List<Arc>();
+
+            foreach (var arc in arcs)
+            {
+                foreach (var circle in circles)
+                {
+                    if (arc.Layer?.Name != circle.Layer?.Name)
+                        continue;
+
+                    if (!arc.Center.DistanceTo(circle.Center).IsEqualTo(0))
+                        continue;
+
+                    if (!arc.Radius.IsEqualTo(circle.Radius))
+                        continue;
+
+                    arcsToRemove.Add(arc);
+                    break;
+                }
+            }
+
+            foreach (var arc in arcsToRemove)
+                entities.Remove(arc);
+        }
     }
 }

OpenNest.IO/Dxf.cs

@@ -27,8 +27,7 @@ namespace OpenNest.IO
         /// </summary>
         public static DxfImportResult Import(string path)
         {
-            using var reader = new DxfReader(path);
-            var doc = reader.Read();
+            var doc = ReadDocument(path);
 
             return new DxfImportResult
             {
@@ -41,8 +40,7 @@ namespace OpenNest.IO
         {
             try
             {
-                using var reader = new DxfReader(path);
-                var doc = reader.Read();
+                var doc = ReadDocument(path);
                 return ConvertEntities(doc);
             }
             catch (Exception ex)
@@ -113,6 +111,23 @@ namespace OpenNest.IO
 
         #region Private
 
+        private static bool IsDwg(string path) =>
+            Path.GetExtension(path).Equals(".dwg", StringComparison.OrdinalIgnoreCase);
+
+        private static CadDocument ReadDocument(string path)
+        {
+            if (IsDwg(path))
+            {
+                using var reader = new DwgReader(path);
+                return reader.Read();
+            }
+            else
+            {
+                using var reader = new DxfReader(path);
+                return reader.Read();
+            }
+        }
+
         private static List<Entity> ConvertEntities(CadDocument doc)
         {
             var entities = new List<Entity>();

OpenNest.IO/Extensions.cs

@@ -181,13 +181,22 @@ namespace OpenNest.IO
         {
             var center = new Vector(ellipse.Center.X, ellipse.Center.Y);
             var majorAxis = new Vector(ellipse.MajorAxisEndPoint.X, ellipse.MajorAxisEndPoint.Y);
-            var semiMajor = System.Math.Sqrt(majorAxis.X * majorAxis.X + majorAxis.Y * majorAxis.Y);
-            var semiMinor = semiMajor * ellipse.RadiusRatio;
-            var rotation = System.Math.Atan2(majorAxis.Y, majorAxis.X);
 
             var startParam = ellipse.StartParameter;
             var endParam = ellipse.EndParameter;
 
+            if (ellipse.Normal.Z < 0)
+            {
+                var newStart = OpenNest.Math.Angle.TwoPI - endParam;
+                var newEnd = OpenNest.Math.Angle.TwoPI - startParam;
+                startParam = newStart;
+                endParam = newEnd;
+            }
+
+            var semiMajor = System.Math.Sqrt(majorAxis.X * majorAxis.X + majorAxis.Y * majorAxis.Y);
+            var semiMinor = semiMajor * ellipse.RadiusRatio;
+            var rotation = System.Math.Atan2(majorAxis.Y, majorAxis.X);
+
             var layer = ellipse.Layer.ToOpenNest();
             var color = ellipse.ResolveColor();
             var lineTypeName = ellipse.ResolveLineTypeName();

OpenNest.IO/OpenNest.IO.csproj

@@ -4,6 +4,9 @@
     <RootNamespace>OpenNest.IO</RootNamespace>
     <AssemblyName>OpenNest.IO</AssemblyName>
   </PropertyGroup>
+  <ItemGroup>
+    <InternalsVisibleTo Include="OpenNest.Tests" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenNest.Core\OpenNest.Core.csproj" />
     <ProjectReference Include="..\OpenNest.Engine\OpenNest.Engine.csproj" />

OpenNest.Posts.Cincinnati/CincinnatiPartSubprogramWriter.cs

@@ -16,11 +16,16 @@ public sealed class CincinnatiPartSubprogramWriter
 {
     private readonly CincinnatiPostConfig _config;
     private readonly CincinnatiFeatureWriter _featureWriter;
+    private readonly CoordinateFormatter _fmt;
+    private readonly Dictionary<int, int> _holeSubprograms;
 
-    public CincinnatiPartSubprogramWriter(CincinnatiPostConfig config)
+    public CincinnatiPartSubprogramWriter(CincinnatiPostConfig config,
+        Dictionary<int, int> holeSubprograms = null)
     {
         _config = config;
         _featureWriter = new CincinnatiFeatureWriter(config);
+        _fmt = new CoordinateFormatter(config.PostedAccuracy);
+        _holeSubprograms = holeSubprograms;
     }
 
     /// <summary>
@@ -44,6 +49,15 @@ public sealed class CincinnatiPartSubprogramWriter
         for (var i = 0; i < ordered.Count; i++)
         {
             var (codes, isEtch) = ordered[i];
+            var isLastFeature = i == ordered.Count - 1;
+
+            // SubProgramCall features are emitted as M98 hole calls
+            if (codes.Count == 1 && codes[0] is SubProgramCall holeCall)
+            {
+                WriteHoleSubprogramCall(w, holeCall, i, isLastFeature);
+                continue;
+            }
+
             var featureNumber = i == 0
                 ? _config.FeatureLineNumberStart
                 : 1000 + i + 1;
@@ -55,7 +69,7 @@ public sealed class CincinnatiPartSubprogramWriter
                 FeatureNumber = featureNumber,
                 PartName = drawingName,
                 IsFirstFeatureOfPart = false,
-                IsLastFeatureOnSheet = i == ordered.Count - 1,
+                IsLastFeatureOnSheet = isLastFeature,
                 IsSafetyHeadraise = false,
                 IsExteriorFeature = false,
                 IsEtch = isEtch,
@@ -70,6 +84,30 @@ public sealed class CincinnatiPartSubprogramWriter
         w.WriteLine($"M99 (END OF {drawingName})");
     }
 
+    private void WriteHoleSubprogramCall(TextWriter w, SubProgramCall call,
+        int featureIndex, bool isLastFeature)
+    {
+        var postSubNum = _holeSubprograms != null && _holeSubprograms.TryGetValue(call.Id, out var num)
+            ? num : call.Id;
+
+        var featureNumber = featureIndex == 0
+            ? _config.FeatureLineNumberStart
+            : 1000 + featureIndex + 1;
+
+        var sb = new StringBuilder();
+        if (_config.UseLineNumbers)
+            sb.Append($"N{featureNumber} ");
+        sb.Append($"G52 X{_fmt.FormatCoord(call.Offset.X)} Y{_fmt.FormatCoord(call.Offset.Y)}");
+        w.WriteLine(sb.ToString());
+
+        w.WriteLine($"M98 P{postSubNum}");
+
+        w.WriteLine("G52 X0 Y0");
+
+        if (!isLastFeature)
+            w.WriteLine("M47");
+    }
+
     /// <summary>
     /// If the program has no leading rapid, inserts a synthetic rapid at the
     /// last motion endpoint (the contour return point). This ensures the feature

OpenNest.Posts.Cincinnati/CincinnatiPostConfig.cs

@@ -1,5 +1,7 @@
+using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Linq;
 
 namespace OpenNest.Posts.Cincinnati
 {
@@ -277,6 +279,24 @@ namespace OpenNest.Posts.Cincinnati
         [DisplayName("Etch Libraries")]
         [Description("Gas-to-library mapping for etch operations.")]
         public List<EtchLibraryEntry> EtchLibraries { get; set; } = new();
+
+        [Category("B. Libraries")]
+        [DisplayName("Selected Library")]
+        [Description("Overrides Material/Thickness/Gas auto-resolution. Pick an existing entry from Material Libraries, or leave blank to auto-resolve.")]
+        [TypeConverter(typeof(MaterialLibraryNameConverter))]
+        public string SelectedLibrary { get; set; } = "";
+
+        public string FindBestLibrary(string materialName, double thickness)
+        {
+            if (MaterialLibraries == null || string.IsNullOrEmpty(materialName))
+                return "";
+
+            return MaterialLibraries
+                .Where(e => string.Equals(e.Material, materialName, StringComparison.OrdinalIgnoreCase))
+                .OrderBy(e => System.Math.Abs(e.Thickness - thickness))
+                .Select(e => e.Library)
+                .FirstOrDefault() ?? "";
+        }
     }
 
     public class MaterialLibraryEntry

OpenNest.Posts.Cincinnati/CincinnatiPostProcessor.cs

@@ -9,7 +9,7 @@ using OpenNest.CNC;
 
 namespace OpenNest.Posts.Cincinnati
 {
-    public sealed class CincinnatiPostProcessor : IConfigurablePostProcessor
+    public sealed class CincinnatiPostProcessor : IConfigurablePostProcessor, IPostProcessorNestAware, IMaterialProvidingPostProcessor
     {
         private static readonly JsonSerializerOptions JsonOptions = new()
         {
@@ -25,6 +25,23 @@ namespace OpenNest.Posts.Cincinnati
 
         object IConfigurablePostProcessor.Config => Config;
 
+        public IEnumerable<string> GetMaterialNames()
+        {
+            if (Config?.MaterialLibraries == null)
+                return System.Array.Empty<string>();
+
+            return Config.MaterialLibraries
+                .Select(e => e.Material)
+                .Where(s => !string.IsNullOrWhiteSpace(s));
+        }
+
+        public void PrepareForNest(Nest nest)
+        {
+            var materialName = nest?.Material?.Name ?? "";
+            var thickness = nest?.Thickness ?? 0.0;
+            Config.SelectedLibrary = Config.FindBestLibrary(materialName, thickness);
+        }
+
         public CincinnatiPostProcessor()
         {
             var configPath = GetConfigPath();
@@ -128,7 +145,8 @@ namespace OpenNest.Posts.Cincinnati
             // Part sub-programs (if enabled)
             if (subprogramEntries != null)
             {
-                var partSubWriter = new CincinnatiPartSubprogramWriter(Config);
+                var partSubWriter = new CincinnatiPartSubprogramWriter(Config,
+                    holeMapping.Count > 0 ? holeMapping : null);
                 var sheetDiagonal = firstPlate != null
                     ? System.Math.Sqrt(firstPlate.Size.Width * firstPlate.Size.Width
                         + firstPlate.Size.Length * firstPlate.Size.Length)

OpenNest.Posts.Cincinnati/MaterialLibraryNameConverter.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+
+namespace OpenNest.Posts.Cincinnati
+{
+    public sealed class MaterialLibraryNameConverter : StringConverter
+    {
+        public override bool GetStandardValuesSupported(ITypeDescriptorContext context) => true;
+
+        public override bool GetStandardValuesExclusive(ITypeDescriptorContext context) => false;
+
+        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
+        {
+            var config = context?.Instance as CincinnatiPostConfig;
+            var names = new List<string> { "" };
+
+            if (config?.MaterialLibraries != null)
+            {
+                names.AddRange(config.MaterialLibraries
+                    .Select(e => e.Library)
+                    .Where(s => !string.IsNullOrWhiteSpace(s))
+                    .Distinct(StringComparer.OrdinalIgnoreCase)
+                    .OrderBy(s => s, StringComparer.OrdinalIgnoreCase));
+            }
+
+            return new StandardValuesCollection(names);
+        }
+    }
+}

OpenNest.Posts.Cincinnati/MaterialLibraryResolver.cs

@@ -10,15 +10,20 @@ public sealed class MaterialLibraryResolver
 
     private readonly List<MaterialLibraryEntry> _materialLibraries;
     private readonly List<EtchLibraryEntry> _etchLibraries;
+    private readonly string _selectedLibrary;
 
     public MaterialLibraryResolver(CincinnatiPostConfig config)
     {
         _materialLibraries = config.MaterialLibraries ?? new List<MaterialLibraryEntry>();
         _etchLibraries = config.EtchLibraries ?? new List<EtchLibraryEntry>();
+        _selectedLibrary = config.SelectedLibrary ?? "";
     }
 
     public string ResolveCutLibrary(string materialName, double thickness, string gas)
     {
+        if (!string.IsNullOrEmpty(_selectedLibrary))
+            return EnsureLibExtension(_selectedLibrary);
+
         var entry = _materialLibraries.FirstOrDefault(e =>
             string.Equals(e.Material, materialName, StringComparison.OrdinalIgnoreCase) &&
             System.Math.Abs(e.Thickness - thickness) <= ThicknessTolerance &&

OpenNest.Posts.Cincinnati/OpenNest.Posts.Cincinnati.csproj

@@ -6,11 +6,19 @@
   <ItemGroup>
     <ProjectReference Include="..\OpenNest.Core\OpenNest.Core.csproj" />
   </ItemGroup>
+  <ItemGroup>
+    <None Update="OpenNest.Posts.Cincinnati.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
   <Target Name="CopyToPostsDir" AfterTargets="Build">
     <PropertyGroup>
       <PostsDir>..\OpenNest\bin\$(Configuration)\$(TargetFramework)\Posts\</PostsDir>
+      <ConfigJson>$(MSBuildProjectDirectory)\OpenNest.Posts.Cincinnati.json</ConfigJson>
+      <DeployedConfigJson>$(PostsDir)OpenNest.Posts.Cincinnati.json</DeployedConfigJson>
     </PropertyGroup>
     <MakeDir Directories="$(PostsDir)" />
     <Copy SourceFiles="$(TargetPath)" DestinationFolder="$(PostsDir)" SkipUnchangedFiles="true" ContinueOnError="true" />
+    <Copy SourceFiles="$(ConfigJson)" DestinationFolder="$(PostsDir)" SkipUnchangedFiles="true" ContinueOnError="true" Condition="!Exists('$(DeployedConfigJson)')" />
   </Target>
 </Project>

OpenNest.Posts.Cincinnati/OpenNest.Posts.Cincinnati.json

@@ -0,0 +1,163 @@
+{
+  "ConfigurationName": "CL940",
+  "PostedUnits": "Inches",
+  "PostedAccuracy": 4,
+  "UseLineNumbers": true,
+  "FeatureLineNumberStart": 1,
+  "UseSheetSubprograms": true,
+  "SheetSubprogramStart": 101,
+  "UsePartSubprograms": false,
+  "PartSubprogramStart": 200,
+  "VariableDeclarationSubprogram": 100,
+  "CoordModeBetweenParts": "G92",
+  "ProcessParameterMode": "LibraryFile",
+  "DefaultAssistGas": "O2",
+  "DefaultEtchGas": "N2",
+  "UseExactStopMode": false,
+  "UseSpeedGas": false,
+  "UseAntiDive": true,
+  "UseSmartRapids": false,
+  "KerfCompensation": "ControllerSide",
+  "DefaultKerfSide": "Left",
+  "InteriorM47": "Always",
+  "ExteriorM47": "Always",
+  "M47OverrideDistanceThreshold": null,
+  "SafetyHeadraiseDistance": 2000,
+  "PalletExchange": "EndOfSheet",
+  "LeadInFeedratePercent": 0.5,
+  "LeadInArcLine2FeedratePercent": 0.5,
+  "LeadOutFeedratePercent": 0.5,
+  "CircleFeedrateMultiplier": 0.8,
+  "ArcFeedrate": "None",
+  "ArcFeedrateRanges": [
+    { "MaxRadius": 0.125, "FeedratePercent": 0.25, "VariableNumber": 123 },
+    { "MaxRadius": 0.75, "FeedratePercent": 0.5, "VariableNumber": 124 },
+    { "MaxRadius": 4.5, "FeedratePercent": 0.8, "VariableNumber": 125 }
+  ],
+  "UserVariableStart": 200,
+  "SheetWidthVariable": 110,
+  "SheetLengthVariable": 111,
+  "MaterialLibraries": [
+    { "Material": "Aluminum", "Thickness": 0.032, "Gas": "AIR", "Library": "AL032AIR" },
+    { "Material": "Aluminum", "Thickness": 0.032, "Gas": "N2", "Library": "AL032N2" },
+    { "Material": "Aluminum", "Thickness": 0.032, "Gas": "O2", "Library": "AL032O2" },
+    { "Material": "Aluminum", "Thickness": 0.050, "Gas": "AIR", "Library": "AL050AIR" },
+    { "Material": "Aluminum", "Thickness": 0.050, "Gas": "N2", "Library": "AL050N2" },
+    { "Material": "Aluminum", "Thickness": 0.050, "Gas": "O2", "Library": "AL050O2" },
+    { "Material": "Aluminum", "Thickness": 0.063, "Gas": "AIR", "Library": "AL063AIR" },
+    { "Material": "Aluminum", "Thickness": 0.063, "Gas": "N2", "Library": "AL063N2" },
+    { "Material": "Aluminum", "Thickness": 0.063, "Gas": "O2", "Library": "AL063O2" },
+    { "Material": "Aluminum", "Thickness": 0.080, "Gas": "AIR", "Library": "AL080AIR" },
+    { "Material": "Aluminum", "Thickness": 0.080, "Gas": "N2", "Library": "AL080N2" },
+    { "Material": "Aluminum", "Thickness": 0.080, "Gas": "O2", "Library": "AL080O2" },
+    { "Material": "Aluminum", "Thickness": 0.090, "Gas": "AIR", "Library": "AL090AIR" },
+    { "Material": "Aluminum", "Thickness": 0.090, "Gas": "N2", "Library": "AL090N2" },
+    { "Material": "Aluminum", "Thickness": 0.090, "Gas": "O2", "Library": "AL090O2" },
+    { "Material": "Aluminum", "Thickness": 0.100, "Gas": "AIR", "Library": "AL100AIR" },
+    { "Material": "Aluminum", "Thickness": 0.100, "Gas": "N2", "Library": "AL100N2" },
+    { "Material": "Aluminum", "Thickness": 0.100, "Gas": "O2", "Library": "AL100O2" },
+    { "Material": "Aluminum", "Thickness": 0.125, "Gas": "AIR", "Library": "AL125AIR" },
+    { "Material": "Aluminum", "Thickness": 0.125, "Gas": "N2", "Library": "AL125N2" },
+    { "Material": "Aluminum", "Thickness": 0.125, "Gas": "O2", "Library": "AL125O2" },
+    { "Material": "Aluminum", "Thickness": 0.190, "Gas": "AIR", "Library": "AL190AIR" },
+    { "Material": "Aluminum", "Thickness": 0.190, "Gas": "N2", "Library": "AL190N2" },
+    { "Material": "Aluminum", "Thickness": 0.190, "Gas": "O2", "Library": "AL190O2" },
+    { "Material": "Aluminum", "Thickness": 0.250, "Gas": "AIR", "Library": "AL250AIR" },
+    { "Material": "Aluminum", "Thickness": 0.250, "Gas": "N2", "Library": "AL250N2" },
+    { "Material": "Aluminum", "Thickness": 0.250, "Gas": "O2", "Library": "AL250O2" },
+    { "Material": "Aluminum", "Thickness": 0.375, "Gas": "AIR", "Library": "AL375AIR" },
+    { "Material": "Aluminum", "Thickness": 0.375, "Gas": "N2", "Library": "AL375N2" },
+    { "Material": "Aluminum", "Thickness": 0.375, "Gas": "O2", "Library": "AL375O2" },
+    { "Material": "Aluminum", "Thickness": 0.500, "Gas": "AIR", "Library": "AL500AIR" },
+    { "Material": "Aluminum", "Thickness": 0.500, "Gas": "N2", "Library": "AL500N2" },
+    { "Material": "Aluminum", "Thickness": 0.500, "Gas": "O2", "Library": "AL500O2" },
+    { "Material": "Aluminum", "Thickness": 0.625, "Gas": "N2", "Library": "AL625N2" },
+    { "Material": "Aluminum", "Thickness": 0.750, "Gas": "AIR", "Library": "AL750AIR" },
+    { "Material": "Aluminum", "Thickness": 0.750, "Gas": "N2", "Library": "AL750N2" },
+    { "Material": "Aluminum", "Thickness": 0.750, "Gas": "O2", "Library": "AL750O2" },
+    { "Material": "Aluminum", "Thickness": 1.000, "Gas": "AIR", "Library": "AL1000AIR" },
+    { "Material": "Aluminum", "Thickness": 1.000, "Gas": "N2", "Library": "AL1000N2" },
+
+    { "Material": "Galvanized Steel", "Thickness": 0.135, "Gas": "N2", "Library": "GALV135N2" },
+    { "Material": "Galvanized Steel", "Thickness": 0.188, "Gas": "N2", "Library": "GALV188N2" },
+
+    { "Material": "Carbon Steel", "Thickness": 0.036, "Gas": "AIR", "Library": "MS036AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.036, "Gas": "N2", "Library": "MS036N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.048, "Gas": "AIR", "Library": "MS048AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.048, "Gas": "N2", "Library": "MS048N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.060, "Gas": "AIR", "Library": "MS060AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.060, "Gas": "N2", "Library": "MS060N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.075, "Gas": "AIR", "Library": "MS075AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.075, "Gas": "N2", "Library": "MS075N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.075, "Gas": "N2", "Library": "MS075N2FE" },
+    { "Material": "Carbon Steel", "Thickness": 0.090, "Gas": "N2", "Library": "MS090N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.105, "Gas": "AIR", "Library": "MS105AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.105, "Gas": "N2", "Library": "MS105N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.120, "Gas": "AIR", "Library": "MS120AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.120, "Gas": "N2", "Library": "MS120N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.120, "Gas": "N2", "Library": "MS120N2FE" },
+    { "Material": "Carbon Steel", "Thickness": 0.135, "Gas": "AIR", "Library": "MS135AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.135, "Gas": "N2", "Library": "MS135N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.135, "Gas": "N2", "Library": "MS135N2FE" },
+    { "Material": "Carbon Steel", "Thickness": 0.135, "Gas": "N2", "Library": "MS135N2Panel" },
+    { "Material": "Carbon Steel", "Thickness": 0.188, "Gas": "AIR", "Library": "MS188AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.188, "Gas": "N2", "Library": "MS188N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.188, "Gas": "N2", "Library": "MS188N2FLOORPLATE" },
+    { "Material": "Carbon Steel", "Thickness": 0.188, "Gas": "O2", "Library": "MS188O2" },
+    { "Material": "Carbon Steel", "Thickness": 0.250, "Gas": "AIR", "Library": "MS250AIR" },
+    { "Material": "Carbon Steel", "Thickness": 0.250, "Gas": "N2", "Library": "MS250N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.250, "Gas": "N2", "Library": "MS250N2FLOORPLATE" },
+    { "Material": "Carbon Steel", "Thickness": 0.250, "Gas": "O2", "Library": "MS250O2" },
+    { "Material": "Carbon Steel", "Thickness": 0.313, "Gas": "O2", "Library": "MS313O2" },
+    { "Material": "Carbon Steel", "Thickness": 0.375, "Gas": "O2", "Library": "MS375O2" },
+    { "Material": "Carbon Steel", "Thickness": 0.500, "Gas": "N2", "Library": "MS500N2" },
+    { "Material": "Carbon Steel", "Thickness": 0.500, "Gas": "O2", "Library": "MS500O2" },
+    { "Material": "Carbon Steel", "Thickness": 0.625, "Gas": "O2", "Library": "MS625O2" },
+    { "Material": "Carbon Steel", "Thickness": 0.750, "Gas": "O2", "Library": "MS750O2" },
+    { "Material": "Carbon Steel", "Thickness": 1.000, "Gas": "O2", "Library": "MS1000O2" },
+
+    { "Material": "Stainless Steel", "Thickness": 0.036, "Gas": "AIR", "Library": "SS036AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.036, "Gas": "N2", "Library": "SS036N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.048, "Gas": "AIR", "Library": "SS048AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.048, "Gas": "N2", "Library": "SS048N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.060, "Gas": "AIR", "Library": "SS060AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.060, "Gas": "N2", "Library": "SS060N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.075, "Gas": "AIR", "Library": "SS075AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.075, "Gas": "N2", "Library": "SS075N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.075, "Gas": "N2", "Library": "SS075N2FE" },
+    { "Material": "Stainless Steel", "Thickness": 0.105, "Gas": "AIR", "Library": "SS105AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.105, "Gas": "N2", "Library": "SS105N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.105, "Gas": "N2", "Library": "SS105N2FE" },
+    { "Material": "Stainless Steel", "Thickness": 0.120, "Gas": "AIR", "Library": "SS120AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.120, "Gas": "N2", "Library": "SS120N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.120, "Gas": "N2", "Library": "SS120N2FE" },
+    { "Material": "Stainless Steel", "Thickness": 0.135, "Gas": "AIR", "Library": "SS135AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.135, "Gas": "N2", "Library": "SS135N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.135, "Gas": "N2", "Library": "SS135N2FE" },
+    { "Material": "Stainless Steel", "Thickness": 0.188, "Gas": "AIR", "Library": "SS188AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.188, "Gas": "N2", "Library": "SS188N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.250, "Gas": "AIR", "Library": "SS250AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.250, "Gas": "N2", "Library": "SS250N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.313, "Gas": "N2", "Library": "SS313N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.375, "Gas": "AIR", "Library": "SS375AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.375, "Gas": "N2", "Library": "SS375N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.500, "Gas": "AIR", "Library": "SS500AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.500, "Gas": "N2", "Library": "SS500N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.625, "Gas": "N2", "Library": "SS625N2" },
+    { "Material": "Stainless Steel", "Thickness": 0.750, "Gas": "AIR", "Library": "SS750AIR" },
+    { "Material": "Stainless Steel", "Thickness": 0.750, "Gas": "N2", "Library": "SS750N2" },
+    { "Material": "Stainless Steel", "Thickness": 1.000, "Gas": "AIR", "Library": "SS1000AIR" },
+    { "Material": "Stainless Steel", "Thickness": 1.000, "Gas": "N2", "Library": "SS1000N2" },
+
+    { "Material": "Phenolic", "Thickness": 0.0, "Gas": "", "Library": "Phenolic" },
+    { "Material": "Gasket", "Thickness": 0.250, "Gas": "N2", "Library": "GASKET250N2" }
+  ],
+  "EtchLibraries": [
+    { "Gas": "AIR", "Library": "EtchAIR" },
+    { "Gas": "N2", "Library": "EtchN2" },
+    { "Gas": "N2", "Library": "EtchN2_fast" },
+    { "Gas": "N2", "Library": "Etchn2_no_mark_pvc" },
+    { "Gas": "O2", "Library": "EtchO2" },
+    { "Gas": "O2", "Library": "ETCHO2FINE" }
+  ]
+}

OpenNest.Tests/CNC/RapidEnumeratorTests.cs

@@ -0,0 +1,84 @@
+using OpenNest.CNC;
+using OpenNest.Geometry;
+using Xunit;
+
+namespace OpenNest.Tests.CNC
+{
+    public class RapidEnumeratorTests
+    {
+        [Fact]
+        public void Enumerate_AbsoluteProgram_OffsetsMotionsByBasePos()
+        {
+            var pgm = new Program(Mode.Absolute);
+            pgm.Codes.Add(new RapidMove(1, 0));
+            pgm.Codes.Add(new LinearMove(2, 0));
+            pgm.Codes.Add(new RapidMove(3, 3));
+
+            var segments = RapidEnumerator.Enumerate(pgm, basePos: new Vector(100, 200), startPos: new Vector(0, 0));
+
+            // Origin → first pierce, then interior rapid from contour end to next rapid target.
+            Assert.Equal(2, segments.Count);
+            Assert.Equal(new Vector(0, 0), segments[0].From);
+            Assert.Equal(new Vector(101, 200), segments[0].To);
+            Assert.Equal(new Vector(102, 200), segments[1].From);
+            Assert.Equal(new Vector(103, 203), segments[1].To);
+        }
+
+        [Fact]
+        public void Enumerate_IncrementalProgram_InterpretsDeltasFromBasePos()
+        {
+            // Pre-lead-in raw program: first rapid normalized to (0,0), Mode=Incremental
+            // (matches ConvertGeometry.ToProgram output).
+            var pgm = new Program(Mode.Incremental);
+            pgm.Codes.Add(new RapidMove(0, 0));
+            pgm.Codes.Add(new LinearMove(5, 0));
+            pgm.Codes.Add(new LinearMove(0, 5));
+            pgm.Codes.Add(new RapidMove(1, 1));
+
+            var segments = RapidEnumerator.Enumerate(pgm, basePos: new Vector(100, 200), startPos: new Vector(0, 0));
+
+            Assert.Equal(2, segments.Count);
+            // First rapid: plate origin → part pierce at basePos.
+            Assert.Equal(new Vector(0, 0), segments[0].From);
+            Assert.Equal(new Vector(100, 200), segments[0].To);
+            // Interior rapid: after deltas (5,0) and (0,5) from basePos, rapid delta (1,1).
+            Assert.Equal(new Vector(105, 205), segments[1].From);
+            Assert.Equal(new Vector(106, 206), segments[1].To);
+        }
+
+        [Fact]
+        public void Enumerate_SubProgramCall_RapidEndsAtAbsoluteHolePierce()
+        {
+            // Main program: lead-in rapid, a line, then a SubProgramCall for a hole.
+            // Sub-program (incremental) starts with RapidMove(radius, 0) to the hole pierce.
+            var sub = new Program(Mode.Incremental);
+            sub.Codes.Add(new RapidMove(0.5, 0));
+            sub.Codes.Add(new LinearMove(0, 0.1));
+
+            var pgm = new Program(Mode.Absolute);
+            pgm.Codes.Add(new RapidMove(0.2, 0.3));             // first pierce (perimeter lead-in)
+            pgm.Codes.Add(new LinearMove(1.0, 1.0));             // contour move
+            pgm.Codes.Add(new SubProgramCall
+            {
+                Id = 1,
+                Program = sub,
+                Offset = new Vector(2, 2),                       // hole center (drawing-local)
+            });
+
+            var basePos = new Vector(100, 200);                  // part.Location
+            var segments = RapidEnumerator.Enumerate(pgm, basePos, startPos: new Vector(0, 0));
+
+            // Expected rapids:
+            //  1. origin → first pierce (0.2+100, 0.3+200) = (100.2, 200.3)
+            //  2. end of contour (1+100, 1+200) = (101, 201) → hole pierce (2+100+0.5, 2+200) = (102.5, 202)
+            //  The sub's internal first rapid is skipped (already drawn in #2).
+            Assert.Equal(2, segments.Count);
+
+            Assert.Equal(new Vector(0, 0), segments[0].From);
+            Assert.Equal(new Vector(100.2, 200.3), segments[0].To);
+
+            Assert.Equal(new Vector(101, 201), segments[1].From);
+            Assert.Equal(new Vector(102.5, 202), segments[1].To);
+        }
+    }
+}

OpenNest.Tests/Engine/CanonicalAngleTests.cs

@@ -0,0 +1,156 @@
+using System.Linq;
+using OpenNest.CNC;
+using OpenNest.Converters;
+using OpenNest.Engine;
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Tests.Engine;
+
+public class CanonicalAngleTests
+{
+    private const double AngleTol = 0.002; // ~0.11°
+
+    private static Drawing MakeRect(double w, double h)
+    {
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, 0)));
+        return new Drawing("rect", pgm);
+    }
+
+    private static Drawing RotateCopy(Drawing src, double angle)
+    {
+        var pgm = src.Program.Clone() as OpenNest.CNC.Program;
+        pgm.Rotate(angle, pgm.BoundingBox().Center);
+        return new Drawing("rotated", pgm);
+    }
+
+    [Fact]
+    public void AxisAlignedRectangle_ReturnsZero()
+    {
+        var d = MakeRect(100, 50);
+        Assert.Equal(0.0, CanonicalAngle.Compute(d), precision: 6);
+    }
+
+    // Program.BoundingBox() has a pre-existing bug where minX/minY initialize to 0 and can
+    // only decrease, so programs whose extents stay in the positive half-plane report a
+    // too-large AABB. To validate MBR-axis-alignment without tripping that bug, extract the
+    // outer perimeter polygon and compute its true AABB from vertices.
+    private static (double length, double width) TrueAabb(OpenNest.CNC.Program pgm)
+    {
+        var entities = ConvertProgram.ToGeometry(pgm).Where(e => e.Layer != SpecialLayers.Rapid);
+        var shapes = ShapeBuilder.GetShapes(entities);
+        var outer = shapes.OrderByDescending(s => s.Area()).First();
+        var poly = outer.ToPolygonWithTolerance(0.1);
+        var minX = poly.Vertices.Min(v => v.X);
+        var maxX = poly.Vertices.Max(v => v.X);
+        var minY = poly.Vertices.Min(v => v.Y);
+        var maxY = poly.Vertices.Max(v => v.Y);
+        return (maxX - minX, maxY - minY);
+    }
+
+    [Theory]
+    [InlineData(0.3)]
+    [InlineData(0.7)]
+    [InlineData(1.2)]
+    public void Rectangle_ReturnsNegatedRotation_Modulo90(double theta)
+    {
+        var rotated = RotateCopy(MakeRect(100, 50), theta);
+        var angle = CanonicalAngle.Compute(rotated);
+
+        // Applying the returned angle should leave MBR axis-aligned.
+        var canonical = rotated.Program.Clone() as OpenNest.CNC.Program;
+        canonical.Rotate(angle, canonical.BoundingBox().Center);
+
+        var (length, width) = TrueAabb(canonical);
+        var longer = System.Math.Max(length, width);
+        var shorter = System.Math.Min(length, width);
+        Assert.InRange(longer, 100 - 0.1, 100 + 0.1);
+        Assert.InRange(shorter, 50 - 0.1, 50 + 0.1);
+    }
+
+    [Fact]
+    public void NearZeroInput_SnapsToZero()
+    {
+        var rotated = RotateCopy(MakeRect(100, 50), 0.0005);
+        Assert.Equal(0.0, CanonicalAngle.Compute(rotated), precision: 6);
+    }
+
+    [Fact]
+    public void DegeneratePolygon_ReturnsZero()
+    {
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(10, 10)));
+        var d = new Drawing("line", pgm);
+        Assert.Equal(0.0, CanonicalAngle.Compute(d), precision: 6);
+    }
+
+    [Fact]
+    public void EmptyProgram_ReturnsZero()
+    {
+        var d = new Drawing("empty", new OpenNest.CNC.Program());
+        Assert.Equal(0.0, CanonicalAngle.Compute(d), precision: 6);
+    }
+}
+
+public class DrawingCanonicalAngleWiringTests
+{
+    private static OpenNest.CNC.Program RotatedRectProgram(double w, double h, double theta)
+    {
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, 0)));
+        if (!OpenNest.Math.Tolerance.IsEqualTo(theta, 0))
+            pgm.Rotate(theta, pgm.BoundingBox().Center);
+        return pgm;
+    }
+
+    [Fact]
+    public void Constructor_ComputesAngleOnProgramAssignment()
+    {
+        var pgm = RotatedRectProgram(100, 50, 0.5);
+        var d = new Drawing("r", pgm);
+        Assert.InRange(d.Source.Angle, -0.52, -0.48);
+    }
+
+    [Fact]
+    public void SetProgram_RecomputesAngle()
+    {
+        var d = new Drawing("r", RotatedRectProgram(100, 50, 0.0));
+        Assert.Equal(0.0, d.Source.Angle, precision: 6);
+
+        d.Program = RotatedRectProgram(100, 50, 0.5);
+        Assert.InRange(d.Source.Angle, -0.52, -0.48);
+    }
+
+    [Fact]
+    public void IsCutOff_SkipsAngleComputation()
+    {
+        var d = new Drawing("cut", RotatedRectProgram(100, 50, 0.5)) { IsCutOff = true };
+        // Re-assign after flag is set so the setter observes IsCutOff.
+        d.Program = RotatedRectProgram(100, 50, 0.5);
+        Assert.Equal(0.0, d.Source.Angle, precision: 6);
+    }
+
+    [Fact]
+    public void RecomputeCanonicalAngle_UpdatesAfterMutation()
+    {
+        var d = new Drawing("r", RotatedRectProgram(100, 50, 0.0));
+        Assert.Equal(0.0, d.Source.Angle, precision: 6);
+
+        // Mutate in-place (doesn't trigger setter).
+        d.Program.Rotate(0.5, d.Program.BoundingBox().Center);
+        Assert.Equal(0.0, d.Source.Angle, precision: 6); // still stale
+
+        d.RecomputeCanonicalAngle();
+        Assert.InRange(d.Source.Angle, -0.52, -0.48);
+    }
+}

OpenNest.Tests/Engine/CanonicalFrameTests.cs

@@ -0,0 +1,84 @@
+using OpenNest.CNC;
+using OpenNest.Engine;
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Tests.Engine;
+
+public class CanonicalFrameTests
+{
+    private static Drawing MakeRect(double w, double h, double rotation)
+    {
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, 0)));
+        if (!Tolerance.IsEqualTo(rotation, 0))
+            pgm.Rotate(rotation, pgm.BoundingBox().Center);
+        return new Drawing("rect", pgm) { Source = new SourceInfo { Angle = -rotation } };
+    }
+
+    [Fact]
+    public void AsCanonicalCopy_AxisAlignsMbr()
+    {
+        var d = MakeRect(100, 50, 0.6);
+        var canonical = CanonicalFrame.AsCanonicalCopy(d);
+
+        var bb = canonical.Program.BoundingBox();
+        var longer = System.Math.Max(bb.Length, bb.Width);
+        var shorter = System.Math.Min(bb.Length, bb.Width);
+        Assert.InRange(longer, 100 - 0.1, 100 + 0.1);
+        Assert.InRange(shorter, 50 - 0.1, 50 + 0.1);
+        Assert.Equal(0.0, canonical.Source.Angle, precision: 6);
+    }
+
+    [Fact]
+    public void AsCanonicalCopy_DoesNotMutateSource()
+    {
+        var d = MakeRect(100, 50, 0.6);
+        var originalBbox = d.Program.BoundingBox();
+        var originalAngle = d.Source.Angle;
+
+        CanonicalFrame.AsCanonicalCopy(d);
+
+        var afterBbox = d.Program.BoundingBox();
+        Assert.Equal(originalBbox.Width, afterBbox.Width, precision: 6);
+        Assert.Equal(originalBbox.Length, afterBbox.Length, precision: 6);
+        Assert.Equal(originalAngle, d.Source.Angle, precision: 6);
+    }
+
+    [Fact]
+    public void FromCanonical_ComposesSourceAngleOntoRotation()
+    {
+        var d = MakeRect(100, 50, 0.0);
+        var part = new Part(d);
+        part.Rotate(0.2); // engine returned a canonical-frame part at R = 0.2
+
+        var placed = CanonicalFrame.FromCanonical(new List<Part> { part }, sourceAngle: -0.5);
+
+        // R' = R + sourceAngle = 0.2 + (-0.5) = -0.3
+        // Part.Rotation comes from Program.Rotation which is normalized to [0, 2PI),
+        // so compare after normalizing the expected value as well.
+        Assert.Single(placed);
+        Assert.Equal(Angle.NormalizeRad(-0.3), placed[0].Rotation, precision: 4);
+    }
+
+    [Fact]
+    public void RoundTrip_RestoresGeometry()
+    {
+        var d = MakeRect(100, 50, 0.4);
+        var canonical = CanonicalFrame.AsCanonicalCopy(d);
+
+        // Place a part at origin in the canonical frame.
+        var part = Part.CreateAtOrigin(canonical);
+        var canonicalBbox = part.BoundingBox;
+
+        var placed = CanonicalFrame.FromCanonical(new List<Part> { part }, d.Source.Angle);
+
+        var originalBbox = d.Program.BoundingBox();
+        Assert.Equal(originalBbox.Width, placed[0].BoundingBox.Width, precision: 2);
+        Assert.Equal(originalBbox.Length, placed[0].BoundingBox.Length, precision: 2);
+    }
+}

OpenNest.Tests/Engine/NestInvarianceTests.cs

@@ -0,0 +1,84 @@
+using OpenNest.CNC;
+using OpenNest.Engine;
+using OpenNest.Engine.BestFit;
+using OpenNest.Geometry;
+using OpenNest.Math;
+using System.Threading;
+
+namespace OpenNest.Tests.Engine;
+
+public class NestInvarianceTests
+{
+    private static OpenNest.CNC.Program MakeLShapedProgram()
+    {
+        // L-shape: 100x50 outer rect with a 50x30 notch removed from top-right.
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(100, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(100, 20)));
+        pgm.Codes.Add(new LinearMove(new Vector(50, 20)));
+        pgm.Codes.Add(new LinearMove(new Vector(50, 50)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, 50)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, 0)));
+        return pgm;
+    }
+
+    private static Drawing MakeImportedAt(double rotation)
+    {
+        var pgm = MakeLShapedProgram();
+        if (!Tolerance.IsEqualTo(rotation, 0))
+            pgm.Rotate(rotation, pgm.BoundingBox().Center);
+        return new Drawing("L", pgm);
+    }
+
+    private static Plate MakePlate() => new Plate(new Size(500, 500))
+    {
+        Quadrant = 1,
+        PartSpacing = 2,
+    };
+
+    private static int RunFillCount(Drawing drawing, Plate plate)
+    {
+        BestFitCache.Clear();
+        var engine = new DefaultNestEngine(plate);
+        var item = new NestItem { Drawing = drawing };
+        var parts = engine.Fill(item, plate.WorkArea(), progress: null, token: CancellationToken.None);
+        return parts?.Count ?? 0;
+    }
+
+    [Theory]
+    [InlineData(0.0)]
+    [InlineData(0.3)]
+    [InlineData(0.8)]
+    [InlineData(1.2)]
+    public void Fill_SameCount_AcrossImportOrientations(double theta)
+    {
+        var baseline = RunFillCount(MakeImportedAt(0.0), MakePlate());
+        var rotated = RunFillCount(MakeImportedAt(theta), MakePlate());
+
+        // Allow +/-1 tolerance for sweep quantization edge effects near plate boundaries.
+        Assert.InRange(rotated, baseline - 1, baseline + 1);
+    }
+
+    [Fact]
+    public void Fill_PlacedPartsStayWithinWorkArea_AcrossImportOrientations()
+    {
+        var plate = MakePlate();
+        var workArea = plate.WorkArea();
+
+        foreach (var theta in new[] { 0.0, 0.3, 0.8, 1.2 })
+        {
+            BestFitCache.Clear();
+            var engine = new DefaultNestEngine(plate);
+            var item = new NestItem { Drawing = MakeImportedAt(theta) };
+            var parts = engine.Fill(item, workArea, progress: null, token: CancellationToken.None);
+
+            Assert.NotNull(parts);
+            foreach (var p in parts)
+            {
+                Assert.InRange(p.BoundingBox.Left, workArea.Left - 0.5, workArea.Right + 0.5);
+                Assert.InRange(p.BoundingBox.Bottom, workArea.Bottom - 0.5, workArea.Top + 0.5);
+            }
+        }
+    }
+}

OpenNest.Tests/Geometry/BoxComparisonTests.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Collections.Generic;
+using OpenNest.Geometry;
+using Xunit;
+
+namespace OpenNest.Tests.Geometry;
+
+public class BoxComparisonTests
+{
+    [Fact]
+    public void GreaterThan_TallerBox_ReturnsTrue()
+    {
+        var tall = new Box(0, 0, 10, 20);
+        var short_ = new Box(0, 0, 10, 10);
+
+        Assert.True(tall > short_);
+        Assert.False(short_ > tall);
+    }
+
+    [Fact]
+    public void GreaterThan_SameWidthLongerBox_ReturnsTrue()
+    {
+        var longer = new Box(0, 0, 20, 10);
+        var shorter = new Box(0, 0, 10, 10);
+
+        Assert.True(longer > shorter);
+        Assert.False(shorter > longer);
+    }
+
+    [Fact]
+    public void LessThan_ShorterBox_ReturnsTrue()
+    {
+        var tall = new Box(0, 0, 10, 20);
+        var short_ = new Box(0, 0, 10, 10);
+
+        Assert.True(short_ < tall);
+        Assert.False(tall < short_);
+    }
+
+    [Fact]
+    public void GreaterThanOrEqual_EqualBoxes_ReturnsTrue()
+    {
+        var a = new Box(0, 0, 10, 20);
+        var b = new Box(0, 0, 10, 20);
+
+        Assert.True(a >= b);
+        Assert.True(b >= a);
+    }
+
+    [Fact]
+    public void LessThanOrEqual_EqualBoxes_ReturnsTrue()
+    {
+        var a = new Box(0, 0, 10, 20);
+        var b = new Box(0, 0, 10, 20);
+
+        Assert.True(a <= b);
+        Assert.True(b <= a);
+    }
+
+    [Fact]
+    public void CompareTo_TallerBox_ReturnsPositive()
+    {
+        var tall = new Box(0, 0, 10, 20);
+        var short_ = new Box(0, 0, 10, 10);
+
+        Assert.True(tall.CompareTo(short_) > 0);
+        Assert.True(short_.CompareTo(tall) < 0);
+    }
+
+    [Fact]
+    public void CompareTo_EqualBoxes_ReturnsZero()
+    {
+        var a = new Box(0, 0, 10, 20);
+        var b = new Box(0, 0, 10, 20);
+
+        Assert.Equal(0, a.CompareTo(b));
+    }
+
+    [Fact]
+    public void Sort_OrdersByWidthThenLength()
+    {
+        var boxes = new List<Box>
+        {
+            new Box(0, 0, 20, 10),
+            new Box(0, 0, 5, 30),
+            new Box(0, 0, 10, 10),
+        };
+
+        boxes.Sort();
+
+        Assert.Equal(10, boxes[0].Width);
+        Assert.Equal(10, boxes[0].Length);
+        Assert.Equal(10, boxes[1].Width);
+        Assert.Equal(20, boxes[1].Length);
+        Assert.Equal(30, boxes[2].Width);
+    }
+}

OpenNest.Tests/Geometry/EllipseConverterTests.cs

@@ -1,14 +1,19 @@
 using OpenNest.Geometry;
+using OpenNest.IO;
 using OpenNest.Math;
 using Xunit;
+using Xunit.Abstractions;
 using System.Linq;
 
 namespace OpenNest.Tests.Geometry;
 
 public class EllipseConverterTests
 {
+    private readonly ITestOutputHelper _output;
     private const double Tol = 1e-10;
 
+    public EllipseConverterTests(ITestOutputHelper output) => _output = output;
+
     [Fact]
     public void EvaluatePoint_AtZero_ReturnsMajorAxisEnd()
     {
@@ -244,6 +249,101 @@ public class EllipseConverterTests
         }
     }
 
+    [Fact]
+    public void DxfImport_ArcBoundingBoxes_Diagnostic()
+    {
+        var path = @"C:\Users\aisaacs\Desktop\11ga tab.dxf";
+        if (!System.IO.File.Exists(path)) return;
+
+        var result = Dxf.Import(path);
+        var all = (System.Collections.Generic.IEnumerable<IBoundable>)result.Entities;
+        var bbox = all.GetBoundingBox();
+        _output.WriteLine($"Overall: X={bbox.X:F4} Y={bbox.Y:F4} W={bbox.Length:F4} H={bbox.Width:F4}");
+
+        for (var i = 0; i < result.Entities.Count; i++)
+        {
+            var e = result.Entities[i];
+            var b = e.BoundingBox;
+            var flag = (b.Length > 1 || b.Width > 1) ? " ***" : "";
+            _output.WriteLine($"{i + 1,3}. {e.GetType().Name,-8} X={b.X:F4} Y={b.Y:F4} W={b.Length:F4} H={b.Width:F4}{flag}");
+        }
+    }
+
+    [Fact]
+    public void ToOpenNest_FlippedNormalZ_ProducesCorrectArcs()
+    {
+        var normal = new ACadSharp.Entities.Ellipse
+        {
+            Center = new CSMath.XYZ(-0.275, -0.245, 0),
+            MajorAxisEndPoint = new CSMath.XYZ(0.0001, 1.245, 0),
+            RadiusRatio = 0.28,
+            StartParameter = 0.017,
+            EndParameter = 1.571,
+            Normal = new CSMath.XYZ(0, 0, 1)
+        };
+
+        var flipped = new ACadSharp.Entities.Ellipse
+        {
+            Center = new CSMath.XYZ(0.275, -0.245, 0),
+            MajorAxisEndPoint = new CSMath.XYZ(-0.0001, 1.245, 0),
+            RadiusRatio = 0.28,
+            StartParameter = 0.017,
+            EndParameter = 1.571,
+            Normal = new CSMath.XYZ(0, 0, -1)
+        };
+
+        var normalArcs = normal.ToOpenNest();
+        var flippedArcs = flipped.ToOpenNest();
+
+        Assert.True(normalArcs.Count > 0);
+        Assert.True(flippedArcs.Count > 0);
+        Assert.True(normalArcs.All(e => e is Arc));
+        Assert.True(flippedArcs.All(e => e is Arc));
+
+        var normalFirst = (Arc)normalArcs.First();
+        var flippedFirst = (Arc)flippedArcs.First();
+        var normalStart = GetArcStart(normalFirst);
+        var flippedStart = GetArcStart(flippedFirst);
+
+        Assert.True(normalStart.X < 0, $"Normal ellipse start X should be negative, got {normalStart.X}");
+        Assert.True(flippedStart.X > 0, $"Flipped ellipse should bulge right, got {flippedStart.X}");
+
+        var normalBbox = GetBoundingBox(normalArcs.Cast<Arc>());
+        var flippedBbox = GetBoundingBox(flippedArcs.Cast<Arc>());
+        Assert.True(flippedBbox.minX > 0, $"Flipped ellipse should stay on positive X side, minX={flippedBbox.minX}");
+        Assert.True(normalBbox.maxX < 0, $"Normal ellipse should stay on negative X side, maxX={normalBbox.maxX}");
+    }
+
+    private static (double minX, double maxX) GetBoundingBox(IEnumerable<Arc> arcs)
+    {
+        var minX = double.MaxValue;
+        var maxX = double.MinValue;
+        foreach (var arc in arcs)
+        {
+            var s = GetArcStart(arc);
+            var e = GetArcEnd(arc);
+            minX = System.Math.Min(minX, System.Math.Min(s.X, e.X));
+            maxX = System.Math.Max(maxX, System.Math.Max(s.X, e.X));
+        }
+        return (minX, maxX);
+    }
+
+    private static Vector GetArcStart(Arc arc)
+    {
+        var angle = arc.IsReversed ? arc.EndAngle : arc.StartAngle;
+        return new Vector(
+            arc.Center.X + arc.Radius * System.Math.Cos(angle),
+            arc.Center.Y + arc.Radius * System.Math.Sin(angle));
+    }
+
+    private static Vector GetArcEnd(Arc arc)
+    {
+        var angle = arc.IsReversed ? arc.StartAngle : arc.EndAngle;
+        return new Vector(
+            arc.Center.X + arc.Radius * System.Math.Cos(angle),
+            arc.Center.Y + arc.Radius * System.Math.Sin(angle));
+    }
+
     private static double MaxDeviationFromEllipse(Arc arc, Vector ellipseCenter,
         double semiMajor, double semiMinor, double rotation, int samples)
     {

OpenNest.Tests/Geometry/WeldEndpointsTests.cs

@@ -0,0 +1,72 @@
+using System.Collections.Generic;
+using OpenNest.Geometry;
+using OpenNest.Math;
+using Xunit;
+
+namespace OpenNest.Tests.Geometry;
+
+public class WeldEndpointsTests
+{
+    [Fact]
+    public void WeldEndpoints_SnapsNearbyLineEndpoints()
+    {
+        var line1 = new Line(0, 0, 10, 0);
+        var line2 = new Line(10.0000005, 0, 20, 0);
+        var entities = new List<Entity> { line1, line2 };
+
+        ShapeBuilder.WeldEndpoints(entities, 0.000001);
+
+        Assert.True(line1.EndPoint.DistanceTo(line2.StartPoint) <= Tolerance.Epsilon);
+    }
+
+    [Fact]
+    public void WeldEndpoints_SnapsArcEndpointByAdjustingAngle()
+    {
+        var line = new Line(0, 0, 10, 0);
+        var arc = new Arc(15, 0, 5, Angle.ToRadians(180.001), Angle.ToRadians(90));
+        var entities = new List<Entity> { line, arc };
+
+        ShapeBuilder.WeldEndpoints(entities, 0.01);
+
+        var arcStart = arc.StartPoint();
+        Assert.True(line.EndPoint.DistanceTo(arcStart) <= 0.01);
+    }
+
+    [Fact]
+    public void WeldEndpoints_DoesNotWeldDistantEndpoints()
+    {
+        var line1 = new Line(0, 0, 10, 0);
+        var line2 = new Line(10.1, 0, 20, 0);
+        var entities = new List<Entity> { line1, line2 };
+
+        ShapeBuilder.WeldEndpoints(entities, 0.000001);
+
+        Assert.True(line1.EndPoint.DistanceTo(line2.StartPoint) > 0.01);
+    }
+
+    [Fact]
+    public void GetShapes_WithWeldTolerance_WeldsBeforeChaining()
+    {
+        var line1 = new Line(0, 0, 10, 0);
+        var line2 = new Line(10.0000005, 0, 10.0000005, 10);
+        var entities = new List<Entity> { line1, line2 };
+
+        var shapes = ShapeBuilder.GetShapes(entities, weldTolerance: 0.000001);
+
+        Assert.Single(shapes);
+        Assert.Equal(2, shapes[0].Entities.Count);
+    }
+
+    [Fact]
+    public void GetShapes_WithoutWeldTolerance_DefaultBehavior()
+    {
+        var line1 = new Line(0, 0, 10, 0);
+        var line2 = new Line(10, 0, 10, 10);
+        var entities = new List<Entity> { line1, line2 };
+
+        var shapes = ShapeBuilder.GetShapes(entities);
+
+        Assert.Single(shapes);
+        Assert.Equal(2, shapes[0].Entities.Count);
+    }
+}

OpenNest.Tests/IO/RemoveDuplicateArcsTests.cs

@@ -0,0 +1,96 @@
+using System.Collections.Generic;
+using System.Linq;
+using OpenNest.Geometry;
+using OpenNest.IO;
+using OpenNest.Math;
+using Xunit;
+
+namespace OpenNest.Tests.IO;
+
+public class RemoveDuplicateArcsTests
+{
+    [Fact]
+    public void RemoveDuplicateArcs_RemovesArcMatchingCircle_SameLayer()
+    {
+        var layer = new Layer("0");
+        var circle = new Circle(10, 10, 5) { Layer = layer };
+        var arc = new Arc(10, 10, 5, 0, Angle.ToRadians(90)) { Layer = layer };
+        var line = new Line(0, 0, 10, 0) { Layer = layer };
+        var entities = new List<Entity> { circle, arc, line };
+
+        CadImporter.RemoveDuplicateArcs(entities);
+
+        Assert.Equal(2, entities.Count);
+        Assert.Contains(circle, entities);
+        Assert.Contains(line, entities);
+        Assert.DoesNotContain(arc, entities);
+    }
+
+    [Fact]
+    public void RemoveDuplicateArcs_KeepsArcOnDifferentLayer()
+    {
+        var layer1 = new Layer("cut");
+        var layer2 = new Layer("etch");
+        var circle = new Circle(10, 10, 5) { Layer = layer1 };
+        var arc = new Arc(10, 10, 5, 0, Angle.ToRadians(90)) { Layer = layer2 };
+        var entities = new List<Entity> { circle, arc };
+
+        CadImporter.RemoveDuplicateArcs(entities);
+
+        Assert.Equal(2, entities.Count);
+        Assert.Contains(arc, entities);
+    }
+
+    [Fact]
+    public void RemoveDuplicateArcs_KeepsArcWithDifferentRadius()
+    {
+        var layer = new Layer("0");
+        var circle = new Circle(10, 10, 5) { Layer = layer };
+        var arc = new Arc(10, 10, 3, 0, Angle.ToRadians(90)) { Layer = layer };
+        var entities = new List<Entity> { circle, arc };
+
+        CadImporter.RemoveDuplicateArcs(entities);
+
+        Assert.Equal(2, entities.Count);
+    }
+
+    [Fact]
+    public void RemoveDuplicateArcs_KeepsArcWithDifferentCenter()
+    {
+        var layer = new Layer("0");
+        var circle = new Circle(10, 10, 5) { Layer = layer };
+        var arc = new Arc(20, 20, 5, 0, Angle.ToRadians(90)) { Layer = layer };
+        var entities = new List<Entity> { circle, arc };
+
+        CadImporter.RemoveDuplicateArcs(entities);
+
+        Assert.Equal(2, entities.Count);
+    }
+
+    [Fact]
+    public void RemoveDuplicateArcs_NoCircles_NoChange()
+    {
+        var arc = new Arc(10, 10, 5, 0, Angle.ToRadians(90));
+        var line = new Line(0, 0, 10, 0);
+        var entities = new List<Entity> { arc, line };
+
+        CadImporter.RemoveDuplicateArcs(entities);
+
+        Assert.Equal(2, entities.Count);
+    }
+
+    [Fact]
+    public void RemoveDuplicateArcs_MultipleArcsMatchOneCircle_RemovesAll()
+    {
+        var layer = new Layer("0");
+        var circle = new Circle(10, 10, 5) { Layer = layer };
+        var arc1 = new Arc(10, 10, 5, 0, Angle.ToRadians(90)) { Layer = layer };
+        var arc2 = new Arc(10, 10, 5, Angle.ToRadians(90), Angle.ToRadians(180)) { Layer = layer };
+        var entities = new List<Entity> { circle, arc1, arc2 };
+
+        CadImporter.RemoveDuplicateArcs(entities);
+
+        Assert.Single(entities);
+        Assert.Contains(circle, entities);
+    }
+}

OpenNest.Tests/Math/FractionTests.cs

@@ -0,0 +1,46 @@
+using OpenNest.Math;
+using Xunit;
+
+namespace OpenNest.Tests.Math;
+
+public class FractionTests
+{
+    [Theory]
+    [InlineData("3/8", 0.375)]
+    [InlineData("1 3/4", 1.75)]
+    [InlineData("1-3/4", 1.75)]
+    [InlineData("1/2", 0.5)]
+    public void Parse_ValidFraction_ReturnsDouble(string input, double expected)
+    {
+        var result = Fraction.Parse(input);
+
+        Assert.Equal(expected, result, 8);
+    }
+
+    [Theory]
+    [InlineData("3/8", true)]
+    [InlineData("abc", false)]
+    [InlineData("1 3/4", true)]
+    public void IsValid_ReturnsExpected(string input, bool expected)
+    {
+        Assert.Equal(expected, Fraction.IsValid(input));
+    }
+
+    [Fact]
+    public void TryParse_InvalidInput_ReturnsFalse()
+    {
+        var result = Fraction.TryParse("abc", out var value);
+
+        Assert.False(result);
+        Assert.Equal(0, value);
+    }
+
+    [Fact]
+    public void ReplaceFractionsWithDecimals_ReplacesFractionInString()
+    {
+        var result = Fraction.ReplaceFractionsWithDecimals("length is 1 3/4 inches");
+
+        Assert.Contains("1.75", result);
+        Assert.DoesNotContain("3/4", result);
+    }
+}

OpenNest.Tests/Shapes/NgonShapeTests.cs

@@ -0,0 +1,51 @@
+using OpenNest.Shapes;
+
+namespace OpenNest.Tests.Shapes;
+
+public class NgonShapeTests
+{
+    [Fact]
+    public void GetDrawing_Octagon_BoundingBoxFitsWithinExpectedSize()
+    {
+        var shape = new NgonShape { Sides = 8, Width = 20 };
+        var drawing = shape.GetDrawing();
+
+        var bbox = drawing.Program.BoundingBox();
+        // Corner-to-corner is larger than flat-to-flat
+        Assert.True(bbox.Width >= 20 - 0.01);
+        Assert.True(bbox.Length >= 20 - 0.01);
+        // But should not be wildly larger (corner-to-corner ~ width / cos(22.5deg) ~ width * 1.0824)
+        Assert.True(bbox.Width < 22);
+        Assert.True(bbox.Length < 22);
+    }
+
+    [Theory]
+    [InlineData(3)]
+    [InlineData(4)]
+    [InlineData(5)]
+    [InlineData(6)]
+    [InlineData(8)]
+    [InlineData(12)]
+    public void GetDrawing_HasOneLinearMovePerSide(int sides)
+    {
+        var shape = new NgonShape { Sides = sides, Width = 20 };
+        var drawing = shape.GetDrawing();
+
+        var moves = drawing.Program.Codes
+            .OfType<OpenNest.CNC.LinearMove>()
+            .Count();
+        Assert.Equal(sides, moves);
+    }
+
+    [Fact]
+    public void GetDrawing_ClampsSidesBelowThreeToTriangle()
+    {
+        var shape = new NgonShape { Sides = 2, Width = 20 };
+        var drawing = shape.GetDrawing();
+
+        var moves = drawing.Program.Codes
+            .OfType<OpenNest.CNC.LinearMove>()
+            .Count();
+        Assert.Equal(3, moves);
+    }
+}

OpenNest.Tests/Shapes/OctagonShapeTests.cs

@@ -1,34 +0,0 @@
-using OpenNest.Shapes;
-
-namespace OpenNest.Tests.Shapes;
-
-public class OctagonShapeTests
-{
-    [Fact]
-    public void GetDrawing_BoundingBoxFitsWithinExpectedSize()
-    {
-        var shape = new OctagonShape { Width = 20 };
-        var drawing = shape.GetDrawing();
-
-        var bbox = drawing.Program.BoundingBox();
-        // Corner-to-corner is larger than flat-to-flat
-        Assert.True(bbox.Width >= 20 - 0.01);
-        Assert.True(bbox.Length >= 20 - 0.01);
-        // But should not be wildly larger (corner-to-corner ~ width / cos(22.5deg) ~ width * 1.0824)
-        Assert.True(bbox.Width < 22);
-        Assert.True(bbox.Length < 22);
-    }
-
-    [Fact]
-    public void GetDrawing_HasEightEdges()
-    {
-        var shape = new OctagonShape { Width = 20 };
-        var drawing = shape.GetDrawing();
-
-        // An octagon program should have 8 linear moves (one per edge)
-        var moves = drawing.Program.Codes
-            .OfType<OpenNest.CNC.LinearMove>()
-            .Count();
-        Assert.Equal(8, moves);
-    }
-}

OpenNest.Training/Program.cs

@@ -89,8 +89,10 @@ int RunDataCollection(string dir, string dbPath, string saveDir, double s, strin
         new Size(48, 24), new Size(120, 10)
     };
 
-    var dxfFiles = Directory.GetFiles(dir, "*.dxf", SearchOption.AllDirectories);
-    Console.WriteLine($"Found {dxfFiles.Length} DXF files");
+    var dxfFiles = Directory.GetFiles(dir, "*.dxf", SearchOption.AllDirectories)
+        .Concat(Directory.GetFiles(dir, "*.dwg", SearchOption.AllDirectories))
+        .ToArray();
+    Console.WriteLine($"Found {dxfFiles.Length} CAD files");
     var resolvedDb = dbPath.EndsWith(".db", StringComparison.OrdinalIgnoreCase) ? dbPath : dbPath + ".db";
     Console.WriteLine($"Database: {Path.GetFullPath(resolvedDb)}");
     Console.WriteLine($"Sheet sizes: {sheetSuite.Length} configurations");

OpenNest/ArchUnits.cs

@@ -1,4 +1,4 @@
-using OpenNest.IO.Bom;
+using OpenNest.Math;
 using System;
 using System.Drawing;
 using System.Text;

OpenNest/ColorScheme.cs

@@ -13,10 +13,13 @@ namespace OpenNest
         private Color edgeSpacingColor;
         private Color previewPartColor;
 
-        public static Color[] PartColors => Drawing.PartColors;
+        public string Name { get; set; } = "Unnamed";
+
+        public Color[] PartColors { get; set; } = Drawing.PartColors;
 
         public static readonly ColorScheme Default = new ColorScheme
         {
+            Name = "Classic",
             BackgroundColor = Color.DarkGray,
             LayoutOutlineColor = Color.Gray,
             LayoutFillColor = Color.WhiteSmoke,

OpenNest/ColorSchemeRegistry.cs

@@ -0,0 +1,203 @@
+using OpenNest.Forms;
+using OpenNest.Properties;
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.IO;
+using System.Linq;
+using System.Windows.Forms;
+
+namespace OpenNest
+{
+    public static class ColorSchemeRegistry
+    {
+        private static readonly Dictionary<string, ColorScheme> builtIns =
+            new(StringComparer.OrdinalIgnoreCase)
+            {
+                ["Classic"] = BuildClassic(),
+                ["Pastel"] = BuildPastel(),
+                ["Dark"] = BuildDark()
+            };
+
+        private static List<ColorScheme> diskCache;
+
+        public static IEnumerable<ColorScheme> AllSchemes
+        {
+            get
+            {
+                diskCache ??= LoadDiskSchemes().ToList();
+                return builtIns.Values.Concat(diskCache);
+            }
+        }
+
+        public static void Refresh() => diskCache = null;
+
+        public static ColorScheme Get(string name)
+        {
+            if (string.IsNullOrWhiteSpace(name))
+                return builtIns["Classic"];
+
+            var hit = AllSchemes.FirstOrDefault(
+                s => string.Equals(s.Name, name, StringComparison.OrdinalIgnoreCase));
+            return hit ?? builtIns["Classic"];
+        }
+
+        public static void ApplyActiveFromSettings()
+        {
+            var name = Settings.Default.ActiveColorScheme;
+            var scheme = Get(name);
+            Apply(scheme);
+        }
+
+        public static void Apply(ColorScheme scheme)
+        {
+            var d = ColorScheme.Default;
+            d.Name = scheme.Name;
+            d.BackgroundColor = scheme.BackgroundColor;
+            d.LayoutOutlineColor = scheme.LayoutOutlineColor;
+            d.LayoutFillColor = scheme.LayoutFillColor;
+            d.BoundingBoxColor = scheme.BoundingBoxColor;
+            d.RapidColor = scheme.RapidColor;
+            d.OriginColor = scheme.OriginColor;
+            d.EdgeSpacingColor = scheme.EdgeSpacingColor;
+            d.PreviewPartColor = scheme.PreviewPartColor;
+            d.PartColors = scheme.PartColors;
+
+            Drawing.PartColors = scheme.PartColors;
+
+            RecolorOpenNests(scheme.PartColors);
+        }
+
+        private static void RecolorOpenNests(Color[] palette)
+        {
+            foreach (Form f in Application.OpenForms)
+            {
+                if (f is not EditNestForm enf)
+                    continue;
+
+                var i = 0;
+                foreach (var drawing in enf.Nest.Drawings)
+                {
+                    if (drawing.IsCutOff)
+                        continue;
+                    drawing.Color = palette[i % palette.Length];
+                    i++;
+                }
+            }
+        }
+
+        private static IEnumerable<ColorScheme> LoadDiskSchemes()
+        {
+            var dir = Path.Combine(AppContext.BaseDirectory, "Schemes");
+            if (!Directory.Exists(dir))
+                yield break;
+
+            foreach (var path in Directory.GetFiles(dir, "*.json"))
+            {
+                ColorScheme scheme;
+                try
+                {
+                    scheme = ColorSchemeSerializer.Deserialize(File.ReadAllText(path));
+                }
+                catch
+                {
+                    continue;
+                }
+                if (!builtIns.ContainsKey(scheme.Name))
+                    yield return scheme;
+            }
+        }
+
+        private static ColorScheme BuildClassic() => new ColorScheme
+        {
+            Name = "Classic",
+            BackgroundColor = Color.DarkGray,
+            LayoutOutlineColor = Color.Gray,
+            LayoutFillColor = Color.WhiteSmoke,
+            BoundingBoxColor = Color.FromArgb(128, 128, 255),
+            RapidColor = Color.DodgerBlue,
+            OriginColor = Color.Gray,
+            EdgeSpacingColor = Color.FromArgb(180, 180, 180),
+            PreviewPartColor = Color.FromArgb(255, 140, 0),
+            PartColors = new[]
+            {
+                Color.FromArgb(205, 92, 92),
+                Color.FromArgb(148, 103, 189),
+                Color.FromArgb(75, 180, 175),
+                Color.FromArgb(210, 190, 75),
+                Color.FromArgb(190, 85, 175),
+                Color.FromArgb(185, 115, 85),
+                Color.FromArgb(120, 100, 190),
+                Color.FromArgb(200, 100, 140),
+                Color.FromArgb(80, 175, 155),
+                Color.FromArgb(195, 160, 85),
+                Color.FromArgb(175, 95, 160),
+                Color.FromArgb(215, 130, 130),
+            }
+        };
+
+        private static ColorScheme BuildPastel() => new ColorScheme
+        {
+            Name = "Pastel",
+            BackgroundColor = Color.FromArgb(70, 75, 85),
+            LayoutOutlineColor = Color.FromArgb(180, 180, 190),
+            LayoutFillColor = Color.FromArgb(245, 245, 248),
+            BoundingBoxColor = Color.FromArgb(128, 128, 255),
+            RapidColor = Color.DodgerBlue,
+            OriginColor = Color.FromArgb(160, 160, 160),
+            EdgeSpacingColor = Color.FromArgb(200, 200, 210),
+            PreviewPartColor = Color.FromArgb(255, 140, 0),
+            PartColors = new[]
+            {
+                Color.FromArgb(122, 179, 209), Color.FromArgb(254, 229, 174),
+                Color.FromArgb(143, 177, 229), Color.FromArgb(167, 172, 227),
+                Color.FromArgb(216, 249, 195), Color.FromArgb(209, 168, 216),
+                Color.FromArgb(222, 157, 190), Color.FromArgb(176, 255, 240),
+                Color.FromArgb(235, 205, 153), Color.FromArgb(177, 225, 180),
+                Color.FromArgb(125, 202, 241), Color.FromArgb(187, 206, 151),
+                Color.FromArgb(251, 175, 190), Color.FromArgb(129, 226, 227),
+                Color.FromArgb(255, 253, 207), Color.FromArgb(235, 205, 255),
+                Color.FromArgb(255, 197, 168), Color.FromArgb(116, 213, 234),
+                Color.FromArgb(190, 169, 122), Color.FromArgb(213, 159, 135),
+                Color.FromArgb(124, 184, 155), Color.FromArgb(255, 189, 214),
+                Color.FromArgb(146, 222, 255), Color.FromArgb(177, 173, 125),
+                Color.FromArgb(177, 166, 202), Color.FromArgb(197, 208, 255),
+                Color.FromArgb(255, 209, 243), Color.FromArgb(210, 255, 237),
+                Color.FromArgb(255, 237, 204), Color.FromArgb(167, 233, 255),
+                Color.FromArgb(182, 220, 255), Color.FromArgb(159, 177, 142),
+                Color.FromArgb(190, 248, 255), Color.FromArgb(187, 169, 136),
+                Color.FromArgb(199, 162, 168), Color.FromArgb(250, 255, 239),
+                Color.FromArgb(222, 233, 255), Color.FromArgb(255, 234, 225),
+                Color.FromArgb(240, 249, 255), Color.FromArgb(152, 176, 176),
+            }
+        };
+
+        private static ColorScheme BuildDark() => new ColorScheme
+        {
+            Name = "Dark",
+            BackgroundColor = Color.FromArgb(30, 30, 34),
+            LayoutOutlineColor = Color.FromArgb(90, 90, 95),
+            LayoutFillColor = Color.FromArgb(50, 50, 55),
+            BoundingBoxColor = Color.FromArgb(100, 160, 220),
+            RapidColor = Color.FromArgb(255, 200, 50),
+            OriginColor = Color.FromArgb(120, 120, 130),
+            EdgeSpacingColor = Color.FromArgb(90, 90, 100),
+            PreviewPartColor = Color.FromArgb(255, 170, 60),
+            PartColors = new[]
+            {
+                Color.FromArgb(255, 85, 85),   // Neon Red
+                Color.FromArgb(80, 220, 255),  // Electric Cyan
+                Color.FromArgb(255, 200, 50),  // Amber
+                Color.FromArgb(130, 255, 130), // Lime Green
+                Color.FromArgb(255, 130, 220), // Hot Pink
+                Color.FromArgb(255, 165, 70),  // Tangerine
+                Color.FromArgb(100, 180, 255), // Sky Blue
+                Color.FromArgb(200, 160, 255), // Lavender
+                Color.FromArgb(50, 230, 180),  // Mint
+                Color.FromArgb(255, 255, 100), // Lemon
+                Color.FromArgb(255, 120, 120), // Salmon
+                Color.FromArgb(140, 230, 255), // Ice Blue
+            }
+        };
+    }
+}

OpenNest/ColorSchemeSerializer.cs

@@ -0,0 +1,84 @@
+using System.Drawing;
+using System.Globalization;
+using System.Linq;
+using System.Text.Json;
+
+namespace OpenNest
+{
+    public static class ColorSchemeSerializer
+    {
+        private static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            WriteIndented = true,
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+        };
+
+        public static string Serialize(ColorScheme scheme)
+        {
+            var dto = new ColorSchemeDto
+            {
+                Name = scheme.Name,
+                BackgroundColor = ToHex(scheme.BackgroundColor),
+                LayoutOutlineColor = ToHex(scheme.LayoutOutlineColor),
+                LayoutFillColor = ToHex(scheme.LayoutFillColor),
+                BoundingBoxColor = ToHex(scheme.BoundingBoxColor),
+                RapidColor = ToHex(scheme.RapidColor),
+                OriginColor = ToHex(scheme.OriginColor),
+                EdgeSpacingColor = ToHex(scheme.EdgeSpacingColor),
+                PreviewPartColor = ToHex(scheme.PreviewPartColor),
+                PartColors = scheme.PartColors.Select(ToHex).ToArray()
+            };
+            return JsonSerializer.Serialize(dto, JsonOptions);
+        }
+
+        public static ColorScheme Deserialize(string json)
+        {
+            var dto = JsonSerializer.Deserialize<ColorSchemeDto>(json, JsonOptions)
+                ?? throw new JsonException("ColorScheme JSON was null");
+
+            return new ColorScheme
+            {
+                Name = dto.Name ?? "Unnamed",
+                BackgroundColor = FromHex(dto.BackgroundColor),
+                LayoutOutlineColor = FromHex(dto.LayoutOutlineColor),
+                LayoutFillColor = FromHex(dto.LayoutFillColor),
+                BoundingBoxColor = FromHex(dto.BoundingBoxColor),
+                RapidColor = FromHex(dto.RapidColor),
+                OriginColor = FromHex(dto.OriginColor),
+                EdgeSpacingColor = FromHex(dto.EdgeSpacingColor),
+                PreviewPartColor = FromHex(dto.PreviewPartColor),
+                PartColors = (dto.PartColors ?? new string[0]).Select(FromHex).ToArray()
+            };
+        }
+
+        private static string ToHex(Color c) =>
+            "#" + c.R.ToString("X2") + c.G.ToString("X2") + c.B.ToString("X2");
+
+        private static Color FromHex(string hex)
+        {
+            if (string.IsNullOrWhiteSpace(hex))
+                return Color.Black;
+            var h = hex.TrimStart('#');
+            if (h.Length < 6)
+                return Color.Black;
+            var r = byte.Parse(h.Substring(0, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            var g = byte.Parse(h.Substring(2, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            var b = byte.Parse(h.Substring(4, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            return Color.FromArgb(r, g, b);
+        }
+
+        private class ColorSchemeDto
+        {
+            public string Name { get; set; }
+            public string BackgroundColor { get; set; }
+            public string LayoutOutlineColor { get; set; }
+            public string LayoutFillColor { get; set; }
+            public string BoundingBoxColor { get; set; }
+            public string RapidColor { get; set; }
+            public string OriginColor { get; set; }
+            public string EdgeSpacingColor { get; set; }
+            public string PreviewPartColor { get; set; }
+            public string[] PartColors { get; set; }
+        }
+    }
+}

OpenNest/Controls/CadText.cs

@@ -0,0 +1,16 @@
+using System.Drawing;
+using OpenNest.Geometry;
+
+namespace OpenNest.Controls
+{
+    public class CadText
+    {
+        public Vector Position { get; set; }
+        public string Value { get; set; }
+        public double Height { get; set; }
+        public double Rotation { get; set; }
+        public string LayerName { get; set; }
+        public StringAlignment HAlign { get; set; }
+        public StringAlignment VAlign { get; set; }
+    }
+}

OpenNest/Controls/CuttingPanel.cs

@@ -24,6 +24,8 @@ namespace OpenNest.Controls
 
         private readonly CheckBox chkTabsEnabled;
         private readonly NumericUpDown nudTabWidth;
+        private readonly RadioButton rbTabAll;
+        private readonly RadioButton rbAutoTab;
         private readonly NumericUpDown nudAutoTabMin;
         private readonly NumericUpDown nudAutoTabMax;
         private readonly NumericUpDown nudPierceClearance;
@@ -112,7 +114,7 @@ namespace OpenNest.Controls
             {
                 HeaderText = "Tabs",
                 Dock = DockStyle.Top,
-                ExpandedHeight = 120,
+                ExpandedHeight = 160,
                 IsExpanded = false
             };
 
@@ -122,44 +124,78 @@ namespace OpenNest.Controls
                 Location = new Point(12, 4),
                 AutoSize = true
             };
-            chkTabsEnabled.CheckedChanged += (s, e) =>
-            {
-                nudTabWidth.Enabled = chkTabsEnabled.Checked;
-                OnParametersChanged();
-            };
             tabsPanel.ContentPanel.Controls.Add(chkTabsEnabled);
 
             tabsPanel.ContentPanel.Controls.Add(new Label
             {
-                Text = "Width:",
+                Text = "Tab Size:",
                 Location = new Point(160, 6),
                 AutoSize = true
             });
 
-            nudTabWidth = CreateNumeric(215, 3, 0.25, 0.0625);
+            nudTabWidth = CreateNumeric(225, 3, 0.25, 0.0625);
             nudTabWidth.Enabled = false;
             tabsPanel.ContentPanel.Controls.Add(nudTabWidth);
 
+            rbTabAll = new RadioButton
+            {
+                Text = "Tab all parts",
+                Location = new Point(28, 28),
+                AutoSize = true,
+                Enabled = false,
+                Checked = true
+            };
+            tabsPanel.ContentPanel.Controls.Add(rbTabAll);
+
+            rbAutoTab = new RadioButton
+            {
+                Text = "Auto-tab when smallest part dimension is between:",
+                Location = new Point(28, 50),
+                AutoSize = true,
+                Enabled = false
+            };
+            tabsPanel.ContentPanel.Controls.Add(rbAutoTab);
+
             tabsPanel.ContentPanel.Controls.Add(new Label
             {
-                Text = "Auto-Tab Min Size:",
-                Location = new Point(12, 32),
+                Text = "Min:",
+                Location = new Point(44, 76),
                 AutoSize = true
             });
 
-            nudAutoTabMin = CreateNumeric(140, 29, 0, 0.0625);
+            nudAutoTabMin = CreateNumeric(77, 73, 0, 0.0625);
+            nudAutoTabMin.Enabled = false;
             tabsPanel.ContentPanel.Controls.Add(nudAutoTabMin);
 
             tabsPanel.ContentPanel.Controls.Add(new Label
             {
-                Text = "Auto-Tab Max Size:",
-                Location = new Point(12, 58),
+                Text = "Max:",
+                Location = new Point(210, 76),
                 AutoSize = true
             });
 
-            nudAutoTabMax = CreateNumeric(140, 55, 0, 0.0625);
+            nudAutoTabMax = CreateNumeric(245, 73, 0, 0.0625);
+            nudAutoTabMax.Enabled = false;
             tabsPanel.ContentPanel.Controls.Add(nudAutoTabMax);
 
+            chkTabsEnabled.CheckedChanged += (s, e) =>
+            {
+                var enabled = chkTabsEnabled.Checked;
+                nudTabWidth.Enabled = enabled;
+                rbTabAll.Enabled = enabled;
+                rbAutoTab.Enabled = enabled;
+                nudAutoTabMin.Enabled = enabled && rbAutoTab.Checked;
+                nudAutoTabMax.Enabled = enabled && rbAutoTab.Checked;
+                OnParametersChanged();
+            };
+
+            rbTabAll.CheckedChanged += (s, e) =>
+            {
+                nudAutoTabMin.Enabled = chkTabsEnabled.Checked && rbAutoTab.Checked;
+                nudAutoTabMax.Enabled = chkTabsEnabled.Checked && rbAutoTab.Checked;
+                OnParametersChanged();
+            };
+
             // Pierce section
             var piercePanel = new CollapsiblePanel
             {
@@ -246,13 +282,13 @@ namespace OpenNest.Controls
                 InternalLeadOut = BuildLeadOut(cboInternalLeadOut, pnlInternalLeadOut),
                 ArcCircleLeadIn = BuildLeadIn(cboArcCircleLeadIn, pnlArcCircleLeadIn),
                 ArcCircleLeadOut = BuildLeadOut(cboArcCircleLeadOut, pnlArcCircleLeadOut),
-                TabsEnabled = chkTabsEnabled.Checked,
+                TabsEnabled = chkTabsEnabled.Checked && rbTabAll.Checked,
                 TabConfig = new NormalTab { Size = (double)nudTabWidth.Value },
                 PierceClearance = (double)nudPierceClearance.Value,
                 RoundLeadInAngles = chkRoundLeadInAngles.Checked,
                 LeadInAngleIncrement = (double)nudLeadInAngleIncrement.Value,
-                AutoTabMinSize = (double)nudAutoTabMin.Value,
-                AutoTabMaxSize = (double)nudAutoTabMax.Value
+                AutoTabMinSize = chkTabsEnabled.Checked && rbAutoTab.Checked ? (double)nudAutoTabMin.Value : 0,
+                AutoTabMaxSize = chkTabsEnabled.Checked && rbAutoTab.Checked ? (double)nudAutoTabMax.Value : 0
             };
         }
 
@@ -267,7 +303,10 @@ namespace OpenNest.Controls
             LoadLeadIn(cboArcCircleLeadIn, pnlArcCircleLeadIn, p.ArcCircleLeadIn);
             LoadLeadOut(cboArcCircleLeadOut, pnlArcCircleLeadOut, p.ArcCircleLeadOut);
 
-            chkTabsEnabled.Checked = p.TabsEnabled;
+            var hasAutoTab = p.AutoTabMinSize > 0 || p.AutoTabMaxSize > 0;
+            chkTabsEnabled.Checked = p.TabsEnabled || hasAutoTab;
+            rbAutoTab.Checked = hasAutoTab;
+            rbTabAll.Checked = !hasAutoTab;
             if (p.TabConfig != null)
                 nudTabWidth.Value = (decimal)p.TabConfig.Size;
             nudPierceClearance.Value = (decimal)p.PierceClearance;

OpenNest/Controls/EntityView.cs

@@ -29,12 +29,14 @@ namespace OpenNest.Controls
         public List<Entity> SimplifierToleranceRight { get; set; }
         public List<Entity> OriginalEntities { get; set; }
         public bool ShowEntityLabels { get; set; }
+        public List<CadText> Texts { get; set; } = new List<CadText>();
 
         private readonly Pen gridPen = new Pen(Color.FromArgb(70, 70, 70));
         private readonly Dictionary<int, Pen> penCache = new Dictionary<int, Pen>();
         private readonly Font labelFont = new Font("Segoe UI", 7f);
         private readonly SolidBrush labelBrush = new SolidBrush(Color.FromArgb(220, 255, 255, 200));
         private readonly SolidBrush labelBackBrush = new SolidBrush(Color.FromArgb(33, 40, 48));
+        private readonly SolidBrush textBrush = new SolidBrush(Color.FromArgb(180, 200, 200, 200));
 
         public event EventHandler<Line> LinePicked;
         public event EventHandler PickCancelled;
@@ -116,6 +118,8 @@ namespace OpenNest.Controls
                 DrawEntity(e.Graphics, entity, pen);
             }
 
+            DrawTexts(e.Graphics);
+
             if (ShowEntityLabels)
                 DrawEntityLabels(e.Graphics);
 
@@ -408,6 +412,7 @@ namespace OpenNest.Controls
                 labelFont.Dispose();
                 labelBrush.Dispose();
                 labelBackBrush.Dispose();
+                textBrush.Dispose();
             }
             base.Dispose(disposing);
         }
@@ -474,6 +479,34 @@ namespace OpenNest.Controls
                 diameter);
         }
 
+        private void DrawTexts(Graphics g)
+        {
+            if (Texts == null || Texts.Count == 0)
+                return;
+
+            using var sf = new StringFormat();
+
+            foreach (var text in Texts)
+            {
+                var pos = PointWorldToGraph(text.Position);
+                var fontSize = LengthWorldToGui(text.Height);
+                if (fontSize < 2f) continue;
+
+                var state = g.Save();
+                g.TranslateTransform(pos.X, pos.Y);
+
+                if (text.Rotation != 0)
+                    g.RotateTransform((float)OpenNest.Math.Angle.ToDegrees(text.Rotation));
+
+                sf.Alignment = text.HAlign;
+                sf.LineAlignment = text.VAlign;
+
+                using var font = new Font("Segoe UI", fontSize, GraphicsUnit.Pixel);
+                g.DrawString(text.Value, font, textBrush, 0, 0, sf);
+                g.Restore(state);
+            }
+        }
+
         private void DrawPoint(Graphics g, Vector pt, Pen pen)
         {
             var pt1 = PointWorldToGraph(pt);

OpenNest/Controls/FileListControl.cs

@@ -22,6 +22,7 @@ namespace OpenNest.Controls
         public HashSet<Guid> SuppressedEntityIds { get; set; }
         public Box Bounds { get; set; }
         public int EntityCount { get; set; }
+        public List<CadText> Texts { get; set; } = new();
     }
 
     public class FileListControl : Control

OpenNest/Controls/PlateRenderer.cs

@@ -385,85 +385,20 @@ namespace OpenNest.Controls
 
         private void DrawRapids(Graphics g)
         {
+            var pen = view.ColorScheme.RapidPen;
             var pos = new Vector(0, 0);
 
             for (var i = 0; i < view.Plate.Parts.Count; ++i)
             {
                 var part = view.Plate.Parts[i];
-                var pgm = part.Program;
+                var segments = RapidEnumerator.Enumerate(part.Program, part.Location, pos);
 
-                var piercePoint = GetFirstPiercePoint(pgm, part.Location);
-                DrawLine(g, pos, piercePoint, view.ColorScheme.RapidPen);
-
-                pos = piercePoint;
-                DrawRapids(g, pgm, part.Location, ref pos, skipFirstRapid: true);
-            }
-        }
-
-        private static Vector GetFirstPiercePoint(Program pgm, Vector partLocation)
-        {
-            for (var i = 0; i < pgm.Length; i++)
-            {
-                if (pgm[i] is SubProgramCall call && call.Program != null)
-                    return GetFirstPiercePoint(call.Program, partLocation + call.Offset);
-
-                if (pgm[i] is Motion motion)
+                foreach (var seg in segments)
                 {
-                    return motion.EndPoint + partLocation;
+                    DrawLine(g, seg.From, seg.To, pen);
+                    pos = seg.To;
                 }
             }
-            return partLocation;
-        }
-
-        private void DrawRapids(Graphics g, Program pgm, Vector basePos, ref Vector pos, bool skipFirstRapid = false)
-        {
-            var firstRapidSkipped = false;
-
-            for (var i = 0; i < pgm.Length; ++i)
-            {
-                var code = pgm[i];
-
-                if (code is SubProgramCall { Program: { } program } call)
-                {
-                    // A SubProgramCall is a coordinate-frame shift, not a physical
-                    // rapid to the hole center. The Cincinnati post emits it as a
-                    // G52 bracket, so the physical rapid is the sub-program's first
-                    // motion, which goes straight from here to the lead-in pierce.
-                    // Look ahead for that pierce point and draw the direct rapid,
-                    // then recurse with skipFirstRapid so the sub doesn't also draw
-                    // its first rapid on top. See docs/cincinnati-post-output.md.
-                    var holeBase = basePos + call.Offset;
-                    var firstPierce = GetFirstPiercePoint(program, holeBase);
-
-                    if (ShouldDrawRapid(skipFirstRapid, ref firstRapidSkipped))
-                        DrawLine(g, pos, firstPierce, view.ColorScheme.RapidPen);
-
-                    var subPos = holeBase;
-                    DrawRapids(g, program, holeBase, ref subPos, skipFirstRapid: true);
-                    pos = subPos;
-                }
-                else if (code is Motion motion)
-                {
-                    var endpt = pgm.Mode == Mode.Incremental
-                        ? motion.EndPoint + pos
-                        : motion.EndPoint;
-
-                    if (code.Type == CodeType.RapidMove && ShouldDrawRapid(skipFirstRapid, ref firstRapidSkipped))
-                        DrawLine(g, pos, endpt, view.ColorScheme.RapidPen);
-
-                    pos = endpt;
-                }
-            }
-        }
-
-        private static bool ShouldDrawRapid(bool skipFirstRapid, ref bool firstRapidSkipped)
-        {
-            if (skipFirstRapid && !firstRapidSkipped)
-            {
-                firstRapidSkipped = true;
-                return false;
-            }
-            return true;
         }
 
         private void DrawAllPiercePoints(Graphics g)

OpenNest/Controls/PlateView.cs

@@ -464,6 +464,9 @@ namespace OpenNest.Controls
 
         protected override void OnPaint(PaintEventArgs e)
         {
+            if (BackColor != ColorScheme.BackgroundColor)
+                BackColor = ColorScheme.BackgroundColor;
+
             e.Graphics.SmoothingMode = SmoothingMode.HighSpeed;
 
             if (DrawOrigin)

OpenNest/Forms/BomImportForm.cs

@@ -165,7 +165,8 @@ namespace OpenNest.Forms
                 else
                 {
                     var lookupName = item.FileName;
-                    if (lookupName.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase))
+                    if (lookupName.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase)
+                        || lookupName.EndsWith(".dwg", StringComparison.OrdinalIgnoreCase))
                         lookupName = Path.GetFileNameWithoutExtension(lookupName);
 
                     if (matchedPaths.TryGetValue(lookupName, out var dxfPath))

OpenNest/Forms/CadConverterForm.cs

@@ -92,7 +92,8 @@ namespace OpenNest.Forms
                     Customer = string.Empty,
                     Bends = result.Bends,
                     Bounds = result.Bounds,
-                    EntityCount = result.Entities.Count
+                    EntityCount = result.Entities.Count,
+                    Texts = ExtractTexts(result.Document),
                 };
 
                 if (InvokeRequired)
@@ -152,6 +153,7 @@ namespace OpenNest.Forms
             entityView1.Entities.Clear();
             entityView1.Entities.AddRange(item.Entities);
             entityView1.Bends = item.Bends ?? new List<Bend>();
+            entityView1.Texts = item.Texts ?? new List<CadText>();
 
             item.Entities.ForEach(e => e.IsVisible = true);
             if (item.Entities.Any(e => e.Layer != null))
@@ -473,7 +475,8 @@ namespace OpenNest.Forms
             {
                 var files = (string[])e.Data.GetData(DataFormats.FileDrop);
                 var dxfFiles = files.Where(f =>
-                    f.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase)).ToArray();
+                    f.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase) ||
+                    f.EndsWith(".dwg", StringComparison.OrdinalIgnoreCase)).ToArray();
                 if (dxfFiles.Length > 0)
                     AddFiles(dxfFiles);
             }
@@ -803,6 +806,102 @@ namespace OpenNest.Forms
 
         #endregion
 
+        private static List<CadText> ExtractTexts(ACadSharp.CadDocument doc)
+        {
+            var texts = new List<CadText>();
+            if (doc == null) return texts;
+
+            foreach (var entity in doc.Entities)
+            {
+                switch (entity)
+                {
+                    case ACadSharp.Entities.MText mtext:
+                        var (mh, mv) = MapAttachmentPoint(mtext.AttachmentPoint);
+                        texts.Add(new CadText
+                        {
+                            Position = new Vector(mtext.InsertPoint.X, mtext.InsertPoint.Y),
+                            Value = ReplaceControlCodes(StripMTextFormatting(mtext.Value)),
+                            Height = mtext.Height,
+                            Rotation = mtext.Rotation,
+                            LayerName = mtext.Layer?.Name,
+                            HAlign = mh,
+                            VAlign = mv,
+                        });
+                        break;
+
+                    case ACadSharp.Entities.TextEntity text:
+                        var useAlignment = text.HorizontalAlignment != 0
+                            || text.VerticalAlignment != 0;
+                        var pt = useAlignment ? text.AlignmentPoint : text.InsertPoint;
+                        var ha = text.HorizontalAlignment switch
+                        {
+                            ACadSharp.Entities.TextHorizontalAlignment.Center => System.Drawing.StringAlignment.Center,
+                            ACadSharp.Entities.TextHorizontalAlignment.Right => System.Drawing.StringAlignment.Far,
+                            _ => System.Drawing.StringAlignment.Near,
+                        };
+                        texts.Add(new CadText
+                        {
+                            Position = new Vector(pt.X, pt.Y),
+                            Value = ReplaceControlCodes(text.Value),
+                            Height = text.Height,
+                            Rotation = text.Rotation,
+                            LayerName = text.Layer?.Name,
+                            HAlign = ha,
+                        });
+                        break;
+                }
+            }
+
+            return texts;
+        }
+
+        private static (System.Drawing.StringAlignment h, System.Drawing.StringAlignment v) MapAttachmentPoint(
+            ACadSharp.Entities.AttachmentPointType apt)
+        {
+            var h = apt switch
+            {
+                ACadSharp.Entities.AttachmentPointType.TopCenter
+                    or ACadSharp.Entities.AttachmentPointType.MiddleCenter
+                    or ACadSharp.Entities.AttachmentPointType.BottomCenter => System.Drawing.StringAlignment.Center,
+                ACadSharp.Entities.AttachmentPointType.TopRight
+                    or ACadSharp.Entities.AttachmentPointType.MiddleRight
+                    or ACadSharp.Entities.AttachmentPointType.BottomRight => System.Drawing.StringAlignment.Far,
+                _ => System.Drawing.StringAlignment.Near,
+            };
+            var v = apt switch
+            {
+                ACadSharp.Entities.AttachmentPointType.MiddleLeft
+                    or ACadSharp.Entities.AttachmentPointType.MiddleCenter
+                    or ACadSharp.Entities.AttachmentPointType.MiddleRight => System.Drawing.StringAlignment.Center,
+                ACadSharp.Entities.AttachmentPointType.BottomLeft
+                    or ACadSharp.Entities.AttachmentPointType.BottomCenter
+                    or ACadSharp.Entities.AttachmentPointType.BottomRight => System.Drawing.StringAlignment.Far,
+                _ => System.Drawing.StringAlignment.Near,
+            };
+            return (h, v);
+        }
+
+        private static string StripMTextFormatting(string text)
+        {
+            if (string.IsNullOrEmpty(text)) return text;
+            var result = System.Text.RegularExpressions.Regex.Replace(text, @"\\[A-Za-z][^;]*;", "");
+            result = result.Replace("{", "").Replace("}", "");
+            return result.Trim();
+        }
+
+        private static string ReplaceControlCodes(string text)
+        {
+            if (string.IsNullOrEmpty(text)) return text;
+            return text
+                .Replace("%%p", "±")
+                .Replace("%%P", "±")
+                .Replace("%%d", "°")
+                .Replace("%%D", "°")
+                .Replace("%%c", "⌀")
+                .Replace("%%C", "⌀")
+                .Replace("%%%", "%");
+        }
+
         private void filterPanel_Paint(object sender, PaintEventArgs e)
         {
 

OpenNest/Forms/EditNestForm.Designer.cs

@@ -47,11 +47,9 @@
             drawingListBox1 = new OpenNest.Controls.DrawingListBox();
             toolStrip2 = new System.Windows.Forms.ToolStrip();
             toolStripButton2 = new System.Windows.Forms.ToolStripButton();
-            toolStripSeparator4 = new System.Windows.Forms.ToolStripSeparator();
+            shapeLibraryButton = new System.Windows.Forms.ToolStripButton();
             editDrawingsButton = new System.Windows.Forms.ToolStripButton();
-            toolStripSeparator1 = new System.Windows.Forms.ToolStripSeparator();
             toolStripButton3 = new System.Windows.Forms.ToolStripButton();
-            toolStripSeparator2 = new System.Windows.Forms.ToolStripSeparator();
             hideNestedButton = new System.Windows.Forms.ToolStripButton();
             ((System.ComponentModel.ISupportInitialize)splitContainer).BeginInit();
             splitContainer.Panel1.SuspendLayout();
@@ -81,8 +79,8 @@
             // 
             // tabControl1
             // 
-            tabControl1.Controls.Add(tabPage1);
             tabControl1.Controls.Add(tabPage2);
+            tabControl1.Controls.Add(tabPage1);
             tabControl1.Dock = System.Windows.Forms.DockStyle.Fill;
             tabControl1.ItemSize = new System.Drawing.Size(100, 22);
             tabControl1.Location = new System.Drawing.Point(0, 0);
@@ -219,7 +217,7 @@
             // 
             toolStrip2.GripStyle = System.Windows.Forms.ToolStripGripStyle.Hidden;
             toolStrip2.ImageScalingSize = new System.Drawing.Size(20, 20);
-            toolStrip2.Items.AddRange(new System.Windows.Forms.ToolStripItem[] { toolStripButton2, toolStripSeparator4, editDrawingsButton, toolStripSeparator1, toolStripButton3, toolStripSeparator2, hideNestedButton });
+            toolStrip2.Items.AddRange(new System.Windows.Forms.ToolStripItem[] { toolStripButton2, shapeLibraryButton, editDrawingsButton, toolStripButton3, hideNestedButton });
             toolStrip2.Location = new System.Drawing.Point(4, 3);
             toolStrip2.Name = "toolStrip2";
             toolStrip2.Size = new System.Drawing.Size(265, 27);
@@ -238,10 +236,15 @@
             toolStripButton2.Text = "Import Drawings";
             toolStripButton2.Click += ImportDrawings_Click;
             //
-            // toolStripSeparator4
+            // shapeLibraryButton
             //
-            toolStripSeparator4.Name = "toolStripSeparator4";
-            toolStripSeparator4.Size = new System.Drawing.Size(6, 27);
+            shapeLibraryButton.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;
+            shapeLibraryButton.Image = Properties.Resources.shapes;
+            shapeLibraryButton.Name = "shapeLibraryButton";
+            shapeLibraryButton.Padding = new System.Windows.Forms.Padding(5, 0, 5, 0);
+            shapeLibraryButton.Size = new System.Drawing.Size(34, 24);
+            shapeLibraryButton.Text = "Shape Library";
+            shapeLibraryButton.Click += ShapeLibrary_Click;
             //
             // editDrawingsButton
             //
@@ -253,11 +256,6 @@
             editDrawingsButton.Text = "Edit Drawings in Converter";
             editDrawingsButton.Click += EditDrawingsInConverter_Click;
             //
-            // toolStripSeparator1
-            // 
-            toolStripSeparator1.Name = "toolStripSeparator1";
-            toolStripSeparator1.Size = new System.Drawing.Size(6, 27);
-            // 
             // toolStripButton3
             //
             toolStripButton3.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Image;
@@ -269,11 +267,6 @@
             toolStripButton3.Text = "Cleanup unused Drawings";
             toolStripButton3.Click += CleanUnusedDrawings_Click;
             //
-            // toolStripSeparator2
-            // 
-            toolStripSeparator2.Name = "toolStripSeparator2";
-            toolStripSeparator2.Size = new System.Drawing.Size(6, 27);
-            // 
             // hideNestedButton
             // 
             hideNestedButton.CheckOnClick = true;
@@ -329,11 +322,9 @@
         private System.Windows.Forms.ColumnHeader utilColumn;
         private System.Windows.Forms.ToolStrip toolStrip2;
         private System.Windows.Forms.ToolStripButton toolStripButton2;
-        private System.Windows.Forms.ToolStripSeparator toolStripSeparator4;
+        private System.Windows.Forms.ToolStripButton shapeLibraryButton;
         private System.Windows.Forms.ToolStripButton editDrawingsButton;
-        private System.Windows.Forms.ToolStripSeparator toolStripSeparator1;
         private System.Windows.Forms.ToolStripButton toolStripButton3;
-        private System.Windows.Forms.ToolStripSeparator toolStripSeparator2;
         private System.Windows.Forms.ToolStripButton hideNestedButton;
         private System.Windows.Forms.ToolStripSeparator toolStripSeparator3;
         private System.Windows.Forms.ToolStripButton toolStripLabel1;

OpenNest/Forms/EditNestForm.cs

@@ -329,7 +329,7 @@ namespace OpenNest.Forms
         {
             var dlg = new OpenFileDialog();
             dlg.Multiselect = true;
-            dlg.Filter = "DXF Files (*.dxf) | *.dxf";
+            dlg.Filter = "CAD Files (*.dxf;*.dwg)|*.dxf;*.dwg|DXF Files (*.dxf)|*.dxf|DWG Files (*.dwg)|*.dwg";
 
             if (dlg.ShowDialog() != DialogResult.OK)
                 return;
@@ -346,7 +346,6 @@ namespace OpenNest.Forms
             drawings.ForEach(d => Nest.Drawings.Add(d));
 
             UpdateDrawingList();
-            tabControl1.SelectedIndex = 1;
         }
 
         public bool Export()
@@ -875,6 +874,18 @@ namespace OpenNest.Forms
             Import();
         }
 
+        private void ShapeLibrary_Click(object sender, EventArgs e)
+        {
+            var form = new ShapeLibraryForm(Nest.Drawings.Select(d => d.Name));
+            form.ShowDialog();
+
+            var drawings = form.GetDrawings();
+            if (drawings.Count == 0) return;
+
+            drawings.ForEach(d => Nest.Drawings.Add(d));
+            UpdateDrawingList();
+        }
+
         private void EditDrawingsInConverter_Click(object sender, EventArgs e)
         {
             if (Nest.Drawings.Count == 0)

OpenNest/Forms/EditNestInfoForm.Designer.cs

@@ -63,7 +63,7 @@
             this.textBox2 = new System.Windows.Forms.TextBox();
             this.label5 = new System.Windows.Forms.Label();
             this.labelMaterial = new System.Windows.Forms.Label();
-            this.materialBox = new System.Windows.Forms.TextBox();
+            this.materialBox = new System.Windows.Forms.ComboBox();
             this.tabPage2 = new System.Windows.Forms.TabPage();
             this.tabPage3 = new System.Windows.Forms.TabPage();
             this.notesBox = new System.Windows.Forms.TextBox();
@@ -516,9 +516,10 @@
             // materialBox
             //
             this.materialBox.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
+            this.materialBox.FormattingEnabled = true;
             this.materialBox.Location = new System.Drawing.Point(135, 159);
             this.materialBox.Name = "materialBox";
-            this.materialBox.Size = new System.Drawing.Size(224, 22);
+            this.materialBox.Size = new System.Drawing.Size(224, 24);
             this.materialBox.TabIndex = 11;
             //
             // label3
@@ -729,6 +730,6 @@
         private System.Windows.Forms.RadioButton radioButton2;
         private System.Windows.Forms.Label label5;
         private System.Windows.Forms.Label labelMaterial;
-        private System.Windows.Forms.TextBox materialBox;
+        private System.Windows.Forms.ComboBox materialBox;
     }
 }

OpenNest/Forms/EditNestInfoForm.cs

@@ -15,6 +15,9 @@ namespace OpenNest.Forms
         {
             InitializeComponent();
 
+            foreach (var name in PostProcessorMaterials.Names)
+                materialBox.Items.Add(name);
+
             timer = new Timer
             {
                 SynchronizingObject = this,

OpenNest/Forms/MainForm.cs

@@ -71,6 +71,7 @@ namespace OpenNest.Forms
             NestEngineRegistry.LoadPlugins(enginesDir);
 
             OptionsForm.ApplyDisabledStrategies();
+            ColorSchemeRegistry.ApplyActiveFromSettings();
 
             foreach (var engine in NestEngineRegistry.AvailableEngines)
                 engineComboBox.Items.Add(engine.Name);
@@ -351,6 +352,9 @@ namespace OpenNest.Forms
                         postProcessorMenuItem.Tag = postProcessor;
                         postProcessorMenuItem.Click += PostProcessor_Click;
                         mnuNestPost.DropDownItems.Add(postProcessorMenuItem);
+
+                        if (postProcessor is IMaterialProvidingPostProcessor materialProvider)
+                            PostProcessorMaterials.AddFrom(materialProvider);
                     }
                 }
             }
@@ -833,7 +837,7 @@ namespace OpenNest.Forms
         {
             if (activeForm == null) return;
 
-            var form = new ShapeLibraryForm();
+            var form = new ShapeLibraryForm(activeForm.Nest.Drawings.Select(d => d.Name));
             form.ShowDialog();
 
             var drawings = form.GetDrawings();
@@ -1157,6 +1161,9 @@ namespace OpenNest.Forms
             if (postProcessor == null)
                 return;
 
+            if (postProcessor is IPostProcessorNestAware nestAware)
+                nestAware.PrepareForNest(activeForm.Nest);
+
             if (postProcessor is IConfigurablePostProcessor configurable)
             {
                 using var configForm = new PostProcessorConfigForm(configurable);

OpenNest/Forms/OptionsForm.Designer.cs

@@ -42,6 +42,8 @@
             this.bottomPanel1 = new OpenNest.Controls.BottomPanel();
             this.strategyGrid = new System.Windows.Forms.DataGridView();
             this.strategyGroupBox = new System.Windows.Forms.GroupBox();
+            this.colorSchemeLabel = new System.Windows.Forms.Label();
+            this.colorSchemeCombo = new System.Windows.Forms.ComboBox();
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
             this.tableLayoutPanel1.SuspendLayout();
             this.bottomPanel1.SuspendLayout();
@@ -95,15 +97,18 @@
             this.tableLayoutPanel1.Controls.Add(this.label1, 0, 1);
             this.tableLayoutPanel1.Controls.Add(this.textBox1, 1, 0);
             this.tableLayoutPanel1.Controls.Add(this.label3, 0, 0);
-            this.tableLayoutPanel1.Controls.Add(this.checkBox1, 0, 2);
+            this.tableLayoutPanel1.Controls.Add(this.colorSchemeLabel, 0, 2);
+            this.tableLayoutPanel1.Controls.Add(this.colorSchemeCombo, 1, 2);
+            this.tableLayoutPanel1.Controls.Add(this.checkBox1, 0, 3);
             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 = 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.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.Size = new System.Drawing.Size(684, 160);
             this.tableLayoutPanel1.TabIndex = 0;
             // 
@@ -198,6 +203,25 @@
             this.strategyGroupBox.TabStop = false;
             this.strategyGroupBox.Text = "Fill Strategies";
             //
+            // colorSchemeLabel
+            //
+            this.colorSchemeLabel.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
+            this.colorSchemeLabel.AutoSize = true;
+            this.colorSchemeLabel.Location = new System.Drawing.Point(3, 92);
+            this.colorSchemeLabel.Name = "colorSchemeLabel";
+            this.colorSchemeLabel.Size = new System.Drawing.Size(145, 16);
+            this.colorSchemeLabel.TabIndex = 10;
+            this.colorSchemeLabel.Text = "Color scheme:";
+            //
+            // colorSchemeCombo
+            //
+            this.colorSchemeCombo.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
+            this.colorSchemeCombo.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
+            this.colorSchemeCombo.Location = new System.Drawing.Point(154, 89);
+            this.colorSchemeCombo.Name = "colorSchemeCombo";
+            this.colorSchemeCombo.Size = new System.Drawing.Size(130, 24);
+            this.colorSchemeCombo.TabIndex = 11;
+            //
             // OptionsForm
             //
             this.AcceptButton = this.saveButton;
@@ -239,5 +263,7 @@
         private System.Windows.Forms.Button button1;
         private System.Windows.Forms.DataGridView strategyGrid;
         private System.Windows.Forms.GroupBox strategyGroupBox;
+        private System.Windows.Forms.Label colorSchemeLabel;
+        private System.Windows.Forms.ComboBox colorSchemeCombo;
     }
 }

OpenNest/Forms/OptionsForm.cs

@@ -68,6 +68,13 @@ namespace OpenNest.Forms
             checkBox1.Checked = Settings.Default.CreateNewNestOnOpen;
             numericUpDown1.Value = (decimal)Settings.Default.AutoSizePlateFactor;
 
+            colorSchemeCombo.Items.Clear();
+            foreach (var scheme in ColorSchemeRegistry.AllSchemes)
+                colorSchemeCombo.Items.Add(scheme.Name);
+            var active = Settings.Default.ActiveColorScheme;
+            var idx = colorSchemeCombo.Items.IndexOf(active);
+            colorSchemeCombo.SelectedIndex = idx >= 0 ? idx : 0;
+
             var disabledNames = ParseDisabledStrategies(Settings.Default.DisabledStrategies);
             foreach (DataGridViewRow row in strategyGrid.Rows)
                 row.Cells["Enabled"].Value = !disabledNames.Contains((string)row.Cells["Name"].Value);
@@ -78,6 +85,7 @@ namespace OpenNest.Forms
             Settings.Default.NestTemplatePath = textBox1.Text;
             Settings.Default.CreateNewNestOnOpen = checkBox1.Checked;
             Settings.Default.AutoSizePlateFactor = (double)numericUpDown1.Value;
+            Settings.Default.ActiveColorScheme = colorSchemeCombo.SelectedItem as string ?? "Classic";
 
             var disabledNames = new List<string>();
             foreach (DataGridViewRow row in strategyGrid.Rows)
@@ -89,6 +97,10 @@ namespace OpenNest.Forms
 
             Settings.Default.Save();
             ApplyDisabledStrategies();
+            ColorSchemeRegistry.ApplyActiveFromSettings();
+
+            foreach (Form f in Application.OpenForms)
+                f.Invalidate(invalidateChildren: true);
         }
 
         /// <summary>

OpenNest/Forms/ShapeLibraryForm.cs

@@ -21,12 +21,17 @@ namespace OpenNest.Forms
         private readonly List<Drawing> addedDrawings = new List<Drawing>();
         private readonly List<ShapeEntry> shapeEntries = new List<ShapeEntry>();
         private readonly List<ParameterBinding> parameterBindings = new List<ParameterBinding>();
+        private readonly HashSet<string> existingNames;
 
         private ShapeEntry selectedEntry;
         private bool suppressPreview;
 
-        public ShapeLibraryForm()
+        public ShapeLibraryForm(IEnumerable<string> existingDrawingNames = null)
         {
+            existingNames = existingDrawingNames != null
+                ? new HashSet<string>(existingDrawingNames, StringComparer.OrdinalIgnoreCase)
+                : new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
             InitializeComponent();
             DiscoverShapes();
             PopulateShapeList();
@@ -259,6 +264,7 @@ namespace OpenNest.Forms
                 if (shape == null) return;
 
                 var drawing = shape.GetDrawing();
+                nameTextBox.Text = shape.GenerateName();
                 previewBox.ShowDrawing(drawing);
 
                 if (drawing?.Program != null)
@@ -405,10 +411,12 @@ namespace OpenNest.Forms
                 if (shape == null) return;
 
                 var drawing = shape.GetDrawing();
+                drawing.Name = GetUniqueName(drawing.Name);
                 drawing.Color = Drawing.GetNextColor();
                 drawing.Quantity.Required = (int)quantityUpDown.Value;
 
                 addedDrawings.Add(drawing);
+                existingNames.Add(drawing.Name);
                 DialogResult = DialogResult.OK;
 
                 addButton.Text = $"Added ({addedDrawings.Count})";
@@ -423,6 +431,19 @@ namespace OpenNest.Forms
             }
         }
 
+        private string GetUniqueName(string baseName)
+        {
+            if (!existingNames.Contains(baseName))
+                return baseName;
+
+            for (var i = 2; ; i++)
+            {
+                var candidate = $"{baseName} ({i})";
+                if (!existingNames.Contains(candidate))
+                    return candidate;
+            }
+        }
+
         private static string FriendlyName(string name)
         {
             if (name.EndsWith("Shape"))

OpenNest/GraphicsHelper.cs

@@ -138,9 +138,20 @@ namespace OpenNest
                         break;
 
                     case CodeType.RapidMove:
-                        cutPath.StartFigure();
-                        leadPath.StartFigure();
-                        AddLine(cutPath, (RapidMove)code, mode, ref curpos);
+                        {
+                            var rapid = (RapidMove)code;
+                            var endpt = rapid.EndPoint;
+                            if (mode == Mode.Incremental)
+                                endpt += curpos;
+                            var dx = endpt.X - curpos.X;
+                            var dy = endpt.Y - curpos.Y;
+                            if (dx * dx + dy * dy > 0.001 * 0.001)
+                            {
+                                cutPath.StartFigure();
+                                leadPath.StartFigure();
+                            }
+                            curpos = endpt;
+                        }
                         break;
 
                     case CodeType.SubProgramCall:
@@ -300,8 +311,17 @@ namespace OpenNest
                         break;
 
                     case CodeType.RapidMove:
-                        Flush();
-                        AddLine(path, (RapidMove)code, mode, ref curpos);
+                        {
+                            var rapid = (RapidMove)code;
+                            var endpt = rapid.EndPoint;
+                            if (mode == Mode.Incremental)
+                                endpt += curpos;
+                            var dx = endpt.X - curpos.X;
+                            var dy = endpt.Y - curpos.Y;
+                            if (dx * dx + dy * dy > 0.001 * 0.001)
+                                Flush();
+                            curpos = endpt;
+                        }
                         break;
 
                     case CodeType.SubProgramCall:

OpenNest/OpenNest.csproj

@@ -15,6 +15,11 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
   </ItemGroup>
+  <ItemGroup>
+    <None Update="Schemes\*.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenNest.Api\OpenNest.Api.csproj" />
     <ProjectReference Include="..\OpenNest.Core\OpenNest.Core.csproj" />

OpenNest/PostProcessorMaterials.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenNest
+{
+    public static class PostProcessorMaterials
+    {
+        private static readonly List<string> materials = new();
+
+        public static IReadOnlyList<string> Names => materials;
+
+        public static void AddFrom(IMaterialProvidingPostProcessor provider)
+        {
+            if (provider == null)
+                return;
+
+            foreach (var name in provider.GetMaterialNames())
+            {
+                if (!string.IsNullOrWhiteSpace(name)
+                    && !materials.Contains(name, StringComparer.OrdinalIgnoreCase))
+                {
+                    materials.Add(name);
+                }
+            }
+
+            materials.Sort(StringComparer.OrdinalIgnoreCase);
+        }
+    }
+}

OpenNest/Properties/Resources.Designer.cs

@@ -250,6 +250,16 @@ namespace OpenNest.Properties {
             }
         }
 
+        /// <summary>
+        ///   Looks up a localized resource of type System.Drawing.Bitmap.
+        /// </summary>
+        internal static System.Drawing.Bitmap shapes {
+            get {
+                object obj = ResourceManager.GetObject("shapes", resourceCulture);
+                return ((System.Drawing.Bitmap)(obj));
+            }
+        }
+
         /// <summary>
         ///   Looks up a localized resource of type System.Drawing.Bitmap.
         /// </summary>

OpenNest/Properties/Resources.resx

@@ -187,4 +187,7 @@
   <data name="delete" type="System.Resources.ResXFileRef, System.Windows.Forms">
     <value>..\Resources\delete.png;System.Drawing.Bitmap, System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a</value>
   </data>
+  <data name="shapes" type="System.Resources.ResXFileRef, System.Windows.Forms">
+    <value>..\Resources\shapes.png;System.Drawing.Bitmap, System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a</value>
+  </data>
 </root>

OpenNest/Properties/Settings.Designer.cs

@@ -226,5 +226,17 @@ namespace OpenNest.Properties {
                 this["CuttingParametersJson"] = value;
             }
         }
+
+        [global::System.Configuration.UserScopedSettingAttribute()]
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+        [global::System.Configuration.DefaultSettingValueAttribute("Classic")]
+        public string ActiveColorScheme {
+            get {
+                return ((string)(this["ActiveColorScheme"]));
+            }
+            set {
+                this["ActiveColorScheme"] = value;
+            }
+        }
     }
 }

OpenNest/Properties/Settings.settings

@@ -53,5 +53,8 @@
     <Setting Name="CuttingParametersJson" Type="System.String" Scope="User">
       <Value Profile="(Default)" />
     </Setting>
+    <Setting Name="ActiveColorScheme" Type="System.String" Scope="User">
+      <Value Profile="(Default)">Classic</Value>
+    </Setting>
   </Settings>
 </SettingsFile>