feat: replace XML nest file format with JSON (v2)

Replace three separate XML metadata files (info, drawing-info,
plate-info) and per-plate G-code placement files with a single
nest.json inside the ZIP archive. Programs remain as G-code text
under a programs/ folder.

This eliminates ~400 lines of hand-written XML read/write code
and fragile ID-based dictionary linking. Now uses System.Text.Json
with DTO records for clean serialization. Also adds Priority and
Constraints fields to drawing serialization (previously omitted).

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

OpenNest.IO/NestFormat.cs

@@ -0,0 +1,126 @@
+using System.Collections.Generic;
+using System.Text.Json;
+
+namespace OpenNest.IO
+{
+    public static class NestFormat
+    {
+        public static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            WriteIndented = true
+        };
+
+        public record NestDto
+        {
+            public int Version { get; init; } = 2;
+            public string Name { get; init; } = "";
+            public string Units { get; init; } = "Inches";
+            public string Customer { get; init; } = "";
+            public string DateCreated { get; init; } = "";
+            public string DateLastModified { get; init; } = "";
+            public string Notes { get; init; } = "";
+            public PlateDefaultsDto PlateDefaults { get; init; } = new();
+            public List<DrawingDto> Drawings { get; init; } = new();
+            public List<PlateDto> Plates { get; init; } = new();
+        }
+
+        public record PlateDefaultsDto
+        {
+            public SizeDto Size { get; init; } = new();
+            public double Thickness { get; init; }
+            public int Quadrant { get; init; } = 1;
+            public double PartSpacing { get; init; }
+            public MaterialDto Material { get; init; } = new();
+            public SpacingDto EdgeSpacing { get; init; } = new();
+        }
+
+        public record DrawingDto
+        {
+            public int Id { get; init; }
+            public string Name { get; init; } = "";
+            public string Customer { get; init; } = "";
+            public ColorDto Color { get; init; } = new();
+            public QuantityDto Quantity { get; init; } = new();
+            public int Priority { get; init; }
+            public ConstraintsDto Constraints { get; init; } = new();
+            public MaterialDto Material { get; init; } = new();
+            public SourceDto Source { get; init; } = new();
+        }
+
+        public record PlateDto
+        {
+            public int Id { get; init; }
+            public SizeDto Size { get; init; } = new();
+            public double Thickness { get; init; }
+            public int Quadrant { get; init; } = 1;
+            public int Quantity { get; init; } = 1;
+            public double PartSpacing { get; init; }
+            public MaterialDto Material { get; init; } = new();
+            public SpacingDto EdgeSpacing { get; init; } = new();
+            public List<PartDto> Parts { get; init; } = new();
+        }
+
+        public record PartDto
+        {
+            public int DrawingId { get; init; }
+            public double X { get; init; }
+            public double Y { get; init; }
+            public double Rotation { get; init; }
+        }
+
+        public record SizeDto
+        {
+            public double Width { get; init; }
+            public double Height { get; init; }
+        }
+
+        public record MaterialDto
+        {
+            public string Name { get; init; } = "";
+            public string Grade { get; init; } = "";
+            public double Density { get; init; }
+        }
+
+        public record SpacingDto
+        {
+            public double Left { get; init; }
+            public double Top { get; init; }
+            public double Right { get; init; }
+            public double Bottom { get; init; }
+        }
+
+        public record ColorDto
+        {
+            public int A { get; init; } = 255;
+            public int R { get; init; }
+            public int G { get; init; }
+            public int B { get; init; }
+        }
+
+        public record QuantityDto
+        {
+            public int Required { get; init; }
+        }
+
+        public record ConstraintsDto
+        {
+            public double StepAngle { get; init; }
+            public double StartAngle { get; init; }
+            public double EndAngle { get; init; }
+            public bool Allow180Equivalent { get; init; }
+        }
+
+        public record SourceDto
+        {
+            public string Path { get; init; } = "";
+            public OffsetDto Offset { get; init; } = new();
+        }
+
+        public record OffsetDto
+        {
+            public double X { get; init; }
+            public double Y { get; init; }
+        }
+    }
+}

OpenNest.IO/NestReader.cs

@@ -1,45 +1,28 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
 using System.IO.Compression;
 using System.Linq;
-using System.Text.RegularExpressions;
+using System.Text.Json;
-using System.Xml;
 using OpenNest.CNC;
 using OpenNest.Geometry;
-using OpenNest.Math;
+using static OpenNest.IO.NestFormat;
 
 namespace OpenNest.IO
 {
     public sealed class NestReader
     {
-        private ZipArchive zipArchive;
+        private readonly Stream stream;
-        private Dictionary<int, Plate> plateDict;
+        private readonly ZipArchive zipArchive;
-        private Dictionary<int, Drawing> drawingDict;
-        private Dictionary<int, Program> programDict;
-        private Dictionary<int, Program> plateProgramDict;
-        private Stream stream;
-        private Nest nest;
-
-        private NestReader()
-        {
-            plateDict = new Dictionary<int, Plate>();
-            drawingDict = new Dictionary<int, Drawing>();
-            programDict = new Dictionary<int, Program>();
-            plateProgramDict = new Dictionary<int, Program>();
-            nest = new Nest();
-        }
 
         public NestReader(string file)
-            : this()
         {
             stream = new FileStream(file, FileMode.Open, FileAccess.Read);
             zipArchive = new ZipArchive(stream, ZipArchiveMode.Read);
         }
 
         public NestReader(Stream stream)
-            : this()
         {
             this.stream = stream;
             zipArchive = new ZipArchive(stream, ZipArchiveMode.Read);
@@ -47,52 +30,12 @@ namespace OpenNest.IO
 
         public Nest Read()
         {
-            const string plateExtensionPattern = "plate-\\d\\d\\d";
+            var nestJson = ReadEntry("nest.json");
-            const string programExtensionPattern = "program-\\d\\d\\d";
+            var dto = JsonSerializer.Deserialize<NestDto>(nestJson, JsonOptions);
 
-            foreach (var entry in zipArchive.Entries)
+            var programs = ReadPrograms(dto.Drawings.Count);
-            {
+            var drawingMap = BuildDrawings(dto, programs);
-                var memstream = new MemoryStream();
+            var nest = BuildNest(dto, drawingMap);
-                using (var entryStream = entry.Open())
-                {
-                    entryStream.CopyTo(memstream);
-                }
-
-                memstream.Position = 0;
-
-                switch (entry.FullName)
-                {
-                    case "info":
-                        ReadNestInfo(memstream);
-                        continue;
-
-                    case "drawing-info":
-                        ReadDrawingInfo(memstream);
-                        continue;
-
-                    case "plate-info":
-                        ReadPlateInfo(memstream);
-                        continue;
-                }
-
-                if (Regex.IsMatch(entry.FullName, programExtensionPattern))
-                {
-                    ReadProgram(memstream, entry.FullName);
-                    continue;
-                }
-
-                if (Regex.IsMatch(entry.FullName, plateExtensionPattern))
-                {
-                    ReadPlate(memstream, entry.FullName);
-                    continue;
-                }
-            }
-
-            LinkProgramsToDrawings();
-            LinkPartsToPlates();
-
-            AddPlatesToNest();
-            AddDrawingsToNest();
 
             zipArchive.Dispose();
             stream.Close();
@@ -100,374 +43,114 @@ namespace OpenNest.IO
             return nest;
         }
 
-        private void ReadNestInfo(Stream stream)
+        private string ReadEntry(string name)
         {
-            var reader = XmlReader.Create(stream);
+            var entry = zipArchive.GetEntry(name)
-            var spacing = new Spacing();
+                ?? throw new InvalidDataException($"Nest file is missing required entry '{name}'.");
+            using var entryStream = entry.Open();
+            using var reader = new StreamReader(entryStream);
+            return reader.ReadToEnd();
+        }
 
-            while (reader.Read())
+        private Dictionary<int, Program> ReadPrograms(int count)
+        {
+            var programs = new Dictionary<int, Program>();
+            for (var i = 1; i <= count; i++)
             {
-                if (!reader.IsStartElement())
+                var entry = zipArchive.GetEntry($"programs/program-{i}");
-                    continue;
+                if (entry == null) continue;
 
-                switch (reader.Name)
+                using var entryStream = entry.Open();
+                var memStream = new MemoryStream();
+                entryStream.CopyTo(memStream);
+                memStream.Position = 0;
+
+                var reader = new ProgramReader(memStream);
+                programs[i] = reader.Read();
+            }
+            return programs;
+        }
+
+        private Dictionary<int, Drawing> BuildDrawings(NestDto dto, Dictionary<int, Program> programs)
+        {
+            var map = new Dictionary<int, Drawing>();
+            foreach (var d in dto.Drawings)
+            {
+                var drawing = new Drawing(d.Name);
+                drawing.Customer = d.Customer;
+                drawing.Color = Color.FromArgb(d.Color.A, d.Color.R, d.Color.G, d.Color.B);
+                drawing.Quantity.Required = d.Quantity.Required;
+                drawing.Priority = d.Priority;
+                drawing.Constraints.StepAngle = d.Constraints.StepAngle;
+                drawing.Constraints.StartAngle = d.Constraints.StartAngle;
+                drawing.Constraints.EndAngle = d.Constraints.EndAngle;
+                drawing.Constraints.Allow180Equivalent = d.Constraints.Allow180Equivalent;
+                drawing.Material = new Material(d.Material.Name, d.Material.Grade, d.Material.Density);
+                drawing.Source.Path = d.Source.Path;
+                drawing.Source.Offset = new Vector(d.Source.Offset.X, d.Source.Offset.Y);
+
+                if (programs.TryGetValue(d.Id, out var pgm))
+                    drawing.Program = pgm;
+
+                map[d.Id] = drawing;
+            }
+            return map;
+        }
+
+        private Nest BuildNest(NestDto dto, Dictionary<int, Drawing> drawingMap)
+        {
+            var nest = new Nest();
+            nest.Name = dto.Name;
+
+            Units units;
+            if (Enum.TryParse(dto.Units, true, out units))
+                nest.Units = units;
+
+            nest.Customer = dto.Customer;
+            nest.DateCreated = DateTime.Parse(dto.DateCreated);
+            nest.DateLastModified = DateTime.Parse(dto.DateLastModified);
+            nest.Notes = dto.Notes;
+
+            // Plate defaults
+            var pd = dto.PlateDefaults;
+            nest.PlateDefaults.Size = new OpenNest.Geometry.Size(pd.Size.Width, pd.Size.Height);
+            nest.PlateDefaults.Thickness = pd.Thickness;
+            nest.PlateDefaults.Quadrant = pd.Quadrant;
+            nest.PlateDefaults.PartSpacing = pd.PartSpacing;
+            nest.PlateDefaults.Material = new Material(pd.Material.Name, pd.Material.Grade, pd.Material.Density);
+            nest.PlateDefaults.EdgeSpacing = new Spacing(pd.EdgeSpacing.Left, pd.EdgeSpacing.Bottom, pd.EdgeSpacing.Right, pd.EdgeSpacing.Top);
+
+            // Drawings
+            foreach (var d in drawingMap.OrderBy(k => k.Key))
+                nest.Drawings.Add(d.Value);
+
+            // Plates
+            foreach (var p in dto.Plates.OrderBy(p => p.Id))
+            {
+                var plate = new Plate();
+                plate.Size = new OpenNest.Geometry.Size(p.Size.Width, p.Size.Height);
+                plate.Thickness = p.Thickness;
+                plate.Quadrant = p.Quadrant;
+                plate.Quantity = p.Quantity;
+                plate.PartSpacing = p.PartSpacing;
+                plate.Material = new Material(p.Material.Name, p.Material.Grade, p.Material.Density);
+                plate.EdgeSpacing = new Spacing(p.EdgeSpacing.Left, p.EdgeSpacing.Bottom, p.EdgeSpacing.Right, p.EdgeSpacing.Top);
+
+                foreach (var partDto in p.Parts)
                 {
-                    case "Nest":
+                    if (!drawingMap.TryGetValue(partDto.DrawingId, out var dwg))
-                        nest.Name = reader["name"];
+                        continue;
-                        break;
 
-                    case "Units":
+                    var part = new Part(dwg);
-                        Units units;
+                    part.Rotate(partDto.Rotation);
-                        TryParseEnum<Units>(reader.ReadString(), out units);
+                    part.Offset(new Vector(partDto.X, partDto.Y));
-                        nest.Units = units;
+                    plate.Parts.Add(part);
-                        break;
-
-                    case "Customer":
-                        nest.Customer = reader.ReadString();
-                        break;
-
-                    case "DateCreated":
-                        nest.DateCreated = DateTime.Parse(reader.ReadString());
-                        break;
-
-                    case "DateLastModified":
-                        nest.DateLastModified = DateTime.Parse(reader.ReadString());
-                        break;
-
-                    case "Notes":
-                        nest.Notes = Uri.UnescapeDataString(reader.ReadString());
-                        break;
-
-                    case "Size":
-                        nest.PlateDefaults.Size = OpenNest.Geometry.Size.Parse(reader.ReadString());
-                        break;
-
-                    case "Thickness":
-                        nest.PlateDefaults.Thickness = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Quadrant":
-                        nest.PlateDefaults.Quadrant = int.Parse(reader.ReadString());
-                        break;
-
-                    case "PartSpacing":
-                        nest.PlateDefaults.PartSpacing = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Name":
-                        nest.PlateDefaults.Material.Name = reader.ReadString();
-                        break;
-
-                    case "Grade":
-                        nest.PlateDefaults.Material.Grade = reader.ReadString();
-                        break;
-
-                    case "Density":
-                        nest.PlateDefaults.Material.Density = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Left":
-                        spacing.Left = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Right":
-                        spacing.Right = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Top":
-                        spacing.Top = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Bottom":
-                        spacing.Bottom = double.Parse(reader.ReadString());
-                        break;
                 }
+
+                nest.Plates.Add(plate);
             }
 
-            reader.Close();
+            return nest;
-            nest.PlateDefaults.EdgeSpacing = spacing;
-        }
-
-        private void ReadDrawingInfo(Stream stream)
-        {
-            var reader = XmlReader.Create(stream);
-            Drawing drawing = null;
-
-            while (reader.Read())
-            {
-                if (!reader.IsStartElement())
-                    continue;
-
-                switch (reader.Name)
-                {
-                    case "Drawing":
-                        var id = int.Parse(reader["id"]);
-                        var name = reader["name"];
-
-                        drawingDict.Add(id, (drawing = new Drawing(name)));
-                        break;
-
-                    case "Customer":
-                        drawing.Customer = reader.ReadString();
-                        break;
-
-                    case "Color":
-                        {
-                            var parts = reader.ReadString().Split(',');
-                        
-                            if (parts.Length == 3)
-                            {
-                                byte r = byte.Parse(parts[0]);
-                                byte g = byte.Parse(parts[1]);
-                                byte b = byte.Parse(parts[2]);
-
-                                drawing.Color = Color.FromArgb(r, g, b);
-                            }
-                            else if (parts.Length == 4)
-                            {
-                                byte a = byte.Parse(parts[0]);
-                                byte r = byte.Parse(parts[1]);
-                                byte g = byte.Parse(parts[2]);
-                                byte b = byte.Parse(parts[3]);
-
-                                drawing.Color = Color.FromArgb(a, r, g, b);
-                            }
-                        }
-                        break;
-
-                    case "Required":
-                        drawing.Quantity.Required = int.Parse(reader.ReadString());
-                        break;
-
-                    case "Name":
-                        drawing.Material.Name = reader.ReadString();
-                        break;
-
-                    case "Grade":
-                        drawing.Material.Grade = reader.ReadString();
-                        break;
-
-                    case "Density":
-                        drawing.Material.Density = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Path":
-                        drawing.Source.Path = reader.ReadString();
-                        break;
-
-                    case "Offset":
-                        {
-                            var parts = reader.ReadString().Split(',');
-
-                            if (parts.Length != 2)
-                                continue;
-
-                            drawing.Source.Offset = new Vector(double.Parse(parts[0]), double.Parse(parts[1]));
-                        }
-                        break;
-                }
-            }
-
-            reader.Close();
-        }
-
-        private void ReadPlateInfo(Stream stream)
-        {
-            var reader = XmlReader.Create(stream);
-            var spacing = new Spacing();
-            Plate plate = null;
-
-            while (reader.Read())
-            {
-                if (!reader.IsStartElement())
-                    continue;
-
-                switch (reader.Name)
-                {
-                    case "Plate":
-                        var id = int.Parse(reader["id"]);
-
-                        if (plate != null)
-                            plate.EdgeSpacing = spacing;
-
-                        plateDict.Add(id, (plate = new Plate()));
-                        break;
-
-                    case "Size":
-                        plate.Size = OpenNest.Geometry.Size.Parse(reader.ReadString());
-                        break;
-
-                    case "Qty":
-                        plate.Quantity = int.Parse(reader.ReadString());
-                        break;
-
-                    case "Thickness":
-                        plate.Thickness = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Quadrant":
-                        plate.Quadrant = int.Parse(reader.ReadString());
-                        break;
-
-                    case "PartSpacing":
-                        plate.PartSpacing = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Name":
-                        plate.Material.Name = reader.ReadString();
-                        break;
-
-                    case "Grade":
-                        plate.Material.Grade = reader.ReadString();
-                        break;
-
-                    case "Density":
-                        plate.Material.Density = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Left":
-                        spacing.Left = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Right":
-                        spacing.Right = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Top":
-                        spacing.Top = double.Parse(reader.ReadString());
-                        break;
-
-                    case "Bottom":
-                        spacing.Bottom = double.Parse(reader.ReadString());
-                        break;
-                }
-            }
-
-            if (plate != null)
-                plate.EdgeSpacing = spacing;
-        }
-
-        private void ReadProgram(Stream stream, string name)
-        {
-            var id = GetProgramId(name);
-            var reader = new ProgramReader(stream);
-            var pgm = reader.Read();
-            programDict.Add(id, pgm);
-        }
-
-        private void ReadPlate(Stream stream, string name)
-        {
-            var id = GetPlateId(name);
-            var reader = new ProgramReader(stream);
-            var pgm = reader.Read();
-            plateProgramDict.Add(id, pgm);
-        }
-
-        private void LinkProgramsToDrawings()
-        {
-            foreach (var drawingItem in drawingDict)
-            {
-                Program pgm;
-
-                if (programDict.TryGetValue(drawingItem.Key, out pgm))
-                    drawingItem.Value.Program = pgm;
-            }
-        }
-
-        private void LinkPartsToPlates()
-        {
-            foreach (var plateProgram in plateProgramDict)
-            {
-                var parts = CreateParts(plateProgram.Value);
-
-                Plate plate;
-
-                if (!plateDict.TryGetValue(plateProgram.Key, out plate))
-                    plate = new Plate();
-
-                plate.Parts.AddRange(parts);
-                plateDict[plateProgram.Key] = plate;
-            }
-        }
-
-        private void AddPlatesToNest()
-        {
-            var plates = plateDict.OrderBy(i => i.Key).Select(i => i.Value).ToList();
-            nest.Plates.AddRange(plates);
-        }
-
-        private void AddDrawingsToNest()
-        {
-            var drawings = drawingDict.OrderBy(i => i.Key).Select(i => i.Value).ToList();
-            drawings.ForEach(d => nest.Drawings.Add(d));
-        }
-
-        private List<Part> CreateParts(Program pgm)
-        {
-            var parts = new List<Part>();
-            var pos = Vector.Zero;
-
-            for (int i = 0; i < pgm.Codes.Count; i++)
-            {
-                var code = pgm.Codes[i];
-
-                switch (code.Type)
-                {
-                    case CodeType.RapidMove:
-                        pos = ((RapidMove)code).EndPoint;
-                        break;
-
-                    case CodeType.SubProgramCall:
-                        var subpgm = (SubProgramCall)code;
-                        var dwg = drawingDict[subpgm.Id];
-                        var part = new Part(dwg);
-                        part.Rotate(Angle.ToRadians(subpgm.Rotation));
-                        part.Offset(pos);
-                        parts.Add(part);
-                        break;
-                }
-            }
-
-            return parts;
-        }
-
-        private int GetPlateId(string name)
-        {
-            return int.Parse(name.Replace("plate-", ""));
-        }
-
-        private int GetProgramId(string name)
-        {
-            return int.Parse(name.Replace("program-", ""));
-        }
-
-        public static T ParseEnum<T>(string value)
-        {
-            return (T)Enum.Parse(typeof(T), value, true);
-        }
-
-        public static bool TryParseEnum<T>(string value, out T e)
-        {
-            try
-            {
-                e = ParseEnum<T>(value);
-                return true;
-            }
-            catch
-            {
-                e = ParseEnum<T>(typeof(T).GetEnumValues().GetValue(0).ToString());
-            }
-
-            return false;
-        }
-
-        private enum NestInfoSection
-        {
-            None,
-            DefaultPlate,
-            Material,
-            EdgeSpacing,
-            Source
         }
     }
 }

OpenNest.IO/NestWriter.cs

@@ -1,32 +1,22 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.IO.Compression;
 using System.Linq;
 using System.Text;
-using System.Xml;
+using System.Text.Json;
 using OpenNest.CNC;
 using OpenNest.Math;
+using static OpenNest.IO.NestFormat;
 
 namespace OpenNest.IO
 {
     public sealed class NestWriter
     {
-        /// <summary>
-        /// Number of decimal places the output is round to.
-        /// This number must have more decimal places than Tolerance.Epsilon
-        /// </summary>
         private const int OutputPrecision = 10;
-
-        /// <summary>
-        /// Fixed-point format string that avoids scientific notation.
-        /// ProgramReader treats 'E' as a code letter, so "6.66E-08" would be
-        /// split into X:"6.66" and E:"-08", corrupting the parsed value.
-        /// </summary>
         private const string CoordinateFormat = "0.##########";
 
         private readonly Nest nest;
-        private ZipArchive zipArchive;
         private Dictionary<int, Drawing> drawingDict;
 
         public NestWriter(Nest nest)
@@ -37,27 +27,21 @@ namespace OpenNest.IO
 
         public bool Write(string file)
         {
-            this.nest.DateLastModified = DateTime.Now;
+            nest.DateLastModified = DateTime.Now;
-
             SetDrawingIds();
 
-            using (var fileStream = new FileStream(file, FileMode.Create))
+            using var fileStream = new FileStream(file, FileMode.Create);
-            using (zipArchive = new ZipArchive(fileStream, ZipArchiveMode.Create))
+            using var zipArchive = new ZipArchive(fileStream, ZipArchiveMode.Create);
-            {
+
-                AddNestInfo();
+            WriteNestJson(zipArchive);
-                AddPlates();
+            WritePrograms(zipArchive);
-                AddPlateInfo();
-                AddDrawings();
-                AddDrawingInfo();
-            }
 
             return true;
         }
 
         private void SetDrawingIds()
         {
-            int id = 1;
+            var id = 1;
-
             foreach (var drawing in nest.Drawings)
             {
                 drawingDict.Add(id, drawing);
@@ -65,241 +49,156 @@ namespace OpenNest.IO
             }
         }
 
-        private void AddNestInfo()
+        private void WriteNestJson(ZipArchive zipArchive)
         {
-            var stream = new MemoryStream();
+            var dto = BuildNestDto();
-            var writer = XmlWriter.Create(stream, new XmlWriterSettings()
+            var json = JsonSerializer.Serialize(dto, JsonOptions);
-            {
-                Indent = true
-            });
 
-            writer.WriteStartDocument();
+            var entry = zipArchive.CreateEntry("nest.json");
-            writer.WriteStartElement("Nest");
+            using var stream = entry.Open();
-            writer.WriteAttributeString("name", nest.Name);
+            using var writer = new StreamWriter(stream, Encoding.UTF8);
-
+            writer.Write(json);
-            writer.WriteElementString("Units", nest.Units.ToString());
-            writer.WriteElementString("Customer", nest.Customer);
-            writer.WriteElementString("DateCreated", nest.DateCreated.ToString());
-            writer.WriteElementString("DateLastModified", nest.DateLastModified.ToString());
-
-            writer.WriteStartElement("DefaultPlate");
-            writer.WriteElementString("Size", nest.PlateDefaults.Size.ToString());
-            writer.WriteElementString("Thickness", nest.PlateDefaults.Thickness.ToString());
-            writer.WriteElementString("Quadrant", nest.PlateDefaults.Quadrant.ToString());
-            writer.WriteElementString("PartSpacing", nest.PlateDefaults.PartSpacing.ToString());
-
-            writer.WriteStartElement("Material");
-            writer.WriteElementString("Name", nest.PlateDefaults.Material.Name);
-            writer.WriteElementString("Grade", nest.PlateDefaults.Material.Grade);
-            writer.WriteElementString("Density", nest.PlateDefaults.Material.Density.ToString());
-            writer.WriteEndElement();
-
-            writer.WriteStartElement("EdgeSpacing");
-            writer.WriteElementString("Left", nest.PlateDefaults.EdgeSpacing.Left.ToString());
-            writer.WriteElementString("Top", nest.PlateDefaults.EdgeSpacing.Top.ToString());
-            writer.WriteElementString("Right", nest.PlateDefaults.EdgeSpacing.Right.ToString());
-            writer.WriteElementString("Bottom", nest.PlateDefaults.EdgeSpacing.Bottom.ToString());
-            writer.WriteEndElement();
-
-            writer.WriteElementString("Notes", Uri.EscapeDataString(nest.Notes));
-
-            writer.WriteEndElement(); // DefaultPlate
-            writer.WriteEndElement(); // Nest
-
-            writer.WriteEndDocument();
-
-            writer.Flush();
-            writer.Close();
-
-            stream.Position = 0;
-
-            var entry = zipArchive.CreateEntry("info");
-            using (var entryStream = entry.Open())
-            {
-                stream.CopyTo(entryStream);
-            }
         }
 
-        private void AddPlates()
+        private NestDto BuildNestDto()
         {
-            int num = 1;
+            return new NestDto
-
-            foreach (var plate in nest.Plates)
             {
-                var stream = new MemoryStream();
+                Version = 2,
-                var name = string.Format("plate-{0}", num.ToString().PadLeft(3, '0'));
+                Name = nest.Name ?? "",
+                Units = nest.Units.ToString(),
+                Customer = nest.Customer ?? "",
+                DateCreated = nest.DateCreated.ToString("o"),
+                DateLastModified = nest.DateLastModified.ToString("o"),
+                Notes = nest.Notes ?? "",
+                PlateDefaults = BuildPlateDefaultsDto(),
+                Drawings = BuildDrawingDtos(),
+                Plates = BuildPlateDtos()
+            };
+        }
 
-                WritePlate(stream, plate);
+        private PlateDefaultsDto BuildPlateDefaultsDto()
-
+        {
-                var entry = zipArchive.CreateEntry(name);
+            var pd = nest.PlateDefaults;
-                using (var entryStream = entry.Open())
+            return new PlateDefaultsDto
+            {
+                Size = new SizeDto { Width = pd.Size.Width, Height = pd.Size.Height },
+                Thickness = pd.Thickness,
+                Quadrant = pd.Quadrant,
+                PartSpacing = pd.PartSpacing,
+                Material = new MaterialDto
                 {
-                    stream.CopyTo(entryStream);
+                    Name = pd.Material.Name ?? "",
+                    Grade = pd.Material.Grade ?? "",
+                    Density = pd.Material.Density
+                },
+                EdgeSpacing = new SpacingDto
+                {
+                    Left = pd.EdgeSpacing.Left,
+                    Top = pd.EdgeSpacing.Top,
+                    Right = pd.EdgeSpacing.Right,
+                    Bottom = pd.EdgeSpacing.Bottom
                 }
-
+            };
-                num++;
-            }
         }
 
-        private void AddPlateInfo()
+        private List<DrawingDto> BuildDrawingDtos()
         {
-            var stream = new MemoryStream();
+            var list = new List<DrawingDto>();
-            var writer = XmlWriter.Create(stream, new XmlWriterSettings()
+            foreach (var kvp in drawingDict.OrderBy(k => k.Key))
             {
-                Indent = true
+                var d = kvp.Value;
-            });
+                list.Add(new DrawingDto
+                {
+                    Id = kvp.Key,
+                    Name = d.Name ?? "",
+                    Customer = d.Customer ?? "",
+                    Color = new ColorDto { A = d.Color.A, R = d.Color.R, G = d.Color.G, B = d.Color.B },
+                    Quantity = new QuantityDto { Required = d.Quantity.Required },
+                    Priority = d.Priority,
+                    Constraints = new ConstraintsDto
+                    {
+                        StepAngle = d.Constraints.StepAngle,
+                        StartAngle = d.Constraints.StartAngle,
+                        EndAngle = d.Constraints.EndAngle,
+                        Allow180Equivalent = d.Constraints.Allow180Equivalent
+                    },
+                    Material = new MaterialDto
+                    {
+                        Name = d.Material.Name ?? "",
+                        Grade = d.Material.Grade ?? "",
+                        Density = d.Material.Density
+                    },
+                    Source = new SourceDto
+                    {
+                        Path = d.Source.Path ?? "",
+                        Offset = new OffsetDto { X = d.Source.Offset.X, Y = d.Source.Offset.Y }
+                    }
+                });
+            }
+            return list;
+        }
 
-            writer.WriteStartDocument();
+        private List<PlateDto> BuildPlateDtos()
-            writer.WriteStartElement("Plates");
+        {
-            writer.WriteAttributeString("count", nest.Plates.Count.ToString());
+            var list = new List<PlateDto>();
-
+            for (var i = 0; i < nest.Plates.Count; i++)
-            for (int i = 0; i < nest.Plates.Count; ++i)
             {
                 var plate = nest.Plates[i];
-
+                var parts = new List<PartDto>();
-                writer.WriteStartElement("Plate");
+                foreach (var part in plate.Parts)
-                writer.WriteAttributeString("id", (i + 1).ToString());
-
-                writer.WriteElementString("Quadrant", plate.Quadrant.ToString());
-                writer.WriteElementString("Thickness", plate.Thickness.ToString());
-                writer.WriteElementString("Size", plate.Size.ToString());
-                writer.WriteElementString("Qty", plate.Quantity.ToString());
-                writer.WriteElementString("PartSpacing", plate.PartSpacing.ToString());
-
-                writer.WriteStartElement("Material");
-                writer.WriteElementString("Name", plate.Material.Name);
-                writer.WriteElementString("Grade", plate.Material.Grade);
-                writer.WriteElementString("Density", plate.Material.Density.ToString());
-                writer.WriteEndElement();
-
-                writer.WriteStartElement("EdgeSpacing");
-                writer.WriteElementString("Left", plate.EdgeSpacing.Left.ToString());
-                writer.WriteElementString("Top", plate.EdgeSpacing.Top.ToString());
-                writer.WriteElementString("Right", plate.EdgeSpacing.Right.ToString());
-                writer.WriteElementString("Bottom", plate.EdgeSpacing.Bottom.ToString());
-                writer.WriteEndElement();
-
-                writer.WriteEndElement(); // Plate
-                writer.Flush();
-            }
-
-            writer.WriteEndElement(); // Plates
-            writer.WriteEndDocument();
-
-            writer.Flush();
-            writer.Close();
-
-            stream.Position = 0;
-
-            var entry = zipArchive.CreateEntry("plate-info");
-            using (var entryStream = entry.Open())
-            {
-                stream.CopyTo(entryStream);
-            }
-        }
-
-        private void AddDrawings()
-        {
-            int num = 1;
-
-            foreach (var dwg in nest.Drawings)
-            {
-                var stream = new MemoryStream();
-                var name = string.Format("program-{0}", num.ToString().PadLeft(3, '0'));
-
-                WriteDrawing(stream, dwg);
-
-                var entry = zipArchive.CreateEntry(name);
-                using (var entryStream = entry.Open())
                 {
-                    stream.CopyTo(entryStream);
+                    var match = drawingDict.Where(dwg => dwg.Value == part.BaseDrawing).FirstOrDefault();
+                    parts.Add(new PartDto
+                    {
+                        DrawingId = match.Key,
+                        X = part.Location.X,
+                        Y = part.Location.Y,
+                        Rotation = part.Rotation
+                    });
                 }
 
-                num++;
+                list.Add(new PlateDto
+                {
+                    Id = i + 1,
+                    Size = new SizeDto { Width = plate.Size.Width, Height = plate.Size.Height },
+                    Thickness = plate.Thickness,
+                    Quadrant = plate.Quadrant,
+                    Quantity = plate.Quantity,
+                    PartSpacing = plate.PartSpacing,
+                    Material = new MaterialDto
+                    {
+                        Name = plate.Material.Name ?? "",
+                        Grade = plate.Material.Grade ?? "",
+                        Density = plate.Material.Density
+                    },
+                    EdgeSpacing = new SpacingDto
+                    {
+                        Left = plate.EdgeSpacing.Left,
+                        Top = plate.EdgeSpacing.Top,
+                        Right = plate.EdgeSpacing.Right,
+                        Bottom = plate.EdgeSpacing.Bottom
+                    },
+                    Parts = parts
+                });
             }
+            return list;
         }
 
-        private void AddDrawingInfo()
+        private void WritePrograms(ZipArchive zipArchive)
         {
-            var stream = new MemoryStream();
+            foreach (var kvp in drawingDict.OrderBy(k => k.Key))
-            var writer = XmlWriter.Create(stream, new XmlWriterSettings()
             {
-                Indent = true
+                var name = $"programs/program-{kvp.Key}";
-            });
+                var stream = new MemoryStream();
+                WriteDrawing(stream, kvp.Value);
 
-            writer.WriteStartDocument();
+                var entry = zipArchive.CreateEntry(name);
-            writer.WriteStartElement("Drawings");
+                using var entryStream = entry.Open();
-            writer.WriteAttributeString("count", nest.Drawings.Count.ToString());
-
-            int id = 1;
-
-            foreach (var drawing in nest.Drawings)
-            {
-                writer.WriteStartElement("Drawing");
-                writer.WriteAttributeString("id", id.ToString());
-                writer.WriteAttributeString("name", drawing.Name);
-
-                writer.WriteElementString("Customer", drawing.Customer);
-                writer.WriteElementString("Color", string.Format("{0}, {1}, {2}, {3}", drawing.Color.A, drawing.Color.R, drawing.Color.G, drawing.Color.B));
-
-                writer.WriteStartElement("Quantity");
-                writer.WriteElementString("Required", drawing.Quantity.Required.ToString());
-                writer.WriteElementString("Nested", drawing.Quantity.Nested.ToString());
-                writer.WriteEndElement();
-
-                writer.WriteStartElement("Material");
-                writer.WriteElementString("Name", drawing.Material.Name);
-                writer.WriteElementString("Grade", drawing.Material.Grade);
-                writer.WriteElementString("Density", drawing.Material.Density.ToString());
-                writer.WriteEndElement();
-
-                writer.WriteStartElement("Source");
-                writer.WriteElementString("Path", drawing.Source.Path);
-                writer.WriteElementString("Offset", string.Format("{0}, {1}", 
-                    drawing.Source.Offset.X, 
-                    drawing.Source.Offset.Y));
-                writer.WriteEndElement(); // Source
-
-                writer.WriteEndElement(); // Drawing
-
-                id++;
-            }
-
-            writer.WriteEndElement(); // Drawings
-            writer.WriteEndDocument();
-
-            writer.Flush();
-            writer.Close();
-
-            stream.Position = 0;
-
-            var entry = zipArchive.CreateEntry("drawing-info");
-            using (var entryStream = entry.Open())
-            {
                 stream.CopyTo(entryStream);
             }
         }
 
-        private void WritePlate(Stream stream, Plate plate)
-        {
-            var writer = new StreamWriter(stream);
-            writer.AutoFlush = true;
-            writer.WriteLine("G90");
-
-            foreach (var part in plate.Parts)
-            {
-                var match = drawingDict.Where(dwg => dwg.Value == part.BaseDrawing).FirstOrDefault();
-                var id = match.Key;
-
-                writer.WriteLine("G00X{0}Y{1}",
-                    part.Location.X.ToString(CoordinateFormat),
-                    part.Location.Y.ToString(CoordinateFormat));
-                writer.WriteLine("G65P{0}R{1}", id, Angle.ToDegrees(part.Rotation));
-            }
-
-            stream.Position = 0;
-        }
-
         private void WriteDrawing(Stream stream, Drawing drawing)
         {
             var program = drawing.Program;
@@ -308,7 +207,7 @@ namespace OpenNest.IO
 
             writer.WriteLine(program.Mode == Mode.Absolute ? "G90" : "G91");
 
-            for (int i = 0; i < drawing.Program.Length; ++i)
+            for (var i = 0; i < drawing.Program.Length; ++i)
             {
                 var code = drawing.Program[i];
                 writer.WriteLine(GetCodeString(code));

docs/superpowers/plans/2026-03-12-nest-file-format-v2.md

@@ -0,0 +1,767 @@
+# Nest File Format v2 Implementation Plan
+
+> **For agentic workers:** REQUIRED: Use superpowers:subagent-driven-development (if subagents available) or superpowers:executing-plans to implement this plan. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Replace the XML+G-code nest file format with a single `nest.json` metadata file plus `programs/` folder inside the ZIP archive.
+
+**Architecture:** Add a `NestFormat` static class containing DTO records and shared JSON options. Rewrite `NestWriter` to serialize DTOs to JSON and write programs under `programs/`. Rewrite `NestReader` to deserialize JSON and read programs from `programs/`. Public API unchanged.
+
+**Tech Stack:** `System.Text.Json` (built into .NET 8, no new packages needed)
+
+**Spec:** `docs/superpowers/specs/2026-03-12-nest-file-format-v2-design.md`
+
+---
+
+## File Structure
+
+| Action | File | Responsibility |
+|--------|------|----------------|
+| Create | `OpenNest.IO/NestFormat.cs` | DTO records for JSON serialization + shared `JsonSerializerOptions` |
+| Rewrite | `OpenNest.IO/NestWriter.cs` | Serialize nest to JSON + write programs to `programs/` folder |
+| Rewrite | `OpenNest.IO/NestReader.cs` | Deserialize JSON + read programs from `programs/` folder |
+
+No other files change. `ProgramReader.cs`, `DxfImporter.cs`, `DxfExporter.cs`, `Extensions.cs`, all domain model classes, and all caller sites remain untouched.
+
+---
+
+## Chunk 1: DTO Records and JSON Options
+
+### Task 1: Create NestFormat.cs with DTO records
+
+**Files:**
+- Create: `OpenNest.IO/NestFormat.cs`
+
+These DTOs are the JSON shape — flat records that map 1:1 with the spec's JSON schema. They live in `OpenNest.IO` because they're serialization concerns, not domain model.
+
+- [ ] **Step 1: Create `NestFormat.cs`**
+
+```csharp
+using System.Text.Json;
+
+namespace OpenNest.IO
+{
+    public static class NestFormat
+    {
+        public static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            WriteIndented = true
+        };
+
+        public record NestDto
+        {
+            public int Version { get; init; } = 2;
+            public string Name { get; init; } = "";
+            public string Units { get; init; } = "Inches";
+            public string Customer { get; init; } = "";
+            public string DateCreated { get; init; } = "";
+            public string DateLastModified { get; init; } = "";
+            public string Notes { get; init; } = "";
+            public PlateDefaultsDto PlateDefaults { get; init; } = new();
+            public List<DrawingDto> Drawings { get; init; } = new();
+            public List<PlateDto> Plates { get; init; } = new();
+        }
+
+        public record PlateDefaultsDto
+        {
+            public SizeDto Size { get; init; } = new();
+            public double Thickness { get; init; }
+            public int Quadrant { get; init; } = 1;
+            public double PartSpacing { get; init; }
+            public MaterialDto Material { get; init; } = new();
+            public SpacingDto EdgeSpacing { get; init; } = new();
+        }
+
+        public record DrawingDto
+        {
+            public int Id { get; init; }
+            public string Name { get; init; } = "";
+            public string Customer { get; init; } = "";
+            public ColorDto Color { get; init; } = new();
+            public QuantityDto Quantity { get; init; } = new();
+            public int Priority { get; init; }
+            public ConstraintsDto Constraints { get; init; } = new();
+            public MaterialDto Material { get; init; } = new();
+            public SourceDto Source { get; init; } = new();
+        }
+
+        public record PlateDto
+        {
+            public int Id { get; init; }
+            public SizeDto Size { get; init; } = new();
+            public double Thickness { get; init; }
+            public int Quadrant { get; init; } = 1;
+            public int Quantity { get; init; } = 1;
+            public double PartSpacing { get; init; }
+            public MaterialDto Material { get; init; } = new();
+            public SpacingDto EdgeSpacing { get; init; } = new();
+            public List<PartDto> Parts { get; init; } = new();
+        }
+
+        public record PartDto
+        {
+            public int DrawingId { get; init; }
+            public double X { get; init; }
+            public double Y { get; init; }
+            public double Rotation { get; init; }
+        }
+
+        public record SizeDto
+        {
+            public double Width { get; init; }
+            public double Height { get; init; }
+        }
+
+        public record MaterialDto
+        {
+            public string Name { get; init; } = "";
+            public string Grade { get; init; } = "";
+            public double Density { get; init; }
+        }
+
+        public record SpacingDto
+        {
+            public double Left { get; init; }
+            public double Top { get; init; }
+            public double Right { get; init; }
+            public double Bottom { get; init; }
+        }
+
+        public record ColorDto
+        {
+            public int A { get; init; } = 255;
+            public int R { get; init; }
+            public int G { get; init; }
+            public int B { get; init; }
+        }
+
+        public record QuantityDto
+        {
+            public int Required { get; init; }
+        }
+
+        public record ConstraintsDto
+        {
+            public double StepAngle { get; init; }
+            public double StartAngle { get; init; }
+            public double EndAngle { get; init; }
+            public bool Allow180Equivalent { get; init; }
+        }
+
+        public record SourceDto
+        {
+            public string Path { get; init; } = "";
+            public OffsetDto Offset { get; init; } = new();
+        }
+
+        public record OffsetDto
+        {
+            public double X { get; init; }
+            public double Y { get; init; }
+        }
+    }
+}
+```
+
+- [ ] **Step 2: Build to verify DTOs compile**
+
+Run: `dotnet build OpenNest.IO/OpenNest.IO.csproj`
+Expected: Build succeeded.
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add OpenNest.IO/NestFormat.cs
+git commit -m "feat: add NestFormat DTOs for JSON nest file format v2"
+```
+
+---
+
+## Chunk 2: Rewrite NestWriter
+
+### Task 2: Rewrite NestWriter to use JSON serialization
+
+**Files:**
+- Rewrite: `OpenNest.IO/NestWriter.cs`
+
+The writer keeps the same public API: `NestWriter(Nest nest)` constructor and `bool Write(string file)`. Internally it builds a `NestDto` from the domain model, serializes it to `nest.json`, and writes each drawing's program to `programs/program-N`.
+
+The G-code writing methods (`WriteDrawing`, `GetCodeString`, `GetLayerString`) are preserved exactly — they write program G-code to streams, which is unchanged. The `WritePlate` method and all XML methods (`AddNestInfo`, `AddPlateInfo`, `AddDrawingInfo`) are removed.
+
+- [ ] **Step 1: Rewrite `NestWriter.cs`**
+
+Replace the entire file. Key changes:
+- Remove `using System.Xml`
+- Add `using System.Text.Json`
+- Remove `AddNestInfo()`, `AddPlateInfo()`, `AddDrawingInfo()`, `AddPlates()`, `WritePlate()` methods
+- Add `BuildNestDto()` method that maps domain model → DTOs
+- `Write()` now serializes `NestDto` to `nest.json` and writes programs to `programs/program-N`
+- Keep `WriteDrawing()`, `GetCodeString()`, `GetLayerString()` exactly as-is
+
+```csharp
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.Compression;
+using System.Linq;
+using System.Text;
+using System.Text.Json;
+using OpenNest.CNC;
+using OpenNest.Math;
+using static OpenNest.IO.NestFormat;
+
+namespace OpenNest.IO
+{
+    public sealed class NestWriter
+    {
+        private const int OutputPrecision = 10;
+        private const string CoordinateFormat = "0.##########";
+
+        private readonly Nest nest;
+        private Dictionary<int, Drawing> drawingDict;
+
+        public NestWriter(Nest nest)
+        {
+            this.drawingDict = new Dictionary<int, Drawing>();
+            this.nest = nest;
+        }
+
+        public bool Write(string file)
+        {
+            nest.DateLastModified = DateTime.Now;
+            SetDrawingIds();
+
+            using var fileStream = new FileStream(file, FileMode.Create);
+            using var zipArchive = new ZipArchive(fileStream, ZipArchiveMode.Create);
+
+            WriteNestJson(zipArchive);
+            WritePrograms(zipArchive);
+
+            return true;
+        }
+
+        private void SetDrawingIds()
+        {
+            var id = 1;
+            foreach (var drawing in nest.Drawings)
+            {
+                drawingDict.Add(id, drawing);
+                id++;
+            }
+        }
+
+        private void WriteNestJson(ZipArchive zipArchive)
+        {
+            var dto = BuildNestDto();
+            var json = JsonSerializer.Serialize(dto, JsonOptions);
+
+            var entry = zipArchive.CreateEntry("nest.json");
+            using var stream = entry.Open();
+            using var writer = new StreamWriter(stream, Encoding.UTF8);
+            writer.Write(json);
+        }
+
+        private NestDto BuildNestDto()
+        {
+            return new NestDto
+            {
+                Version = 2,
+                Name = nest.Name ?? "",
+                Units = nest.Units.ToString(),
+                Customer = nest.Customer ?? "",
+                DateCreated = nest.DateCreated.ToString("o"),
+                DateLastModified = nest.DateLastModified.ToString("o"),
+                Notes = nest.Notes ?? "",
+                PlateDefaults = BuildPlateDefaultsDto(),
+                Drawings = BuildDrawingDtos(),
+                Plates = BuildPlateDtos()
+            };
+        }
+
+        private PlateDefaultsDto BuildPlateDefaultsDto()
+        {
+            var pd = nest.PlateDefaults;
+            return new PlateDefaultsDto
+            {
+                Size = new SizeDto { Width = pd.Size.Width, Height = pd.Size.Height },
+                Thickness = pd.Thickness,
+                Quadrant = pd.Quadrant,
+                PartSpacing = pd.PartSpacing,
+                Material = new MaterialDto
+                {
+                    Name = pd.Material.Name ?? "",
+                    Grade = pd.Material.Grade ?? "",
+                    Density = pd.Material.Density
+                },
+                EdgeSpacing = new SpacingDto
+                {
+                    Left = pd.EdgeSpacing.Left,
+                    Top = pd.EdgeSpacing.Top,
+                    Right = pd.EdgeSpacing.Right,
+                    Bottom = pd.EdgeSpacing.Bottom
+                }
+            };
+        }
+
+        private List<DrawingDto> BuildDrawingDtos()
+        {
+            var list = new List<DrawingDto>();
+            foreach (var kvp in drawingDict.OrderBy(k => k.Key))
+            {
+                var d = kvp.Value;
+                list.Add(new DrawingDto
+                {
+                    Id = kvp.Key,
+                    Name = d.Name ?? "",
+                    Customer = d.Customer ?? "",
+                    Color = new ColorDto { A = d.Color.A, R = d.Color.R, G = d.Color.G, B = d.Color.B },
+                    Quantity = new QuantityDto { Required = d.Quantity.Required },
+                    Priority = d.Priority,
+                    Constraints = new ConstraintsDto
+                    {
+                        StepAngle = d.Constraints.StepAngle,
+                        StartAngle = d.Constraints.StartAngle,
+                        EndAngle = d.Constraints.EndAngle,
+                        Allow180Equivalent = d.Constraints.Allow180Equivalent
+                    },
+                    Material = new MaterialDto
+                    {
+                        Name = d.Material.Name ?? "",
+                        Grade = d.Material.Grade ?? "",
+                        Density = d.Material.Density
+                    },
+                    Source = new SourceDto
+                    {
+                        Path = d.Source.Path ?? "",
+                        Offset = new OffsetDto { X = d.Source.Offset.X, Y = d.Source.Offset.Y }
+                    }
+                });
+            }
+            return list;
+        }
+
+        private List<PlateDto> BuildPlateDtos()
+        {
+            var list = new List<PlateDto>();
+            for (var i = 0; i < nest.Plates.Count; i++)
+            {
+                var plate = nest.Plates[i];
+                var parts = new List<PartDto>();
+                foreach (var part in plate.Parts)
+                {
+                    var match = drawingDict.Where(dwg => dwg.Value == part.BaseDrawing).FirstOrDefault();
+                    parts.Add(new PartDto
+                    {
+                        DrawingId = match.Key,
+                        X = part.Location.X,
+                        Y = part.Location.Y,
+                        Rotation = part.Rotation
+                    });
+                }
+
+                list.Add(new PlateDto
+                {
+                    Id = i + 1,
+                    Size = new SizeDto { Width = plate.Size.Width, Height = plate.Size.Height },
+                    Thickness = plate.Thickness,
+                    Quadrant = plate.Quadrant,
+                    Quantity = plate.Quantity,
+                    PartSpacing = plate.PartSpacing,
+                    Material = new MaterialDto
+                    {
+                        Name = plate.Material.Name ?? "",
+                        Grade = plate.Material.Grade ?? "",
+                        Density = plate.Material.Density
+                    },
+                    EdgeSpacing = new SpacingDto
+                    {
+                        Left = plate.EdgeSpacing.Left,
+                        Top = plate.EdgeSpacing.Top,
+                        Right = plate.EdgeSpacing.Right,
+                        Bottom = plate.EdgeSpacing.Bottom
+                    },
+                    Parts = parts
+                });
+            }
+            return list;
+        }
+
+        private void WritePrograms(ZipArchive zipArchive)
+        {
+            foreach (var kvp in drawingDict.OrderBy(k => k.Key))
+            {
+                var name = $"programs/program-{kvp.Key}";
+                var stream = new MemoryStream();
+                WriteDrawing(stream, kvp.Value);
+
+                var entry = zipArchive.CreateEntry(name);
+                using var entryStream = entry.Open();
+                stream.CopyTo(entryStream);
+            }
+        }
+
+        private void WriteDrawing(Stream stream, Drawing drawing)
+        {
+            var program = drawing.Program;
+            var writer = new StreamWriter(stream);
+            writer.AutoFlush = true;
+
+            writer.WriteLine(program.Mode == Mode.Absolute ? "G90" : "G91");
+
+            for (var i = 0; i < drawing.Program.Length; ++i)
+            {
+                var code = drawing.Program[i];
+                writer.WriteLine(GetCodeString(code));
+            }
+
+            stream.Position = 0;
+        }
+
+        private string GetCodeString(ICode code)
+        {
+            switch (code.Type)
+            {
+                case CodeType.ArcMove:
+                    {
+                        var sb = new StringBuilder();
+                        var arcMove = (ArcMove)code;
+
+                        var x = System.Math.Round(arcMove.EndPoint.X, OutputPrecision).ToString(CoordinateFormat);
+                        var y = System.Math.Round(arcMove.EndPoint.Y, OutputPrecision).ToString(CoordinateFormat);
+                        var i = System.Math.Round(arcMove.CenterPoint.X, OutputPrecision).ToString(CoordinateFormat);
+                        var j = System.Math.Round(arcMove.CenterPoint.Y, OutputPrecision).ToString(CoordinateFormat);
+
+                        if (arcMove.Rotation == RotationType.CW)
+                            sb.Append(string.Format("G02X{0}Y{1}I{2}J{3}", x, y, i, j));
+                        else
+                            sb.Append(string.Format("G03X{0}Y{1}I{2}J{3}", x, y, i, j));
+
+                        if (arcMove.Layer != LayerType.Cut)
+                            sb.Append(GetLayerString(arcMove.Layer));
+
+                        return sb.ToString();
+                    }
+
+                case CodeType.Comment:
+                    {
+                        var comment = (Comment)code;
+                        return ":" + comment.Value;
+                    }
+
+                case CodeType.LinearMove:
+                    {
+                        var sb = new StringBuilder();
+                        var linearMove = (LinearMove)code;
+
+                        sb.Append(string.Format("G01X{0}Y{1}",
+                            System.Math.Round(linearMove.EndPoint.X, OutputPrecision).ToString(CoordinateFormat),
+                            System.Math.Round(linearMove.EndPoint.Y, OutputPrecision).ToString(CoordinateFormat)));
+
+                        if (linearMove.Layer != LayerType.Cut)
+                            sb.Append(GetLayerString(linearMove.Layer));
+
+                        return sb.ToString();
+                    }
+
+                case CodeType.RapidMove:
+                    {
+                        var rapidMove = (RapidMove)code;
+
+                        return string.Format("G00X{0}Y{1}",
+                            System.Math.Round(rapidMove.EndPoint.X, OutputPrecision).ToString(CoordinateFormat),
+                            System.Math.Round(rapidMove.EndPoint.Y, OutputPrecision).ToString(CoordinateFormat));
+                    }
+
+                case CodeType.SetFeedrate:
+                    {
+                        var setFeedrate = (Feedrate)code;
+                        return "F" + setFeedrate.Value;
+                    }
+
+                case CodeType.SetKerf:
+                    {
+                        var setKerf = (Kerf)code;
+
+                        switch (setKerf.Value)
+                        {
+                            case KerfType.None: return "G40";
+                            case KerfType.Left: return "G41";
+                            case KerfType.Right: return "G42";
+                        }
+
+                        break;
+                    }
+
+                case CodeType.SubProgramCall:
+                    {
+                        var subProgramCall = (SubProgramCall)code;
+                        break;
+                    }
+            }
+
+            return string.Empty;
+        }
+
+        private string GetLayerString(LayerType layer)
+        {
+            switch (layer)
+            {
+                case LayerType.Display:
+                    return ":DISPLAY";
+
+                case LayerType.Leadin:
+                    return ":LEADIN";
+
+                case LayerType.Leadout:
+                    return ":LEADOUT";
+
+                case LayerType.Scribe:
+                    return ":SCRIBE";
+
+                default:
+                    return string.Empty;
+            }
+        }
+    }
+}
+```
+
+- [ ] **Step 2: Build to verify NestWriter compiles**
+
+Run: `dotnet build OpenNest.sln`
+Expected: Build succeeded.
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add OpenNest.IO/NestWriter.cs
+git commit -m "feat: rewrite NestWriter to use JSON format v2"
+```
+
+---
+
+## Chunk 3: Rewrite NestReader
+
+### Task 3: Rewrite NestReader to use JSON deserialization
+
+**Files:**
+- Rewrite: `OpenNest.IO/NestReader.cs`
+
+The reader keeps the same public API: `NestReader(string file)`, `NestReader(Stream stream)`, and `Nest Read()`. Internally it reads `nest.json`, deserializes to `NestDto`, reads programs from `programs/program-N`, and assembles the domain model.
+
+All XML parsing, plate G-code parsing, dictionary-linking (`LinkProgramsToDrawings`, `LinkPartsToPlates`), and the helper enums/methods are removed.
+
+- [ ] **Step 1: Rewrite `NestReader.cs`**
+
+Replace the entire file:
+
+```csharp
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.IO;
+using System.IO.Compression;
+using System.Linq;
+using System.Text.Json;
+using OpenNest.CNC;
+using OpenNest.Geometry;
+using static OpenNest.IO.NestFormat;
+
+namespace OpenNest.IO
+{
+    public sealed class NestReader
+    {
+        private readonly Stream stream;
+        private readonly ZipArchive zipArchive;
+
+        public NestReader(string file)
+        {
+            stream = new FileStream(file, FileMode.Open, FileAccess.Read);
+            zipArchive = new ZipArchive(stream, ZipArchiveMode.Read);
+        }
+
+        public NestReader(Stream stream)
+        {
+            this.stream = stream;
+            zipArchive = new ZipArchive(stream, ZipArchiveMode.Read);
+        }
+
+        public Nest Read()
+        {
+            var nestJson = ReadEntry("nest.json");
+            var dto = JsonSerializer.Deserialize<NestDto>(nestJson, JsonOptions);
+
+            var programs = ReadPrograms(dto.Drawings.Count);
+            var drawingMap = BuildDrawings(dto, programs);
+            var nest = BuildNest(dto, drawingMap);
+
+            zipArchive.Dispose();
+            stream.Close();
+
+            return nest;
+        }
+
+        private string ReadEntry(string name)
+        {
+            var entry = zipArchive.GetEntry(name)
+                ?? throw new InvalidDataException($"Nest file is missing required entry '{name}'.");
+            using var entryStream = entry.Open();
+            using var reader = new StreamReader(entryStream);
+            return reader.ReadToEnd();
+        }
+
+        private Dictionary<int, Program> ReadPrograms(int count)
+        {
+            var programs = new Dictionary<int, Program>();
+            for (var i = 1; i <= count; i++)
+            {
+                var entry = zipArchive.GetEntry($"programs/program-{i}");
+                if (entry == null) continue;
+
+                using var entryStream = entry.Open();
+                var memStream = new MemoryStream();
+                entryStream.CopyTo(memStream);
+                memStream.Position = 0;
+
+                var reader = new ProgramReader(memStream);
+                programs[i] = reader.Read();
+            }
+            return programs;
+        }
+
+        private Dictionary<int, Drawing> BuildDrawings(NestDto dto, Dictionary<int, Program> programs)
+        {
+            var map = new Dictionary<int, Drawing>();
+            foreach (var d in dto.Drawings)
+            {
+                var drawing = new Drawing(d.Name);
+                drawing.Customer = d.Customer;
+                drawing.Color = Color.FromArgb(d.Color.A, d.Color.R, d.Color.G, d.Color.B);
+                drawing.Quantity.Required = d.Quantity.Required;
+                drawing.Priority = d.Priority;
+                drawing.Constraints.StepAngle = d.Constraints.StepAngle;
+                drawing.Constraints.StartAngle = d.Constraints.StartAngle;
+                drawing.Constraints.EndAngle = d.Constraints.EndAngle;
+                drawing.Constraints.Allow180Equivalent = d.Constraints.Allow180Equivalent;
+                drawing.Material = new Material(d.Material.Name, d.Material.Grade, d.Material.Density);
+                drawing.Source.Path = d.Source.Path;
+                drawing.Source.Offset = new Vector(d.Source.Offset.X, d.Source.Offset.Y);
+
+                if (programs.TryGetValue(d.Id, out var pgm))
+                    drawing.Program = pgm;
+
+                map[d.Id] = drawing;
+            }
+            return map;
+        }
+
+        private Nest BuildNest(NestDto dto, Dictionary<int, Drawing> drawingMap)
+        {
+            var nest = new Nest();
+            nest.Name = dto.Name;
+
+            Units units;
+            if (Enum.TryParse(dto.Units, true, out units))
+                nest.Units = units;
+
+            nest.Customer = dto.Customer;
+            nest.DateCreated = DateTime.Parse(dto.DateCreated);
+            nest.DateLastModified = DateTime.Parse(dto.DateLastModified);
+            nest.Notes = dto.Notes;
+
+            // Plate defaults
+            var pd = dto.PlateDefaults;
+            nest.PlateDefaults.Size = new Size(pd.Size.Width, pd.Size.Height);
+            nest.PlateDefaults.Thickness = pd.Thickness;
+            nest.PlateDefaults.Quadrant = pd.Quadrant;
+            nest.PlateDefaults.PartSpacing = pd.PartSpacing;
+            nest.PlateDefaults.Material = new Material(pd.Material.Name, pd.Material.Grade, pd.Material.Density);
+            nest.PlateDefaults.EdgeSpacing = new Spacing(pd.EdgeSpacing.Left, pd.EdgeSpacing.Bottom, pd.EdgeSpacing.Right, pd.EdgeSpacing.Top);
+
+            // Drawings
+            foreach (var d in drawingMap.OrderBy(k => k.Key))
+                nest.Drawings.Add(d.Value);
+
+            // Plates
+            foreach (var p in dto.Plates.OrderBy(p => p.Id))
+            {
+                var plate = new Plate();
+                plate.Size = new Size(p.Size.Width, p.Size.Height);
+                plate.Thickness = p.Thickness;
+                plate.Quadrant = p.Quadrant;
+                plate.Quantity = p.Quantity;
+                plate.PartSpacing = p.PartSpacing;
+                plate.Material = new Material(p.Material.Name, p.Material.Grade, p.Material.Density);
+                plate.EdgeSpacing = new Spacing(p.EdgeSpacing.Left, p.EdgeSpacing.Bottom, p.EdgeSpacing.Right, p.EdgeSpacing.Top);
+
+                foreach (var partDto in p.Parts)
+                {
+                    if (!drawingMap.TryGetValue(partDto.DrawingId, out var dwg))
+                        continue;
+
+                    var part = new Part(dwg);
+                    part.Rotate(partDto.Rotation);
+                    part.Offset(new Vector(partDto.X, partDto.Y));
+                    plate.Parts.Add(part);
+                }
+
+                nest.Plates.Add(plate);
+            }
+
+            return nest;
+        }
+    }
+}
+```
+
+- [ ] **Step 2: Build to verify NestReader compiles**
+
+Run: `dotnet build OpenNest.sln`
+Expected: Build succeeded.
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add OpenNest.IO/NestReader.cs
+git commit -m "feat: rewrite NestReader to use JSON format v2"
+```
+
+---
+
+## Chunk 4: Smoke Test
+
+### Task 4: Manual smoke test via OpenNest.Console
+
+**Files:** None modified — this is a verification step.
+
+Use the `OpenNest.Console` project (or the MCP server) to verify round-trip: create a nest, save it, reload it, confirm data is intact.
+
+- [ ] **Step 1: Build the full solution**
+
+Run: `dotnet build OpenNest.sln`
+Expected: Build succeeded with no errors.
+
+- [ ] **Step 2: Round-trip test via MCP tools**
+
+Use the OpenNest MCP tools to:
+1. Create a drawing (e.g. a rectangle via `create_drawing`)
+2. Create a plate via `create_plate`
+3. Fill the plate via `fill_plate`
+4. Save the nest via the console app or verify `get_plate_info` shows parts
+5. If a nest file exists on disk, load it with `load_nest` and verify `get_plate_info` returns the same data
+
+- [ ] **Step 3: Inspect the ZIP contents**
+
+Unzip a saved nest file and verify:
+- `nest.json` exists with correct structure
+- `programs/program-1` (etc.) exist with G-code content
+- No `info`, `drawing-info`, `plate-info`, or `plate-NNN` files exist
+
+- [ ] **Step 4: Commit any fixes**
+
+If any issues were found and fixed, commit them:
+
+```bash
+git add -u
+git commit -m "fix: address issues found during nest format v2 smoke test"
+```

docs/superpowers/specs/2026-03-12-nest-file-format-v2-design.md

@@ -0,0 +1,134 @@
+# Nest File Format v2 Design
+
+## Problem
+
+The current nest file format stores metadata across three separate XML files (`info`, `drawing-info`, `plate-info`) plus per-plate G-code files for part placements inside a ZIP archive. This results in ~400 lines of hand-written XML read/write code, fragile dictionary-linking to reconnect drawings/plates by ID after parsing, and the overhead of running the full G-code parser just to extract part positions.
+
+## Design
+
+### File Structure
+
+The nest file remains a ZIP archive. Contents:
+
+```
+nest.json
+programs/
+  program-1
+  program-2
+  ...
+```
+
+- **`nest.json`** — single JSON file containing all metadata and part placements.
+- **`programs/program-N`** — G-code text for each drawing's CNC program (1-indexed, no zero-padding). Previously stored at the archive root as `program-NNN` (zero-padded). Parsed by `ProgramReader`, written by existing G-code serialization logic. Format unchanged.
+
+Plate G-code files (`plate-NNN`) are removed. Part placements are stored inline in `nest.json`.
+
+### JSON Schema
+
+```json
+{
+  "version": 2,
+  "name": "string",
+  "units": "Inches | Millimeters",
+  "customer": "string",
+  "dateCreated": "2026-03-12T10:30:00",
+  "dateLastModified": "2026-03-12T14:00:00",
+  "notes": "string (plain JSON, no URI-escaping)",
+  "plateDefaults": {
+    "size": { "width": 0.0, "height": 0.0 },
+    "thickness": 0.0,
+    "quadrant": 1,
+    "partSpacing": 0.0,
+    "material": { "name": "string", "grade": "string", "density": 0.0 },
+    "edgeSpacing": { "left": 0.0, "top": 0.0, "right": 0.0, "bottom": 0.0 }
+  },
+  "drawings": [
+    {
+      "id": 1,
+      "name": "string",
+      "customer": "string",
+      "color": { "a": 255, "r": 0, "g": 0, "b": 0 },
+      "quantity": { "required": 0 },
+      "priority": 0,
+      "constraints": {
+        "stepAngle": 0.0,
+        "startAngle": 0.0,
+        "endAngle": 0.0,
+        "allow180Equivalent": false
+      },
+      "material": { "name": "string", "grade": "string", "density": 0.0 },
+      "source": {
+        "path": "string",
+        "offset": { "x": 0.0, "y": 0.0 }
+      }
+    }
+  ],
+  "plates": [
+    {
+      "id": 1,
+      "size": { "width": 0.0, "height": 0.0 },
+      "thickness": 0.0,
+      "quadrant": 1,
+      "quantity": 1,
+      "partSpacing": 0.0,
+      "material": { "name": "string", "grade": "string", "density": 0.0 },
+      "edgeSpacing": { "left": 0.0, "top": 0.0, "right": 0.0, "bottom": 0.0 },
+      "parts": [
+        { "drawingId": 1, "x": 0.0, "y": 0.0, "rotation": 0.0 }
+      ]
+    }
+  ]
+}
+```
+
+Key details:
+- **Version**: `"version": 2` at the top level for future format migration.
+- Drawing `id` values are 1-indexed, matching `programs/program-N` filenames.
+- Part `rotation` is stored in **radians** (matches internal domain model, no conversion needed).
+- Part `drawingId` references the drawing's `id` in the `drawings` array.
+- **Dates**: local time, serialized via `DateTime.ToString("o")` (ISO 8601 round-trip format with timezone offset).
+- **Notes**: stored as plain JSON strings. The v1 URI-escaping (`Uri.EscapeDataString`) is not needed since JSON handles special characters natively.
+- `quantity.required` is the only quantity persisted; `nested` is computed at load time from part placements.
+- **Units**: enum values match the domain model: `Inches` or `Millimeters`.
+- **Size**: uses `width`/`height` matching the `OpenNest.Geometry.Size` struct.
+- **Drawing.Priority** and **Drawing.Constraints** (stepAngle, startAngle, endAngle, allow180Equivalent) are now persisted (v1 omitted these).
+- **Empty collections**: `drawings` and `plates` arrays are always present (may be empty `[]`). The `programs/` folder is empty when there are no drawings.
+
+### Serialization Approach
+
+Use `System.Text.Json` with small DTO (Data Transfer Object) classes for serialization. The DTOs map between the domain model and the JSON structure, keeping serialization concerns out of the domain classes.
+
+### What Changes
+
+| File | Change |
+|------|--------|
+| `NestWriter.cs` | Replace all XML writing and plate G-code writing with JSON serialization. Programs written to `programs/` folder. |
+| `NestReader.cs` | Replace all XML parsing, plate G-code parsing, and dictionary-linking with JSON deserialization. Programs read from `programs/` folder. |
+
+### What Stays the Same
+
+| File | Reason |
+|------|--------|
+| `ProgramReader.cs` | G-code parsing for CNC programs is unchanged. |
+| `NestWriter` G-code writing (`WriteDrawing`, `GetCodeString`) | G-code serialization for programs is unchanged. |
+| `DxfImporter.cs`, `DxfExporter.cs`, `Extensions.cs` | Unrelated to nest file format. |
+| Domain model classes | No changes needed. |
+
+### Public API
+
+The public API is unchanged:
+- `NestReader(string file)` and `NestReader(Stream stream)` constructors preserved.
+- `NestReader.Read()` returns `Nest`.
+- `NestWriter(Nest nest)` constructor preserved.
+- `NestWriter.Write(string file)` returns `bool`.
+
+### Callers (no changes needed)
+
+- `MainForm.cs:329` — `new NestReader(path)`
+- `MainForm.cs:363` — `new NestReader(dlg.FileName)`
+- `EditNestForm.cs:212` — `new NestWriter(Nest)`
+- `EditNestForm.cs:223` — `new NestWriter(nst)`
+- `Document.cs:27` — `new NestWriter(Nest)`
+- `OpenNest.Console/Program.cs:94` — `new NestReader(nestFile)`
+- `OpenNest.Console/Program.cs:190` — `new NestWriter(nest)`
+- `OpenNest.Mcp/InputTools.cs:30` — `new NestReader(path)`