refactor(engine): separate plate placement from job allocation

OpenNest.Engine/Jobs/Placement/DefaultPlateNester.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace OpenNest;
+
+/// <summary>
+/// Migrated built-in placement strategy for the whole-job runner. Reuses <see cref="DefaultNestEngine"/>
+/// fill/pack geometry but owns its own run-scoped bookkeeping: remaining demand is read from the
+/// request and placement counts are derived from returned placements, so the engine's private
+/// <see cref="NestItem.Quantity"/> mutations never feed back into job accounting.
+/// </summary>
+/// <remarks>
+/// A private <see cref="Drawing"/> per requirement is created once per solve and reused across every
+/// candidate trial (the runner reuses one <see cref="IPlateNester"/> instance per job). This is safe
+/// because the engines mutate <see cref="NestItem.Quantity"/> (per-trial) and canonical-frame copies,
+/// never the shared <see cref="Drawing"/> or its <c>Quantity</c>. Identity is by Drawing reference,
+/// never by name. Each trial still gets a fresh private <see cref="Plate"/>.
+/// </remarks>
+public sealed class DefaultPlateNester : IPlateNester
+{
+    private readonly Func<Plate, DefaultNestEngine> engineFactory;
+    private readonly Dictionary<string, Drawing> drawingsById = new(StringComparer.Ordinal);
+    private readonly Dictionary<Drawing, string> idByDrawing = new(ReferenceEqualityComparer.Instance);
+
+    public DefaultPlateNester() : this(static plate => new DefaultNestEngine(plate))
+    {
+    }
+
+    /// <param name="engineFactory">Injectable for tests; defaults to <see cref="DefaultNestEngine"/>.</param>
+    public DefaultPlateNester(Func<Plate, DefaultNestEngine> engineFactory)
+    {
+        this.engineFactory = engineFactory ?? throw new ArgumentNullException(nameof(engineFactory));
+    }
+
+    public PlateCandidate Place(PlatePlacementRequest request, IProgress<NestJobProgress> progress = null,
+        CancellationToken token = default)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+        token.ThrowIfCancellationRequested();
+
+        var plate = DrawingJobMapper.CreatePlate(request.Stock);
+        var items = new List<NestItem>(request.Parts.Count);
+        foreach (var requirement in request.Parts)
+        {
+            if (!drawingsById.TryGetValue(requirement.Id, out var drawing))
+            {
+                drawing = DrawingJobMapper.CreateDrawing(requirement);
+                drawingsById.Add(requirement.Id, drawing);
+                idByDrawing.Add(drawing, requirement.Id);
+            }
+
+            // Quantity is the request's remaining demand; the engine may mutate this per-trial item,
+            // and that mutation is deliberately discarded — placement counts come from the result.
+            items.Add(new NestItem
+            {
+                Drawing = drawing,
+                Quantity = requirement.Quantity,
+                Priority = requirement.Priority,
+                StepAngle = DrawingJobMapper.LegacyStep(requirement.Rotation),
+                RotationStart = requirement.Rotation.Start,
+                RotationEnd = requirement.Rotation.End
+            });
+        }
+
+        var engine = engineFactory(plate) ?? throw new InvalidOperationException("Engine factory returned null.");
+        var legacyProgress = CandidateProgressBridge.Create(progress, request.Stock.Id);
+        var parts = engine.Nest(items, legacyProgress, token);
+        token.ThrowIfCancellationRequested();
+        if (parts == null) throw new InvalidOperationException("Engine returned null placements.");
+
+        var placements = new List<NestJobPlacement>(parts.Count);
+        foreach (var part in parts)
+        {
+            if (part?.BaseDrawing == null || !idByDrawing.TryGetValue(part.BaseDrawing, out var id))
+                throw new InvalidOperationException("Placement does not reference a known requirement drawing.");
+            placements.Add(new NestJobPlacement(id, 0, part.Location.X, part.Location.Y, part.Rotation));
+        }
+
+        return new PlateCandidate(placements);
+    }
+}

OpenNest.Engine/Jobs/Placement/StripPlateNester.cs

@@ -0,0 +1,77 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace OpenNest;
+
+/// <summary>
+/// Migrated built-in placement strategy for the whole-job runner. Reuses <see cref="StripNestEngine"/>
+/// iterative shrink-fill/pack geometry with the same run-scoped bookkeeping as <see cref="DefaultPlateNester"/>:
+/// remaining demand is read from the request and placement counts are derived from returned placements.
+/// </summary>
+/// <remarks>
+/// A private <see cref="Drawing"/> per requirement is created once per solve and reused across trials
+/// (safe: the engine mutates per-trial <see cref="NestItem.Quantity"/> and canonical copies, never the
+/// shared Drawing). Identity is by Drawing reference. Each trial gets a fresh private <see cref="Plate"/>.
+/// </remarks>
+public sealed class StripPlateNester : IPlateNester
+{
+    private readonly Func<Plate, StripNestEngine> engineFactory;
+    private readonly Dictionary<string, Drawing> drawingsById = new(StringComparer.Ordinal);
+    private readonly Dictionary<Drawing, string> idByDrawing = new(ReferenceEqualityComparer.Instance);
+
+    public StripPlateNester() : this(static plate => new StripNestEngine(plate))
+    {
+    }
+
+    /// <param name="engineFactory">Injectable for tests; defaults to <see cref="StripNestEngine"/>.</param>
+    public StripPlateNester(Func<Plate, StripNestEngine> engineFactory)
+    {
+        this.engineFactory = engineFactory ?? throw new ArgumentNullException(nameof(engineFactory));
+    }
+
+    public PlateCandidate Place(PlatePlacementRequest request, IProgress<NestJobProgress> progress = null,
+        CancellationToken token = default)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+        token.ThrowIfCancellationRequested();
+
+        var plate = DrawingJobMapper.CreatePlate(request.Stock);
+        var items = new List<NestItem>(request.Parts.Count);
+        foreach (var requirement in request.Parts)
+        {
+            if (!drawingsById.TryGetValue(requirement.Id, out var drawing))
+            {
+                drawing = DrawingJobMapper.CreateDrawing(requirement);
+                drawingsById.Add(requirement.Id, drawing);
+                idByDrawing.Add(drawing, requirement.Id);
+            }
+
+            items.Add(new NestItem
+            {
+                Drawing = drawing,
+                Quantity = requirement.Quantity,
+                Priority = requirement.Priority,
+                StepAngle = DrawingJobMapper.LegacyStep(requirement.Rotation),
+                RotationStart = requirement.Rotation.Start,
+                RotationEnd = requirement.Rotation.End
+            });
+        }
+
+        var engine = engineFactory(plate) ?? throw new InvalidOperationException("Engine factory returned null.");
+        var legacyProgress = CandidateProgressBridge.Create(progress, request.Stock.Id);
+        var parts = engine.Nest(items, legacyProgress, token);
+        token.ThrowIfCancellationRequested();
+        if (parts == null) throw new InvalidOperationException("Engine returned null placements.");
+
+        var placements = new List<NestJobPlacement>(parts.Count);
+        foreach (var part in parts)
+        {
+            if (part?.BaseDrawing == null || !idByDrawing.TryGetValue(part.BaseDrawing, out var id))
+                throw new InvalidOperationException("Placement does not reference a known requirement drawing.");
+            placements.Add(new NestJobPlacement(id, 0, part.Location.X, part.Location.Y, part.Rotation));
+        }
+
+        return new PlateCandidate(placements);
+    }
+}