refactor(cutting): merge circle lead settings into internal leads

Full circles now take InternalLeadIn/InternalLeadOut like every other
cutout; the ArcCircle lead settings and the cutting panel's Arc / Circle
tab are removed. Circle-specific geometry handling (radius clamp, angle
rounding, pierce zone) is unchanged.

Older nest files and desktop settings still load: their arcCircleLeadIn/
arcCircleLeadOut keys are ignored and no longer written, so re-planned
circles take the internal leads. Saved part programs are untouched.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

OpenNest.Core/CNC/CuttingPlanning/OwnedCuttingParameters.cs

@@ -33,10 +33,8 @@ internal static class OwnedCuttingParameters
             PierceDiameter = Dimension(source.PierceDiameter),
             ExternalLeadIn = CopyLeadIn(source.ExternalLeadIn),
             InternalLeadIn = CopyLeadIn(source.InternalLeadIn),
-            ArcCircleLeadIn = CopyLeadIn(source.ArcCircleLeadIn),
             ExternalLeadOut = CopyLeadOut(source.ExternalLeadOut),
             InternalLeadOut = CopyLeadOut(source.InternalLeadOut),
-            ArcCircleLeadOut = CopyLeadOut(source.ArcCircleLeadOut),
             RoundLeadInAngles = source.RoundLeadInAngles,
             LeadInAngleIncrement = source.LeadInAngleIncrement,
             TabConfig = source.TabConfig == null

OpenNest.Core/CNC/CuttingPlanning/PreparedContours.cs

@@ -208,17 +208,15 @@ public sealed class PreparedContours
         return pins.Any(p => p?.IsResolved != false) ? new PreparedContours(unpinned, pins, token) : unpinned;
     }
 
-    // The pin's leads replace every contour type's leads, since the type the emitter detects is
+    // The pin's leads replace both lead sets, since the type the emitter detects is
     // not the caller's concern; angle rounding is off because a pinned entry never moves.
     private static CuttingParameters PinParameters(CuttingParameters shared, ContourCutPin pin)
     {
         var owned = OwnedCuttingParameters.Copy(shared);
         owned.ExternalLeadIn = pin.LeadIn;
         owned.InternalLeadIn = pin.LeadIn;
-        owned.ArcCircleLeadIn = pin.LeadIn;
         owned.ExternalLeadOut = pin.LeadOut;
         owned.InternalLeadOut = pin.LeadOut;
-        owned.ArcCircleLeadOut = pin.LeadOut;
         owned.RoundLeadInAngles = false;
         owned.TabsEnabled = pin.HasTab;
         if (pin.HasTab)

OpenNest.Core/CNC/CuttingPlanning/StateFingerprint.cs

@@ -83,8 +83,6 @@ internal static class StateFingerprint
             Out(p.ExternalLeadOut);
             Lead(p.InternalLeadIn);
             Out(p.InternalLeadOut);
-            Lead(p.ArcCircleLeadIn);
-            Out(p.ArcCircleLeadOut);
             Number(p.PierceClearance);
             Number(p.PierceDiameter);
             Flag(p.RoundLeadInAngles);

OpenNest.Core/CNC/CuttingStrategy/ContourCuttingStrategy.cs

@@ -1103,8 +1103,7 @@ namespace OpenNest.CNC.CuttingStrategy
         {
             return contourType switch
             {
-                ContourType.ArcCircle => Parameters.ArcCircleLeadIn ?? Parameters.InternalLeadIn,
-                ContourType.Internal => Parameters.InternalLeadIn,
+                ContourType.Internal or ContourType.ArcCircle => Parameters.InternalLeadIn,
                 _ => Parameters.ExternalLeadIn,
             };
         }
@@ -1113,8 +1112,7 @@ namespace OpenNest.CNC.CuttingStrategy
         {
             return contourType switch
             {
-                ContourType.ArcCircle => Parameters.ArcCircleLeadOut ?? Parameters.InternalLeadOut,
-                ContourType.Internal => Parameters.InternalLeadOut,
+                ContourType.Internal or ContourType.ArcCircle => Parameters.InternalLeadOut,
                 _ => Parameters.ExternalLeadOut,
             };
         }

OpenNest.Core/CNC/CuttingStrategy/CuttingParameters.cs

@@ -15,13 +15,14 @@ namespace OpenNest.CNC.CuttingStrategy
         public LeadIn ExternalLeadIn { get; set; } = new NoLeadIn();
         public LeadOut ExternalLeadOut { get; set; } = new NoLeadOut();
 
+        /// <summary>
+        /// The lead-in of every cutout, full circles included; circles still get their own
+        /// geometry handling (radius clamp, angle rounding) when the lead is emitted.
+        /// </summary>
         public LeadIn InternalLeadIn { get; set; } =
             new LineLeadIn { Length = 0.125, ApproachAngle = 90 };
         public LeadOut InternalLeadOut { get; set; } = new NoLeadOut();
 
-        public LeadIn ArcCircleLeadIn { get; set; } = new NoLeadIn();
-        public LeadOut ArcCircleLeadOut { get; set; } = new NoLeadOut();
-
         public double PierceClearance { get; set; } = 0.0625;
 
         /// <summary>

OpenNest.Data/MachineCuttingDefaults.cs

@@ -55,17 +55,15 @@ public static class MachineCuttingDefaults
 
         var scale = Scale(machine!.Units, nest.Units);
         var kerf = settings.Kerf * scale;
-        // Each contour type gets its own instance, as the cutting panel builds them.
+        // Each lead set gets its own instance, as the cutting panel builds them.
         if (ToLeadIn(settings.LeadIn, scale, kerf) is { } leadIn)
         {
             if (leadIn is not CleanHoleLeadIn)
                 parameters.ExternalLeadIn = leadIn;
             parameters.InternalLeadIn = ToLeadIn(settings.LeadIn, scale, kerf);
-            parameters.ArcCircleLeadIn = ToLeadIn(settings.LeadIn, scale, kerf);
         }
         parameters.ExternalLeadOut = ToLeadOut(settings.LeadOut, scale);
         parameters.InternalLeadOut = ToLeadOut(settings.LeadOut, scale);
-        parameters.ArcCircleLeadOut = ToLeadOut(settings.LeadOut, scale);
         parameters.Kerf = kerf;
         parameters.MachineName = machine.Name;
         parameters.MaterialName = nest.Material.Name;

OpenNest.FrontEnd.Tests/CuttingPlanFrontEndTests.cs

@@ -216,7 +216,6 @@ public class CuttingPlanFrontEndTests : IDisposable
     {
         ExternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 45 },
         InternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 45 },
-        ArcCircleLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 45 },
         ExternalLeadOut = new NoLeadOut(),
         InternalLeadOut = new NoLeadOut(),
         PierceClearance = 0.05,

OpenNest.IO.Tests/CuttingParametersSerializerTests.cs

@@ -20,7 +20,6 @@ public class CuttingParametersSerializerTests
         {
             ExternalLeadIn = leadIn,
             InternalLeadIn = leadIn,
-            ArcCircleLeadIn = leadIn,
             TabConfig = new NormalTab { Size = 0.42, TabLeadIn = leadIn },
         };
 
@@ -28,7 +27,6 @@ public class CuttingParametersSerializerTests
 
         AssertEquivalent(leadIn, restored.ExternalLeadIn);
         AssertEquivalent(leadIn, restored.InternalLeadIn);
-        AssertEquivalent(leadIn, restored.ArcCircleLeadIn);
         AssertEquivalent(leadIn, restored.TabConfig.TabLeadIn);
     }
 
@@ -43,7 +41,6 @@ public class CuttingParametersSerializerTests
         {
             ExternalLeadOut = leadOut,
             InternalLeadOut = leadOut,
-            ArcCircleLeadOut = leadOut,
             TabConfig = new NormalTab { Size = 0.42, TabLeadOut = leadOut },
         };
 
@@ -51,7 +48,6 @@ public class CuttingParametersSerializerTests
 
         AssertEquivalent(leadOut, restored.ExternalLeadOut);
         AssertEquivalent(leadOut, restored.InternalLeadOut);
-        AssertEquivalent(leadOut, restored.ArcCircleLeadOut);
         AssertEquivalent(leadOut, restored.TabConfig.TabLeadOut);
     }
 
@@ -118,11 +114,6 @@ public class CuttingParametersSerializerTests
         Assert.Equal(43, lineOut.ApproachAngle);
         Assert.Equal(0.12, Assert.IsType<ArcLeadIn>(restored.InternalLeadIn).Radius);
         Assert.Equal(0.09, Assert.IsType<ArcLeadOut>(restored.InternalLeadOut).Radius);
-        var cleanHole = Assert.IsType<CleanHoleLeadIn>(restored.ArcCircleLeadIn);
-        Assert.Equal(0.8, cleanHole.LineLength);
-        Assert.Equal(0.3, cleanHole.ArcRadius);
-        Assert.Equal(0.04, cleanHole.Kerf);
-        Assert.IsType<NoLeadOut>(restored.ArcCircleLeadOut);
         Assert.True(restored.TabsEnabled);
         Assert.Equal(0.375, Assert.IsType<NormalTab>(restored.TabConfig).Size);
         Assert.Equal(0.0625, restored.PierceClearance);
@@ -133,6 +124,26 @@ public class CuttingParametersSerializerTests
         AssertEquivalent(new SequenceParameters(), restored.Sequencing);
     }
 
+    [Fact]
+    public void Deserialize_LegacyArcCircleLeads_AreDroppedInFavorOfTheInternalLeads()
+    {
+        const string json = """
+            {
+              "internalLeadIn": { "type": "Line", "length": 0.125, "approachAngle": 90 },
+              "internalLeadOut": { "type": "None" },
+              "arcCircleLeadIn": { "type": "CleanHole", "lineLength": 0.8,
+                                   "arcRadius": 0.3, "kerf": 0.04 },
+              "arcCircleLeadOut": { "type": "Arc", "radius": 0.09 }
+            }
+            """;
+
+        var restored = CuttingParametersSerializer.Deserialize(json);
+
+        Assert.Equal(0.125, Assert.IsType<LineLeadIn>(restored.InternalLeadIn).Length);
+        Assert.IsType<NoLeadOut>(restored.InternalLeadOut);
+        Assert.DoesNotContain("arcCircle", CuttingParametersSerializer.Serialize(restored));
+    }
+
     [Theory]
     [InlineData(0)]
     [InlineData(-1)]
@@ -150,10 +161,8 @@ public class CuttingParametersSerializerTests
 
         Assert.IsType<NoLeadIn>(restored.ExternalLeadIn);
         Assert.IsType<NoLeadIn>(restored.InternalLeadIn);
-        Assert.IsType<NoLeadIn>(restored.ArcCircleLeadIn);
         Assert.IsType<NoLeadOut>(restored.ExternalLeadOut);
         Assert.IsType<NoLeadOut>(restored.InternalLeadOut);
-        Assert.IsType<NoLeadOut>(restored.ArcCircleLeadOut);
         Assert.Equal(0, Assert.IsType<NormalTab>(restored.TabConfig).Size);
         Assert.Equal(0, restored.PierceClearance);
         Assert.Equal(0, restored.PierceDiameter);
@@ -297,8 +306,6 @@ public class CuttingParametersSerializerTests
         ExternalLeadOut = CreateLeadOut("Line"),
         InternalLeadIn = CreateLeadIn("CleanHole"),
         InternalLeadOut = CreateLeadOut("Arc"),
-        ArcCircleLeadIn = CreateLeadIn("LineArc"),
-        ArcCircleLeadOut = CreateLeadOut("None"),
         PierceClearance = 0.17,
         PierceDiameter = 0.41,
         RoundLeadInAngles = true,

OpenNest.IO/CuttingParametersDto.cs

@@ -19,8 +19,9 @@ public class CuttingParametersDto
     public LeadOutDto ExternalLeadOut { get; set; }
     public LeadInDto InternalLeadIn { get; set; }
     public LeadOutDto InternalLeadOut { get; set; }
-    public LeadInDto ArcCircleLeadIn { get; set; }
-    public LeadOutDto ArcCircleLeadOut { get; set; }
+
+    // Older files also stored arcCircleLeadIn/arcCircleLeadOut. Circles now use the internal
+    // leads, so those keys are ignored on read and no longer written.
     public bool TabsEnabled { get; set; }
 
     // Legacy settings only stored tabWidth. A missing TabConfig uses that width;

OpenNest.IO/CuttingParametersSerializer.cs

@@ -63,8 +63,6 @@ public static class CuttingParametersSerializer
             ExternalLeadOut = ToLeadOutDto(parameters.ExternalLeadOut),
             InternalLeadIn = ToLeadInDto(parameters.InternalLeadIn),
             InternalLeadOut = ToLeadOutDto(parameters.InternalLeadOut),
-            ArcCircleLeadIn = ToLeadInDto(parameters.ArcCircleLeadIn),
-            ArcCircleLeadOut = ToLeadOutDto(parameters.ArcCircleLeadOut),
             TabsEnabled = parameters.TabsEnabled,
             TabWidth = parameters.TabConfig?.Size ?? 0.25,
             TabConfig = ToTabDto(parameters.TabConfig),
@@ -97,8 +95,6 @@ public static class CuttingParametersSerializer
             ExternalLeadOut = FromLeadOutDto(dto.ExternalLeadOut),
             InternalLeadIn = FromLeadInDto(dto.InternalLeadIn),
             InternalLeadOut = FromLeadOutDto(dto.InternalLeadOut),
-            ArcCircleLeadIn = FromLeadInDto(dto.ArcCircleLeadIn),
-            ArcCircleLeadOut = FromLeadOutDto(dto.ArcCircleLeadOut),
             TabsEnabled = dto.TabsEnabled,
             TabConfig = dto.TabConfig == null
                 ? new NormalTab { Size = dto.TabWidth }

OpenNest.Tests/Cincinnati/CincinnatiPostRegressionTests.cs

@@ -301,8 +301,6 @@ public class CincinnatiPostRegressionTests
         part.ApplyLeadIns(
             new CuttingParameters
             {
-                ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-                ArcCircleLeadOut = new NoLeadOut(),
                 ExternalLeadIn = new LineLeadIn { Length = leadIn, ApproachAngle = 90 },
                 ExternalLeadOut = new NoLeadOut(),
             },

OpenNest.Tests/Cincinnati/HolePlacementRegressionTests.cs

@@ -169,8 +169,6 @@ public class HolePlacementRegressionTests
         part.ApplyLeadIns(
             new CuttingParameters
             {
-                ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-                ArcCircleLeadOut = new NoLeadOut(),
                 ExternalLeadIn = new LineLeadIn { Length = 0.25, ApproachAngle = 90 },
                 ExternalLeadOut = new NoLeadOut(),
             },

OpenNest.Tests/CincinnatiCIFiber/CIFiberPostProcessorTests.cs

@@ -184,7 +184,6 @@ public class CIFiberPostProcessorTests
         {
             InternalLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
             ExternalLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
         };
         TestLeadIns.Apply(plate);
 

OpenNest.Tests/CincinnatiCIFiber/CIFiberSampleRegressionTests.cs

@@ -54,14 +54,13 @@ public class CIFiberSampleRegressionTests
         var plate = nest.Plates[0];
         plate.CuttingParameters = new CuttingParameters
         {
-            // OpenNest's own short perpendicular linear leads, including the
-            // circles (ArcCircleLeadIn). TF5200 13.2.4.1 requires a LINEAR
+            // OpenNest's own short perpendicular linear leads; circles take the
+            // internal lead. TF5200 13.2.4.1 requires a LINEAR
             // first motion block after G41/G42, so holes must have linear
             // leads. (The sample itself pierces holes at their centre and
             // uses 0.125 in perimeter leads; see the saved-lead-in test.)
             InternalLeadIn = new LineLeadIn { Length = 0.075, ApproachAngle = 90 },
             ExternalLeadIn = new LineLeadIn { Length = 0.075, ApproachAngle = 90 },
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.075, ApproachAngle = 90 },
             PierceClearance = 0.02,
         };
 

OpenNest.Tests/CuttingPlanning/ContinuedContourCheckTests.cs

@@ -116,7 +116,6 @@ public class ContinuedContourCheckTests
     {
         ExternalLeadIn = new LineLeadIn { Length = 0.2, ApproachAngle = 90 },
         InternalLeadIn = new LineLeadIn { Length = 0.1, ApproachAngle = 90 },
-        ArcCircleLeadIn = new LineLeadIn { Length = 0.1, ApproachAngle = 90 },
         ExternalLeadOut = new NoLeadOut(),
         InternalLeadOut = new NoLeadOut(),
     };

OpenNest.Tests/CuttingPlanning/ContourCandidateEmissionTests.cs

@@ -175,7 +175,7 @@ public class ContourCandidateEmissionTests
         var parameters = ExplicitContourTests.Parameters();
         parameters.RoundLeadInAngles = true;
         parameters.LeadInAngleIncrement = 90;
-        parameters.ArcCircleLeadIn = new LineLeadIn { Length = 2 };
+        parameters.InternalLeadIn = new LineLeadIn { Length = 2 };
         var p = ExplicitContourTests.Square(false);
         foreach (var center in new[] { new Vector(3, 3), new Vector(7, 7) })
         {

OpenNest.Tests/CuttingPlanning/ContourEntryFeasibilityTests.cs

@@ -116,7 +116,6 @@ public class ContourEntryFeasibilityTests
         var parameters = ExplicitContourTests.Parameters();
         parameters.ExternalLeadIn = new NoLeadIn();
         parameters.InternalLeadIn = new NoLeadIn();
-        parameters.ArcCircleLeadIn = new NoLeadIn();
         var clean = ExplicitContourTests.Square(false);
         var prepared = PreparedContours.Capture(clean, parameters);
         var choice = prepared.Entry(0, 0, new Vector(0, 5));

OpenNest.Tests/CuttingPlanning/ContourRecoveryFileTests.cs

@@ -106,7 +106,6 @@ public class ContourRecoveryFileTests
         {
             parameters.ExternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
             parameters.InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
-            parameters.ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
         }
         return parameters;
     }

OpenNest.Tests/CuttingPlanning/CuttingGridOrderTests.cs

@@ -90,7 +90,6 @@ public class CuttingGridOrderTests
         {
             ExternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 },
             InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 },
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 },
         };
 
         var result = CuttingPlanService.Plan(CuttingPlanRequest.ForPlate(plate,

OpenNest.Tests/CuttingPlanning/CuttingReplayContractTests.cs

@@ -171,7 +171,6 @@ public class CuttingReplayContractTests
         var settings = ExplicitContourTests.Parameters();
         settings.RoundLeadInAngles = true;
         settings.LeadInAngleIncrement = 90;
-        settings.ArcCircleLeadIn = new LineLeadIn { Length = 10 };
         var clean = PreparedContourTests.Holes();
         if (shape == "mixed-circles") clean.Codes.OfType<ArcMove>().Last().Rotation = RotationType.CW;
         if (shape == "arcs")
@@ -181,6 +180,11 @@ public class CuttingReplayContractTests
             clean.ArcTo(4, 3, 5, 3, RotationType.CCW);
             clean.LineTo(6, 3);
         }
+        else
+        {
+            // Circles clamp an over-long lead to their radius; the arc slot has no clamp.
+            settings.InternalLeadIn = new LineLeadIn { Length = 10 };
+        }
         var part = new Part(new Drawing("native", clean));
         var snapshot = CuttingPlanService.Capture(new CuttingPlanRequest([part], Start, confirmedParameters: settings));
         var ready = CuttingPlanService.Plan(snapshot);

OpenNest.Tests/CuttingPlanning/ExplicitContourTests.cs

@@ -71,7 +71,7 @@ public class ExplicitContourTests
         var parameters = Parameters("line");
         parameters.RoundLeadInAngles = true;
         parameters.LeadInAngleIncrement = 90;
-        parameters.ArcCircleLeadIn = new LineLeadIn { Length = 2 };
+        parameters.InternalLeadIn = new LineLeadIn { Length = 2 };
         var result = new ContourCuttingStrategy { Parameters = parameters }.Apply(program, new Vector(20, 20));
         var calls = result.Program.Codes.OfType<SubProgramCall>().ToArray();
         Assert.Equal(2, calls.Length);
@@ -124,7 +124,6 @@ public class ExplicitContourTests
         {
             ExternalLeadIn = lead,
             InternalLeadIn = lead,
-            ArcCircleLeadIn = lead,
             ExternalLeadOut = new NoLeadOut(),
             InternalLeadOut = new NoLeadOut(),
             PierceClearance = 0.05

OpenNest.Tests/CuttingPlanning/HoleDepartureTests.cs

@@ -44,10 +44,8 @@ public class HoleDepartureTests
         {
             ExternalLeadIn = lead,
             InternalLeadIn = lead,
-            ArcCircleLeadIn = lead,
             ExternalLeadOut = new NoLeadOut(),
             InternalLeadOut = new NoLeadOut(),
-            ArcCircleLeadOut = new NoLeadOut(),
             PierceClearance = 0
         };
     }

OpenNest.Tests/CuttingPlanning/HoleLookAheadTests.cs

@@ -25,7 +25,6 @@ public class HoleLookAheadTests
     {
         var p = ExplicitContourTests.Parameters();
         p.InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
-        p.ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
         p.PierceClearance = 0;
         return p;
     }

OpenNest.Tests/CuttingPlanning/ImportedArcHoleTests.cs

@@ -25,10 +25,8 @@ public class ImportedArcHoleTests
         {
             ExternalLeadIn = lead,
             InternalLeadIn = lead,
-            ArcCircleLeadIn = lead,
             ExternalLeadOut = new NoLeadOut(),
             InternalLeadOut = new NoLeadOut(),
-            ArcCircleLeadOut = new NoLeadOut(),
             PierceClearance = 0.0625
         };
     }

OpenNest.Tests/CuttingPlanning/InterlockingHoleRouteTests.cs

@@ -28,7 +28,6 @@ public class InterlockingHoleRouteTests
         {
             parameters.ExternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
             parameters.InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
-            parameters.ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
         }
         var before = parts.Select(p => ExplicitContourTests.Fingerprint(p.Program)).ToArray();
         var snapshot = CuttingPlanService.Capture(new CuttingPlanRequest(parts,

OpenNest.Tests/CuttingPlanning/JointCuttingPlanTests.cs

@@ -16,7 +16,6 @@ public class JointCuttingPlanTests
         var (part, parameters) = Crossing();
         parameters.ExternalLeadIn = new NoLeadIn();
         parameters.InternalLeadIn = new NoLeadIn();
-        parameters.ArcCircleLeadIn = new NoLeadIn();
         var unchanged = Unchanged(part, parameters);
         var source = Read(part.Program, part.Location);
         Assert.Contains(new ReleasedContourState(reportMissingLeadIns: false).Check(source, Vector.Zero, 1),

OpenNest.Tests/CuttingPlanning/OwnedCuttingParameterTests.cs

@@ -36,10 +36,8 @@ public class OwnedCuttingParameterTests
             PierceDiameter = 0.3,
             ExternalLeadIn = leadIn,
             InternalLeadIn = leadIn,
-            ArcCircleLeadIn = leadIn,
             ExternalLeadOut = leadOut,
             InternalLeadOut = leadOut,
-            ArcCircleLeadOut = leadOut,
             TabConfig = tab,
             TabsEnabled = true,
             SupportTabs = true,
@@ -122,7 +120,7 @@ public class OwnedCuttingParameterTests
             case "null-settings": source = null; break;
             case "null-sequence": source.Sequencing = null; break;
             case "null-assignment": source.Assignment = null; break;
-            case "null-lead": source.ArcCircleLeadIn = null; break;
+            case "null-lead": source.InternalLeadIn = null; break;
             case "null-leadout": source.InternalLeadOut = null; break;
             case "null-tab": source.TabsEnabled = true; break;
             case "dimension": source.PartSpacing = -1; break;
@@ -131,7 +129,7 @@ public class OwnedCuttingParameterTests
             case "enum": source.Assignment.Method = (SequenceMethod)6; break;
             case "tab-lead": source.TabConfig = new NormalTab { TabLeadIn = new ArcLeadIn { Radius = double.PositiveInfinity } }; break;
             case "custom-in": source.InternalLeadIn = new CustomLeadIn(); break;
-            case "custom-out": source.ArcCircleLeadOut = new CustomLeadOut(); break;
+            case "custom-out": source.InternalLeadOut = new CustomLeadOut(); break;
             case "custom-tab": source.TabConfig = new CustomTab(); break;
             case "custom-settings": source = new CustomParameters(); break;
             case "custom-sequence": source.Sequencing = new CustomSequence(); break;

OpenNest.Tests/CuttingPlanning/PerimeterLookAheadTests.cs

@@ -165,7 +165,7 @@ public class PerimeterLookAheadTests
         var parameters = Parameters();
         parameters.RoundLeadInAngles = false;
         parameters.PierceClearance = 0;
-        parameters.ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
+        parameters.InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
         var arrival = location + new Vector(20, 8);
         var before = ExplicitContourTests.Fingerprint(part.Program);
         var snapshot = CuttingPlanService.Capture(new CuttingPlanRequest([part], arrival,

OpenNest.Tests/CuttingPlanning/PierceZoneTests.cs

@@ -322,10 +322,8 @@ public class PierceZoneTests
     {
         ExternalLeadIn = new LineLeadIn { Length = 1, ApproachAngle = 90 },
         InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 },
-        ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 },
         ExternalLeadOut = new NoLeadOut(),
         InternalLeadOut = new NoLeadOut(),
-        ArcCircleLeadOut = new NoLeadOut(),
         PierceClearance = 0,
         PierceDiameter = pierceDiameter,
     };

OpenNest.Tests/CuttingPlanning/PinnedContourTests.cs

@@ -168,7 +168,6 @@ public class PinnedContourTests
     {
         ExternalLeadIn = new ArcLeadIn { Radius = 0.15 },
         InternalLeadIn = new ArcLeadIn { Radius = 0.15 },
-        ArcCircleLeadIn = new ArcLeadIn { Radius = 0.15 },
         ExternalLeadOut = new NoLeadOut(),
         InternalLeadOut = new NoLeadOut(),
         PierceClearance = 0.05

OpenNest.Tests/CuttingPlanning/PreparedContourTests.cs

@@ -188,7 +188,7 @@ public class PreparedContourTests
     {
         var source = Holes();
         var parameters = ExplicitContourTests.Parameters();
-        parameters.ArcCircleLeadIn = new LineLeadIn { Length = 10 };
+        parameters.InternalLeadIn = new LineLeadIn { Length = 10 };
         parameters.RoundLeadInAngles = true;
         parameters.LeadInAngleIncrement = 90;
         var prepared = PreparedContours.Capture(source, parameters);

OpenNest.Tests/CuttingPlanning/ProblemNestRegressionTests.cs

@@ -129,7 +129,6 @@ public partial class ProblemNestRegressionTests(ITestOutputHelper output)
         var parameters = new CuttingParameters();
         parameters.ExternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
         parameters.InternalLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
-        parameters.ArcCircleLeadIn = new LineLeadIn { Length = 0.15, ApproachAngle = 90 };
         return parameters;
     }
 

OpenNest.Tests/CuttingPlanning/SettingsFreshnessTests.cs

@@ -71,7 +71,7 @@ public class SettingsFreshnessTests
         switch (slot)
         {
             case "lead-in": settings.InternalLeadIn = new CustomLeadIn(); break;
-            case "lead-out": settings.ArcCircleLeadOut = new CustomLeadOut(); break;
+            case "lead-out": settings.InternalLeadOut = new CustomLeadOut(); break;
             case "tab": settings.TabConfig = new CustomTab(); break;
             case "tab-lead-in": settings.TabConfig = new NormalTab { TabLeadIn = new CustomLeadIn() }; break;
             case "sequence": settings.Sequencing = new CustomSequence(); break;
@@ -172,10 +172,8 @@ public class SettingsFreshnessTests
                     {
                         ExternalLeadIn = lead,
                         InternalLeadIn = lead,
-                        ArcCircleLeadIn = lead,
                         ExternalLeadOut = leadOut,
                         InternalLeadOut = leadOut,
-                        ArcCircleLeadOut = leadOut,
                         TabConfig = tab,
                         TabsEnabled = true
                     };

OpenNest.Tests/CuttingPlanning/SideCoverageRegressionTests.cs

@@ -238,7 +238,6 @@ public class SideCoverageRegressionTests
     {
         ExternalLeadIn = new LineLeadIn { Length = length, ApproachAngle = angle },
         InternalLeadIn = new LineLeadIn { Length = length, ApproachAngle = angle },
-        ArcCircleLeadIn = new LineLeadIn { Length = length },
         ExternalLeadOut = new NoLeadOut(),
         InternalLeadOut = new NoLeadOut(),
         TabsEnabled = false,

OpenNest.Tests/CuttingStrategy/HoleSubProgramTests.cs

@@ -123,8 +123,6 @@ public class HoleSubProgramTests
         {
             Parameters = new CuttingParameters
             {
-                ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-                ArcCircleLeadOut = new NoLeadOut(),
             },
         };
 
@@ -167,8 +165,6 @@ public class HoleSubProgramTests
             {
                 RoundLeadInAngles = true,
                 LeadInAngleIncrement = 5.0,
-                ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-                ArcCircleLeadOut = new NoLeadOut(),
             },
         };
 
@@ -222,8 +218,6 @@ public class HoleSubProgramTests
         {
             Parameters = new CuttingParameters
             {
-                ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-                ArcCircleLeadOut = new NoLeadOut(),
             },
         };
 
@@ -283,8 +277,6 @@ public class HoleSubProgramTests
         {
             RoundLeadInAngles = true,
             LeadInAngleIncrement = 5.0,
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.125, ApproachAngle = 90 },
-            ArcCircleLeadOut = new NoLeadOut(),
             ExternalLeadIn = new LineLeadIn { Length = 0.25, ApproachAngle = 90 },
             ExternalLeadOut = new NoLeadOut(),
         };

OpenNest.Tests/CuttingStrategy/PartLeadInTransformTests.cs

@@ -32,7 +32,7 @@ public class PartLeadInTransformTests
         new()
         {
             ExternalLeadIn = new LineLeadIn { Length = 0.5, ApproachAngle = 90 },
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
+            InternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
         };
 
     private static Part MakeLeadInPart(Drawing drawing, double rotation)

OpenNest.Tests/Data/MachineCuttingDefaultsTests.cs

@@ -48,14 +48,14 @@ public class MachineCuttingDefaultsTests
 
         Assert.True(MachineCuttingDefaults.ApplyTo(parameters, Machine(LineArc), NestOf(0.25)));
 
-        foreach (var leadIn in new[] { parameters.ExternalLeadIn, parameters.InternalLeadIn, parameters.ArcCircleLeadIn })
+        foreach (var leadIn in new[] { parameters.ExternalLeadIn, parameters.InternalLeadIn })
         {
             var lineArc = Assert.IsType<LineArcLeadIn>(leadIn);
             Assert.Equal(0.125, lineArc.LineLength);
             Assert.Equal(0.0625, lineArc.ArcRadius);
             Assert.Equal(90, lineArc.ApproachAngle);
         }
-        foreach (var leadOut in new[] { parameters.ExternalLeadOut, parameters.InternalLeadOut, parameters.ArcCircleLeadOut })
+        foreach (var leadOut in new[] { parameters.ExternalLeadOut, parameters.InternalLeadOut })
         {
             var line = Assert.IsType<LineLeadOut>(leadOut);
             Assert.Equal(0.0625, line.Length);
@@ -118,7 +118,6 @@ public class MachineCuttingDefaultsTests
 
         Assert.Equal(0.3, Assert.IsType<LineLeadIn>(parameters.ExternalLeadIn).Length);
         Assert.Equal(0.012, Assert.IsType<CleanHoleLeadIn>(parameters.InternalLeadIn).Kerf);
-        Assert.IsType<CleanHoleLeadIn>(parameters.ArcCircleLeadIn);
     }
 
     [Fact]

OpenNest.Tests/Diagnostics/PostVerificationAnalyzerTests.cs

@@ -607,6 +607,5 @@ public class PostVerificationAnalyzerTests
     {
         ExternalLeadIn = new LineLeadIn { Length = 0.5 },
         InternalLeadIn = new LineLeadIn { Length = 0.5 },
-        ArcCircleLeadIn = new LineLeadIn { Length = 0.5 }
     };
 }

OpenNest.Tests/DrawingProgramSnapshotTests.cs

@@ -205,7 +205,7 @@ public class DrawingProgramSnapshotTests
             part.ApplyLeadIns(new CuttingParameters
             {
                 ExternalLeadIn = new LineLeadIn { Length = 0.5, ApproachAngle = 90 },
-                ArcCircleLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
+                InternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
             }, new Vector(-5, -5));
             part.LeadInsLocked = true;
             Assert.Contains(part.Program.Codes.OfType<LinearMove>(), move => move.Layer == LayerType.Leadin);

OpenNest.Tests/IO/PartLeadInSerializationTests.cs

@@ -310,7 +310,7 @@ public class PartLeadInSerializationTests
     {
         ExternalLeadIn = new LineLeadIn { Length = 0.5, ApproachAngle = 90 },
         ExternalLeadOut = new LineLeadOut { Length = 0.25 },
-        ArcCircleLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
+        InternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
         TabsEnabled = true,
         TabConfig = new NormalTab { Size = 0.15 },
     };

OpenNest.Tests/Reporting/NestReportTestData.cs

@@ -103,7 +103,7 @@ public static class NestReportTestData
         {
             ExternalLeadIn = new LineLeadIn { Length = 0.5, ApproachAngle = 90 },
             ExternalLeadOut = new LineLeadOut { Length = 0.25 },
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
+            InternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 90 },
             TabsEnabled = true,
             TabConfig = new NormalTab { Size = 0.15 },
         }, new Vector(-5, -5));

OpenNest.Tests/TabbedCutouts/TabbedCutoutBuilderTests.cs

@@ -240,7 +240,6 @@ public class TabbedCutoutBuilderTests
         {
             ExternalLeadIn = new LineLeadIn { Length = 0.25, ApproachAngle = 90 },
             InternalLeadIn = new ArcLeadIn { Radius = 0.1 },
-            ArcCircleLeadIn = new LineLeadIn { Length = 0.1, ApproachAngle = 90 },
         });
         Assert.True(planned.IsReady, planned.Describe);
         Assert.True(part.RestoreLeadInProgram(planned.Program, false));

OpenNest.WinForms.Tests/Forms/CuttingInspectionPanelTests.cs

@@ -957,10 +957,8 @@ public class CuttingInspectionPanelTests
     {
         ExternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 45 },
         InternalLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 45 },
-        ArcCircleLeadIn = new LineLeadIn { Length = 0.3, ApproachAngle = 45 },
         ExternalLeadOut = new NoLeadOut(),
         InternalLeadOut = new NoLeadOut(),
-        ArcCircleLeadOut = new NoLeadOut(),
     };
 
     private static void PumpUntil(Func<bool> condition)

OpenNest/Actions/ActionLeadIn.cs

@@ -576,8 +576,7 @@ namespace OpenNest.Actions
         {
             return contourType switch
             {
-                ContourType.ArcCircle => parameters.ArcCircleLeadIn ?? parameters.InternalLeadIn,
-                ContourType.Internal => parameters.InternalLeadIn,
+                ContourType.Internal or ContourType.ArcCircle => parameters.InternalLeadIn,
                 _ => parameters.ExternalLeadIn,
             };
         }

OpenNest/Controls/CuttingPanel.cs

@@ -24,15 +24,11 @@ namespace OpenNest.Controls
             cboExternalLeadOut;
         private readonly ComboBox cboInternalLeadIn,
             cboInternalLeadOut;
-        private readonly ComboBox cboArcCircleLeadIn,
-            cboArcCircleLeadOut;
 
         private readonly Panel pnlExternalLeadIn,
             pnlExternalLeadOut;
         private readonly Panel pnlInternalLeadIn,
             pnlInternalLeadOut;
-        private readonly Panel pnlArcCircleLeadIn,
-            pnlArcCircleLeadOut;
 
         private readonly CheckBox chkTabsEnabled;
         private readonly NumericUpDown nudTabWidth;
@@ -56,7 +52,6 @@ namespace OpenNest.Controls
                 {
                     0 => ContourType.External,
                     1 => ContourType.Internal,
-                    2 => ContourType.ArcCircle,
                     _ => null,
                 };
             }
@@ -68,8 +63,8 @@ namespace OpenNest.Controls
                 var index = value.Value switch
                 {
                     ContourType.External => 0,
-                    ContourType.Internal => 1,
-                    ContourType.ArcCircle => 2,
+                    // Circles share the internal leads.
+                    ContourType.Internal or ContourType.ArcCircle => 1,
                     _ => -1,
                 };
 
@@ -88,7 +83,6 @@ namespace OpenNest.Controls
 
             var tabExternal = new TabPage("External") { Padding = new Padding(4) };
             var tabInternal = new TabPage("Internal") { Padding = new Padding(4) };
-            var tabArcCircle = new TabPage("Arc / Circle") { Padding = new Padding(4) };
 
             SetupTab(
                 tabExternal,
@@ -104,17 +98,9 @@ namespace OpenNest.Controls
                 out cboInternalLeadOut,
                 out pnlInternalLeadOut
             );
-            SetupTab(
-                tabArcCircle,
-                out cboArcCircleLeadIn,
-                out pnlArcCircleLeadIn,
-                out cboArcCircleLeadOut,
-                out pnlArcCircleLeadOut
-            );
 
             tabControl.Controls.Add(tabExternal);
             tabControl.Controls.Add(tabInternal);
-            tabControl.Controls.Add(tabArcCircle);
 
             var tabWrapper = new Panel { Dock = DockStyle.Top, Height = 340 };
             tabWrapper.Controls.Add(tabControl);
@@ -264,8 +250,6 @@ namespace OpenNest.Controls
                 ExternalLeadOut = BuildLeadOut(cboExternalLeadOut, pnlExternalLeadOut),
                 InternalLeadIn = BuildLeadIn(cboInternalLeadIn, pnlInternalLeadIn),
                 InternalLeadOut = BuildLeadOut(cboInternalLeadOut, pnlInternalLeadOut),
-                ArcCircleLeadIn = BuildLeadIn(cboArcCircleLeadIn, pnlArcCircleLeadIn),
-                ArcCircleLeadOut = BuildLeadOut(cboArcCircleLeadOut, pnlArcCircleLeadOut),
                 TabsEnabled = chkTabsEnabled.Checked && rbTabAll.Checked,
                 TabConfig = new NormalTab { Size = (double)nudTabWidth.Value },
                 PierceClearance = (double)nudPierceClearance.Value,
@@ -284,8 +268,6 @@ namespace OpenNest.Controls
             LoadLeadOut(cboExternalLeadOut, pnlExternalLeadOut, p.ExternalLeadOut);
             LoadLeadIn(cboInternalLeadIn, pnlInternalLeadIn, p.InternalLeadIn);
             LoadLeadOut(cboInternalLeadOut, pnlInternalLeadOut, p.InternalLeadOut);
-            LoadLeadIn(cboArcCircleLeadIn, pnlArcCircleLeadIn, p.ArcCircleLeadIn);
-            LoadLeadOut(cboArcCircleLeadOut, pnlArcCircleLeadOut, p.ArcCircleLeadOut);
 
             chkTabsEnabled.Checked = p.TabsEnabled || p.SupportTabs;
             rbSupportTab.Checked = p.SupportTabs;
@@ -385,7 +367,7 @@ namespace OpenNest.Controls
         private void PopulateDropdowns()
         {
             foreach (
-                var combo in new[] { cboExternalLeadIn, cboInternalLeadIn, cboArcCircleLeadIn }
+                var combo in new[] { cboExternalLeadIn, cboInternalLeadIn }
             )
             {
                 combo.Items.AddRange(LeadInTypes);
@@ -393,7 +375,7 @@ namespace OpenNest.Controls
             }
 
             foreach (
-                var combo in new[] { cboExternalLeadOut, cboInternalLeadOut, cboArcCircleLeadOut }
+                var combo in new[] { cboExternalLeadOut, cboInternalLeadOut }
             )
             {
                 combo.Items.AddRange(LeadOutTypes);
@@ -405,11 +387,9 @@ namespace OpenNest.Controls
         {
             cboExternalLeadIn.SelectedIndexChanged += OnLeadInTypeChanged;
             cboInternalLeadIn.SelectedIndexChanged += OnLeadInTypeChanged;
-            cboArcCircleLeadIn.SelectedIndexChanged += OnLeadInTypeChanged;
 
             cboExternalLeadOut.SelectedIndexChanged += OnLeadOutTypeChanged;
             cboInternalLeadOut.SelectedIndexChanged += OnLeadOutTypeChanged;
-            cboArcCircleLeadOut.SelectedIndexChanged += OnLeadOutTypeChanged;
         }
 
         private void OnLeadInTypeChanged(object sender, EventArgs e)
@@ -436,8 +416,6 @@ namespace OpenNest.Controls
                 return pnlExternalLeadIn;
             if (combo == cboInternalLeadIn)
                 return pnlInternalLeadIn;
-            if (combo == cboArcCircleLeadIn)
-                return pnlArcCircleLeadIn;
             return null;
         }
 
@@ -447,8 +425,6 @@ namespace OpenNest.Controls
                 return pnlExternalLeadOut;
             if (combo == cboInternalLeadOut)
                 return pnlInternalLeadOut;
-            if (combo == cboArcCircleLeadOut)
-                return pnlArcCircleLeadOut;
             return null;
         }
 

OpenNest/Forms/CuttingInspectionPanel.cs

@@ -1154,7 +1154,7 @@ internal sealed class CuttingInspectionPanel : UserControl
     private void ShowSettings()
     {
         settingsLabel.Text = $"Outside: {Describe(parameters.ExternalLeadIn)} · Holes: {Describe(parameters.InternalLeadIn)} · "
-            + $"Arcs: {Describe(parameters.ArcCircleLeadIn)} · Tabs: {(parameters.TabsEnabled ? "on" : "off")}";
+            + $"Tabs: {(parameters.TabsEnabled ? "on" : "off")}";
     }
 
     private static string Describe(LeadIn leadIn)

docs/machine-cutting-defaults.md

@@ -21,8 +21,8 @@ machine, material, grade and thickness recorded on the parameters. A plate that
 parameters keeps them: changing the machine, material or thickness does not rewrite leads
 the plate was planned with.
 
-The machine holds one lead-in and one lead-out per thickness; both go to external, internal
-and arc/circle contours. Types map as follows:
+The machine holds one lead-in and one lead-out per thickness; both go to external and internal
+contours (internal covers full circles). Types map as follows:
 
 | Machine type | Lead-in |
 |---|---|

docs/nest-file-format.md

@@ -97,6 +97,12 @@ cross-platform DTO mapping; the desktop settings serializer delegates to it so
 existing saved settings keep their JSON contract. Settings are independent of
 the saved part programs: restoring settings never regenerates those programs.
 
+Lead settings are external (the perimeter) and internal (every cutout, full
+circles included). Older files and desktop settings also stored
+`arcCircleLeadIn`/`arcCircleLeadOut`; these are ignored on read and no longer
+written, so circles in a re-planned older nest take its internal leads. Saved
+part programs keep the leads they were cut with.
+
 ## Clamp zones
 
 Each plate may carry an optional `clamps` array of fixed rectangular keep-out

docs/problem-nests.md

@@ -30,7 +30,7 @@ nest's. A different outcome at the same or a better rank is only reported. When
 intended, update the baseline.
 
 Plates use their own cutting parameters. A plate without them uses line lead-ins of 0.15 at
-90 degrees (external, internal and arc/circle) and no lead-outs.
+90 degrees (external and internal) and no lead-outs.
 
 ## Adding a nest