feat: add RowFillStrategy and ColumnFillStrategy with registry integration

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

OpenNest.Engine/Strategies/ColumnFillStrategy.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+using OpenNest.Engine.Fill;
+
+namespace OpenNest.Engine.Strategies;
+
+public class ColumnFillStrategy : IFillStrategy
+{
+    public string Name => "Column";
+    public NestPhase Phase => NestPhase.Custom;
+    public int Order => 160;
+
+    public List<Part> Fill(FillContext context)
+    {
+        var filler = new StripeFiller(context, NestDirection.Vertical);
+        return filler.Fill();
+    }
+}

OpenNest.Engine/Strategies/RowFillStrategy.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+using OpenNest.Engine.Fill;
+
+namespace OpenNest.Engine.Strategies;
+
+public class RowFillStrategy : IFillStrategy
+{
+    public string Name => "Row";
+    public NestPhase Phase => NestPhase.Custom;
+    public int Order => 150;
+
+    public List<Part> Fill(FillContext context)
+    {
+        var filler = new StripeFiller(context, NestDirection.Horizontal);
+        return filler.Fill();
+    }
+}

OpenNest.Tests/Strategies/FillPipelineTests.cs

@@ -24,7 +24,7 @@ public class FillPipelineTests
 
         engine.Fill(item, plate.WorkArea(), null, System.Threading.CancellationToken.None);
 
-        Assert.True(engine.PhaseResults.Count >= 4,
+        Assert.True(engine.PhaseResults.Count >= 6,
             $"Expected phase results from all strategies, got {engine.PhaseResults.Count}");
     }
 
@@ -41,7 +41,8 @@ public class FillPipelineTests
         Assert.True(engine.WinnerPhase == NestPhase.Pairs ||
                     engine.WinnerPhase == NestPhase.Linear ||
                     engine.WinnerPhase == NestPhase.RectBestFit ||
-                    engine.WinnerPhase == NestPhase.Extents);
+                    engine.WinnerPhase == NestPhase.Extents ||
+                    engine.WinnerPhase == NestPhase.Custom);
     }
 
     [Fact]

OpenNest.Tests/Strategies/FillStrategyRegistryTests.cs

@@ -1,3 +1,4 @@
+using System.Linq;
 using OpenNest.Engine.Strategies;
 
 namespace OpenNest.Tests.Strategies;
@@ -9,11 +10,13 @@ public class FillStrategyRegistryTests
     {
         var strategies = FillStrategyRegistry.Strategies;
 
-        Assert.True(strategies.Count >= 4, $"Expected at least 4 built-in strategies, got {strategies.Count}");
+        Assert.True(strategies.Count >= 6, $"Expected at least 6 built-in strategies, got {strategies.Count}");
         Assert.Contains(strategies, s => s.Name == "Pairs");
         Assert.Contains(strategies, s => s.Name == "RectBestFit");
         Assert.Contains(strategies, s => s.Name == "Extents");
         Assert.Contains(strategies, s => s.Name == "Linear");
+        Assert.Contains(strategies, s => s.Name == "Row");
+        Assert.Contains(strategies, s => s.Name == "Column");
     }
 
     [Fact]
@@ -34,4 +37,19 @@ public class FillStrategyRegistryTests
 
         Assert.Equal("Linear", last.Name);
     }
+
+    [Fact]
+    public void Registry_RowAndColumnOrderedBetweenPairsAndRectBestFit()
+    {
+        var strategies = FillStrategyRegistry.Strategies;
+        var pairsOrder = strategies.First(s => s.Name == "Pairs").Order;
+        var rectOrder = strategies.First(s => s.Name == "RectBestFit").Order;
+        var rowOrder = strategies.First(s => s.Name == "Row").Order;
+        var colOrder = strategies.First(s => s.Name == "Column").Order;
+
+        Assert.True(rowOrder > pairsOrder, "Row should run after Pairs");
+        Assert.True(colOrder > pairsOrder, "Column should run after Pairs");
+        Assert.True(rowOrder < rectOrder, "Row should run before RectBestFit");
+        Assert.True(colOrder < rectOrder, "Column should run before RectBestFit");
+    }
 }