diff --git a/OpenNest.Tests/Strategies/FillPipelineTests.cs b/OpenNest.Tests/Strategies/FillPipelineTests.cs
new file mode 100644
index 0000000..69c9ffc
--- /dev/null
+++ b/OpenNest.Tests/Strategies/FillPipelineTests.cs
@@ -0,0 +1,62 @@
+using OpenNest.Geometry;
+
+namespace OpenNest.Tests.Strategies;
+
+public class FillPipelineTests
+{
+    private static Drawing MakeRectDrawing(double w, double h, string name = "rect")
+    {
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new OpenNest.CNC.RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new OpenNest.CNC.LinearMove(new Vector(w, 0)));
+        pgm.Codes.Add(new OpenNest.CNC.LinearMove(new Vector(w, h)));
+        pgm.Codes.Add(new OpenNest.CNC.LinearMove(new Vector(0, h)));
+        pgm.Codes.Add(new OpenNest.CNC.LinearMove(new Vector(0, 0)));
+        return new Drawing(name, pgm);
+    }
+
+    [Fact]
+    public void Pipeline_PopulatesPhaseResults()
+    {
+        var plate = new Plate(120, 60);
+        var engine = new DefaultNestEngine(plate);
+        var item = new NestItem { Drawing = MakeRectDrawing(20, 10) };
+
+        engine.Fill(item, plate.WorkArea(), null, System.Threading.CancellationToken.None);
+
+        Assert.True(engine.PhaseResults.Count >= 4,
+            $"Expected phase results from all strategies, got {engine.PhaseResults.Count}");
+    }
+
+    [Fact]
+    public void Pipeline_SetsWinnerPhase()
+    {
+        var plate = new Plate(120, 60);
+        var engine = new DefaultNestEngine(plate);
+        var item = new NestItem { Drawing = MakeRectDrawing(20, 10) };
+
+        var parts = engine.Fill(item, plate.WorkArea(), null, System.Threading.CancellationToken.None);
+
+        Assert.True(parts.Count > 0);
+        Assert.True(engine.WinnerPhase == NestPhase.Pairs ||
+                    engine.WinnerPhase == NestPhase.Linear ||
+                    engine.WinnerPhase == NestPhase.RectBestFit ||
+                    engine.WinnerPhase == NestPhase.Extents);
+    }
+
+    [Fact]
+    public void Pipeline_RespectsCancellation()
+    {
+        var plate = new Plate(120, 60);
+        var engine = new DefaultNestEngine(plate);
+        var item = new NestItem { Drawing = MakeRectDrawing(20, 10) };
+        var cts = new System.Threading.CancellationTokenSource();
+        cts.Cancel();
+
+        // Pre-cancelled token should return empty or partial results without throwing
+        var parts = engine.Fill(item, plate.WorkArea(), null, cts.Token);
+
+        // Should not throw — graceful degradation
+        Assert.NotNull(parts);
+    }
+}
diff --git a/OpenNest.Tests/Strategies/FillStrategyRegistryTests.cs b/OpenNest.Tests/Strategies/FillStrategyRegistryTests.cs
new file mode 100644
index 0000000..497b533
--- /dev/null
+++ b/OpenNest.Tests/Strategies/FillStrategyRegistryTests.cs
@@ -0,0 +1,35 @@
+namespace OpenNest.Tests.Strategies;
+
+public class FillStrategyRegistryTests
+{
+    [Fact]
+    public void Registry_DiscoversBuiltInStrategies()
+    {
+        var strategies = FillStrategyRegistry.Strategies;
+
+        Assert.True(strategies.Count >= 4, $"Expected at least 4 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");
+    }
+
+    [Fact]
+    public void Registry_StrategiesAreOrderedByOrder()
+    {
+        var strategies = FillStrategyRegistry.Strategies;
+
+        for (var i = 1; i < strategies.Count; i++)
+            Assert.True(strategies[i].Order >= strategies[i - 1].Order,
+                $"Strategy '{strategies[i].Name}' (Order={strategies[i].Order}) should not precede '{strategies[i - 1].Name}' (Order={strategies[i - 1].Order})");
+    }
+
+    [Fact]
+    public void Registry_LinearIsLast()
+    {
+        var strategies = FillStrategyRegistry.Strategies;
+        var last = strategies[strategies.Count - 1];
+
+        Assert.Equal("Linear", last.Name);
+    }
+}