diff --git a/src/tests/Dragon-ISO.Engine.Tests/Pipeline/ManagedNearestNeighborFrameScalerTests.cs b/src/tests/Dragon-ISO.Engine.Tests/Pipeline/ManagedNearestNeighborFrameScalerTests.cs
index 589abd0..66e520a 100644
--- a/src/tests/Dragon-ISO.Engine.Tests/Pipeline/ManagedNearestNeighborFrameScalerTests.cs
+++ b/src/tests/Dragon-ISO.Engine.Tests/Pipeline/ManagedNearestNeighborFrameScalerTests.cs
@@ -69,4 +69,41 @@ public class ManagedNearestNeighborFrameScalerTests
         var centerOffset = (1080 / 2 * 1920 + 1920 / 2) * 4;
         dst.Pixels.Span[centerOffset].Should().Be(0x10);
     }
+
+    // ============================================================
+    // Zero-dimension source guard
+    // ============================================================
+    //
+    // A malformed/glitched NDI frame can report a zero dimension. Pre-fix this
+    // divided by zero in ComputeFitRect (Pillarbox/Letterbox) or drove a
+    // degenerate copy loop (Stretch). The guard must absorb it as a black frame
+    // at the target size rather than throw into the pipeline supervisor.
+
+    [Theory]
+    [InlineData(0, 100)]
+    [InlineData(100, 0)]
+    [InlineData(0, 0)]
+    public void ZeroDimensionSource_DoesNotThrow_AndYieldsBlackTargetSizedFrame(int srcW, int srcH)
+    {
+        var scaler = new ManagedNearestNeighborFrameScaler();
+        var src = Solid(Math.Max(srcW, 1), Math.Max(srcH, 1), 0x10, 0x20, 0x30, 0xFF) with
+        {
+            Width = srcW,
+            Height = srcH,
+        };
+
+        ProcessedFrame dst = default!;
+        var act = () => dst = scaler.Scale(src, 1280, 720, AspectMode.Pillarbox, 77);
+        act.Should().NotThrow();
+
+        dst.Width.Should().Be(1280);
+        dst.Height.Should().Be(720);
+        dst.Pixels.Length.Should().Be(1280 * 720 * 4);
+        dst.TimestampTicks.Should().Be(77);
+        // Black, fully opaque: B=G=R=0, A=0xFF.
+        dst.Pixels.Span[0].Should().Be(0x00);
+        dst.Pixels.Span[1].Should().Be(0x00);
+        dst.Pixels.Span[2].Should().Be(0x00);
+        dst.Pixels.Span[3].Should().Be(0xFF);
+    }
 }