diff --git a/tests/AcDream.App.Tests/Streaming/LandblockBuildOriginTests.cs b/tests/AcDream.App.Tests/Streaming/LandblockBuildOriginTests.cs
index 1de0a773..678a5452 100644
--- a/tests/AcDream.App.Tests/Streaming/LandblockBuildOriginTests.cs
+++ b/tests/AcDream.App.Tests/Streaming/LandblockBuildOriginTests.cs
@@ -221,6 +221,21 @@ public sealed class LandblockBuildOriginTests
             origin));
         streamer.Start();
 
+#if DEBUG
+        // The near-payload tripwire is config-divergent by design ("fail loud
+        // in Debug builds and strip in Release" — LandblockStreamer.HandleJob):
+        // in Debug the Debug.Assert fires and the VSTest host translates it
+        // into a thrown DebugAssertException, which the worker's catch folds
+        // into a Failed completion (#351).
+        var failed = Assert.IsType<LandblockStreamResult.Failed>(
+            await DrainFirstAsync(streamer));
+
+        Assert.Contains(
+            "Far-tier factory returned Near payload",
+            failed.Error,
+            StringComparison.Ordinal);
+        Assert.Equal(84ul, failed.Generation);
+#else
         var loaded = Assert.IsType<LandblockStreamResult.Loaded>(
             await DrainFirstAsync(streamer));
 
@@ -229,6 +244,7 @@ public sealed class LandblockBuildOriginTests
         Assert.Same(PhysicsDatBundle.Empty, loaded.Landblock.PhysicsDats);
         Assert.Null(loaded.Build.EnvCells);
         Assert.Equal(origin, loaded.Build.Origin);
+#endif
     }
 
     [Fact]