diff --git a/tests/Aetheria.Shared.Tests/EconomyNullGuardTests.cs b/tests/Aetheria.Shared.Tests/EconomyNullGuardTests.cs
new file mode 100644
index 000000000..61b0cea12
--- /dev/null
+++ b/tests/Aetheria.Shared.Tests/EconomyNullGuardTests.cs
@@ -0,0 +1,53 @@
+using System;
+using System.Linq;
+using Xunit;
+
+// A recipe read from disk can hold null lists. The checks refuse it as an L-recipe fault naming the record; they never throw
+// (finding null-fills-throws).
+public sealed class EconomyNullGuardTests
+{
+    private static void Null(EconomyFixture f, string list) =>
+        f.EditRecipe("commodity:plate", r =>
+        {
+            if (list == "Fills") r.Fills = null;
+            if (list == "Inputs") r.Inputs = null;
+            if (list == "Upkeep") r.Upkeep = null;
+        });
+
+    [Theory]
+    [InlineData("Fills")]
+    [InlineData("Inputs")]
+    [InlineData("Upkeep")]
+    public void ANullListIsAnLRecipeFaultNotAThrow(string list)
+    {
+        using var f = EconomyFixture.Healthy();
+        Null(f, list);
+        var report = EconomyChecks.Check(f.Cache);
+        Assert.Contains(report.Faults, x => x.Invariant == EconomyChecks.LRecipe && x.Record == "recipe:commodity:plate" && x.Message.Contains(list));
+    }
+
+    [Theory]
+    [InlineData("Fills")]
+    [InlineData("Inputs")]
+    [InlineData("Upkeep")]
+    public void EveryRuleSurvivesANullList(string list)
+    {
+        using var f = EconomyFixture.Healthy();
+        Null(f, list);
+        EconomyChecks.Recipe(f.Cache);
+        EconomyChecks.Lore(f.Cache);
+        EconomyChecks.SourceSink(f.Cache);
+        EconomyChecks.Productive(f.Cache);
+        EconomyChecks.ConsumerDemand(f.Cache);
+        Assert.NotEmpty(EconomyChecks.Deep(f.Cache));
+    }
+
+    [Fact]
+    public void ANullEntryInAListIsAnLRecipeFault()
+    {
+        using var f = EconomyFixture.Healthy();
+        f.EditRecipe("commodity:plate", r => r.Inputs.Add(null));
+        var report = EconomyChecks.Check(f.Cache);
+        Assert.Contains(report.Faults, x => x.Invariant == EconomyChecks.LRecipe && x.Record == "recipe:commodity:plate" && x.Message.Contains("Inputs"));
+    }
+}