diff --git a/SVSim.UnitTests/Services/Inventory/InventoryHistoryTests.cs b/SVSim.UnitTests/Services/Inventory/InventoryHistoryTests.cs
index 4a86e70..3dbd39a 100644
--- a/SVSim.UnitTests/Services/Inventory/InventoryHistoryTests.cs
+++ b/SVSim.UnitTests/Services/Inventory/InventoryHistoryTests.cs
@@ -305,4 +305,28 @@ public class InventoryHistoryTests
         Assert.That(primaryCount, Is.EqualTo(300), "primary viewer pruned to cap");
         Assert.That(otherCount, Is.EqualTo(50), "other viewer untouched by primary's prune");
     }
+
+    [Test]
+    public async Task Commit_writes_history_row_with_Unknown_source_when_caller_omits_Source()
+    {
+        using var factory = new SVSim.UnitTests.Infrastructure.SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        using var scope = factory.Services.CreateScope();
+        var inv = scope.ServiceProvider.GetRequiredService<SVSim.Database.Services.Inventory.IInventoryService>();
+
+        // No configure callback — Source defaults to Unknown.
+        await using (var tx = await inv.BeginAsync(viewerId))
+        {
+            await tx.GrantAsync(SVSim.Database.Enums.UserGoodsType.Rupy, 0, 10);
+            await tx.CommitAsync();
+        }
+
+        using var verifyScope = factory.Services.CreateScope();
+        var ctx = verifyScope.ServiceProvider.GetRequiredService<SVSim.Database.SVSimDbContext>();
+        var rows = await ctx.ViewerAcquireHistory.AsNoTracking()
+            .Where(h => h.ViewerId == viewerId).ToListAsync();
+        Assert.That(rows, Has.Count.EqualTo(1));
+        Assert.That(rows[0].AcquireType, Is.EqualTo((int)GrantSource.Unknown));
+        Assert.That(rows[0].Message, Is.EqualTo("Unknown"));
+    }
 }