diff --git a/tests/ZB.MOM.WW.ScadaBridge.Transport.IntegrationTests/Import/NativeAlarmSourceImportTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Transport.IntegrationTests/Import/NativeAlarmSourceImportTests.cs
index 2d6b9600..6c1a77ac 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.Transport.IntegrationTests/Import/NativeAlarmSourceImportTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.Transport.IntegrationTests/Import/NativeAlarmSourceImportTests.cs
@@ -103,15 +103,17 @@ public sealed class NativeAlarmSourceImportTests : IDisposable
         string connection = "OpcUaPrimary",
         string sourceRef = "ns=3;s=Boiler.Alarm",
         string? filter = "severity>500",
-        bool locked = false) => new(name)
+        bool locked = false,
+        bool inherited = false,
+        bool lockedInDerived = false) => new(name)
         {
             Description = "boiler native alarms",
             ConnectionName = connection,
             SourceReference = sourceRef,
             ConditionFilter = filter,
             IsLocked = locked,
-            IsInherited = false,
-            LockedInDerived = false,
+            IsInherited = inherited,
+            LockedInDerived = lockedInDerived,
         };
 
     [Fact]
@@ -121,7 +123,8 @@ public sealed class NativeAlarmSourceImportTests : IDisposable
         {
             var ctx = scope.ServiceProvider.GetRequiredService<ScadaBridgeDbContext>();
             var t = new Template("Pump") { Description = "tpl" };
-            t.NativeAlarmSources.Add(MakeSource(locked: true));
+            // Set every flag non-default so BuildTemplate's fidelity is exercised.
+            t.NativeAlarmSources.Add(MakeSource(locked: true, inherited: true, lockedInDerived: true));
             ctx.Templates.Add(t);
             await ctx.SaveChangesAsync();
         }
@@ -155,6 +158,39 @@ public sealed class NativeAlarmSourceImportTests : IDisposable
             Assert.Equal("ns=3;s=Boiler.Alarm", src.SourceReference);
             Assert.Equal("severity>500", src.ConditionFilter);
             Assert.True(src.IsLocked);
+            Assert.True(src.IsInherited);
+            Assert.True(src.LockedInDerived);
+        }
+    }
+
+    [Fact]
+    public async Task Import_Overwrite_NoChange_EmitsNoNativeSourceAudit()
+    {
+        // An idempotent Overwrite (bundle == target) must produce ZERO
+        // TemplateNativeAlarmSource* audit rows — the "no audit noise" invariant.
+        await using (var scope = _provider.CreateAsyncScope())
+        {
+            var ctx = scope.ServiceProvider.GetRequiredService<ScadaBridgeDbContext>();
+            var t = new Template("Pump") { Description = "same" };
+            t.NativeAlarmSources.Add(MakeSource("Boiler", locked: true, lockedInDerived: true));
+            ctx.Templates.Add(t);
+            await ctx.SaveChangesAsync();
+        }
+        var sessionId = await ExportAllTemplatesAndLoadAsync();
+
+        await using (var scope = _provider.CreateAsyncScope())
+        {
+            var importer = scope.ServiceProvider.GetRequiredService<IBundleImporter>();
+            await importer.ApplyAsync(sessionId,
+                new List<ImportResolution> { new("Template", "Pump", ResolutionAction.Overwrite, null) },
+                user: "bob");
+        }
+
+        await using (var scope = _provider.CreateAsyncScope())
+        {
+            var ctx = scope.ServiceProvider.GetRequiredService<ScadaBridgeDbContext>();
+            Assert.False(await ctx.AuditLogEntries.AnyAsync(a =>
+                a.Action.StartsWith("TemplateNativeAlarmSource")));
         }
     }
 
diff --git a/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/EntitySerializerTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/EntitySerializerTests.cs
index 57c5eda8..1846aab7 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/EntitySerializerTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/EntitySerializerTests.cs
@@ -215,7 +215,7 @@ public sealed class EntitySerializerTests
             SourceReference = "ns=3;s=Boiler.Alarm",
             ConditionFilter = "severity>500",
             IsLocked = true,
-            IsInherited = false,
+            IsInherited = true,
             LockedInDerived = true,
         });
 
@@ -230,6 +230,7 @@ public sealed class EntitySerializerTests
         Assert.Equal("ns=3;s=Boiler.Alarm", dtoSrc.SourceReference);
         Assert.Equal("severity>500", dtoSrc.ConditionFilter);
         Assert.True(dtoSrc.IsLocked);
+        Assert.True(dtoSrc.IsInherited);
         Assert.True(dtoSrc.LockedInDerived);
 
         var rtSrc = Assert.Single(Assert.Single(sut.FromBundleContent(dto).Templates).NativeAlarmSources);
@@ -239,6 +240,7 @@ public sealed class EntitySerializerTests
         Assert.Equal("ns=3;s=Boiler.Alarm", rtSrc.SourceReference);
         Assert.Equal("severity>500", rtSrc.ConditionFilter);
         Assert.True(rtSrc.IsLocked);
+        Assert.True(rtSrc.IsInherited);
         Assert.True(rtSrc.LockedInDerived);
     }