diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs
index 32553578..884fa318 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs
@@ -188,6 +188,44 @@ public sealed class DriverHostActorNativeAlarmTests : RuntimeActorTestBase
         alerts.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
     }
 
+    /// <summary>A native alarm whose <c>AlarmEventArgs.OperatorComment</c> is set flows through
+    /// <c>DriverHostActor.ForwardNativeAlarm</c> into the published <see cref="AlarmTransitionEvent"/>:
+    /// <c>Comment</c> carries the operator string and <c>User</c> is <c>"device"</c> (a non-null comment
+    /// signals the upstream alarm system provided an operator origin, but without a specific user identity).
+    /// </summary>
+    [Fact]
+    public void Native_alarm_operator_comment_flows_to_transition_event()
+    {
+        var db = NewInMemoryDbFactory();
+        var deploymentId = SeedDeploymentWithAlarmTag(db, RevA,
+            Equip: "eq-1", Driver: "drv-1", FullName: "Temp.HiHi", Folder: null, Name: "temp_hi");
+
+        var alerts = CreateTestProbe();
+        SubscribeToAlerts(alerts);
+
+        var (actor, publish) = SpawnHostAndApply(db, deploymentId);
+
+        // Send an alarm whose OperatorComment is set — simulates an upstream acknowledge-with-comment.
+        actor.Tell(new DriverInstanceActor.AttributeAlarmPublished("drv-1", new AlarmEventArgs(
+            new StubAlarmHandle(),
+            SourceNodeId: "Temp",
+            ConditionId: "Temp.HiHi",
+            AlarmType: "OffNormalAlarm",
+            Message: "investigating",
+            Severity: AlarmSeverity.High,
+            SourceTimestampUtc: Ts,
+            Kind: AlarmTransitionKind.Acknowledge,
+            OperatorComment: "investigating")));
+
+        // OPC UA condition update is ungated — drain it.
+        publish.ExpectMsg<OpcUaPublishActor.AlarmStateUpdate>(TimeSpan.FromSeconds(5));
+
+        // The published AlarmTransitionEvent must carry the comment + the "device" user marker.
+        var evt = alerts.ExpectMsg<AlarmTransitionEvent>(TimeSpan.FromSeconds(5));
+        evt.Comment.ShouldBe("investigating");
+        evt.User.ShouldBe("device");
+    }
+
     /// <summary>Subscribe <paramref name="probe"/> to the <c>alerts</c> DPS topic and wait for the ack.
     /// The Subscribe is sent FROM the probe so the SubscribeAck returns to it. Mirrors the
     /// ScriptedAlarmHostActor test harness.</summary>