diff --git a/src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptLogCompanionSink.cs b/src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptLogCompanionSink.cs
index 4f955ead..fb1aff35 100644
--- a/src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptLogCompanionSink.cs
+++ b/src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptLogCompanionSink.cs
@@ -47,7 +47,8 @@ public sealed class ScriptLogCompanionSink : ILogEventSink
         if (logEvent.Level < _minMirrorLevel) return;
 
         var scriptName = "unknown";
-        if (logEvent.Properties.TryGetValue(ScriptLoggerFactory.ScriptNameProperty, out var prop)
+        if ((logEvent.Properties.TryGetValue(ScriptLoggerFactory.ScriptNameProperty, out var prop)
+             || logEvent.Properties.TryGetValue(ScriptLoggerFactory.ScriptIdProperty, out prop))
             && prop is ScalarValue sv && sv.Value is string s)
         {
             scriptName = s;
diff --git a/tests/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests/ScriptLogCompanionSinkTests.cs b/tests/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests/ScriptLogCompanionSinkTests.cs
index dd456eb3..1169b6ed 100644
--- a/tests/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests/ScriptLogCompanionSinkTests.cs
+++ b/tests/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests/ScriptLogCompanionSinkTests.cs
@@ -136,6 +136,36 @@ public sealed class ScriptLogCompanionSinkTests
         Should.NotThrow(() => companion.Emit(ev));
     }
 
+    /// <summary>
+    ///     Tests that an Error event carrying only ScriptId (no ScriptName) is mirrored
+    ///     with the ScriptId value — not the "unknown" fallback.
+    ///     Evaluators built by ScriptLoggerFactory bind ScriptId, not ScriptName.
+    /// </summary>
+    [Fact]
+    public void ScriptId_used_as_fallback_when_ScriptName_absent()
+    {
+        var mainSink = new CapturingSink();
+        var mainLogger = new LoggerConfiguration()
+            .MinimumLevel.Verbose().WriteTo.Sink(mainSink).CreateLogger();
+
+        var scriptLogger = new LoggerConfiguration()
+            .MinimumLevel.Verbose()
+            .WriteTo.Sink(new ScriptLogCompanionSink(mainLogger))
+            .CreateLogger();
+
+        // Bind ScriptId only — no ScriptName — as the evaluator path does.
+        scriptLogger.ForContext(ScriptLoggerFactory.ScriptIdProperty, "script-abc-123")
+                    .Error("evaluator error");
+
+        mainSink.Events.Count.ShouldBe(1);
+        var forwarded = mainSink.Events[0];
+        // ScriptName property in the forwarded event must be the ScriptId value, not "unknown".
+        forwarded.Properties.ShouldContainKey("ScriptName");
+        ((ScalarValue)forwarded.Properties["ScriptName"]).Value
+            .ShouldBe("script-abc-123",
+                "companion sink should fall back to ScriptId when ScriptName is absent");
+    }
+
     /// <summary>Tests that null main logger is rejected.</summary>
     [Fact]
     public void Null_main_logger_rejected()