diff --git a/src/ScadaLink.Transport/Serialization/EntityDtos.cs b/src/ScadaLink.Transport/Serialization/EntityDtos.cs
index 58e58c2..53112b6 100644
--- a/src/ScadaLink.Transport/Serialization/EntityDtos.cs
+++ b/src/ScadaLink.Transport/Serialization/EntityDtos.cs
@@ -78,7 +78,8 @@ public sealed record TemplateAlarmDto(
     int PriorityLevel,
     AlarmTriggerType TriggerType,
     string? TriggerConfiguration,
-    bool IsLocked);
+    bool IsLocked,
+    string? OnTriggerScriptName);
 
 public sealed record TemplateScriptDto(
     string Name,
diff --git a/src/ScadaLink.Transport/Serialization/EntitySerializer.cs b/src/ScadaLink.Transport/Serialization/EntitySerializer.cs
index 3197ee7..eb6a989 100644
--- a/src/ScadaLink.Transport/Serialization/EntitySerializer.cs
+++ b/src/ScadaLink.Transport/Serialization/EntitySerializer.cs
@@ -29,37 +29,53 @@ public sealed class EntitySerializer
                 Name: f.Name,
                 ParentName: f.ParentFolderId is { } pid && folderNameById.TryGetValue(pid, out var pname) ? pname : null,
                 SortOrder: f.SortOrder)).ToList(),
-            Templates: aggregate.Templates.Select(t => new TemplateDto(
-                Name: t.Name,
-                FolderName: t.FolderId is { } fid && folderNameById.TryGetValue(fid, out var fname) ? fname : null,
-                BaseTemplateName: t.ParentTemplateId is { } btid && templateNameById.TryGetValue(btid, out var bname) ? bname : null,
-                Description: t.Description,
-                Attributes: t.Attributes.Select(a => new TemplateAttributeDto(
-                    Name: a.Name,
-                    Value: a.Value,
-                    DataType: a.DataType,
-                    IsLocked: a.IsLocked,
-                    Description: a.Description,
-                    DataSourceReference: a.DataSourceReference)).ToList(),
-                Alarms: t.Alarms.Select(a => new TemplateAlarmDto(
-                    Name: a.Name,
-                    Description: a.Description,
-                    PriorityLevel: a.PriorityLevel,
-                    TriggerType: a.TriggerType,
-                    TriggerConfiguration: a.TriggerConfiguration,
-                    IsLocked: a.IsLocked)).ToList(),
-                Scripts: t.Scripts.Select(s => new TemplateScriptDto(
-                    Name: s.Name,
-                    Code: s.Code,
-                    TriggerType: s.TriggerType,
-                    TriggerConfiguration: s.TriggerConfiguration,
-                    ParameterDefinitions: s.ParameterDefinitions,
-                    ReturnDefinition: s.ReturnDefinition,
-                    IsLocked: s.IsLocked,
-                    MinTimeBetweenRuns: s.MinTimeBetweenRuns)).ToList(),
-                Compositions: t.Compositions.Select(c => new TemplateCompositionDto(
-                    InstanceName: c.InstanceName,
-                    ComposedTemplateName: templateNameById.TryGetValue(c.ComposedTemplateId, out var cn) ? cn : string.Empty)).ToList())).ToList(),
+            Templates: aggregate.Templates.Select(t =>
+            {
+                // Build per-template script-id → name lookup once so the alarm
+                // projection below resolves OnTriggerScriptId by name in O(1).
+                // Scripts can only target sibling scripts on the same template
+                // (TemplateAlarm.OnTriggerScriptId FK is scoped to TemplateId),
+                // so we don't need a global script index.
+                var scriptNameById = t.Scripts.ToDictionary(s => s.Id, s => s.Name);
+                return new TemplateDto(
+                    Name: t.Name,
+                    FolderName: t.FolderId is { } fid && folderNameById.TryGetValue(fid, out var fname) ? fname : null,
+                    BaseTemplateName: t.ParentTemplateId is { } btid && templateNameById.TryGetValue(btid, out var bname) ? bname : null,
+                    Description: t.Description,
+                    Attributes: t.Attributes.Select(a => new TemplateAttributeDto(
+                        Name: a.Name,
+                        Value: a.Value,
+                        DataType: a.DataType,
+                        IsLocked: a.IsLocked,
+                        Description: a.Description,
+                        DataSourceReference: a.DataSourceReference)).ToList(),
+                    Alarms: t.Alarms.Select(a => new TemplateAlarmDto(
+                        Name: a.Name,
+                        Description: a.Description,
+                        PriorityLevel: a.PriorityLevel,
+                        TriggerType: a.TriggerType,
+                        TriggerConfiguration: a.TriggerConfiguration,
+                        IsLocked: a.IsLocked,
+                        // Carry the on-trigger script by NAME — the importer resolves
+                        // this back to a script id once the parent template's scripts
+                        // have been persisted and assigned ids. If the FK doesn't
+                        // resolve in this aggregate (e.g. corrupt/orphan row), the
+                        // name comes through as null and the importer leaves the
+                        // FK null on the imported alarm.
+                        OnTriggerScriptName: a.OnTriggerScriptId is { } sid && scriptNameById.TryGetValue(sid, out var sn) ? sn : null)).ToList(),
+                    Scripts: t.Scripts.Select(s => new TemplateScriptDto(
+                        Name: s.Name,
+                        Code: s.Code,
+                        TriggerType: s.TriggerType,
+                        TriggerConfiguration: s.TriggerConfiguration,
+                        ParameterDefinitions: s.ParameterDefinitions,
+                        ReturnDefinition: s.ReturnDefinition,
+                        IsLocked: s.IsLocked,
+                        MinTimeBetweenRuns: s.MinTimeBetweenRuns)).ToList(),
+                    Compositions: t.Compositions.Select(c => new TemplateCompositionDto(
+                        InstanceName: c.InstanceName,
+                        ComposedTemplateName: templateNameById.TryGetValue(c.ComposedTemplateId, out var cn) ? cn : string.Empty)).ToList());
+            }).ToList(),
             SharedScripts: aggregate.SharedScripts.Select(s => new SharedScriptDto(
                 Name: s.Name,
                 Code: s.Code,
diff --git a/tests/ScadaLink.Transport.Tests/Serialization/EntitySerializerTests.cs b/tests/ScadaLink.Transport.Tests/Serialization/EntitySerializerTests.cs
index eeed2d8..d9b00db 100644
--- a/tests/ScadaLink.Transport.Tests/Serialization/EntitySerializerTests.cs
+++ b/tests/ScadaLink.Transport.Tests/Serialization/EntitySerializerTests.cs
@@ -79,15 +79,6 @@ public sealed class EntitySerializerTests
             IsLocked = true,
             Description = "PSI",
         });
-        basic.Alarms.Add(new TemplateAlarm("High")
-        {
-            Id = 1,
-            TemplateId = 1,
-            PriorityLevel = 2,
-            TriggerType = AlarmTriggerType.RangeViolation,
-            TriggerConfiguration = "{\"threshold\":100}",
-            IsLocked = false,
-        });
         basic.Scripts.Add(new TemplateScript("OnUpdate", "return 1;")
         {
             Id = 1,
@@ -98,6 +89,19 @@ public sealed class EntitySerializerTests
             IsLocked = false,
             MinTimeBetweenRuns = TimeSpan.FromSeconds(30),
         });
+        basic.Alarms.Add(new TemplateAlarm("High")
+        {
+            Id = 1,
+            TemplateId = 1,
+            PriorityLevel = 2,
+            TriggerType = AlarmTriggerType.RangeViolation,
+            TriggerConfiguration = "{\"threshold\":100}",
+            IsLocked = false,
+            // FU-B / #37 — alarm fires "OnUpdate" script when triggered. The FK is
+            // an in-aggregate script id; the DTO carries the name and the
+            // importer resolves the FK on the way back in.
+            OnTriggerScriptId = 1,
+        });
 
         var assembly = new Template("Assembly") { Id = 2, FolderId = 1 };
         assembly.Compositions.Add(new TemplateComposition("MotorA")
@@ -115,6 +119,15 @@ public sealed class EntitySerializerTests
 
         var sut = new EntitySerializer();
         var dto = sut.ToBundleContent(aggregate);
+
+        // FU-B / #37 — verify the DTO carries OnTriggerScriptName by NAME (not id).
+        // The bundle is portable across environments so a script-id FK can't
+        // survive a round-trip; resolution back to a script id is the importer's
+        // job once the parent template's scripts have been re-persisted.
+        var dtoBasic = Assert.Single(dto.Templates, t => t.Name == "Basic");
+        var dtoAlarm = Assert.Single(dtoBasic.Alarms);
+        Assert.Equal("OnUpdate", dtoAlarm.OnTriggerScriptName);
+
         var roundTripped = sut.FromBundleContent(dto);
 
         var rtBasic = Assert.Single(roundTripped.Templates, t => t.Name == "Basic");
@@ -129,6 +142,9 @@ public sealed class EntitySerializerTests
         Assert.Equal(AlarmTriggerType.RangeViolation, rtAlarm.TriggerType);
         Assert.Equal("{\"threshold\":100}", rtAlarm.TriggerConfiguration);
         Assert.Equal(2, rtAlarm.PriorityLevel);
+        // FromBundleContent leaves OnTriggerScriptId null — the importer
+        // resolves it post-persist when target-DB script ids are known.
+        Assert.Null(rtAlarm.OnTriggerScriptId);
 
         var rtScript = Assert.Single(rtBasic.Scripts);
         Assert.Equal("OnUpdate", rtScript.Name);