diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ConfigComposerTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ConfigComposerTests.cs
index fcd73702..39ead635 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ConfigComposerTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ConfigComposerTests.cs
@@ -4,6 +4,7 @@ using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
 using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
 using ZB.MOM.WW.OtOpcUa.ControlPlane.AdminOperations;
 using ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.Harness;
+using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
 
 namespace ZB.MOM.WW.OtOpcUa.ControlPlane.Tests;
 
@@ -85,6 +86,58 @@ public sealed class ConfigComposerTests : ControlPlaneActorTestBase
         artifact.RevisionHash.ShouldMatch("^[0-9a-f]{64}$");
     }
 
+    /// <summary>
+    ///     Verifies that <see cref="ConfigComposer.SnapshotAndFlattenAsync"/> serialises a
+    ///     <see cref="Device"/>'s <c>HostAddress</c> into the artifact blob and that
+    ///     <see cref="DeploymentArtifact.ParseComposition(ReadOnlySpan{byte})"/> decodes it back
+    ///     as the equipment's <see cref="ZB.MOM.WW.OtOpcUa.OpcUaServer.EquipmentNode.DeviceHost"/>
+    ///     (follow-up E). Guards the real serialize→decode seam: if ConfigComposer's Device
+    ///     serialisation ever drifted, DeviceHost would silently become null in production
+    ///     (feature E degrades to a warn-skip) while hand-rolled artifact tests stayed green.
+    /// </summary>
+    [Fact]
+    public async Task DeviceHost_survives_ConfigComposer_to_ParseComposition_round_trip()
+    {
+        var f = NewInMemoryDbFactory();
+        await using (var db = f.CreateDbContext())
+        {
+            db.ServerClusters.Add(NewCluster("c1"));
+            db.Namespaces.Add(new Namespace
+            {
+                NamespaceId = "ns-eq", ClusterId = "c1",
+                Kind = NamespaceKind.Equipment, NamespaceUri = "urn:eq",
+            });
+            db.DriverInstances.Add(new DriverInstance
+            {
+                DriverInstanceId = "drv-1", ClusterId = "c1", NamespaceId = "ns-eq",
+                Name = "Focas", DriverType = "Focas", DriverConfig = "{}",
+            });
+            db.Devices.Add(new Device
+            {
+                DeviceId = "dev-1", DriverInstanceId = "drv-1",
+                Name = "dev-1", DeviceConfig = "{\"HostAddress\":\"10.9.9.9:8193\"}",
+            });
+            db.UnsAreas.Add(new UnsArea { UnsAreaId = "area-1", ClusterId = "c1", Name = "area-1" });
+            db.UnsLines.Add(new UnsLine { UnsLineId = "line-1", UnsAreaId = "area-1", Name = "line-1" });
+            db.Equipment.Add(new Equipment
+            {
+                EquipmentId = "eq-1", DriverInstanceId = "drv-1", DeviceId = "dev-1",
+                UnsLineId = "line-1", Name = "machine-1", MachineCode = "MACHINE_001",
+            });
+            await db.SaveChangesAsync();
+        }
+
+        await using var readDb = f.CreateDbContext();
+        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(readDb);
+        var composition = DeploymentArtifact.ParseComposition(artifact.Blob);
+
+        var node = composition.EquipmentNodes.ShouldHaveSingleItem();
+        node.EquipmentId.ShouldBe("eq-1");
+        node.DriverInstanceId.ShouldBe("drv-1");
+        node.DeviceId.ShouldBe("dev-1");
+        node.DeviceHost.ShouldBe("10.9.9.9:8193");
+    }
+
     private static readonly DateTime FixedTimestamp = new(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
 
     private static ServerCluster NewCluster(string id) => new()
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.csproj b/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.csproj
index 26b18aef..3b55cf6c 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.csproj
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.csproj
@@ -22,6 +22,7 @@
 
     <ItemGroup>
         <ProjectReference Include="..\..\..\src\Server\ZB.MOM.WW.OtOpcUa.ControlPlane\ZB.MOM.WW.OtOpcUa.ControlPlane.csproj"/>
+        <ProjectReference Include="..\..\..\src\Server\ZB.MOM.WW.OtOpcUa.Runtime\ZB.MOM.WW.OtOpcUa.Runtime.csproj"/>
         <ProjectReference Include="..\..\..\src\Core\ZB.MOM.WW.OtOpcUa.Configuration\ZB.MOM.WW.OtOpcUa.Configuration.csproj"/>
         <ProjectReference Include="..\..\..\src\Core\ZB.MOM.WW.OtOpcUa.Commons\ZB.MOM.WW.OtOpcUa.Commons.csproj"/>
     </ItemGroup>