docs(uns): clarify HasLazyChildren + cluster EntityId, add tie-break test (review I1/I2/M2)

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/UnsNode.cs

@@ -40,7 +40,12 @@ public sealed class UnsNode
     /// <summary>Badge count. For equipment this is tag + virtual-tag count; for container nodes it is the direct child count.</summary>
     public int ChildCount { get; set; }
 
-    /// <summary>True when this node has children that are loaded lazily (equipment with <see cref="ChildCount"/> &gt; 0).</summary>
+    /// <summary>
+    /// Gets a value indicating whether this node has children that load lazily (equipment with tags/virtual tags).
+    /// Structural nodes (Cluster/Area/Line) always carry <c>false</c> even when they have eager children, so a
+    /// renderer must decide whether to show an expand chevron with <c>Children.Count &gt; 0 || HasLazyChildren</c>,
+    /// not on <c>HasLazyChildren</c> alone.
+    /// </summary>
     public bool HasLazyChildren { get; init; }
 
     /// <summary>Eagerly-materialised children. Empty for lazy-loaded equipment until expanded.</summary>
@@ -162,7 +167,7 @@ public static class UnsTreeAssembly
                 ? cluster.Name
                 : $"{cluster.Site} ({cluster.Name})",
             ClusterId = cluster.ClusterId,
-            EntityId = cluster.ClusterId,
+            EntityId = cluster.ClusterId, // Cluster's own logical id IS its ClusterId — EntityId mirrors it for uniform navigation.
             HasLazyChildren = false,
         };
         node.Children.AddRange(areaNodes);

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Uns/UnsTreeAssemblyTests.cs

@@ -43,6 +43,7 @@ public sealed class UnsTreeAssemblyTests
 
         var cluster = tree.Single().Children.Single();
         cluster.Key.ShouldBe("clu:c1");
+        cluster.EntityId.ShouldBe("c1");
 
         var area = cluster.Children.Single();
         area.Kind.ShouldBe(UnsNodeKind.Area);
@@ -120,9 +121,12 @@ public sealed class UnsTreeAssemblyTests
     public void Build_orders_deterministically()
     {
         // Two enterprises out of order; clusters/areas/lines/equipment scrambled.
+        // Two clusters with identical Name but different ClusterId to verify tie-break ordering.
         var clusters = new[]
         {
             new ClusterRow("cZ", "zeta", "SiteZ", "Zeta"),
+            new ClusterRow("c9", "zeta", "SiteZ", "Zeta"),
+            new ClusterRow("c8", "zeta", "SiteZ", "Zeta"),
             new ClusterRow("c2", "alpha", "Site2", "Bravo"),
             new ClusterRow("c1", "alpha", "Site1", "Alpha"),
         };
@@ -162,5 +166,9 @@ public sealed class UnsTreeAssemblyTests
         // Equipment under l1 ordered by Name then EquipmentId: "EquipA"(e1) < "EquipB"(e2).
         var l1 = a1.Children.Single(l => l.Key == "line:l1");
         l1.Children.Select(eq => eq.Key).ShouldBe(new[] { "eq:e1", "eq:e2" });
+
+        // Clusters with the same Name tie-break by ClusterId ordinal: "c8" < "c9" < "cZ".
+        var zetaEnt = tree.Single(e => e.Key == "ent:zeta");
+        zetaEnt.Children.Select(c => c.Key).ShouldBe(new[] { "clu:c8", "clu:c9", "clu:cZ" });
     }
 }