diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/UnsTreeService.cs b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/UnsTreeService.cs
index a5837358..692df0ad 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/UnsTreeService.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/UnsTreeService.cs
@@ -248,7 +248,9 @@ public sealed class UnsTreeService(
         }
         catch (DbUpdateException)
         {
-            // A concurrent add slipped a same-(equipment,tag) or same-name row past the pre-check.
+            // The UX_UnsTagReference_Equip_Tag unique index tripped: a concurrent add slipped a
+            // same-(equipment,tag) row past the pre-check. (Effective-name collisions have no DB
+            // uniqueness — those are caught by the authoring guard and the deploy gate, not here.)
             return new UnsMutationResult(false, "Add failed — a reference at one of these tags was created concurrently. Reload and retry.");
         }
     }