test(adminui): cover divergent-prefix {{equip}} rejection; use EquipToken constant in message

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

@@ -375,7 +375,8 @@ public interface IUnsTreeService
     /// <param name="equipmentId">The owning equipment.</param>
     /// <param name="input">The operator-editable virtual-tag fields.</param>
     /// <param name="ct">A token to cancel the operation.</param>
-    /// <returns>Success, or one of the guard failures.</returns>
+    /// <returns>Success, or one of the guard failures; or if the chosen script uses the <c>{{equip}}</c>
+    /// token but the equipment has no derivable single tag base.</returns>
     Task<UnsMutationResult> CreateVirtualTagAsync(string equipmentId, VirtualTagInput input, CancellationToken ct = default);
 
     /// <summary>
@@ -389,7 +390,8 @@ public interface IUnsTreeService
     /// <param name="input">The new operator-editable virtual-tag fields.</param>
     /// <param name="rowVersion">The concurrency token the caller last read.</param>
     /// <param name="ct">A token to cancel the operation.</param>
-    /// <returns>Success, a missing-row failure, a guard failure, or a concurrency failure.</returns>
+    /// <returns>Success, a missing-row failure, a guard failure, or a concurrency failure; or if the
+    /// chosen script uses the <c>{{equip}}</c> token but the equipment has no derivable single tag base.</returns>
     Task<UnsMutationResult> UpdateVirtualTagAsync(string virtualTagId, VirtualTagInput input, byte[] rowVersion, CancellationToken ct = default);
 
     /// <summary>

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

@@ -908,12 +908,10 @@ public sealed class UnsTreeService(IDbContextFactory<OtOpcUaConfigDbContext> dbF
         var fullNames = configs.Select(TagConfigFullName.Extract);
         if (EquipmentScriptPaths.DeriveEquipmentBase(fullNames) is null)
         {
-            // NOTE: literal {{equip}} must survive — in a C# interpolated string `{{`/`}}`
-            // collapse to single braces, so keep the token text in a NON-interpolated segment.
             return new UnsMutationResult(false,
                 $"Equipment '{equipmentId}' has no single tag base, so the "
-                + "{{equip}} token can't be resolved. Add at least one driver tag under this "
-                + "equipment (all sharing one object prefix), or remove {{equip}} from the script.");
+                + $"{EquipmentScriptPaths.EquipToken} token can't be resolved. Add at least one driver tag under this "
+                + $"equipment (all sharing one object prefix), or remove {EquipmentScriptPaths.EquipToken} from the script.");
         }
         return null;
     }