fix(uns): enforce #122 on line reparent across clusters (final review)

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

@@ -408,6 +408,41 @@ public sealed class UnsTreeService(IDbContextFactory<OtOpcUaConfigDbContext> dbF
         }
 
         db.Entry(entity).Property(e => e.RowVersion).OriginalValue = rowVersion;
+
+        // Decision #122: a reparent to a different area must not orphan driver-bound equipment
+        // from its driver's cluster.  Resolve the new area's cluster and check every bound
+        // equipment item under this line against it.
+        if (newUnsAreaId != entity.UnsAreaId)
+        {
+            var newAreaCluster = await db.UnsAreas
+                .Where(a => a.UnsAreaId == newUnsAreaId)
+                .Select(a => (string?)a.ClusterId)
+                .FirstOrDefaultAsync(ct);
+
+            if (newAreaCluster is not null)
+            {
+                var boundEquipment = await db.Equipment
+                    .Where(eq => eq.UnsLineId == unsLineId && eq.DriverInstanceId != null)
+                    .Select(eq => new { eq.EquipmentId, eq.DriverInstanceId })
+                    .ToListAsync(ct);
+
+                foreach (var eq in boundEquipment)
+                {
+                    var driverCluster = await db.DriverInstances
+                        .Where(d => d.DriverInstanceId == eq.DriverInstanceId)
+                        .Select(d => d.ClusterId)
+                        .FirstOrDefaultAsync(ct);
+
+                    if (driverCluster is not null && driverCluster != newAreaCluster)
+                    {
+                        return new UnsMutationResult(
+                            false,
+                            $"Cannot move line to area '{newUnsAreaId}': equipment '{eq.EquipmentId}' is bound to a driver in cluster '{driverCluster}' (decision #122). Re-home or unbind it first.");
+                    }
+                }
+            }
+        }
+
         entity.UnsAreaId = newUnsAreaId;
         entity.Name = name;
         entity.Notes = string.IsNullOrWhiteSpace(notes) ? null : notes;