Add loading sheet edit flow

Distribution/Features/LoadingEvent/LoadingSheetService.cs

@@ -64,15 +64,14 @@ public class LoadingSheetService(
         if (sheet.Status != LoadingSheetStatus.Planned)
             throw new InvalidOperationException("Items can only be changed while the sheet is Planned");
 
-        // Upsert by (item, warehouse, shop PO item): a matching row gets its quantity
-        // updated in place, a new combination is added. Rows for combinations not present
-        // in this request are left untouched, so a later save can top up the same PO
-        // item's remaining quantity from a different warehouse without losing what was
-        // already planned from the first one.
+        // The request is the full desired item list: a row matching (item, warehouse,
+        // shop PO item) gets its quantity updated in place, a new combination is added,
+        // and rows for combinations not present in the request are removed.
         await uow.BeginAsync(ct);
         try
         {
             var newItems = new List<LoadingSheetItem>();
+            var keptItems = new List<LoadingSheetItem>();
             foreach (var input in request.Items)
             {
                 var existing = sheet.Items.FirstOrDefault(i =>
@@ -81,7 +80,10 @@ public class LoadingSheetService(
                     i.FK_ShopPOItemId == input.FK_ShopPOItemId);
 
                 if (existing is not null)
+                {
                     existing.QuantityDispatched = input.Quantity;
+                    keptItems.Add(existing);
+                }
                 else
                     newItems.Add(new LoadingSheetItem
                     {
@@ -92,10 +94,14 @@ public class LoadingSheetService(
                         QuantityDispatched = input.Quantity
                     });
             }
+
+            var removedItems = sheet.Items.Where(i => !keptItems.Contains(i)).ToList();
+            if (removedItems.Count > 0)
+                repo.RemoveItems(removedItems);
             if (newItems.Count > 0)
                 await repo.AddItemsAsync(newItems);
 
-            var shopPOItemIds = sheet.Items.Select(i => i.FK_ShopPOItemId)
+            var shopPOItemIds = keptItems.Select(i => i.FK_ShopPOItemId)
                 .Concat(newItems.Select(i => i.FK_ShopPOItemId))
                 .Where(x => x.HasValue)
                 .Select(x => x!.Value)