.

src/Modules/Basket/Core/Model/Products.cs

@@ -16,7 +16,7 @@ private Products(IReadOnlyList<Product> items)
         _items = items;
     }
 
-    public static Products Empty => new([]);
+    public static readonly Products Empty = new([]);
     public Products AddItem(Product item)
     {
         var items = new List<Product>(_items);
@@ -32,7 +32,7 @@ public Products AddItem(Product item)
             items[index] = newItem;   
         }
 
-        return [..items];
+        return new Products(items);
     }
 
     public Products AddItems(IEnumerable<Product> items)

src/Modules/Basket/Infrastructure/Repositories/RedisCustomerBasketRepository.cs

@@ -32,7 +32,7 @@ public RedisCustomerBasketRepository(IConnectionMultiplexer connectionMultiplexe
 
         var items = model.Items.Select(static item => new Product(new ItemId(item.ItemId), new ItemQuantity(item.Quantity)));
 
-        return CustomerBasket.Empty(customerId).AddItems(items);
+        return CustomerBasket.Active(customerId, [..items]);
     }
 
     public async Task<Result<UpdateBasketSuccess>> Update(CustomerBasket basket, CancellationToken cancellationToken = default)

src/Modules/Warehouse/Core/Model/Entity.cs

@@ -1,6 +1,22 @@
+using System.Numerics;
+
 namespace Warehouse.Core.Model;
 
-public class WarehouseItem
+public readonly record struct ItemQuantity(int Value) : IAdditionOperators<ItemQuantity, ItemQuantity, ItemQuantity>, ISubtractionOperators<ItemQuantity, ItemQuantity, ItemQuantity>
+{
+    public static readonly ItemQuantity Zero = new(0);
+    public static ItemQuantity operator +(ItemQuantity left, ItemQuantity right)
+    {
+        return new ItemQuantity(left.Value + right.Value);
+    }
+
+    public static ItemQuantity operator -(ItemQuantity left, ItemQuantity right)
+    {
+        var res = left.Value - right.Value;
+        return res < 0 ? Zero : new ItemQuantity(res);
+    }
+}
+
+public sealed record WarehouseItem(ProductId ProductId, ItemQuantity Quantity)
 {
-
 }