feat(sales): snapshot the product name and unit in the order-line audit payload (#747)

src/Cluckwork.Application/Features/Sales/AddOrderItem/AddOrderItemHandler.cs

@@ -203,6 +203,13 @@ await audit.WriteAsync(
                 {
                     salesOrderItemId = result.Value.Id,
                     productId = product.Id,
+                    // #747 — snapshotted, never resolved by a reader later: a
+                    // renamed product would otherwise re-render this row under
+                    // a name the seller never saw (#720's rule, applied to the
+                    // name). The unit is here because quantity alone is
+                    // ambiguous — 8 trays and 8 eggs are both "8".
+                    productName = product.Name,
+                    unit = unit.ToString(),
                     quantity = command.Quantity,
                     unitPriceMinorUnits = unitPrice.MinorUnits,
                     listUnitPriceMinorUnits,

src/Cluckwork.Application/Features/Sales/UpdateOrderItem/UpdateOrderItemHandler.cs

@@ -1,12 +1,14 @@
 namespace Cluckwork.Application.Features.Sales.UpdateOrderItem;
 
 using Cluckwork.Application.Common;
+using Cluckwork.Application.Features.Catalog;
 using Cluckwork.Application.Features.Sales;
 using Cluckwork.Domain.Common;
 using Cluckwork.Domain.Sales;
 
 public sealed class UpdateOrderItemHandler(
     ISalesOrderRepository orders,
+    IProductRepository products,
     IAuditWriter audit,
     IUnitOfWork unitOfWork)
 {
@@ -40,6 +42,15 @@ public async Task<Result> HandleAsync(UpdateOrderItemCommand command, Cancellati
         var beforeProductId = existing?.ProductId;
         var beforeListUnitPriceMinorUnits = existing?.ListUnitPriceMinorUnits;
         var beforeListPriceBasis = existing?.ListPriceBasis.ToString();
+        // #747 — the unit comes off the line's own snapshot; the name needs a
+        // product read, because SalesOrderItem carries ProductId and no name.
+        // Read HERE, at the moment of the edit: that is what this row is a
+        // record of. Null only if the product row is gone, which leaves the id
+        // in the payload as the stable join key.
+        var beforeUnit = existing?.Unit.ToString();
+        var beforeProductName = existing is null
+            ? null
+            : (await products.GetByIdAsync(existing.ProductId, ct))?.Name;
 
         var result = order.UpdateItem(command.ItemId, command.Quantity, unitPrice);
         if (result.IsFailure)
@@ -56,6 +67,8 @@ await audit.WriteAsync(
             {
                 salesOrderItemId = command.ItemId,
                 productId = beforeProductId!.Value,
+                productName = beforeProductName,
+                unit = beforeUnit,
                 before = new
                 {
                     quantity = beforeQuantity!.Value,

tests/Cluckwork.Api.IntegrationTests/SalesOrderAuditPayloadTests.cs

@@ -99,6 +99,10 @@ public async Task UpdateItem_RecordsThePriceItChangedFromAndTo()
         // later removal, which cascades the row away.
         Assert.Equal(itemId, root.GetProperty("salesOrderItemId").GetGuid());
         Assert.Equal(productId, root.GetProperty("productId").GetGuid());
+        // #747 — same snapshot on the edit path. Read at the moment of the
+        // edit, which is the right question for an UpdateItem row.
+        Assert.Equal("Large Eggs", root.GetProperty("productName").GetString());
+        Assert.Equal("Egg", root.GetProperty("unit").GetString());
 
         // The price it changed FROM and the price it changed TO. Reading these
         // through a reference held across order.UpdateItem would make them
@@ -187,6 +191,12 @@ public async Task AddItem_RecordsListPriceBasisByName()
         Assert.Equal(ListPrice, root.GetProperty("listUnitPriceMinorUnits").GetInt64());
         Assert.Equal(DiscountedPrice, root.GetProperty("unitPriceMinorUnits").GetInt64());
         Assert.Equal(productId, root.GetProperty("productId").GetGuid());
+        // #747 — the NAME and the UNIT, snapshotted. A reader resolving the id
+        // live would get today's name, so a renamed product would re-render
+        // history under a name the seller never saw. "Large Eggs" and "Egg" are
+        // distinct strings, so transposing the two fields reddens here.
+        Assert.Equal("Large Eggs", root.GetProperty("productName").GetString());
+        Assert.Equal("Egg", root.GetProperty("unit").GetString());
         Assert.Equal(10, root.GetProperty("quantity").GetInt32());
         Assert.Equal("USD", root.GetProperty("currencyCode").GetString());
         Assert.Equal(2, root.GetProperty("currencyMinorUnit").GetInt32());