fixes

pkg/cart/mutation_add_item.go

@@ -2,6 +2,7 @@ package cart
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"log"
@@ -11,6 +12,20 @@ import (
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
+// decodeExtra unpacks the dynamic product data carried as raw JSON. Invalid
+// payloads are logged and dropped rather than failing the mutation.
+func decodeExtra(b []byte) map[string]json.RawMessage {
+	if len(b) == 0 {
+		return nil
+	}
+	m := map[string]json.RawMessage{}
+	if err := json.Unmarshal(b, &m); err != nil {
+		log.Printf("AddItem: invalid extra_json: %v", err)
+		return nil
+	}
+	return m
+}
+
 // mutation_add_item.go
 //
 // Registers the AddItem cart mutation in the generic mutation registry.
@@ -18,10 +33,13 @@ import (
 //
 // Behavior:
 //   - Validates quantity > 0
-//   - If an item with same SKU exists -> increases quantity
+//   - If an item with the same item id (ItemId) exists -> increases quantity
 //   - Else creates a new CartItem with computed tax amounts
 //   - Totals recalculated automatically via WithTotals()
 //
+// Item identity is the catalog item id (ItemId), not the SKU: the product
+// service is looked up by id and the returned SKU is reference-only.
+//
 // NOTE: Any future field additions in messages.AddItem that affect pricing / tax
 // must keep this handler in sync.
 var ErrPaymentInProgress = errors.New("payment in progress")
@@ -35,9 +53,10 @@ func (c *CartMutationContext) AddItem(g *CartGrain, m *cart_messages.AddItem) er
 		return fmt.Errorf("AddItem: invalid quantity %d", m.Quantity)
 	}
 
-	// Merge with any existing item having same SKU and matching StoreId (including both nil).
+	// Merge with any existing item having the same item id and matching StoreId
+	// (including both nil). Identity is the id; SKU is reference-only.
 	for _, existing := range g.Items {
-		if existing.Sku != m.Sku {
+		if existing.ItemId != m.ItemId {
 			continue
 		}
 		sameStore := (existing.StoreId == nil && m.StoreId == nil) ||
@@ -61,6 +80,14 @@ func (c *CartMutationContext) AddItem(g *CartGrain, m *cart_messages.AddItem) er
 		if existing.StoreId == nil && m.StoreId != nil {
 			existing.StoreId = m.StoreId
 		}
+		// Refresh dynamic product data with the latest payload.
+		if extra := decodeExtra(m.ExtraJson); extra != nil {
+			existing.Extra = extra
+		}
+		// Replace custom fields when provided on the re-add.
+		if len(m.CustomFields) > 0 {
+			existing.CustomFields = m.CustomFields
+		}
 
 		return nil
 	}
@@ -114,6 +141,9 @@ func (c *CartMutationContext) AddItem(g *CartGrain, m *cart_messages.AddItem) er
 		ArticleType: m.ArticleType,
 
 		StoreId: m.StoreId,
+
+		Extra:        decodeExtra(m.ExtraJson),
+		CustomFields: m.CustomFields,
 	}
 
 	if needsReservation && c.UseReservations(cartItem) {