more cart

internal/ucp/cart.go

@@ -185,10 +185,11 @@ func parseCartID(r *http.Request) (uint64, bool) {
 
 func cartGrainToResponse(id string, g *cart.CartGrain) CartResponse {
 	resp := CartResponse{
-		Id:    id,
-		Items: make([]CartItem, 0, len(g.Items)),
-		Totals: Totals{Currency: g.Currency},
-		Status: "active",
+		Id:                id,
+		Items:             make([]CartItem, 0, len(g.Items)),
+		Totals:            Totals{Currency: g.Currency},
+		Status:            "active",
+		AppliedPromotions: g.AppliedPromotions,
 	}
 	if g.CheckoutStatus != nil && *g.CheckoutStatus != "" {
 		resp.Status = string(*g.CheckoutStatus)

internal/ucp/checkout.go

@@ -542,6 +542,16 @@ func (c *OrderHTTPClient) CreateOrder(ctx context.Context, checkoutID uint64, g
 // buildOrderLines converts a checkout grain's cart items and delivery selections
 // into order lines, matching the format expected by the order service.
 func buildOrderLines(g *checkout.CheckoutGrain) []orderLine {
+	hasFreeShipping := false
+	if g.CartState != nil {
+		for _, ap := range g.CartState.AppliedPromotions {
+			if ap.Type == "free_shipping" && !ap.Pending {
+				hasFreeShipping = true
+				break
+			}
+		}
+	}
+
 	lines := make([]orderLine, 0, len(g.CartState.Items)+len(g.Deliveries))
 	for _, it := range g.CartState.Items {
 		if it == nil {
@@ -569,7 +579,14 @@ func buildOrderLines(g *checkout.CheckoutGrain) []orderLine {
 		})
 	}
 	for _, d := range g.Deliveries {
-		if d == nil || d.Price.IncVat <= 0 {
+		if d == nil {
+			continue
+		}
+		unitPrice := d.Price.IncVat
+		if hasFreeShipping {
+			unitPrice = 0
+		}
+		if unitPrice <= 0 && !hasFreeShipping {
 			continue
 		}
 		lines = append(lines, orderLine{
@@ -577,10 +594,35 @@ func buildOrderLines(g *checkout.CheckoutGrain) []orderLine {
 			Sku:       d.Provider,
 			Name:      "Delivery",
 			Quantity:  1,
-			UnitPrice: d.Price.IncVat,
+			UnitPrice: unitPrice,
 			TaxRate:   2500, // 25% in basis points
 		})
 	}
+
+	// Reflected applied promotions as negative discount lines
+	if g.CartState != nil {
+		for _, ap := range g.CartState.AppliedPromotions {
+			if ap.Pending {
+				continue
+			}
+			discountVal := int64(0)
+			if ap.Discount != nil {
+				discountVal = ap.Discount.IncVat.Int64()
+			}
+			if discountVal <= 0 {
+				continue
+			}
+			lines = append(lines, orderLine{
+				Reference: "promo-" + ap.PromotionId,
+				Sku:       "promo-" + ap.PromotionId,
+				Name:      "Promotion: " + ap.Name,
+				Quantity:  1,
+				UnitPrice: money.Cents(-discountVal),
+				TaxRate:   2500, // default standard tax rate (25%) in basis points
+			})
+		}
+	}
+
 	return lines
 }
 

internal/ucp/types.go

@@ -122,10 +122,11 @@ type VoucherInput struct {
 
 // CartResponse is the UCP cart response body.
 type CartResponse struct {
-	Id     string     `json:"id"`
-	Items  []CartItem `json:"items,omitempty"`
-	Totals Totals     `json:"totals"`
-	Status string     `json:"status"`
+	Id                string                  `json:"id"`
+	Items             []CartItem              `json:"items,omitempty"`
+	Totals            Totals                  `json:"totals"`
+	Status            string                  `json:"status"`
+	AppliedPromotions []cart.AppliedPromotion `json:"appliedPromotions,omitempty"`
 }
 
 // CartItem is the UCP wire format for a cart line item in responses.