better

cmd/cart/mutation_initialize_checkout.go

@@ -28,22 +28,17 @@ import (
 //     parallel checkout attempts are possible, add higher-level guards
 //     (e.g. reject if PaymentInProgress already true unless reusing
 //     the same OrderReference).
-func init() {
-	RegisterMutation[messages.InitializeCheckout](
-		"InitializeCheckout",
-		func(g *CartGrain, m *messages.InitializeCheckout) error {
-			if m == nil {
-				return fmt.Errorf("InitializeCheckout: nil payload")
-			}
-			if m.OrderId == "" {
-				return fmt.Errorf("InitializeCheckout: missing orderId")
-			}
 
-			g.OrderReference = m.OrderId
-			g.PaymentStatus = m.Status
-			g.PaymentInProgress = m.PaymentInProgress
-			return nil
-		},
-		// No WithTotals(): monetary aggregates are unaffected.
-	)
+func InitializeCheckout(g *CartGrain, m *messages.InitializeCheckout) error {
+	if m == nil {
+		return fmt.Errorf("InitializeCheckout: nil payload")
+	}
+	if m.OrderId == "" {
+		return fmt.Errorf("InitializeCheckout: missing orderId")
+	}
+
+	g.OrderReference = m.OrderId
+	g.PaymentStatus = m.Status
+	g.PaymentInProgress = m.PaymentInProgress
+	return nil
 }