Fix

frontend/pshared/lib/service/payment/quotation.dart

@@ -34,6 +34,8 @@ class QuotationService {
       '/multiquote/$organizationRef',
       request.toJson(),
     );
-    return PaymentQuotesResponse.fromJson(response).quote.toDomain();
+    final parsed = PaymentQuotesResponse.fromJson(response);
+    final idempotencyKey = response['idempotencyKey'] as String?;
+    return parsed.quote.toDomain(idempotencyKey: idempotencyKey);
   }
 }