With new approach of Safari browser we have problem to autheticate users on third-site domain:
a) On our webiste user log-in and create auth cookie valid for servicedomain.com
b) user is using our service on his own domain client.com by inserting HTML into his code. Eg. <script src='https://servicedomain.com/app.js' />
c) Thanks to cookie in (a) step and script pointing at servicedomain.com in (b) step, we can distinguish if it is logged user (with right cookie) or common guest.
But with Safari 12 and "Prevent cross-site tracking" mode not any more. How to solve this? To tell user go to Safari setting and uncheck this mode is not a way.
