We have historically broken run-safari on a variety of occasions. We should either: 1. Push everyone towards run-minibrowser and drop run-safari, to avoid giving people the expectation it works. 2. Set up some form of testing automation to ensure run-safari remains functional.
<rdar://problem/78789239>
Last I heard our preferred solution for the overwhelming majority of these issues is rdar://74245355
Breakages aside, the problem I ran into with Payment Request API is that minibrowser doesn't have - and probably never will have - ApplePay integration, which Safari does. So it was not possible for me to adequately test my patches. Having said that, Payment Request may be kinda unique in the way it interfaces with a system component. I'm not sure how many other APIs that do that, but it's something to consider if you go with option 1.
*** This bug has been marked as a duplicate of bug 189234 ***