Hi… No, LiteFS is very flexible, and the answer is rarely “you’re screwed”—but rather “you need to do a little more work.”
In this case, you can emit the fly-replay header from within your own application logic, right before you would have started downloading from the external source. (You can get the location of the current primary in /litefs/.primary.)
Alternatively, it might be easier, when you’re just getting started, to do a client-side redirect to a POST instead. This would cost you an extra trip to the client, but it sounds like these won’t be very frequent.
litefs mount is this supervisor; it won’t run any of the other commands that you pass it until it’s contacted the primary and gotten all of the latest snapshots from there, etc.
(This older Rails thread might give you an idea of what’s involved a bit more concretely.)
Hope this helps a little!