Function check 

pub async fn check(fresh: Factory<'_>) -> Report

Run every check that a plain factory can drive.

That a store keeps a restored append’s written bytes as they stand and reads them back through its upcaster is check_upcasting’s, which this does not run, because it needs a store built with an upcaster and an older export; a backend that can be a restore’s target runs both.

Panics

Only if the factory itself fails; contract violations are collected into the Report rather than raised, so bringing up a backend surfaces all of them at once.