Seed one account as far as the schema allows (a row of every two-ended
model, every column of those rows and of the account row, the instance
settings, a sharing grant), export it both ways and restore each file
into a fresh account, over the live account, and from a version-1 file
in the old shapes. The files, counts, parsed payload, preview, restore
outcome, reported phases, audit rows, wide-event fields and every row the
account holds afterwards are compared with golden copies after ids,
ciphertext and run-time timestamps are normalised. Refusals, skip reports
and the schema's issue list for malformed files are pinned the same way.
The seed moves out of the round-trip test into a shared fixture module
so both files fill the same account.
