R-449. Until today one upgrade out of 53 had ever been measured - Nextcloud, by
hand, in a spike - and the whole update arc was designed against that single data
point.
Per edge: deploy at FROM, seed through the app's OWN interface, prove the seed
reads back, swap to TO, ask the app for the data again, then put the FROM images
back and record what happens - verbatim, and never called a rollback.
Success is an application-level readback, not file identity: survive2.py's
sha256+inode rule is right for a redeploy and wrong for an upgrade, because a
migration is supposed to rewrite files. And nothing is ever seeded by hand (R-156)
- an app with no non-browser route is recorded inconclusive, never faked.
C3 is a negative control whose TO image exits immediately, and it must be run
first: it came back failed, which is what makes the greens mean anything.
The bookstack fixture uses artisan for both halves and carries its own negative
control on every call, because the obvious HTTP-login readback cannot work: the
template's https APP_URL makes the session cookies secure, so curl over http gets
419 on every login and it looks exactly like a wrong password.
