Written as Argon2id in the PHC string format, $argon2id$v=19$m=19456,t=2,p=1$<salt>$<hash>.
pbkdf2-sha256$<iterations>$<salt>$<hash>, written before, is still read and checked.
An address no account holds gets one without a password, which signs in once its owner
sets one (password-reset), follows a sign-in link or connects a provider. An account
already a member keeps its membership, so adding it again changes nothing but a role.
An account adopted, or given a role, whose address nobody proved may have been signed up
by someone else expecting this, so it is distrusted.
Read and committed beyond the request’s reach, as an area’s principal seldom owns its
members’ records. Without sessions, a session open in the area stays open until its
cookie expires.
Signs account in to an area whose principal is another of its records, such as an
organization it belongs to; the session is listed as the account’s. The caller, an
Admitter of its own, has checked that the account may act as principal.