`GET /api/auth/me` grows an `accountAccess` block: the accounts this caller
may act on, the one the browser is inside right now, and the booleans a UI
binds directly — `canSwitch`, and `canWrite` per account. Every value is
resolved server-side. A client that worked out what it may do from grant rows
would be a second program deciding one person's access to a health record, and
the two answer differently the first time an expiry or a revocation appears.
`canWrite` is false for every grant in v1 because invitations write READ only.
It is resolved through the grant state machine rather than hardcoded, so the
day a WRITE grant exists the answer changes without this file being edited.
The route becomes an actor surface. It has to be: the switcher, the banner
naming whose record is open, and the way back out all read this payload, and
under a bare `requireAuth()` the whole app shell would refuse the moment a
switch was on. Every field it returns is still the caller's own.
The active record is published as a full entry, not an id to look up. A banner
that had to join two fields could render unnamed the moment they disagreed;
here the active entry is one of the listed ones, selected by the pass that
built them. A stamp left behind by a grant that lapsed reads as not switched —
the same answer the resolver gives the next delegated request.
Not published: the other account's avatar. Those bytes are owner-scoped, so a
URL here would resolve to a refusal and paint a broken image. Clients keep the
initials fallback.