-- A machine already enrolled is moved to the new bus by being told its membership for it
-- (novox/hq design 28, task 5.2). Until this, a membership — bus address, fingerprint, password,
-- transport — existed only in the enrolment reply, and nothing could hand one to a machine that
-- had already joined. The row is the membership sealed to that machine, composed into its
-- declaration as a file it reads after applying; the plaintext exists once, at minting, and then
-- only on the machine. One per node: the mesh moves to one bus.
create table bus_membership (
  node   uuid        primary key references node(id) on delete cascade,
  sealed text        not null,
  since  timestamptz not null default now()
);