-- A module says how it is healthy, and the node-engine judges it (novox/hq ADR 0240, to-be 48 Phase A).
--
-- Every machine's node-engine states the health of every long-running resource it runs for a module — a
-- container that stays up, a process that stays up, a service stated running — in every report and as an
-- event between reports. The controller keeps the newest statement per machine, here, so the release
-- gate, `node show` and a controller started again all read the same word; and with it, per module, how
-- many statements in a row said a resource of it was unhealthy — `module.<module>.<machine>.unhealthy` is
-- raised on the second (ADR 0240 §4).
--
-- One row per machine, replaced, as node_report is: the question is the machine's state now. A machine
-- whose node-engine is older than the judging has no row, and its health is not known — never healthy,
-- never unhealthy.
create table node_health (
    node      uuid        primary key references node(id) on delete cascade,
    -- The statement's version (the engine's liveness contract).
    contract  int         not null,
    -- When the node-engine looked, on the machine's clock: the order of its statements. An older one
    -- than this is refused.
    said_at   timestamptz not null,
    -- When this controller heard it, on its own: what "since the send" is judged by.
    heard_at  timestamptz not null default now(),
    -- [{module, resource, kind, target, state, reason, since, streak, restarts}], as the engine said them.
    resources jsonb       not null default '[]',
    -- {module: statements in a row saying a resource of it is unhealthy}.
    streaks   jsonb       not null default '{}'
);