-- The node records: which machines this mesh knows about.
--
-- novox/hq ADR 0006 — inventory holds nodes, modules, assignments and versions, and this is the
-- first of the four. The others arrive with delivery, which is not built; a table nothing writes
-- to is a guess about a shape, and guesses about shapes are what migrations make expensive.

create table node (
    id       uuid        primary key default gen_random_uuid(),

    -- What a person calls this machine. Unique because it is how a node is named when a token is
    -- issued for it (`token issue --node workstation`), and a name that matched two records would
    -- make that command ambiguous at exactly the moment it grants access to the mesh.
    name     text        not null unique,

    created  timestamptz not null default now(),

    -- The last profile the node reported: what it can run, which is the input to deciding what it
    -- should run (novox/hq 09-the-node-lifecycle, step 4).
    --
    -- Held opaquely, as the document the node sent. The host owns that shape and the control
    -- plane's job here is to keep the last one faithfully, not to have an opinion about it — so a
    -- host that learns to report something new does not need this schema to change first.
    profile  jsonb,

    -- When this node was last heard from.
    --
    -- There is no `state` column, and its absence is deliberate. The lifecycle has four states,
    -- but two of them — unmanaged and hosted — are situations of a *machine* that the mesh has
    -- not been told about, so they cannot be rows here. The remaining pair, enrolled and
    -- disconnected, are described in novox/hq ADR 0004 as the same node in two situations rather
    -- than two kinds of thing, and the difference between them is how long it has been since this
    -- column moved.
    --
    -- Stored as a state it would have to be written by something noticing a node had gone quiet —
    -- and nothing notices silence. It would be correct while nodes were talking and wrong exactly
    -- when it mattered.
    last_seen timestamptz
);

-- "Has this node been unreachable for a week" is the control plane's question by definition
-- (novox/hq ADR 0006 — nobody else is watching), so the column it is asked of is indexed.
create index node_last_seen on node (last_seen nulls first);