-- A declaration says the assignment generation it was composed from, and every send is recorded
-- (novox/hq issue 234).
--
-- On 2026-10-04 a declaration newer in sequence than every other named four fewer modules than the
-- assignments held, and the machine undeclared all four. The sequence orders arrival; it cannot tell a
-- later send that carries an older view of the assignments. And nothing the mesh kept said which process
-- sent it, from what view: the node row holds only the digest of the last send.

-- The assignment generation: one counter for the mesh, raised in the same transaction as every change to
-- what is assigned where. A trigger, not a line in each writer: an assignment is also taken by a node's
-- removal (on delete cascade) and renamed with its module (on update cascade), which no writer in Go
-- sees, and a rule kept only by the writers that remember it is the rule this issue found broken. Seeded
-- at 1, so every declaration composed after this claims a generation and none claims zero ("none").
create table assignment_generation (
    one        boolean primary key default true check (one),
    generation bigint  not null
);
insert into assignment_generation (one, generation) values (true, 1);

create function raise_assignment_generation() returns trigger language plpgsql as $$
begin
    update assignment_generation set generation = generation + 1;
    return null;
end
$$;

-- Per row, so a statement that changes nothing raises nothing: an assignment repeated (`on conflict do
-- nothing` inserts no row) and an update that leaves a row as it was (the WHEN below; a plain UPDATE fires a
-- row trigger whether or not it changed anything). A statement that changes several rows raises once per
-- row, which only ever moves it forward. Two triggers, because only an update has both OLD and NEW.
create trigger assignment_generation_raised
    after insert or delete on assignment
    for each row execute function raise_assignment_generation();
create trigger assignment_generation_raised_by_update
    after update on assignment
    for each row when (old is distinct from new) execute function raise_assignment_generation();

-- The generation a machine was last sent, written in the same transaction as the digest of that send, so
-- what the mesh WOULD send is stamped the same way and reads as byte for byte what it DID send when
-- nothing else changed (as sent_epoch, migration 0068). Null for a send without one.
alter table node add column sent_generation bigint;
-- Whether the machine's node-engine said it reads a generation (its reports' `reads_generation`): until
-- it has, it is sent none, because an older node-engine refuses a key it does not know, whole.
alter table node add column reads_generation boolean not null default false;

-- Every send: the machine, its sequence, who sent it — the lease epoch the sender acted under and the
-- caller, process and build — the generation it was composed from, its digest and the modules it named.
-- Written after the declaration is away, with the node row's record of it. A refusal by the machine of a
-- send for its generation is kept on the send it refused, so the condition it raises names the sender
-- from here; a refusal of a sequence the mesh has no send for is kept as a row of its own, `recorded`
-- false, whose sender is said to be unknown. `counter_raised_to` is the generation the mesh's counter was
-- raised to when the refusal showed the counter behind the machine (a store put back from a backup). The
-- newest 200 per machine are kept.
create table declaration_send (
    id           bigserial   primary key,
    node         uuid        not null references node (id) on delete cascade,
    sequence     bigint,
    epoch        bigint,
    sender       text        not null,
    generation   bigint,
    digest       text        not null,
    modules      text[]      not null default '{}',
    sent_at      timestamptz not null default now(),
    refused_at   timestamptz,
    -- refused_applied is the generation the machine said it had applied when it refused this send.
    refused_applied bigint,
    counter_raised_to bigint,
    recorded     boolean     not null default true
);
create index declaration_send_node on declaration_send (node, id desc);
create index declaration_send_sequence on declaration_send (node, sequence);
create index declaration_send_refused on declaration_send (refused_at) where refused_at is not null;