-- The version of the host running on a machine, as the machine reports it.
--
-- novox/hq 04-ISSUES/087. A host parses a declaration strictly: a field it does not know makes it
-- refuse the whole declaration and apply nothing. That is deliberate — it keeps a half-understood
-- declaration off a machine — and it makes every new field in a declaration a flag day, hosts before
-- controller. The mesh had no record of which host a machine runs, so it could neither refuse to send
-- a declaration a machine cannot parse nor say which machines were behind. The order was kept by
-- somebody remembering it.
--
-- The machine has been reporting this since ADR 0141 and the control plane discarded it: the field was
-- absent from the controller's own copy of the report, so it was unmarshalled into nothing.
--
-- Null for a machine that has not reported since this column existed, which is not the same as a
-- machine running no host — so a reader is never told a version the mesh does not have.
alter table node add column host_version text;