-- 0024: distinguish always-on (24x7 server) hosts from intermittent
-- hosts (laptops/workstations that legitimately sleep). Default 1 so
-- every existing and future host keeps today's offline/alert
-- semantics unless explicitly opted out. Column-level ALTER per the
-- repo's migration rules (no table rebuild — hosts has inbound FKs).
ALTER TABLE hosts ADD COLUMN always_on INTEGER NOT NULL DEFAULT 1;