-- Phase B1: make 'microvm' a runtime a mission can ask for, and give nodes a
-- place to declare what they can actually host.
--
-- Placement for microVMs is a HARD predicate, not a preference. gw-04 — where
-- every mission runs today — is itself a VM without nested virtualisation, so
-- it has no /dev/kvm and never will. tank / morpheus / architect do. A microvm
-- mission scheduled onto a node without KVM cannot start, so the scheduler has
-- to be able to tell the difference, which means the node has to report it.
--
-- `capabilities` is deliberately a jsonb blob rather than a `has_kvm boolean`:
-- the next predicate (a baked rootfs present, a particular CLI image, a GPU)
-- should not need a migration, and the node is the only honest source for any
-- of them.

ALTER TABLE missions DROP CONSTRAINT IF EXISTS missions_runtime_kind_check;
ALTER TABLE missions ADD CONSTRAINT missions_runtime_kind_check
  CHECK (runtime_kind IN ('zeroclaw', 'local_herdr', 'microvm'));

-- Default '{}' and not null: a node that has never reported is "capable of
-- nothing known", which is the safe reading. An absent capability must never
-- be mistaken for an unqueried one — a node with no entry and a node that
-- reported `kvm: false` should both fail a KVM predicate, and with this
-- default they do.
ALTER TABLE nodes ADD COLUMN IF NOT EXISTS capabilities jsonb NOT NULL DEFAULT '{}'::jsonb;

-- Placement asks "which online nodes have KVM", so index the lookup.
CREATE INDEX IF NOT EXISTS nodes_capabilities_idx ON nodes USING gin (capabilities);