-- A walk waits for its delivery's word (novox/hq ADR 0239).
--
-- A plan is from now on the walk of one delivery's trunk commit across the machines: tier by tier, one
-- machine first and judged at the gate. While the mesh-delivery seat has a holder on record, a walk that
-- moves no core module is opened by the merge and waits — nothing asked, nothing registered, nothing sent —
-- until the delivery's owner says it may start, or a person does (`plans go`). Kept with the plan, as one
-- document: who it waits for, and when, by whom and why it was let go or stopped. Null for every plan
-- before this and for a walk on the controller's own path, which waits for nobody.
alter table release_plan add column delivery jsonb;