-- Existing lists go PRIVATE; sharing becomes an explicit act.
--
-- The Checklist.visibility DEFAULT stays HOUSEHOLD, because a list made from
-- here on is meant to be shared. But applying that default RETROACTIVELY would
-- publish twenty lists written years before anyone else had an account —
-- including work and side-project lists — to every household member the moment
-- the first one is created. Nothing written before accounts existed should
-- become visible without someone choosing it.
--
-- Reversible from the UI: the list page has a share/private toggle (owner only).
UPDATE "Checklist" SET "visibility" = 'PRIVATE' WHERE "visibility" = 'HOUSEHOLD';