-- Posts can be hidden from timelines (profile feed as seen by others, the
-- global home feed) and from public collections by their owner. Hidden posts
-- still appear to the owner on their own profile and in private collections.
ALTER TABLE posts
    ADD COLUMN IF NOT EXISTS is_hidden BOOLEAN NOT NULL DEFAULT FALSE;

-- Partial index keeps the "visible posts, newest first" timeline/feed scans
-- cheap by excluding hidden rows from the index entirely.
CREATE INDEX IF NOT EXISTS posts_user_created_visible_idx
    ON posts (user_id, created_at DESC)
    WHERE is_hidden = FALSE;