-- Per-user save-limit overrides, set by admins from the panel. NULL means
-- "use the plan default" (free: 1 bookmark, 5 public + 5 private collections;
-- premium: 5 bookmarks, unlimited collections). A non-NULL value caps that
-- resource for this specific user, regardless of plan.
ALTER TABLE users
    ADD COLUMN IF NOT EXISTS bookmark_limit           INT,
    ADD COLUMN IF NOT EXISTS public_collection_limit  INT,
    ADD COLUMN IF NOT EXISTS private_collection_limit INT;

ALTER TABLE users
    ADD CONSTRAINT users_limit_overrides_nonneg CHECK (
        (bookmark_limit           IS NULL OR bookmark_limit           >= 0) AND
        (public_collection_limit  IS NULL OR public_collection_limit  >= 0) AND
        (private_collection_limit IS NULL OR private_collection_limit >= 0)
    );