Function check_tighten_only 

pub fn check_tighten_only(
    parent: &Manifest,
    merged: &Manifest,
) -> Result<(), ManifestError>

Consent floors are tighten-only (CONTEXT.md §adapter profile): a profile may demand more approval than its parent, never less. Refused at registration if the merged profile loosens an approval-class floor (require_approval, or the at-cap over_cap behavior). Capacity limits (max_instances_per_owner) are not approval-class and are not floored here.