Function run_check 

pub fn run_check<B, T>(
    view: &AccountView<'_>,
    args: &B::Args,
) -> Result<BehaviorChecked<B, B::CheckOutput>, ProgramError>
where
    T: LayoutContract + Pod,
    B: HopperBehavior<T>,

Run behavior B’s check phase against view, loading the typed state through the normal validated path, and mint the proof token.

This is the explicit form that future context integration can call for each behavior(...) attachment. RUN_CHECK = false behaviors yield an error here rather than a vacuous proof: a token must mean the check actually ran.