Function serve_with_selection_policy 

pub fn serve_with_selection_policy<R: Repository + ?Sized>(
    repository: &ValidatedRepository<'_, '_, R>,
    request: Request<'_>,
    storage: &mut SelectionStorage<'_>,
    options: WantOptions,
    output: &mut impl Write,
) -> Result<Response>

Serve selected wants under an explicit host grant and occurrence cap. The validated repository must be the host-authorized immutable projection. All wants are checked before ACKs, pack output or host cache integration.