Function admit_container_agent 

pub(super) async fn admit_container_agent(
    grant: ContainerGrant,
    req: Request<Body>,
    next: Next,
) -> Response

A container agent’s token: allowed only on crate::backend::container_credential::container_route_allowed. There it stands in for the instance key it replaced (so jekt tiers and identity behave as for any agent), with the caller pinned to the grant’s agent by caller_middleware.