my $user_id = $self->session("user_id");
my $user = get_user($user_id) // do {
    my $promise = $delegate_to_worker_that_already_knows_user->(
        request => $req, user_id => $user_id,
        otherwise_register_for => $my_worker_id
    );
    $promise ? return : load_user("name");
    ...