Write an ‘alert’ helper 

hook 'before_template_render' => sub {
    my $tokens = shift;

    if( session('username') ) {
        $tokens->{'username'} = session('username');
        $tokens->{'is_admin'} = 1 if session('is_admin');
    }
    my $global_tokens = $global{tokens};
    while(my($key, $value) = each %$global_tokens) {
        $tokens->{$key} = $value unless exists $tokens->{$key};
    }
};