Function serve_axum_fs 

pub async fn serve_axum_fs<S>(
    port: u16,
    state: S,
    modules: OptionalModules,
    max_connections: Option<usize>,
) -> Result<()>
where
    S: StatusApi + AvailabilityApi + HotShotAvailabilityApi + NodeApi + TokenApi + CatchupApi + SubmitApi + StateSignatureApi + ConfigApi + HotShotEventsApi + Clone + Send + Sync + 'static,

Serve the query API used by the filesystem-backed storage mode: status, availability, node, token, catchup, and state-signature are always on (tide registered them unconditionally); submit, config, and hotshot-events follow Options. Filesystem storage doesn’t implement the reward/merklized-state/explorer/database traits, so those modules aren’t served (a request to one of their routes 404s, matching tide).