async fn poll_once(
client: &Client,
state: &Arc<AppState>,
clock: &ClockHandle,
) -> Result<Option<(SignedManifestSet, VerifiedFleetSnapshot)>>async fn poll_once(
client: &Client,
state: &Arc<AppState>,
clock: &ClockHandle,
) -> Result<Option<(SignedManifestSet, VerifiedFleetSnapshot)>>