Function wait_mesh 

pub async fn wait_mesh<T>(
    rx: PortReceiver<ValueMesh<T>>,
    max_idle_time: Duration,
    fallback: ValueMesh<T>,
    reported: impl Fn(&T) -> bool,
) -> Result<ValueMesh<T>, ValueMesh<T>>
where
    T: Send + Sync + Clone + 'static,

Collect an accumulated ValueMesh<T> from rx until every rank has been reported or max_idle_time elapses with no update.

reported decides whether a rank’s current value counts as “reported” (e.g. moved off a NotExist/Timeout placeholder). The accumulator emits the full mesh over the target region, so completion is “every cell reported”. Returns Ok(mesh) once all ranks are reported, or Err(mesh) carrying the latest snapshot (or fallback if nothing arrived) on idle timeout / channel close.