% monoref -- minimal example
% Compile once with LuaLaTeX:  lualatex 01-minimal.tex
\documentclass{article}
\usepackage{monoref}
\begin{document}

\section{First}\label{sec:first}
This document has \lastpage\ page(s) in total.
The next part is Section~\ref{sec:second} on page~\pageref{sec:second}
(resolved forward, in one pass).

\section{Second}\label{sec:second}
Back to Section~\ref{sec:first} on page~\pageref{sec:first}.

\end{document}