When has a LaTeX document compiled enough times for cross-references to be final?

When LaTeX cross-references stabilize across repeated compiles

In a standard pdfLaTeX run the first pass writes label data to the .aux file. Subsequent reads of that file by ref commands produce the familiar ?? and undefined-reference warnings until the label data from a prior run is available. This is why a single initial pass is never sufficient for final references.

Likely explanation

LaTeX’s built-in rerun warning indicates that labels changed between the current and previous run but it reports only one pending pass. If those labels continue shifting in later runs additional passes follow. Elements such as table-of-contents page numbers longtable column widths and hyperref bookmarks have independent stabilization behavior and often require three to four runs before their values stop changing.

Confirmed facts

• Comparing the .aux file between two consecutive runs is a reliable convergence test for basic cross-references: when the file content (or hash) is identical and no Rerun warning appears cross-references are finalized.
• Table-of-contents list-of-figures list-of-tables longtable column widths and hyperref bookmarks frequently need more than two runs to converge.
• With a bibliography the engine sequence is LaTeX to BibTeX/Biber to LaTeX; convergence is confirmed only after the .aux file is identical across two consecutive runs after bibliography processing.

Steps for your automated pipeline

1. Run pdflatex once to generate the initial .aux.
2. Run pdflatex again. If the log contains no Rerun warning and the .aux hash matches between run 2 and run 3 basic cross-references and most page-layout elements are stable.
3. If the document contains longtable extensive toc or hyperref bookmarks continue running pdflatex until the .aux hash is identical across two consecutive runs (typically three or four total runs).
4. If a bibliography via BibTeX or Biber is included run the cycle pdflatex to bibtex/biber to pdflatex then repeat pdflatex until the .aux file is unchanged between the last two runs.
5. For pipeline automation invoke latexmk -pdf -p; it reruns until generated files stop changing which delegates the convergence decision and handles both bibliography and complex layout elements.

If your pipeline currently assumes only basic cross-references and no bibliography the two-run test after the initial compile is sufficient. Do you include a bibliography or page-layout elements such as longtable extensive toc or hyperref bookmarks? This determines whether the simpler test applies or the full convergence cycle is required.