Comparison stopped at the first divergence on a page, so one displaced line
reported every line behind it and a slipped page hid what followed: a
468-page reference reported 4 differences while hiding 465 pages. The line
streams are aligned instead — nearest resync within 60 lines, contiguous
divergences merged, neighbouring lines off by the same amount collapsed to
a count — and it reports 5766. Reference PDFs are cached by file hash
(corpus 9:00 cold against 5:41 cached), each run prints its counts against
the last, and --quick skips what measured over 50 pages.