On PDFs where every list item starts with ● at the left margin and content
at a fixed offset, histogram column detection sees the gap between marker
and content as a gutter and splits each line across two phantom "columns,"
scrambling the reading order (Anthropic's Mythos system card p.73–74).
- layout: reject gutter candidates where the smaller side is ≥80%
standalone bullet-marker glyphs (•, ●, ○, ◦, ▪, ▫, ◆, ◇, ■, □)
- markdown/classify: add starts_with_bullet_marker helper (narrower than
is_list_item — excludes numbered/lettered patterns like 1. and a) so
numbered section headings stay as headings)
- markdown/convert: skip heuristic heading detection on lines that start
with a bullet marker
- markdown/classify: strip a leading bullet wrapped in a bold/italic run
(e.g. "**● Label:**" → "- **Label:**") — some PDFs put the marker inside
the same bold run as the label
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Caption detection was incorrectly classifying "Table of Contents" as a
caption because it starts with "Table ". Now "Table" and "Figure"
prefixes require a digit, parenthesis, or hash after them — matching
actual captions like "Table 1", "Figure 3.2" but not titles.
Also removes debug logging left from previous iteration.
Benchmark improvement: MHS 0.52→0.54, overall 0.757→0.761.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
