Replace ad-hoc bold/ratio heading checks with a unified scoring system
based on font size rarity. For each line, compute:
score = font_rarity * 0.5 + bold * 0.3 + standalone * 0.2
Font rarity measures how infrequently a font size appears across the
document — heading fonts are rare while body text is common. This
approach (from opendataloader's ModeWeightStatistics) naturally adapts
to each document's font distribution instead of relying on fixed
thresholds.
Guards: require font_size >= 0.95 * base_size (no small-font headings),
word_count >= 3, and standalone (paragraph break before).
Benchmark improvement: MHS 0.56→0.58, MHS-S 0.66→0.70, overall +0.003.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
