Previous approach used hardcoded text patterns + position heuristics in
assign_block_role — fragile across journal layouts.
Current approach: after the structural gate holds a heading and the zone
is resolved, normalize any block that is:
- in frontmatter_main_zone
- role=unknown_structural (held by gate — no heading evidence)
- seed_role in heading roles (section_heading, subsection_heading, etc.)
- on page 1-2
...to frontmatter_noise. This uses only layout-derived signals (zone,
structural gate decision, seed_role), no text matching, no position/width
thresholds. Cannot accidentally eat legitimate headings because only
blocks the structural gate explicitly rejected are affected.
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