seo-headings-structurelisted

# seo-headings-structure (M7c) A clean, single-rooted heading tree and proper semantic landmarks make a page's outline machine-readable — the same structure that AI engines use to extract answer blocks and that search engines use to understand content scope. Schema/entity context: `references/schema-tier1.md`. ## Audits Working from the PageSnapshot (`rendered_dom` if present, else `raw_html`): 1. **Single H1**: exactly one `<h1>` per page. Zero H1s, or multiple H1s, are both findings. 2. **No skipped levels**: nesting descends one level at a time (an `<h2>` may be followed by `<h3>`, not directly by `<h4>`). Build the outline and flag any jump. 3. **Descriptive text**: each heading names its section in human terms — flag empty headings, headings used purely for visual styling, and generic placeholders ("Section 1", "Welcome"). 4. **Semantic landmarks**: detect `<main>`, `<article>`, `<section>`, `<nav>`, `<header>`, `<footer>`; flag when headings live inside non-semantic `<div>` soup or when more than one `<main>` exists. 5. **Outline ↔ landmark agreement**: sectioning elements should carry their own heading; orphan landmarks and headings outside any landmark are findings. Good heading structure feeds AI answer-block extraction: clear H2/H3 boundaries map to candidate quotable passages. ## Fixes - **Heading-level restructuring** — re-leveling H2-H6 to remove skips or to nest correctly (fixable: **proposed**). This alters the visual hierarchy, so it requires per-item acce