seo-indexability (M2)

If a page can't be crawled, indexed, or canonicalized correctly, every other signal is wasted — this is the floor under the Search score. Schema-side context: references/schema-tier1.md.

Audits

Working from the PageSnapshot (rendered_dom if present, else raw_html) plus response headers:

Canonical: exactly one <link rel="canonical">; absolute HTTPS URL; classify self-referential vs cross-domain vs chained (canonical points to a URL that itself canonicalizes elsewhere). Flag canonical that resolves to a redirect or 4xx.
Canonical + noindex: the lethal combination on the same URL (a noindex page used as a canonical target, or a canonicalized page also carrying noindex) — contradictory signals that drop the page.
Robots directives: <meta name="robots"> and the X-Robots-Tag header for noindex/nofollow/none; reconcile header vs meta (header wins).
Duplicate clusters: near-identical title/H1/body across URLs with no consolidating canonical.
Pagination: paginated series signals (self-canonical per page; do not canonicalize page 2+ to page 1 — that delists deep items).
Site health (covers M3): redirect chains/loops (>1 hop = warn, >3 hops or loop = fail), internal links returning 4xx/5xx, soft-404 (200 status on an empty/"not found" page), mixed content (HTTP subresources on HTTPS), HTTP-to-HTTPS enforcement, orphan pages (no internal inlinks), and click-depth from the homepage.

Fixes

AUTO (fixable: auto): inject a single self-referential absolute-HTTPS <link rel="canonical"> when absent; remove an accidental noindex on a page the user has confirmed should be indexed. Both are deterministic, additive/removal-only diffs for fix.
ADVISORY (fixable: advisory): redirect chains/loops, status codes, HTTP-to-HTTPS, and mixed-content origin fixes live in server/CDN config — the tool never writes these; it reports the exact change.
PROPOSED (fixable: proposed): duplicate-cluster consolidation (which URL is canonical is an editorial call) — draft a per-cluster canonical plan for the user to accept.
Never fabricate which URL "should" win or whether a page is intentionally noindexed — ask the user or leave a clearly-marked TODO placeholder.