seo-sitemaps (M17)

Sitemaps are the discovery contract you hand the crawler — they should list exactly the canonical, indexable URLs and nothing else. Schema rules for related markup: references/schema-tier1.md.

Audits

Working from the PageSnapshot (rendered_dom if present, else raw_html) plus fetched /sitemap.xml and /robots.txt:

Presence & validity: locate XML sitemap(s) (/sitemap.xml, robots Sitemap: lines, sitemap index); parse as well-formed XML against the sitemaps.org schema.
Size limits: each sitemap <=50,000 URLs and <=50MB uncompressed; if exceeded, expect a sitemap index splitting the set.
Extensions: where relevant, validate image:, video:, and news: namespace entries (correct namespace declared, required child elements present).
lastmod accuracy: <lastmod> is valid ISO 8601 and reflects real last-modified time — not a build-time stamp on every URL (which trains crawlers to ignore it).
robots referencing: at least one absolute Sitemap: line in robots.txt.
Sitemap-to-canonical consistency: no URL in the sitemap is noindex, redirected, 4xx/5xx, or non-canonical (self-referencing canonical only). Cross-check indexability with M-indexability.
Orphan reconciliation: diff sitemap URLs against the internal link graph — flag indexable pages absent from the sitemap and sitemap URLs unreachable by internal links.

Fixes

AUTO: generate or repair XML sitemap entries (correct <loc>, accurate <lastmod> from observed last-modified data, valid image:/video: extension children where media exists) and add an absolute Sitemap: line to robots.txt. These are additive/deterministic diffs for fix.
PROPOSED: removing or splitting entries (e.g. dropping non-canonical/noindex URLs, sharding into a sitemap index) — drafted, accepted per-item.
ADVISORY: changing site-wide lastmod strategy or canonical decisions — described, never written by the tool.
Never fabricate lastmod times, media URLs, or canonical targets — pull from observed data, ask the user, or leave a clearly-marked TODO placeholder per the schema fixable contract.