SOP: build a clean sitemap for a scaled set

SOP: build a clean sitemap for a scaled set
The sitemap is a contract, not a dump of every route.

— Step 1 (Dev): Generate from the indexable-pages query only. Gate: a URL with noindex must never appear — cross-check the two lists.
— Step 2 (Dev): Split at 50,000 URLs or 50MB per file; use a sitemap index. Gate: oversized file → split, don't truncate silently.
— Step 3 (Data): Stamp lastmod from the real record update time, not the build time. Gate: every URL same lastmod → it's lying, fix it.
— Step 4 (Ops): Status-check a 2% sample. Gate: any 3xx/4xx/5xx in the sample → quarantine the segment before submit.
— Step 5 (SEO): Submit and monitor coverage per sitemap file, so you can localize problems to a template.

Guardrail: one sitemap file per template type for clean diagnosis.

Ship gate: don't publish until all boxes are checked.