Constant SITE_PAGE_PREFIX 

pub const SITE_PAGE_PREFIX: &str = "https://andrejorsula.github.io/atune/latest/";

This site’s own pages, absolute, as a doc comment has to spell them.

mkdocs.yml sets site_url: https://andrejorsula.github.io/atune/ and builds directory URLs, and mike inserts the version segment — so docs/x/y.md publishes at <site>/<version>/x/y/. latest is the alias guaranteed to exist for every state of the project: before the first release it aliases dev, and from the first release it follows the newest released version.

This is the only version segment prose may cite, and that is now enforced rather than assumed (§1.3.141, closed at §1.3.156). Detection keys on SITE_ROOT instead — any …/atune/<segment>/… URL is found — while the segment itself must be latest. Before that, the whole literal was what site_links_page_relative and check_guide_links’s second and third checks matched on, so a citation of any other segment was invisible to all three: a doc comment carrying …/atune/dev/concepts/nonexistent/ was republished verbatim onto a generated page, named a page that does not exist, and left cargo dev check-guide-links green — with nothing else in the tree able to see it, because rustdoc, mkdocs --strict and an offline link check all ignore an external URL by construction.