Function site_base 

pub(crate) fn site_base() -> Result<String, Error>

mkdocs.yml’s site_url, with a guaranteed trailing slash.

The one place the published site’s own address is written down. D41 puts it in the map so the resolver never reads it from a live config that mike has already rewritten (§1.3.121); the map still has exactly one source, which is this file.

A line scan rather than a YAML parse. mkdocs.yml carries mkdocs-material’s !relative tag, which a strict YAML loader refuses outright, and atune_dev has no YAML dependency to add for one scalar. Fail-closed: a missing or commented-out site_url is an error naming the file, not a default.

A line scan still has to read the line the way YAML does, though — see scalar.