Walks every tracked .md file, resolves each relative inline link against
the directory the file lives in, and fails with the file:line and the
unresolved target if it is not on disk. Skips http(s)/mailto, pure
anchors, and links inside fenced code blocks (a template being shown to
the reader is sample text, not a live link).
This is the check that would have caught the 2,793 dead links in the
generated traceability matrix at the commit that introduced them, and the
handful of hand-written ones repaired alongside it. Nobody clicks 2,800
links, which is why the defect survived for months.
Two documented exceptions rather than silent ones: docs-site/SUMMARY.md
is copied into docs/ by publish-docs before rendering, so its links are
resolved from docs/ — which is what makes it catch a nav entry pointing
at a page that does not exist; and docs/README.md and docs/api-redirect.md
are generated by that same job and so are absent from the repo by design.
The header states what it deliberately cannot see, in the house style of
check-frontend-boundary.sh: it validates paths, not anchors. Resolving a
fragment needs a renderer's heading-slug rules, which differ between
Gitea, GitHub and mdBook, so a link to a renamed heading still passes.
The package.json script and CI wiring are added separately.
