zio Cross-Linker
The guide is provided verbatim in the linking agent's instructions (single source of truth:
references/guide.md). It carries the shell recipes that measure inbound links, the rules for where a
link may and may not sit, the anchor rules, and the bounds that keep an edit from damaging a finished
page.
Nothing mounts this skill today: src/crossref.ts imports the reference directly, because a
single-purpose agent needs it on turn 1 of every run and progressive disclosure would only add a turn
and a way to skip it. The directory is a skill so that a consumer which needs it sometimes — the
docs-integrator, choosing cross-references while wiring a new page — can mount it without moving any
content.