What it is
The half of a documentation site that has nothing to do with how it looks. It reads a content collection and computes the structure — the sidebar tree, the breadcrumb trail, the previous and next links, the table of contents.
Why it is separate
A content helper that also renders markup decides how your site is built. That
is the second borrowed decision, and it is why computing is a separate package
from rendering rather than shipped inside it. @teasim/astra renders nothing,
and @teasim/astro and @teasim/aster know nothing about content. Either half
works on its own.
Markdown twins
Every page is served twice: once as HTML for people, once as markdown for
machines. /about has /about.md beside it, and the site publishes llms.txt
and llms-full.txt so a model can read the whole thing without parsing your
markup.
Validation that names the page
Schema problems are reported in dev with the slug that caused them. A missing
title, a link that points nowhere, a prev that names a page that does not
exist — each one is a console line naming the file, not a build failure.