## I have read the
[CONTRIBUTING.md](https://github.com/supabase/supabase/blob/master/CONTRIBUTING.md)
file.
YES
## What kind of change does this PR introduce?
Feature, bug fix.
Part 3 of 6 in a stack that splits the library redesign into reviewable
pieces.
## What is the current behavior?
An agent can already fetch any guide as Markdown, but has no way to find
out what guides exist: the entry point is a rendered React page.
The exporter also fails quietly in ways that ship wrong output rather
than failing the build:
- An unknown component silently unwraps to its children, so a component
rename drops its rendered content.
- A registry item that cannot be read produces a page with no file
listing.
- A link to a missing page produces a 404 URL.
- An unrecognized install framework produces a plausible command for the
wrong CLI.
- Only absolute `/library/docs` links are rewritten, so in-page anchors
and sibling links break in the export.
## What is the new behavior?
`/library` negotiates Markdown the same way the guides do — `Accept:
text/markdown`, or an explicit `/library/index.md` — and returns a
categorized catalog with every block, its description, its framework
variants, and a link to each guide's Markdown.
`config/library.ts` is the single catalog description the generator
reads, and a test ties it to the content directory in both directions: a
guide cannot be added without a catalog entry, or listed without a
guide.
Each quiet failure above now throws, and links resolve against the page
they appear on and are checked against the set of published documents.
```bash
curl -H 'Accept: text/markdown' https://supabase.com/library
```
## Additional context
`config/library.ts` also carries the category and preview metadata the
redesigned homepage consumes in the last PR of the stack; here it is
exercised by the Markdown index and its test.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **New Features**
- Added a browsable library catalog covering categories, blocks, starter
apps, and supported frameworks.
- Added Markdown versions of the library homepage and documentation for
compatible tools and workflows.
- Added framework-aware links and expanded registry information,
including dependencies and source details.
- Markdown requests now work for the homepage and documentation, while
browser requests continue receiving HTML.
- **Bug Fixes**
- Improved document link handling, metadata validation, slug
consistency, and detection of duplicate or missing documentation
entries.
- **Tests**
- Added coverage for catalog routes, Markdown generation, homepage
negotiation, document parsing, and framework-specific links.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: Ivan Vasilov <vasilov.ivan@gmail.com>
