Astro, fix .md in links

Using Obsidian to edit my Markdown files, I’ve started to link lessons using Obsidian’s own internal linking.

It’s great because with Obsidian link tracking I can move a file around, change folder or filename, and links don’t break.

Links however use a .md extension, since we’re linking markdown files here.

[3-absolute-positioning](../css-positioning/3-absolute-positioning.md)

So since I’m using Astro, links don’t work as they point to a URL ending with .md.

I found this rehype plugin for Astro: https://github.com/vernak2539/astro-rehype-relative-markdown-links

It fixes this exact problem and I’m so grateful this exists, but didn’t (at the time of writing) install on Astro 3, required Astro 2. Maybe now it’s updated.

Anyway since it’s a single file I copied the file locally and imported in my Astro config.

Only thing I noticed is, maybe because I use content collections, my content collection path was prepended to URLs now, so I hardcoded a little custom fix in the code that only works in my use case, but well, job done.