View *.mdc rules files in rendered Markdown on GitHub

Showcase Built for Cursor
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GitHub doesn’t recognize .mdc as markdown so every Cursor rule you look at on GitHub is raw source. Frontmatter soup, unrendered headings, fenced code blocks as plaintext. Mermaid flowcharts? A wall of --> arrows.

I built a UserScript to fix that. It detects and renders *.mdc files on GitHub - rendering Markdown, code-fence syntax highlighting, and even Mermaid flowcharts. It renders by default, but also adds a toggle so you can drop back to the raw source. If you get a deep link to a line number, it does not automatically render; you’ll jump directly to the line of code, as intended.

Example

Example rendering of MDC on GitHub

Install

  1. Install a UserScript engine, such as Violentmonkey or Tampermonkey. GreaseMonkey probably works too.
  2. Install the UserScript from GreasyFork
  3. Open any .mdc on GitHub
  4. Done!