Indeed, I have it open source, but want to preserve my anonymity here. The main gist of it is Quartz as a static site frontend bundle, backed by Decap as an editor, so that non technical users can edit documents. The validation is twofold - frontmatter is validated by a typical yaml validator library, and then I created markdown body validation using some popular markdown AST libraries, so there are two sets of schemas - one for the frontmatter, one for the body, and documents must conform via ci. I ship it with a basic cli that essentially does validation and has a few other utilities. Not really that much magic, maybe 500 lines of code or so in the CLI and another few hundred lines doing validation and the other utilties. It's all in typescript, so I use the same validation in Decap when people do edits.