Markdoc custom tag definitions can include arbitrary AST transforms on the child nodes, as in this example: https://markdoc.dev/docs/examples#tabs https://markd

Markdoc custom tag definitions can include arbitrary AST transforms on the child nodes, as in this example: https://markdoc.dev/docs/examples#tabs https://markdoc.dev/docs/examples#tabs In order to do this, you need some API, so you can't just define the tags in JSON.