Is there an existing issue for this?

• I have searched the existing issues

What is the missing lexer?

Typst is a new markup language and I've noticed that chroma doesn't support it.

The syntax documentation can be found here:
https://typst.app/docs/reference/syntax/

Links to existing syntax definitions

Github Linguist uses the following:
https://github.com/michidk/typst-grammar/blob/master/grammars/tmlanguage.json