[racket] Indentation

Hi!

I want to try and get auto-indentation for Pyret working in DrRacket.
What APIs should I be looking at for doing this?  It seems like a
color-lexer is about the limit of what I can do via the get-info of a
#lang, right?  Do I need to implement a drracket:language:language<%>?
 A mode?

I'm a little confused about what my options are for getting a handle
on the stream of definitions text, and what interface I'll have when I
do.

I think just some pointers to existing approaches (didn't ProfessorJ
have an indenter at some point?) would be helpful.

Thanks!
Joe