It passes through the client User-Agent unchanged. I've not yet looked at anything else although I doubt it will do anything but pass through the client headers.
It might be interesting to send confusing or contradictory request headers and see how it reacts.
yeah, i'd definitely try sending it all sorts of weird things. Can you setup a path that will respond with a ton of data? Maybe a bunch of things that it will try to parse? etc
"GET /headers" will dump the request headers, but note this has gone through one layer of munging by nginx and another by Mojolicious, so don't draw any conclusions about what you see in the response without bearing that in mind!
I'd be interested to hear if you spot anything surprising.
EDIT: And in case you haven't seen it, "torsocks" is a tool that lets any (?) other program speak Tor, e.g. it works with both curl and nc.
