I second the motion for obeying cache control headers from the origin.
In particular, I have found Fastly’s support for the Surrogate-Control header useful avoiding something getting stuck in browser cache forever. Maybe not applicable to the ‘js/css assets’ use case, though.
Another ‘ambitious’ thing: I’ve seen lots of apps using a passthrough CDN merely to split requests out by path to different origins. So for example, mayonnaise.app would route to a static marketing site, but mayonnaise.app/joshua would route to a web application.
Being able to do this and get asset caching without using a CDN product would be a win!
This is related to my other post about path-based routing. Only here, we would be routing organization-wide instead of between components within an app.