Cool idea. For a long time I wanted to have some sort of API cache for offline hacking. I'm oftentimes on a train and would like to continue working on my apps which access external apis. I played with polipo and a couple of other options but never had successful results that worked across the board. I once wrote an extension into one of my apps that saved every request (minus access_code or other identifiers) in a local sqlite db and would simply return the cache in case internet is gone. However, it was implemented poorly and too much of a hassle.
With this, I expect it could be easy to add caching support, I'll have a look and maybe fork it :)
thanks!