Hi,
thanks for this project, I'm finding it very useful.

I'm not entirely comfortable having lorri do builds in the background, I'd rather control when the builds happen. But I very much want to leverage your intelligent, correct shell caching behaviour.

I'd like to be able to do:

$ lorri shell

and have it be cache the result to ./.lorri/env or similar, in the same way the direnv use_nix functions do, but with your cache invalidation logic.

Similarly, I'd like to be able to use something like:

#! /usr/bin/env lorri
#! lorri shell -i bash ...
...

in scripts to get fast shells. I don't have a lot of insight into how the shebang gadget should look, I hope it's clear.

This seems like it might be a relatively straightforward extension to lorri. With your approval and guidance I'd be happy to take a stab at it.