I will recommend to use a folder similar to artifacts, potentially called "build/rescache.json" or "cache/rscache.js" or "cache/rs/cache.json". Two main reasons:

* mixing user-code with generated code could be problematic, specially when it comes to SVN/Git, where a folder is easier to deal with.
* we might want to cache more things, like application.json (merged), or compiled templates, etc.