Yay! Thank you for this time-saving feature! It is quite helpful.
Minor nitpick: perhaps the function-name should be :cached->res since the files are called .cached?
It makes no functional difference and would require another source update, but I found that when I was first experimenting with decoding and repacking .cached files I had a number of errors due to accidentally typing .cache and forgetting the 'd'. Having the function be written without the 'd' would only seem to add to confusion.
In other news, I think the bike shed should be painted blue.