Combine _attachment files as a preprocessing step in a couchapp

Question

I have a couchapp with the following structure in the _attachments directory:

_attachments/
|-- code
|   |-- model.js
|   |-- primary.js
|   |-- router.js
|   `-- view.js
|-- index.html
`-- style
    `-- main.css

When I run couchapp push, I want all the files in _attachments/code (or any arbitrary directory within _attachments) to be combined into a single file that I can reference in _attachments/code/index.html. It would be helpful to specify an order of files within a directory.

There is a couchapp hook available to compress files, but I don't see an easy way to combine them, especially since that may mean outputting some intermediate file, ensuring the original files don't get uploaded, and cleaning up.

Is a hook to combine files the best way, and if so, how would you recommend it work?