Only upload changed files for the ‘Publish’ button

Small feature, probably a lot of work to implement:
When I make a small change to a single file in my app, like the css file, could I upload just that file? Maybe in the cloud directory, have an option for reloading selected files instead of only deleting.

Or have some way that it can be set to only upload files that have changed since the last upload?

Thanks again for your great product!