Since launching Rewind for Shopify 2 years ago, we've helped thousands of Shopify customers backup and recover deleted items. One of the most common uses for Rewind is rewinding themes to a previous version.
In the past, we've made customers download the rewind theme, and then upload the new theme to their Shopify store. We did this for a few reasons:
Shopify has a limit of 10 MB when uploading new themes, and
It allowed customers to preview the theme before publishing it, to ensure it was the one they wanted.
However, users found this to be cumbersome, and one of our top support questions was what to do with the theme download.
Today I'm happy to say that Rewind will now rewind a Shopify theme directly, without the need to upload or download any files. Rewinding the published theme will push all the assets back into the currently published theme, and rewinding a theme that was backed up but is not there will create a new, unpublished theme.