How to BATCH assign Finder Tags - to assign to ALL items within a directory?

The Finder does not offer recursive tagging down through a hierarchy of folders, or obversely, the means to undo that action.

One would require a custom made application that supports directory recursion, and the ability to apply one or more tags to all, or selective file types — and the ability to add, change, or remove those tags in that hierarchy. Do not expect Apple to write this tool.

Apple's Automator has a tagging action that only understands the standard tag colors, and not custom tag names. I wrote an Automator application several years ago that, if I remember correctly, could apply and remove tags to a directory structure.