To do this, it looks like I should run convert, then import the new file and remove the old file. However, the converted file doesn’t get the flexible attributes, so I also need to figure out how to copy those from the old file to the new, and there seems to be no obvious way to do that.
Update: I got it working using the plan I said above. I exported flexible attributes by finding the ones I’d set by looking the sqlite database, then querying for them.
there’s an “auto” field which may do what you want in the future (I’m not familiar)
https://beets.readthedocs.io/en/stable/plugins/convert.html#configuration
As far as I can tell, the auto field would not help.
I figured out a better way. This converts into the original collection and preserves flexible attributes.
beet convert -k -y QUERY
convert:
delete_originals: true
dest: /some_dir_deleted_after_convert