On GitHub, project team members are able to add labels to your issues on a project. If your issue is a POSSE copy of an original post on your site, Bridgy should backfeed these as "tag-of" responses to the original post. cc: @dshanske
Bridgy Publish already supports POSSEing tag-of posts in reply to GitHub issues, as labels on those issues, and this is the backfeed counterpart. Brainstormed here: https://indieweb.org/tag-reply#How_to_post_a_tag-reply.
This is similar to issue #776 which is the same backfeed feature request but for Flickr.
This is also the “labeled” specific subfeature of issue #833 which documents many more backfeed for GitHub requests.
And similar to this comment on #811 (original post) requesting Bridgy Publish untag-of support, it’s worth considering Bridgy Backfeed untag-of support (the “unlabeled” specific subfeature of #833), so when someone removes a label from your issue, your original issue post is notified. However, the brainstorming of how to markup untagging is still ongoing, and thus may need to wait for more discussion before implementing.