After a preliminary skim, my first thought is:
As well as branches, GitHub also reveals tags. They are similar but differentiated both in the git protocol and in GitHub.
Discussion
It may be that tags need their own event kind or some other solution to be more discoverable. I think they way I have them in there right now is basically as a “comment” on a commit checkpoint. Then from a discoverability standpoint you would just search the remote events for the correct commit hash