Github template repos could be hugely exciting, I think, as a way of supporting the sharing of base Binder environments, but one thing that could be irritating, and get overlooked, is the tweaking of Binder button paths in README files.
At the moment the Binder button link URL take the form of an explicit link to MyBinder with the path to the repo:
If you clone a repo, or generate a repo from a template repo, that path is carried along as the button link.
What would be nice would be to be able to specify a link of the form:
document.referrer ?) and use that URL to launch the Binder.
I guess federated Binder complicates this a little, because there is going to be forwarding from the landing page to the actual Binder server; so in that case, perhaps a second way of handling the original referrer also needs to be supported for the federated case, perhaps by rewriting the URL into the actual server URL in the normal way.
By the by, I also note that if you copy a branch URL from Github (eg
https://github.com/binder-examples/latex/tree/yuvipanda-patch-1 into MyBinder and try to launch the repo, it throws an error, where you might optimistically expect the
/tree/BRANCH to be automatically parsed from the Github repo URL form element into the Branch form element. (Would a naive user know how to do that conversion themselves?) If a Binder button was in a branch README, and the referrer button/link call was supported, that would raise this error.