How best to comment on proposal?

[dpastoor]

It didn't seem like a PR is appropriate, as it was more commentary, rather than changes. I thought maybe going to git blame and then commenting in-line in the latest commit that edited that line, but that seems hard to track conversations over time.

Very exciting proposal!

[romainfrancois]

I believe in PR that are not necessarily meant to be merged. see e.g. this article from @yihui
https://yihui.name/en/2017/09/pull-requests-as-a-teaching-tool/