comments
Where you can comment
on a published blog article, and on a set someone made public
reading is open to everyone; writing a comment needs an account
On a blog
the box at the foot of an article comments on the article
hover any line and use the speech-bubble on the right to comment on that one line — the badge shows how many are already there
every comment has a Reply, and replies nest
⌘/Ctrl+Enter sends, Escape cancels
What a comment is
a comment is an ordinary set that you own, holding a reference to the line and its own public marker
so it appears in your expand as a read-only child of the commented node
comments arrive on reload rather than live