This is not a very common use-case so I don't expect much, but it is similar enough to other things that already exist that I figured it's worth asking.
I'd like a way to determine when someone mentions a project in a comment on a Differential revision (more accurately, I'd like to have Differential revisions where a project was mentioned). This could either be as a field on one of the existing conduit queries, or if there were a way to trigger a herald rule that converted the mention to a tag/subscriber, I'll take that as well (this seems like a much bigger deal because it would require herald rules to run on comment actions etc). If I could read all the comment text on a revision, that's fine too.
Why do I want this? We have a process in our Github environment (I'm trying to ease the transition to Phabricator where possible) where the author can trigger a deploy (after a revision has been accepted by reviewers) by commenting with :shipit:, which a bot picks up and acts on. I can already achieve this behavior with explicit tags to a #shipit project, I'm trying to see if I can make it work all the way with a mention in a comment.