"_Comments are not for extended discussion_" is in my opinion a very valuable thing to imbue in the community.

Occasionally I've been on one end or another of the following situation:

- Person A makes a comment / statement
- Person B leaves a comment / feedback
- Person A resolves the issue and wants to say "_thanks_" or "_done_", etc... but refrains
- Person B now has a hanging comment that should be removed, but they don't get notified that action has been taken

For example:

- I recently commented on [this question][1], with an initial "_please note that shopping recommendations are off topic_", followed by a brief answer in a single comment. I was in two minds about including the off topic note, but did so anyway.
- grawity then (very fairly) pointed out that the OP did indeed ask in a compatible way.
- At this point, I wanted to say something along the lines of "_thank you for pointing that out, I've removed my comment and written a more complete answer_", notifying grawity, and allowing them to remove their comment. In fact, I did that, but then deleted it ~10 minutes later... (indecisive much?)

Another common example is a request for more information... e.g: "_Please share the output of `x`_". Once the OP has provided the information, the comment is often stale and unnecessary - people typically comment again saying "_done_", or rely on responders coming back to the question to see if there is an update.

---

So... what is the most suitable resolution here?

- It's not an issue that needs to be addressed.
- Introduce a new feature such that authors and tagged users can acknowledge a comment, notifying the commenting user.
- Person A responds with such a comment anyway, Person B is notified and deletes their comment, but then Person A has a hanging comment...
- Using flags as suggested by Journeyman Geek below is suitable, despite the fact that users don't get notifications.

  [1]: https://superuser.com/questions/1449065