What are the rules for notifications in chat?

Question

Background

All right, I've gotten pretty used to how notifications work in the Q&A areas. This is aided by the fact that I get an autocompletion dropdown when I start typing @someone.

Now, however, StackExchange suggested I take a long comment chain to chat, and being a good citizen, I did. And now, in this totally new world, I'm lost as to what to do to get the other participant to be notified (in the top bar) of my messages in chat.

I wasn't sure if he'd be notified by default (just because the original comment chain was in reply to a post of his), so I tried to begin with @hisName but didn't get autocompletion, so I assumed the "tagging-notification" feature doesn't work in chat.

Next I tried to click the reply button (that says "link my next chat message as a reply to this") on the first message in the chat, which was an automatic message by "Feeds" that quoted the other person's answer. But when I sent my message, I saw that in the resulting chat line, the other person wasn't tagged - the user who was tagged was "Feeds". So I assumed that also wouldn't work to make the intended recipient get notified.

The question

Can I get an authoritative answer regarding when notifications are delivered (to the top bar) and when not?

In particular:

• If I @tag an user (manually, without clicking any reply button, because I don't like hunting for tiny buttons), will he get notified?
• If I just write in a chat that got started by accepting "Stack Exchange's suggestion to continue in chat", will the one who posted the original question/answer be notified?
• If I tag the special Feeds user, will the one who posted the original question/answer be notified?

Answer 1

If I @tag an user (manually, without clicking any reply button, because I don't like hunting for tiny buttons), will he get notified?

As far as I can tell from some testing, no. It seems that other users in a moved-to-chat thread don't autocomplete, suggesting that SE doesn't consider them pingable yet. I would conjecture that this is because the user never technically entered the room, so they aren't eligible for pinging. Normally, you can @tag a user without clicking the reply button, though—this isn't a comment-only feature.

Clicking the reply button does send a ping to the user, despite them never entering the room.

If I just write in a chat that got started by accepting "Stack Exchange's suggestion to continue in chat", will the one who posted the original question/answer be notified?

No. The room is like a normal chat room, not like a post, so it doesn't send pings to the post author.

The post author will see the comment announcing that the conversation has been moved to chat, but after that, no further notifications occur simply because they are the post author.

If I tag the special Feeds user, will the one who posted the original question/answer be notified?

No. I don't believe there's any logic to convert an @Feeds ping to a notification for the post author. I also tested this, and it didn't send me a ping on my own post.