Is this really the expected behavior ?
I'm generally not a fan of the whole mentions = invite idea.
Maybe I just want to mention someone so other people can easily click his username or just do it by habit.
IMHO are mentions and invites 2 seperate functions, but that's just me.

So you think the issue should be mentions add users to channels?....

Either way, please stream line this function so people don't assume falsely that when tagged in a thread, people are already in a room, because there is no user had joined the room-message.

I'm absolutely for a streamlined version, how do discussions in public rooms work? Can you invite people by mention there?
In my opinion there need to be some Checkboxes in Admin-> Messages.

[ X ] Mentions in public channels trigger invite
[ X ] Mentions in public discussions trigger invite
[ ] Mentions in private groups trigger invite
[ ] Mentions in direct messages trigger invite

But that would be a feature request.

Back to your described issue, I can only find this in the official documenation:

Joining new channels and starting direct messages
There are three ways of joining a public channel; through search, invites, or mentions.

So yes, the expected behaviour would probably be that mentions in public threads trigger an invite. At least there is no exception stated in the documentation that this won't work in threads.

It's just all in all not not really consistent imo.

IMHO are mentions and invites 2 seperate functions, but that's just me.

Agree with you.
And maybe it could be servers side configurable settings (Does mention invites to public channel)

In my opinion there need to be some Checkboxes in Admin-> Messages.

Totally agree! That would be nice!

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

I quite like Slack's approach to this. Give the option to the user.

I think we have some issues open for this, and it seems like it should be very easy to implement this system message instead RocketChat/Rocket.Chat#2194 . But is off topic for this bug :)

@sampaiodiego Is this issue open to work on?

We can have this feature as pointed out in the earlier comment

I am thinking of 2 ways by which we can do this:

1. In current codebase:
   A callback can be added in the Mentions.js file which will run afterSaveMessage and check if the mentioned user is present (subscribed) to the room or not. This function will send message as shown in the image and contain the 3 buttons. And a bot (ex. rocket.cat) can notify the user if let them know is chosen or add them to room if Invite Them is chosen.
   But, I am not clear how a user is added to the room when mentioned and how to add the ui buttons in the next message.

2. In a Rocket.Chat App:
   A Rocket.Chat app can be created which can use the methods - getMembers, addMember and the uikit blocks to display the buttons for invite them and do nothing.
   But, I am not sure if we can do this without modifiying the message (we will have to suppress the mention if the user is not in the room) because our callback has to run after the message is saved.

Please point me out the direction where I should start working.
Thank you. 😃

Maybe related mentioning @all in a thread doesnt notify all users in a channel.
Should i open a new issue or is this configureable via settings and i just wasnt able to find it?

@aditya-mitra I'd say doing it as a Rocket.Chat App is preferred, but you should be able to use UiKit without an app too.

I don't think you need to change the original message though, you just need to send an ephemeral message with those actions if the message had a mention to a non-member.

@sampaiodiego @aditya-mitra
Just tagging along :)

If a Rocket.Chat App is needed, I can collaborate with @aditya-mitra and help out. I have basic familiarity on how Rocket.Chat App works and how to make one, I have made a prototype app too, you can check on my GitHub here :)

Please let me know If I can help with it. Thanks :)

If a Rocket.Chat App is needed, I can collaborate with @aditya-mitra and help out.

Thank you @yash-rajpal 🎉

@sampaiodiego We shall start working on it from Saturday. 😄

RC now tells you if a person isnt in the channel you mentioned them in.