Chats / ChatMessages

!!!!!ATTENTION!!!!

Check out docs/API/chats.md for a description and API docs. Description is also given here.

Implemented features

• Attachments
• Deletion of own messages
• Removal of remote messages
• Mark as read
• lastMessage
• Streaming endpoint for chats
• Notification rework
• Basic formatting: linkify
• Make newlines work again
• Fix unread counts
• Add read endpoint for single chat messages
• Check out enum type for notification types
• Move notification migration code to migration and out of the Notification module
• Validate with Mime.valid?
• Move all after-transaction code to after the transaction
• Chats: change id to flake id
• ChatController: Mark-as-read rethought.

Chats

Chats are a way to represent an IM-style conversation between two actors. They are not the same as direct messages and they are not Statuses, even though they have a lot in common.

Why Chats?

There are no 'visibility levels' in ActivityPub, their definition is purely a Mastodon convention. Direct Messaging between users on the fediverse has mostly been modeled by using ActivityPub addressing following Mastodon conventions on normal Note objects. In this case, a 'direct message' would be a message that has no followers addressed and also does not address the special public actor, but just the recipients in the to field. It would still be a Note and is presented with other Notes as a Status in the API.

This is an awkward setup for a few reasons:

• As DMs generally still follow the usual Status conventions, it is easy to accidentally pull somebody into a DM thread by mentioning them. (e.g. "I hate @badguy so much")
• It is possible to go from a publicly addressed Status to a DM reply, back to public, then to a 'followers only' reply, and so on. This can be become very confusing, as it is unclear which user can see which part of the conversation.
• The standard Status format of implicit addressing also leads to rather ugly results if you try to display the messages as a chat, because all the recipients are always mentioned by name in the message.
• As direct messages are posted with the same api call (and usually same frontend component) as public messages, accidentally making a public message private or vice versa can happen easily. Client bugs can also lead to this, accidentally making private messages public.

As a measure to improve this situation, the Conversation concept and related Pleroma extensions were introduced. While it made it possible to work around a few of the issues, many of the problems remained and it didn't see much adoption because it was too complicated to use correctly.

Chats explained

For this reasons, Chats are a new and different entity, both in the API as well as in ActivityPub. A quick overview:

• Chats are meant to represent an instant message conversation between two actors. For now these are only 1-on-1 conversations, but the other actor can be a group in the future.
• Chat messages have the ActivityPub type ChatMessage. They are not Notes. Servers that don't understand them will just drop them.
• The only addressing allowed in ChatMessages is one single ActivityPub actor in the to field.
• There's always only one Chat between two actors. If you start chatting with someone and later start a 'new' Chat, the old Chat will be continued.
• ChatMessages are posted with a different api, making it very hard to accidentally send a message to the wrong person.
• ChatMessages don't show up in the existing timelines.