Feature Issue

User Story

As a user
I want my notifications in the Activity center to be synced across devices
So that I don't have to see notifications that have already been viewed and open 1-1 and group chats twice so that they are displayed on the home screen on both synced devices

Description

Currently, if open a 1-1 chat or join a group chat in the Activity center on one of the synchronized devices, then the chat will be moved to the home screen on only this device, on the second one it will remain in the Activity center.
Also, this behavior is relevant for notifications on mentions/replies in group chats and communities.

Steps (for group chat, as an example):

1. Device1:
   Create multiaccount

2. Device2 and Device3:
   Recover the same multiaccount on both devices

3. Device1:
   Create a group chat with the multiaccount that was recovered on Device2 and Device3

4. Device2:
   Open Activity center and join the group

5. Device2 and Device3:
   Pair devices

6. Device2
   Send a message to the group

7. Check Device3

Expected result for Device3: the group chat is displayed on the home screen, the Activity center is empty

Acceptance Criteria

• when receiving a message in 1-1 chat or an invitation to a group chat, the chat is moved to the Home screen on both devices after opening/joining it on one of the synchronized devices; the Activity center is cleared on both devices
• when receiving a notification on mention/reply in a group/community, the Activity center is cleared on both devices after opening it on one of the synchronized devices

Notes

Currently, there is a case that should be taken into account when implementing and testing the feature.
If start a 1-1 chat on the primary device before pairing, then pair devices, and send a message from the primary device in the 1-1 chat, then on the secondary device this chat will appear in the Activity Center.
The expected result is 1-1 chat appears on the home screen on the secondary device after pairing and sending a message from the primary device.