This is a very early-stage proposal and does not consider detailed design yet.

Keychat on the phone is the primary device, and Keychat on the computer is the secondary device.

On the phone there are 10 IDs. By default, the first ID is used on the phone, and the second ID is reserved for use on the computer.

After the user has already been using Keychat on their phone, they download and start using Keychat on their computer. On the login page there is a button to log in by scanning a QR code with the phone. When the user scans this code with Keychat on their phone, the second ID is logged in on the computer.

On both the phone and the computer, the first ID and the second ID are linked locally. They are named “Alice’s first ID” and “Alice’s second ID” respectively.

When Bob’s first ID adds Alice’s first ID as a friend, Alice’s first ID will automatically send a message to Bob’s first ID: “This is Alice’s second ID.” If Bob also uses a second ID, his first ID will also automatically send a message to Alice: “This is Bob’s second ID.”

These four IDs then form a small group consisting of four IDs.

If Alice’s first ID pulls Bob’s first ID into an MLS group, after Bob’s first ID joins, it will then pull Bob’s own second ID into the group.

In addition, Alice’s first ID and second ID also have a dedicated chat room. This room can be used to send MLS group invitations, and it can also serve as a personal Notes.