Local-first Matrix

We’ve been working on running Matrix peer-to-peer: no servers in the middle, just devices talking to each other directly via Element X on your phone. Federated Matrix already has rules for access control, and they work fine when servers can mostly talk to each other. However, P2P is a different story. Devices go offline, networks partition, and the same rules start producing weird results.

Here’s the kind of thing that breaks: You demote an admin. A minute later they’re admin again, and now you’ve been demoted. When two admins act at the same time on different sides of a partition, the network has to pick a winner once it reconverges, and if one of them knows how the rules work, they can rig the outcome. This talk is about what we learned trying to fix it: why the obvious approaches don’t hold up, what actually does, and where Matrix is going next.