Design an offline-first client that syncs edits across devices

Design the client side of an app in which users edit data over an unreliable network. Every edit is saved to local storage on the device as it is made, and the user keeps working while the connection is poor or gone. When the network comes back, the client syncs with the server, and edits to the same data from several devices have to be reconciled.

Cover the local store, how changes are recorded and sent, the sync protocol and how conflicts between devices are resolved.