Crate weapon 

This is a library for enabling cross-device local-first event syncing. It was created for Yap.Town, so it doesn’t include much that was not needed for that project.

Syncing strategy:

1. Each of the user’s devices gets a unique ID.
2. As users use your app, instead of the app modifying the state directly, they generate “events”. Events are associated with the device generated them, as well as a timestamp and an index within the device’s events.
3. Starting from a default initial state, these events are “applied” in chronological order to get the current state.
4. When syncing:
5. The user’s device asks the server how many events the server has, then sends any events that it has that the server doesn’t.
6. The user’s device tells the server what events it has, then the server responds with the events that the user’s device doesn’t have.

Sounds simple, but there are a few tricky parts that this library handles.

Modules

data_model

Traits

AppState

Extension trait that provides apply_event for backward compatibility

PartialAppState

Core trait for partial event processing without derived state computation