I’m mostly interested in the architectural side rather than a specific tool: how people separate domain state from transport, where optimistic state lives, and how retry / reconciliation is usually modeled without leaking everywhere.
Still useful to see how existing systems approach client IDs though.
The one thing I'll add is we found "keeping UI responsive while syncing in the background" is highly platform dependent since all platforms have their quirks, but for React Native we have a detailed blog post and code (admittedly tightly coupled to powersync, but should provide a starting point) https://www.powersync.com/blog/keep-background-apps-fresh-wi...