Connectivity is a spectrum, not a boolean
The hard case isn't 'no signal'. It's one bar, with requests that hang for ninety seconds and then fail. Apps that only handle the offline boolean feel broken precisely when users need them most.
Treat slow as a first-class state. Timeouts should be short, retries should be explicit, and the UI should never lie about what's been saved.
Decide who wins a conflict before you write code
Two devices edit the same record offline. One of those edits is going to lose, or a human is going to arbitrate. That's a product call with real consequences, and it cannot be deferred to the sync layer.
Local-first makes everything else faster
Once reads come from a local database, the entire app feels instant, online or not. The network becomes a background sync concern rather than something sitting in front of every interaction.
