Every AI feature I've worked on has done the same quiet thing: collect the user's text, send it to someone else's server, pay per token, and pray the network holds. That's fine until it isn't:
Your user is on a flight, with no network and a dead feature.
It's a journaling app, where "we send your private thoughts to a third party" is a hard no.
Finance notices the OpenAI bill climbing in a straight line with usage.
There's another option most React Native devs still treat as exotic: run the model on the device. No API call, no network, no per-token cost. The first time I wired this into an offline text-enhancement tool with Expo, the surprise wasn't that it worked. It's that the actual model code was about six lines. The hard parts were everywhere except the model.
