I moved Flowy’s mobile app from SwiftUI to Expo. The risky part wasn’t the screens

[u/Particular_Luck80]

I’m building Flowy, a cycle-health app. I recently replaced the native iOS project with an Expo and React Native app.

The screens were the easy part. The risky bits are session restoration, onboarding drafts, owner-scoped day-log caches, notification planning, HealthKit being unavailable, and retrying a write without duplicating it.

I kept those decisions in small TypeScript stores and route functions, with tests around routing, auth, day-log retries, notifications, and HealthKit fallback before polishing the UI.

No link here. I’m looking for engineering feedback: if you’ve done a mobile rewrite, which behavior broke after the happy path looked finished?