How We Built Stock Picks Mobile: Architecture Notes

Real production choices from the Stock Picks build:

What held up:

• expo-router — file-based routing meant App Intents deep-links came free
• EAS Update (OTA) — shipping JS fixes without App Store review saved us during the iOS 27 rush
• react-native-skia — the charting layer that made 60fps order books possible
• Zustand for state — simple, fast, survived three refactors

What we'd redo:

• Started with FlashList everywhere (FlatList early was a mistake)
• Should have shipped App Intents on day one — retrofitting navigation was the hard part
• The fingerprint.config.js footgun above

The full case study, with the parts that broke, is on the site.