iOS 27 Killed Fixed-Size Layouts — What RN Devs Must Change

The rule change: on iOS 27, iPhone apps can be resized (Stage Manager-adjacent windows). "Full screen only" no longer opts out.

What breaks in RN apps:

• Hard-coded 'Dimensions' values read once at mount
• Absolutely-positioned overlays that assume a fixed viewport
• Custom safe-area math that assumed a single device class

What works:

• Flexbox + 'useWindowDimensions()' (reactive)
• 'SafeAreaView' / 'react-native-safe-area-context'
• ScrollViews that actually scroll

Test protocol: rotate, resize, split-screen on iPad simulator. If the layout holds, you're clean. Stock Picks's trading screens needed exactly two fixes — the chart container and a modal.