Platform status

Platform status for Ferrule, a React Native UI library for iOS, Android and web. What has been run, on what, and what has not.

Platform	Status	How it was checked
iOS	Simulator only	Ran on an iOS 26.5 simulator (iPhone 17 Pro Max): XCUITest suite, screenshots, large text, RTL, reduced motion. Both the example app and a fresh bare app.
Android	Emulator and one phone	Scripted flow with real taps, typing and hardware back on a Pixel 8a (Android 17) and an API 37 emulator. Screenshots, font scale 2, RTL and reduced motion on the emulator only. A fresh bare app also built and ran on the emulator, with real taps.
Web	Browser builds	`react-native-web` in Chrome: keyboard, focus trap, Escape, RTL, reduced motion, plus a fresh Expo web export. Toast, Modal, Sheet and keyboard checks also ran in the WebKit and Firefox builds that Playwright ships, which are not Safari or Firefox as released.

A physical Pixel 8a on Android 17 (API 37) also ran the scripted flows with real input: safe areas, keyboard, gestures, toasts and the native views in that flow. The Android status above covers one phone, not a range of them. iOS has not run on a physical device. An iPad mini simulator was checked for layout and safe area only. Status reflects versions read on 2026-11-07.

Ferrule targets iOS, Android and web. Other platforms are out of scope.

@leoanimesh/ferrule-native has its own, narrower status: iOS 26.5 simulator, API 37 emulator and one Pixel 8a on Android 17. No physical iPhone, and iOS below 26 not run. See its coverage table.

Consistency

The harness (apps/example) has a metrics screen that renders each component in a fixed 320dp column and logs its measured size. scripts/compare-metrics.mjs compares the logs and fails on any difference over 1dp.

Last run with the same font on iOS, Android and web: 27 of 30 probes within 1dp, all within 1.4dp. The three over 1dp are widths of text that hugs its content (button.lg, text.caption.hug, text.h1.hug), where each platform's text engine rounds tracking differently. No layout changes because of them, and the script still reports them, on purpose.

compare-metrics.mjs still exits 1 at its default 1dp tolerance because of those three probes. They are not hidden behind a wider tolerance.

Native variants (native prop, @leoanimesh/ferrule-native) are deliberately outside this comparison: they look like the platform, not like each other. The metrics screen forces native={false}.

Differences that are deliberate:

The default font is each platform's system font, so no install is needed. Text widths match only when you load one font on all platforms. See theming. Glyph rendering still differs slightly by OS.
Hover appears only where a pointer exists. Focus rings appear for keyboard focus, not touch or mouse clicks.
Screen readers behave as each platform does: VoiceOver, TalkBack and browser ones phrase things differently.
Right-to-left is live on web, and needs a restart on iOS and Android, because React Native fixes it per process.

Known limits

React Native 0.86 is the floor, set by Reanimated 4.7. Older apps cannot use Ferrule.
Safe area is estimated without a native dependency. On edge-to-edge Android, pass real insets to FerruleProvider.
Overlays use React Native's Modal. That brings OS focus handling, but iOS cannot show two sibling modals at once, so render a sheet inside the modal that opens it.
Toasts sit above everything, at the bottom by default, so one can cover a bottom sheet's controls until it times out or is dismissed. Set position="top" to avoid that. They do not move for the keyboard.
The web bundle carries Reanimated. A fresh Expo web app with one Button is 283 kB gzipped against 107 kB when empty. Of the code added, nearly all is Reanimated; @leoanimesh/ferrule itself is 27 kB before gzip. Later components add little. Expo's unstable tree shaking (EXPO_UNSTABLE_METRO_OPTIMIZE_GRAPH=1 EXPO_UNSTABLE_TREE_SHAKING=1) brought the same app to 215 kB, and it still ran.
check scans with patterns, not a full parser, so unusual import forms can slip past it.