The Live Activity is one function marked with the expo-widgets 'widget' directive (Expo SDK 56). Metro serializes it into the widget extension's own JS runtime, where @expo/ui/swift-ui primitives (ZStack, Circle, Image, Button) become real SwiftUI views, so the Lock Screen banner and the compact, minimal and expanded Dynamic Island layouts share one Header, MoonArc and ToggleChip. The app does the astronomy on the JS thread with suncalc v2 (rise, set, altitude, illumination, elapsed rise-to-set fraction for moon and sun) and pushes an update once a minute. The arc dots, body position and terminator shadow are plain layout math on those props; the countdown is a SwiftUI date Text with the relative style, so it ticks between updates. Images are copied into the app-group container (widgetsDirectory), with 96 px thumbnails for the island, which drops oversized images. The sun/moon chip is a Live Activity Button whose intent reaches the app via addUserInteractionListener; ActivityKit replays intents, so requests are idempotent. Mode flips use the animation modifier, which needs the included patch-package patch giving expo-widgets nodes stable SwiftUI identity. The in-app screen uses Reanimated 4 worklets and react-native-svg. iOS only (ActivityKit 16.2+, island on iPhone 14 Pro or newer), development build required, not Expo Go. Tested on the iOS 18 simulator.
A sun and moon position Live Activity for iOS: a Lock Screen and Dynamic Island widget that tracks either body along a dotted arc from rise to set. Built with expo-widgets, the moon card shows phase, illumination and a live rise or set countdown; a button flips it to the sun with daylight progress and sunset time. Drop it into any Expo app that wants a glanceable sky tracker.
A hold-to-confirm button whose progress bar is the light itself: a Skia shader sweeps the pill over a 2 second hold, and lifting early rewinds it. Every colour, radius and timing was fitted frame by frame against a reference recording, so the sweep and the flood at the end are measured, not guessed. Drop it on any destructive confirm: leaving a session, deleting an account.
A pill button lit by a Skia aurora: two soft lights sit just below the bottom edge and bleed up into the surface, blooming under your finger. Colours, spread, drift and press feel are all props, and glass mode swaps the fill for iOS 26 Liquid Glass with a blur fallback everywhere else. Drop it in as the primary CTA on an onboarding, paywall or checkout screen.
A snap carousel of voice cards, pixel-matched to Claude's voice settings: the centred card glows from a Skia shader driven by the audio it plays. Cards ease down a measured scale curve as they leave the centre, dots track the scroll, and a selection haptic fires once the snap settles. Drop it into an onboarding or settings flow where a user auditions voices.
