Companion mode (React Native)

A wrst app can run standalone (a self-contained watch app) or as a companion to a phone app. Companion mode is designed to work alongside React Native: the watch app talks to its paired phone app over the platform link (WatchConnectivity on iOS, the Wearable Data Layer on Android).

Add a watch app to a React Native project

Run this inside your existing React Native project:

npx @wrst/core init --companion .

This adds the watch app and wires up the phone side via the @wrst/react-native bridge.

The Companion API (watch side)

Import Companion from wrst:

import { Companion } from "@wrst/core";

• Companion.isCompanionAvailable - reactive boolean: is the paired phone app reachable right now? Use it directly in JSX and it updates when the link changes.
• Companion.reason - why the link is unavailable (or null when available), for UI text.
• Companion.sendMessage(message) - send a message to the phone (fire-and-forget).
• Companion.onMessage(handler) - subscribe to messages pushed from the phone; returns a subscription with unsubscribe().

import { useEffect, useState, Text, Button } from "@wrst/core";
import { Companion } from "@wrst/core";
 
const [last, setLast] = useState("");
 
useEffect(() => {
  const sub = Companion.onMessage((msg) => setLast(JSON.stringify(msg)));
  return () => sub.unsubscribe();
}, []);
 
// elsewhere:
// <Button onPress={() => Companion.sendMessage({ type: 'ping' })}>...</Button>