Build strategies

mp auto-detects how to build your project. Priority: Rock → EAS local → expo run:*.

Set buildStrategy in config to pin a specific one.

Rock

Detected when rock.config.{mjs,mts,js,ts,cjs,cts} exists.

pnpm exec rock run:ios     --configuration Release --destination simulator --device <udid>
pnpm exec rock run:android --variant release --device <serial>

mp watches for › Opening … on <device> then SIGTERMs Rock (it would otherwise stream Metro logs forever).

Cache: Rock has built-in .rock/ local cache + remote providers (GitHub Releases, S3, R2, BYO). See Rock remote cache.

EAS local

Detected when eas.json has a profile named e2e-test, e2e, or preview.

pnpm exec eas build --profile <profile> --platform ios --local
pnpm exec eas build --profile <profile> --platform android --local

EAS local emits .tar.gz (iOS) and .apk (Android). mp extracts and installs.

Cache: Uses Expo Remote Build Cache when buildCacheProvider: 'eas' is set in app.json. Quota per billing cycle: 10 (free), 50 (Production), 100 (Enterprise).

Requires: fastlane installed (brew install fastlane).

expo run:*

Detected when package.json has expo + an app config (app.config.{ts,js} or app.json) and the previous two strategies didn't match.

pnpm expo run:ios     --configuration Release --device <udid>
pnpm expo run:android --variant release --device <serial>

mp watches for › Opening … on <device> then SIGTERMs the child.

Custom hooks

When auto-detect doesn't fit, declare your own:

maestroparallel.config.ts

import { spawn } from 'node:child_process';
import { join } from 'node:path';

function spawnAsync(cmd: string, args: string[], cwd: string): Promise<number> {
  return new Promise((resolve) => {
    const child = spawn(cmd, args, { cwd, stdio: 'inherit' });
    child.on('error', () => resolve(127));
    child.on('close', (code) => resolve(code ?? 0));
  });
}

export default {
  bundleId: 'com.example.app',
  build: {
    android: {
      async buildAndInstallFirst({ device, cwd, log }) {
        log('custom build android');
        const code = await spawnAsync(
          'pnpm', ['expo', 'run:android', '--variant', 'release', '--device', device.buildTargetId],
          cwd,
        );
        if (code !== 0) return null;
        return { path: join(cwd, 'android/app/build/outputs/apk/release/app-release.apk') };
      },
      // Optional — defaults to `adb install -r <apk>`.
      // installExisting: async ({ device }, artifact) => { ... },
    },
    // ios analogous
  },
};

buildAndInstallFirst runs on the first device of each platform group. Return the artifact path so mp can reuse-install it on the rest via adb install -r / xcrun simctl install. Return null on failure — mp falls back to existing install.