warden dev

warden dev replaces expo run:ios in a worktree: it claims a device, installs the dev build cached for your native fingerprint, starts Metro on a leased port and opens the dev client. Use it whenever you or your agent need the app running.

warden dev                  # ios by default
warden dev android          # an emulator
warden dev ios -- --clear   # extra args go to `expo start`
warden dev ios --json       # one line { udid, port, metroUrl, leaseIds } once Metro is ready

What it does

1. Checks the bundle id and expo-dev-client.
2. Claims a device and leases a Metro port (default range 8081:100).
3. Installs the build for this fingerprint: installed, cache, EAS, then local build.
4. Starts Metro on the leased port.
5. Opens the dev client once the port is verified to serve this checkout.

warden dev owns its Metro. A Metro left running by another worktree is refused, never attached to. It holds the device and the port until Metro exits; Ctrl-C releases both. The --json line is printed first, so an agent can read the udid and metroUrl and pass them to warden ui open <bundleId> --metro <metroUrl>.

Metro gets WARDEN_WORKTREE (the checkout directory name) and WARDEN_BRANCH (absent on a detached HEAD) in its environment, so app.config.ts can name the dev server after the worktree. Native builds never see them, so the fingerprint is unchanged.

Why not expo run:*

expo run:ios rebuilds natively in every worktree: Xcode's DerivedData is keyed by the checkout's path, so a fresh worktree compiles every pod again even when the native code is identical. warden caches the built app by native fingerprint, shared by every worktree of the repo.

• Same fingerprint as any earlier build (any worktree, EAS or local): no prebuild, no Xcode, seconds to a running app.
• A native change: one local build, cached for every other worktree.
• Two worktrees missing the same hash at once share one build (build lock).

Options

Variants

A dev client and an e2e build can sit side by side in warden.config.ts:

projects: [{
  name: "app",
  bundleId: { ios: "com.example.app" },
  build: { configuration: "Release" },                                  // e2e: JS embedded
  fingerprint: { include: "native+js", jsInputs: ["src/**"] },
  variants: {
    dev: { build: { configuration: "Debug" }, fingerprint: { include: "native" } }, // dev client: JS from Metro
  },
}]

warden dev picks dev when it exists. A variant's keys replace the project's own wholesale. Compiler caches, prebuilt React Native and the cache order are in App builds.