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Prerequisites

  • Revyl CLI installed and authenticated (revyl auth login)
  • An Expo or React Native project with a dev client build

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Step 1: Configure hot reload

Initialization detects the framework and writes named build profiles. In a monorepo, run revyl init --detect from the Expo app directory. If detection still needs correction, edit build.framework and the generated development profile, then run revyl config validate. Configure the custom URL scheme in the Expo app before building the development client; the scheme is attached to the build artifact rather than authored in .revyl/config.yaml. See Configuration Files for the profile schema and Dev Loop Framework Guides for framework-specific setup.

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Step 2: Upload a dev build

Upload a development client build. It lands on the Revyl branch named after your Git branch, which the first upload creates, or on the app’s default branch outside a Git checkout:
For Expo, this is a dev client build. For bare React Native, it’s your debug build. revyl build runs in the cloud. The dev loop remains local unless you use revyl dev --remote. revyl dev resolves one named profile/platform recipe, runs on the branch named after your Git branch, and installs that branch’s default build. Pass --branch <name> to both build and dev to use another branch. For every branch and build rule, see Dev Loop.

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Step 3: Start the dev loop

You may omit the flags when the result is deterministic. revyl dev first prefers one unique development-like profile and then accepts only a sole eligible profile or platform. It prompts for remaining choices interactively and fails with the valid choices non-interactively. This is invocation-time selection, not an active/default profile. This:
  1. Starts your local dev server (Expo via npx expo start --dev-client, or Metro via npx react-native start)
  2. Creates a Revyl relay to expose it to cloud devices
  3. Installs the dev client build on a cloud device
  4. Opens the device session in your browser
Normal runs keep advisory HMR diagnostics quiet so they do not look like startup failures. If you are troubleshooting relay or HMR internals, run with revyl dev --debug to print the diagnostic probes. Now edit code locally and see changes reflected on the device instantly.

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Platform and build overrides

The selected recipe remains fixed for the dev context. Forced builds, remote builds, and later revyl dev rebuild operations all use that same recipe. If Revyl starts Expo and verifies relay transport but times out proving the first Expo manifest, retry with --force-hot-reload first. This launches after the relay and dev server start, skipping only the manifest and bundle proof. If the app loads, keep working; if the dev client shows a project load error, restart Expo/Metro or capture revyl device report --session-id <id> --json. If you already run Expo with its own tunnel, you can collapse the manual device start + deep-link step into one command:
--no-build reuses an existing build and keeps rebuilds off for this session. Add --branch <name> to require a specific branch’s build. --tunnel accepts either the full Expo dev-client link or the raw https://... tunnel URL. Passing the full dev-client link does not depend on an authored scheme field in the local Revyl config. Prefer the Revyl relay first in cloud-agent environments; use Expo tunnel fallback only after device screenshots or revyl device report --session-id <id> --json show force mode still did not load through the relay.

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Step 4: Interact with the device

Use revyl device commands to observe, act, and verify in a tight loop.
Always follow the observe-act-verify pattern: screenshot before an action, take the action, then screenshot again to confirm the result. Scroll through content with swipe:

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Step 5: Verify flows live

While the dev loop is active, verify outcomes with device commands:

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Step 6: Create tests from the session

After verifying a flow manually, convert the device session into a regression test:

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Step 7: Promote to regression

Once the test is stable, push and run it:

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Device-first flow

Start a plain device session first, then attach and run the dev loop on it:
When the dev loop exits, the attached session stays running. Run revyl dev --context checkout again to resume, or revyl dev stop to detach.

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Context management

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Team sharing

All developers push builds to a shared app container (the app_id in config). Each developer gets their own cloud device session, relay URL, and local server. For JS projects, multiple developers can share the same dev build and still see their own code changes.