Integrate an existing application

1. Identify the framework, entrypoint, existing scripts, output directory, package manager, and Node.js version. Watt 3 requires Node.js 22.19.0+.
2. Choose the specific capability before falling back to @platformatic/node.
3. Add a watt.json identifying the capability through module. Preserve existing JSON5/YAML/TOML configuration rather than converting it to a v4 configuration module.
4. Keep application build commands separate from orchestration. Do not make a Watt build command recursively call itself through an overwritten build script.
5. Keep dependency versions compatible with the installed Watt 3 release. Install only when authorized and use the existing package manager and lockfile.
6. Review public listener ownership, path prefixes, static assets, environment loading, startup dependencies, and shutdown behavior.

Generic Node.js application

{
  "module": "@platformatic/node",
  "node": { "main": "./server.js" },
  "runtime": {
    "server": { "hostname": "0.0.0.0", "port": "{PORT}" }
  }
}

Prefer a create() export returning the supported server/framework instance, so Watt can manage its lifecycle. Preserve a self-listening application only after checking the Node capability's listener and shutdown contract. Do not add a second listener.

Use application.commands.build for a required compile step and point node.main at its output. Native type stripping does not compile decorators or replace bundling.

Adding to a workspace

Add an application entry to the existing root or use its existing autoload convention. Keep IDs unique and paths relative to the owning configuration. The root's entrypoint selects the publicly exposed app; internal callers use http://<id>.plt.local.

The v3 import/resolve commands still exist. They can modify configuration, clone repositories, or install dependencies; inspect their help and use them deliberately. See CLI and enterprise.

Test representative routes, assets, internal calls, production output, and shutdown when authorized. Integrating a framework into Watt 3 is not a migration to Watt 4.