webkernel/lifecycle

Declaring Metadata

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Put a declaration in the composer.json of the package that owns the task. Lifecycle reads the root package and installed dependencies when it handles a supported event.

1. Add a lifecycle section

{
  "extra": {
    "webkernel": {
      "lifecycle": {
        "checks": [],
        "events": {},
        "actions": []
      }
    }
  }
}

Each section is optional. Merge this object into the existing manifest; keep the package's other Composer fields.

Key	Use it for
`checks`	Supported PHP-version failure conditions.
`events`	Callbacks attached to a supported Composer script event.
`actions`	Action classes run by the built-in post-autoload worker.

2. Make classes autoloadable

{
  "autoload": {
    "psr-4": { "Acme\\Build\\": "src/" }
  },
  "extra": {
    "webkernel": {
      "lifecycle": {
        "actions": ["Acme\\Build\\GenerateManifest"]
      }
    }
  }
}

Place Acme\Build\GenerateManifest at src/GenerateManifest.php. Use normal autoload metadata for callbacks that must be available in consuming projects; a dependency's development autoload rules are not a production extension contract.

3. Choose class references

Reference	Resolution
`Acme\Build\GenerateManifest`	Used directly if the class is autoloadable.
`GenerateManifest`	Resolved under the declaring package's sole PSR-4 prefix.
`Events\AfterDump::run`	Prefixes the class while retaining the method suffix.

Use fully qualified, autoloadable names when a package has multiple PSR-4 prefixes. Write them without a leading backslash in JSON; the declaration validator's class-name grammar does not accept that prefix. Missing fully qualified classes still fail resolution or target validation.

How declarations are read

The root declaration comes from Composer's root package object. For installed packages, Lifecycle reads composer.json from the installation manager's resolved path; if that manifest is unavailable, it falls back to Composer's stored package metadata. Read or JSON errors stop the operation.

Validated declarations are cached for the Composer instance. Package install/update/uninstall events invalidate that cache. Do not depend on editing manifests halfway through a running event to change an already collected job list.

Next step

Choose Composer Events, Checks or Actions. The complete key list is in the Declaration Schema.