OptionalactionContribute dropdown action groups (each with nested actions) to the matched node; the group's
type/data are set automatically, so returning Node.makeActionGroup(...) output is fine.
OptionalactionsOptionalconnectorOptionalpositionOptionalrelationOptionalurlURL binding for the nodes this extension produces (key + resolution); see UrlBinding.
Options for creating a graph builder extension with simplified API. All callbacks must return Effects for dependency injection. Effects may defect — defects are caught, logged, and the extension returns empty results. Use Effect.orDie on any failable effects inside callbacks.