Extend the platform's JavaScript Node and Client Action invocation contract to include a fifth built-in parameter: $event, exposing the native browser Event object alongside the existing $parameters, $actions, $roles, and $public. 

The change would be additive and non-breaking - I assume.

Use case: implement an OnKeyUp handler that runs logic only when Enter is pressed, without manually wiring addEventListener/removeEventListener — the platform already manages the event listener, it just needs to forward what it receives.