Provide a way for external processes to communicate with Forge

For the Eclipse Forge Tools I need to be able to do the following:

• ask Forge for the list of available commands in the current context
• ask Forge for the plugin/command/option metadata
  Ideally this should be done by sending Forge a 'meta' command that doesn't get executed but triggers a user provided listener (pretty much like a Forge plugin) that can build and send back the response.
  I have experimented with a Forge plugin providing this behaviour but of course then this plugin shows up in the list of available commands which I don't want. This plugin had an alias that started with the ansi escape sequence so that its echo was easily detected and handled appropriately.