To make any node navigable, add trace info in its generators, as described in Debugger#TraceableNodes
Fork in generation plans
There's new statement in generation plans, fork with <another generation plan> to branch transformation sequence at a given point.
At the end of the day, transformation of a model may end up with multiple output models. All transient output models have same name but different stereotype and share same output location (determined by input model), therefore further artefacts (like textgen) end up together. Neware of name clashes if roots in different output models are generated into files with identical names.