See design comments at

http://www.fast-downward.org/ForDevelopers/LongTermPlans#Task_Transformations

since this will require several steps, we are turning this into a meta issue.

This is related to the general component coordination problem. One question is
whether transformations should be parameters of evaluators in the first place.
See issue559 for more information, specifically the comments from September 2018.

I like the current iteration of the wiki text, and from my perspective the
accompanying task on the task board can be marked as done.

Yes, I think these are all heuristics. (The constructor of the PotentialOptimizer 
class accepts an Options object, but it would be better to pass the options 
individually since it is not a plugin.)

I'm not sure if this the right issue for this, but I don't know where else to
put this right now, so:

I tried to find out if there are other places than heuristic.cc where task
transformations provided by the user are used. I don't know if the following
grep is the best way to do this, but here is what I got:

grep "get<shared_ptr<AbstractTask>>" **/*.{h,cc}
cegar/additive_cartesian_heuristic.cc:       
opts.get<shared_ptr<AbstractTask>>("transform"));
heuristic.cc:      task(opts.get<shared_ptr<AbstractTask>>("transform")),
pdbs/pattern_collection_generator_hillclimbing.cc:        "transform",
opts.get<shared_ptr<AbstractTask>>("transform"));
potentials/potential_optimizer.cc:    :
task(opts.get<shared_ptr<AbstractTask>>("transform")),
potentials/single_potential_heuristics.cc:    const AbstractTask &task =
*opts.get<shared_ptr<AbstractTask>>("transform");

I assume all of these are just heuristics, but it would be good if someone more
familiar with the relevant bits of the code could verify this.

We discussed this issue today and added notes about it to the wiki:
http://www.fast-downward.org/ForDevelopers/LongTermPlans#Task_Transformations

We need to think about how to deal with task transformations in general path-
dependent heuristics such as the landmark heuristic.