> First, it is hard, especially in at least somewhat portable manner.

I'm curious what portability concerns you've run into with JSON serialization. Unless you need to deal with binary data for some reason, I don't immediately see an issue.

> Such representation, which is by the way specified to be executable bidirectionally (roll back capabilities), is a full blown program

Of course this depends on the complexity of your problem, but I'd imagine this could be as simple as a few configuration flags for some problems. You have a function to execute the process that takes the configuration and a function to roll back that takes the same configuration. This does tie the representation very closely to the program itself so it doesn't work if you want to be able to change the program and have previously generated "plans" continue to work.