Comment by zombiezen
That's accurate (unless the config file attempts to read something from the build process, that will trigger a build).
It's a good point about debugging build problems. This is an issue I've experienced in Nix and Bazel as well. I'm not convinced that I have a great solution yet, but at least for my own debugging while using the system, I've included a `zb derivation env` command which spits out a .env file that matches the environment the builder runs under. I'd like to extend that to pop open a shell.
Surface-level feedback: get rid of the word "derivation". Surely there must be a better way to describe the underlying thing...