Don’t tell it what not to do. Roughly, it doesn’t have the concept of ”not foobar”: mentioning such a negation in a prompt doesn’t do what a human would expect, and will instead cause ”foobar” activation and possibly also everything that is ”not” + ”foobar”, leading to inattention/off-task behavior as seen here.

You want your prompt to resonate with the desired output in a perfect harmony, and a ”don’t do X” is a bum note.

I agree. OP’s statement ”the need to template environment variables across a subset of jobs suggests an architectural error in the workflow design” does not ring true for cases where you want developers to be able to quickly deploy a separate environment for each development branch, especially if said branch needs to connect to a matching backend/API/other service.