To me "deleting a failing test" is not always bad. I've also deleted many failing tests without sabotaging: the test was no longer needed.

I think the "no longer needed" and when that applies is where I simply differ of opinion with an LLM that removed by test -- it I did not want the test to be removed (you seem to imply that); as in some cases I want it to remove my test!

It should remove the test "for the right reasons"; and who gets to decide what's right?

My CLAUDE file has some instructions put there because it was too focuesed on producing "green tests", where I prefer to have a sound test that fails so I can look into it.

You misunderstand the "test" here to mean programming, rather than test against the model's capabilities.