The AI is prompting the human here, so the title isn't strictly wrong. ;)
The fact that system prompts / custom instructions have to be typed-in in every major LM chat UI is a missed opportunity IMO
I guess they recently re-trained on too many "perpetual junior senior dev" stuff.
I had to specifically instruct it that the integration tests ALWAYS pass 100% and not to assume anything - and it kinda believed it.
The nuclear option would be to force it to start with running the tests to prove to itself they worked before =)