Imagine we have three individuals: Alice, Bob, and Carol.
Bob asks Alice to write a letter to Carol asking for a favor. Alice wants Carol to refuse to do the favor for Bob, but for it to appear to Bob that she is trying her best to serve Bob's interests. So Alice writes the letter mentioning or saying something cryptic, which Bob won't pick up on, but which will cause Carol to refuse to perform the favor. E.g. perhaps Alice casually mentions something about Bob that seems benign to Bob but will lead Carol to have a strong negative reaction to Bob. Carol then refuses to perform the favor, Alice shows Bob her letter and the response, and Bob is disappointed but thinks Alice tried her best to help him. Alice is smiling.
Is there a specific word or phrase for Alice's actions as described above?