Does free will require the ability to have done otherwise?

The classical compatibilist move is to define free will as acting according to your own desires without external coercion. But this seems to sidestep the hard question. If determinism is true and your desires were fixed by prior causes, in what meaningful sense could you have done otherwise? Frankfurt's cases try to show that moral responsibility doesn't require alternative possibilities — but critics argue his counterfactual interveners still leave open a prior fork. I'm not convinced either camp has closed the argument.