nprofile1qy2hwumn8ghj7un9d3shjtnddaehgu3wwp6kyqpq4wsy68pyduanfdrqrrrr7j62qezr0nemfvsprcvkyk7xz49gyrxsnzuqnt (nprofile…uqnt) I'd have to dig in, but I suspect it's possible to only make signing available to a process that already received a confirmation.
Either way, if you want to have a mounted file system, you're going to need access controls to it anyway. And the way you access the ssh agent is through a socket on the file system, so it seems that you'll have to solve that problem anyway. Or am I wrong?