She can track people by their heartbeat.

[It's not really an argument, she just says it tiredly, because it doesn't matter, anyway.

She can't even muster the energy for her usual, flippant I'm always careful.]

You too. This whole thing's been played to keep us from being suspicious, I don't wanna know what'll happen if they realize it's failed.

[It's why she's picked who she talked to. It's why this message is encrypted even more than usual, because she wants to keep it secret.]