A contract? I'm not sure why one would be required in a situation such as this, but if you really felt it was necessary, I wouldn't refuse.

[ She notices the Vision, of course. That square shape... he must be from Liyue, then, but she would have guessed that anyway. Who else would bring up a contract within fifteen seconds of meeting someone? Navia's Vision is hanging down between her shoulder blades, tied securely in her bikini straps and obscured by her hair; she'll show it off if she needs to, but she doesn't feel the need just yet. ]

A verbal contract would suffice, I'm guessing?