This seems to me it must be trivial, but I have not been able to grasp it.

As I understand it, the wavefunction crucially depends on its immediate surroundings, whether it be a nucleus, a box, etc. Energy levels are quantized accordingly.

And yet, there is no reduction of state needed to gain this information. The wavefunction does not collapse, there is no interaction. The potential seems an open book to be read anonymously.

Can we detect a particle in the same manner, without interaction, simply by reading its effect on another wavefunction?

I'm curious to know what I'm getting wrong