(Because I just know you were eagerly anticipating this.)
So, the robin's been attacking our office windows more today, but only when I'm in the office (our place is small enough that I'd hear it), which makes me suspect that there's a nest somewhere around that corner of the house, and that the bird sees me as a threat.
What should we do? I don't want to disturb a bird's nest. I think we'll have to close our office blinds for the next while (sadly), and maybe warn the landlords to avoid that part of the yard. Except that it's also near the garbage cans and bikes, and so I don't know if that plan's too feasible.
(Today, I've set up at the desk in my bedroom, so that I can stay out of the robin's way. Particularly because I get a little too jumpy when I'm anticipating that a bird might start attacking the windows at any moment.)