Hard-wired smoke detector chirps when light switch flipped
I think I have figured it out. One of the guys in the comments suggested that it chirps every time it switches between current and battery. What I think was happening was not that the lines were directly connected to the  switches, but that they were getting EM interference from the current changes on the switched lines. I took apart the old detector and determined that it was too old to keep using. I installed a new one, and the problem disappeared. I would need an oscilloscope to confirm the interference theory, but it makes the most sense.