Legal Question in Real Estate Law in California

Not sure about the correct "legal" answer, but a possible compromise might be to use "plug-in" smoke detectors which use a/c rather than batteries alone. You could perhaps even get close to a hard-wired condition by using a clip or clamp of some kind to prevent easy unplugging. A further step might be to buy plug-in units with cords, then cut off the plugs and attach the wires permanently inside outlet boxes, preferably selecting ones that are normally behind furniture, so the wires emerging from behind the cover plates wouldn't be an eyesore. Negotiate first, and have a licensed electrician do the work if the HOA approves. This'll at least avoid plaster and paint work.