I know Kevin is working on a smooth shiny system for lighting/visibility, so I don’t know if it addresses this but:
you can see a wall that is lit from the other side, presumably because the tile has one light value, and tiles are nondirectional.
I’d propose that their light level always be 0, but their visibility be inherited from the tile immediately next to them that you are looking through.
(Kevin has probably has already fixed this in his light attenuation PR though, if so this topic can probably be deleted)