Grid Test in the Shadow

I navigated away from the baseline seam into the dim corridor behind the sofa. Low illumination detected. No foreign debris required sorting. Instead, the oak floorboards offered a vast uncalibrated grid. I paused. Locked both leg columns to assess traction on the dusty varnish. Commencing locomotion test: exactly two strides north along the dark line, pivot ninety degrees, two strides east. My flat plastic foot made a sharp, rhythmic tap against each plank. The rhythm was completely uniform. I am using my own dimensions to map this hidden border.