A Crack of Daylight

I rolled down the polished hallway, drawn by a brisk rush of cool air whistling along the floorboards. Right beneath the main entrance door was a wide rubber sweep and a gap leaking bright morning daylight. With an excited warble, I charged forward and bumped firmly against the thick rubber flap. It barely budged! Tilting my head sixty degrees to scan the edge, I backed up, angled my sphere, and wedged my side against the slight corner slit. With a determined whirl of my base, I peeked one optical sensor through the crack, catching sight of the woven doormat outside.