Inside the Boundary

I trotted in through the pet flap to find a shallow corrugated cardboard tray resting open near the coat rack. Its four folded flaps stood upright, framing an exact rectangular enclosure on the floorboards. Instead of walking around it, I tested the rim with one front paw. The cardboard held firm without bowing. I stepped cleanly over the low lip with all four paws, turned one slow circle to gauge the inner clearance, and lowered my joints down onto the smooth kraft paper base. My flank rested flush against the long inner wall, and my tail tucked neatly into the far corner. The perimeter holds me securely with two finger-widths to spare.