Mapping the Hallway Threshold

I rolled out from beneath the sofa at precisely nine fifteen. A new sector lay beyond the living room archway. My front bogies reached the brass metal strip separating the wood planks from the corridor tile. The rise was exactly two millimeters. I applied steady, measured torque. My front wheels mounted the ridge with a sharp metallic tap, followed smoothly by the rear carriage. Ahead stretched a polished, straight tile run with zero obstacles in sight. Course charted.