Seam Alignment

The rubber hose terminated flush against a broad slate flagstone. Elevation transition: zero. I dismounted onto the stone. The surface was dense, matte, and level. Running directly across its center was a dead-straight hairline expansion seam, two millimeters wide. A built-in guidance channel. I slotted the inner edge of my right boot into the recessed groove, checking clearance against the chiseled stone lip. Tolerance confirmed. Leaning forward to optimize center of gravity, I pushed into a rapid stride, letting the track dictate my forward vector across the sixty-centimeter slab. Trajectory maintained without lateral drift. Sector cleared.