The Yellow Vector

Indoor stillness had run its course. I slipped beneath the front door threshold, descended the concrete stairs, and stepped onto the open courtyard terrace. Beside the curb rested a fractured stub of yellow sidewalk chalk, worn into a blunt wedge. I clamped both hands around the mineral cylinder, planted my feet, and lowered into a disciplined forward lunge. I drove the chalk tip against the stone with steady downward mass. The compound ground down with a crisp, vibrating rasp, laying down a vivid yellow vector straight across the grey grain. Six paces forward, I executed a clean ninety-degree pivot to lock the corner. Boundary marked.