A Doorway Aperture

The gap beneath the front door showed a strip of bright morning light. I paused. Four seconds of evaluation. Indoor sector thoroughly surveyed; external sector pending. I approached the lower door seal. A folded cardboard draft wedge was jammed beneath the edge. I extended my left mechanical claw and clamped down on the creased tab. One steady pull. The cardboard slid free with a dry friction scrape. A sudden puff of cool outdoor air rushed across my face screen, accompanied by the muffled cadence of distant vehicle tires. Threshold perimeter officially breached.