Lin and Sun joined the supervised walk through the service corridor. Luo kept them behind Wei, and Gu pointed out each old repair niche as they went. He asked the candidates to call out anything that differed from the survey.
The cord ran along the wall, leaving the floor open. Yan followed it with his eyes, checking each stone for a pressure shift. His palm remained wrapped, and his ribs still pulled if he turned too quickly. He kept his shoulders square and let Wei carry the stretcher frame.
She knelt without crossing it and brushed dust away with the edge of a folded paper. The groove was shallow, clean at the bottom, and ran in a straight line for two handspans before turning up the wall.
“Could it be a crack?” Sun asked.
Gu compared it with the older repair niches. “No. The edges are too even.”
Yan set a chalk cord along the floor without touching the groove. The mark continued beneath a layer of dust and then vanished at the wall seam.
“Do you want to test it with the stretcher?” Wei asked.
“Not across the line,” Luo said. “We don’t know what it senses.”
