Every walkable seen tile shares one near-dark gunmetal floor — machine tiles included, so chassis plates never mismatch the room; cable runs and conduit keep the amber-warm service read; the tester pedestal matches the game ground. Defense: Cameron called the floor direction after the porcelain patches fought the machine plates. The identity's frame is the hero composition — white towers and signals standing in darkness — and one dark ground realizes it at room scale while every fog treatment keeps its channel (seen stays the only lit floor; heard/remembered/blueprint unchanged). Amended into interface/flat-materials.md in this commit.