one spinor · two cubis · the 720° belt that comes home

0 → 360 → −720 (behind cubi-2) → 0 → −360 (behind cubi-1) → 720 → 0 · net winding 0 · it closes only because you went to 720, not 360

the 7 waypoints

start0° · home (+1)
turn 1360° · flipped (−1)
behind cubi-2−720° · home (+1)
midpoint0° · flat
behind cubi-1−360° · flipped (−1)
turn forward720° · home (+1)
return0° · closed

why 720 and not 360

a spinor is a belt: 360° leaves it twisted (−1, flipped), 720° lets it loop around and come home flat (+1). your +720/−720 front-and-behind passes are the two full twists that untwist the belt across both cubis. a 360-only loop would end flipped — never home.

One spinor as a twisting ribbon threading a closed circuit through two qubits. It twists 360 to a flipped state, then 720 behind the second qubit back home, crosses flat, 360 flipped behind the first, 720 forward home, and closes untwisted. It closes only because the spinor uses the full 720-degree double cover.