Fig 7Pull request — the gateClick approve or press space to clear reviewpull request open
Review cleared: the gate can openWagons waiting on the branch roadBarrier arm: down while review is pendingDesk: approve the review (click or space)A pull request is a gate, not a move. D and E sit on the branch road and cannot reach main on their own: the barrier is down and the lamp is dark. Once a reviewer clears it, the barrier lifts, the wagons run onto main, and M appears with two parents, C and E.