A progressive-rollout controller built as a funicular: two cars share one cable over a summit pulley, so the new version's share and the old version's share are geometric complements that can never disagree. A canary hold pins the midpoint until confirmed, and rollback releases the winch to fall back under damped physics.
pnpm dlx shadcn@latest add "https://design.helpmarq.com/r/passing-loop.json"