Exercise 1: Tracing Step 6 in Detail — Possible Solution ==================================================================== WHAT markUsed ACTUALLY CALLS ------------------------------ After the PATCH /api/items/:id/use request succeeds, markUsed calls notifyChange() from ItemsContext - one single function call, with no reference to the alerts dashboard, the recipe suggestions, or any other specific feature at all. WHAT notifyChange() DOES ------------------------------ notifyChange() increments the shared version number stored in ItemsContext. It carries no information about what specifically changed - just that something did. HOW THAT ONE CALL REACHES BOTH FEATURES ------------------------------ Both useExpiryAlerts (backing the alerts dashboard) and the hook backing RecipeSuggestions independently include version in their own useEffect dependency array. Whenever version changes, React re-runs both of those effects on its own, each one re-fetching its own data from its own Express route (the alerts route, and the recipe suggestion route respectively) - entirely independently of each other and independently of markUsed itself. WHY NEITHER IS "CALLED DIRECTLY" ------------------------------ markUsed never references either hook, either route, or either component by name - it only ever touches the shared version counter. The alerts dashboard and recipe suggestions both react purely because they chose to subscribe to that shared signal, not because anything explicitly told them to update. WHY THIS WORKS AS AN ANSWER ------------------------------ It correctly traces the exact call (notifyChange(), not any feature-specific function), correctly explains what that call does (increments a plain counter), and correctly explains how both features end up updating through their own independent subscriptions rather than through any direct call from markUsed.