XState Statecharts

XState is a library for building state machines and statecharts—formal models of application behavior. Instead of imperative code ("if buttonClicked, then show dialog, but only if userIsAuthenticated"), you declare states (idle, loading, success, error) and transitions (click → loading → success). This makes complex logic testable, visible, and predictable. XState is especially powerful for async flows: fetching data, handling errors, retrying, timeouts, and cancellations all become explicit transitions, reducing bugs.