How do React.lazy and dynamic import() enable code splitting?

It tests your understanding of React code-splitting and the Suspense boundary contract. A strong answer covers four things in order: first, lazy takes a loader returning a dynamic import Promise; second, React calls the loader only on first render and caches the Promise and resolved module; third, the resolved default export must be a valid React component; fourth, Suspense catches the thrown Promise and renders a fallback until resolution. A red flag is conflating Suspense with generic loading states or believing lazy preloads before mount.