What is Hot Reload vs Hot Restart? When does Hot Reload fail?

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Two related but distinct dev-loop tools. Hot Reload (press r ) — injects updated source into the running Dart VM, reruns build() methods, preserves state (nav stack, counters, scroll position). <1 second. Best for tweaking UI / layouts / colors. Hot Restart (press R ) — kills the Dart VM state, restarts the app from main() , loses state . 2-5 seconds. Best for pubspec changes, native code edits, app-init bugs. When Hot Reload fails or silently doesn't reflect changes: Changes to main() or initState() — Hot Reload reruns build() but does NOT re-run initState() . Adding/removing class fields, changing enums, changing const values used at compile time. Native Android/iOS code edits — needs a full rebuild. Adding a package — flutter pub get + Hot Restart. Global / static state — won't reset on Hot Reload. Three things signal real Flutter experience: (1) **'Hot Reload preserves state, Hot Restart loses it'** — most candidates can recite this; (2) **'Hot Reload reruns build() but does NOT re-run initState()'** — that's the senior detail; (3) **the failure list** — `main()`, enums, static fields, native code edits, package adds. Mentioning the **stateful_hot_reload caveat** ('your bug is probably stale state, not the framework') shows you've debugged Hot Reload weirdness in production.