ui-states-and-feedback

From the author

Enforces the non-happy paths every screen owes the user — loading/empty/error/content resolved in ONE switch over an AsyncValue or sealed view state, never an isLoading+error+data bool triple; a delayed skeleton shaped like the result instead of a spinner that flashes; a refresh that keeps stale content on screen; "nothing yet" distinguished from "nothing matches this filter", each with its own action; error text from a typed Failure code (never e.toString()) plus a retry that invalidates the provider; the surface ladder inline, snackbar, banner, dialog, with a modal earned only by a decision that must resolve now; soft-delete + Undo over a confirmation; showDialog's null dismissal handled as its own outcome; ScaffoldMessenger captured before an await; and announcements for eye-only changes. Use when writing loading, empty, error, or offline UI, calling AsyncValue.when, showDialog, showModalBottomSheet, showSnackBar or showMaterialBanner, or adding a confirmation, Undo, or retry.