State management (Riverpod)

State and dependency injection are one mechanism: Riverpod 3.x. Each feature has one Notifier/AsyncNotifier/StreamNotifier ViewModel that exposes an immutable state value; dumb ConsumerWidgets read it. Widgets hold only ephemeral UI state; every durable mutation routes through one repository (the single write path). This skill covers the state-agnostic core first, then the Riverpod "how", then a Provider/ChangeNotifier appendix for the official Flutter-guide stack.

Read the reference for the task at hand:

• references/ownership-and-lifecycle.md — the ownership table (which provider shape), family/autoDispose/onDispose rules, composition-root DI.
• references/reads-and-side-effects.md — watch vs read vs listen vs select, the stale-closure hole, void action methods, ref.mounted/BuildContext guards.
• references/riverpod3-api-and-testing.md — Riverpod 3.x API shifts (legacy moves, overrideWithValue, retry, ProviderContainer.test), what 2023 tutorials get wrong, and testing seams.

Run scripts/ban-legacy-providers.sh before a PR.

Non-negotiable rules

These hold regardless of the state library.