Flutter core

Build Flutter clients as thin, typed consumers of an API — one Dart codebase per product, business state lives in providers, not widgets.

Dart 3 essentials

• sound null safety is the default — don't reach for ! without a documented invariant that makes it safe
• records for lightweight multi-value returns ((String, int)), not a throwaway class
• pattern matching / switch expressions over if/else chains on a type
• sealed classes for closed variant hierarchies (e.g. Loading/Data/Error UI state) — the compiler flags a missing case in an exhaustive switch

State management — Riverpod is house default

• Riverpod is the house default for a new project. Check pubspec.yaml, the lockfile, and the installed major's migration guide before choosing APIs; preserve an existing Bloc/Provider design.
• widgets stay dumb: read a provider, render, dispatch an event. Business logic and mutable state live in providers/notifiers, not in State objects
• no BuildContext threading to reach state — that dependency is what Riverpod removes

Project layout — feature-first