Library
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Tests must exercise code from lib; never reproduce the implementation or mock the production class under test.
Avoid the late keyword, because it turns a compile time check into a runtime LateInitializationError; initialize in the constructor or use a nullable type.
Keep model objects immutable and hold changing state, such as which items are checked, separately, because mutating a field may not trigger setState and leaves the UI stale.
Test a page by launching the app and navigating to it, not by wrapping it in its own MaterialApp, so routes, providers and results are tested for real.
Prefer switch, polymorphism, collection functions or early returns over if-else, and keep if-else for two equally weighted branches.
Log through package:chirp, or developer.log in a Flutter app without chirp, and never print(), because print loses the error and stack trace.
Keep ternaries on one line; when a condition spans lines, use an immediately invoked function or if-else so each branch stays readable and debuggable.
Replace if-else and multi-line or nested ternaries in build methods with a Builder that uses early returns, so each conditional state is easy to read.
Give reusable widgets Widget parameters with a DefaultTextStyle instead of String parameters for user-facing text, so callers can pass icons, rich text or their own style.
Inspect local conventions before adding public API, state management, abstractions or configuration.
Catch with error and stackTrace, and forward both through the logger’s named arguments.
Keep reactive state in signals scoped to a controller, preferably state_beacon, instead of ChangeNotifier or ValueNotifier, so derived values cannot go stale.
Use braces and put every control-flow body on a separate line.
In Flutter mobile apps, tapping the background outside a text field must dismiss the keyboard by removing focus; check this for every field you add.
Extract UI sections into public widget classes instead of Widget _buildX() methods, so tests can find them by type and the tree stays easy to query.
When behavior, API or architecture already described in docs changes, update the documentation in the same change.
Configure Dart linting with package:lint and never suggest other lint packages such as very_good_analysis or flutter_lints.
When one condition picks between UI variants, branch once and build one complete widget per variant instead of repeating the condition on every property.
For async_return_with_no_await, add await and preserve the async method.
In widgets and other classes with dispose(), delay work with a Timer you cancel in dispose(), because Future.delayed cannot be cancelled.
Give the main widget of every widget file a dartdoc comment that says where it is used and what makes it unique, not a restatement of its name.
Use package:provider with context.read and context.watch for state management, instead of riverpod or get_it.
Handle Flutter forms with package:reactive_forms instead of Form, TextFormField and TextEditingController, so form state and validation live in one model.
Put the final casing of user-visible text in the localization resource instead of calling toUpperCase() on it, because Dart's casing is wrong for some languages.
Organize code by feature and call repositories directly, because UseCase and layer-first folders add indirection and boilerplate without value.
Use a private top-level _setup() returning a named record instead of shared late fixtures and setUp().
Use package:context_plus to bind objects to widget scopes and watch them, instead of provider, riverpod, get_it or hand-written InheritedWidgets.
Keep a StatefulWidget and its State class next to each other, with no function, variable or other class declared between them.
Name a widget that a route pushes *Page in *_page.dart, never *Screen, because Flutter already calls a route's configuration a Page and a screen is hardware.
Never send analytics events from a Flutter build() method, directly or through a helper, because rebuilds are not user events and produce duplicate counts.
Do not use package:bloc or flutter_bloc for state management; streams are hard to test, and a synchronous ChangeNotifier is simpler for most code.
Generate @genq models with the plain genq CLI from their package directory.
Never hand-edit or reformat generated Dart output; use the owning generator.
Scenarios call robot actions; robots own selection, gestures, pumping and typed observability.
Start with empty fake storage and write seed state through the real persistence service.
Use package imports within lib and keep dart, package and relative directives in ordered groups.
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