Flutter Dev

Flutter cross-platform development guide covering widget patterns, Riverpod/Bloc state management, GoRouter navigation, performance optimization, and platfor...

Security Scan

This is an instruction-only Flutter development guide (documentation + code samples) and does not request credentials, install code, or perform any unexpected actions — it is internally consistent with its stated purpose.

Purpose & Capability

Name/description (Flutter dev guide) match the contents: reference files and SKILL.md provide widget patterns, state management, navigation, performance, testing, and platform notes. No unrelated credentials, binaries, or installs are requested.

Instruction Scope

SKILL.md and the reference files are purely documentation and code examples. They do not instruct the agent to read system files, access environment variables, contact external endpoints beyond illustrative placeholders (e.g., https://api.example.com), or exfiltrate data.

Install Mechanism

No install spec and no code files that would be executed. Being instruction-only means nothing is downloaded or written to disk during install.

Credentials

No required environment variables, credentials, or config paths are declared or referenced. Code samples use placeholder endpoints and typical package names appropriate for Flutter networking/state management.

Persistence & Privilege

Skill is not always-enabled and does not request persistent agent privileges or modify other skills. Autonomous invocation defaults are unchanged and are not combined with any broad access in this skill.

Assessment

This skill is documentation and example code only — it does not require secrets or perform installs. It's safe to read and use as a reference, but before copying examples into production: (1) review networking examples (they use placeholder base URLs like api.example.com) and replace with your real endpoints; (2) avoid leaving verbose logging (the LoggingInterceptor prints request bodies) in production since it can expose sensitive data; and (3) verify package versions and licenses in your own project. If you need the skill to run code or access systems, ask for a version that declares explicit installs and required environment variables so you can review them.

Flutter Development Guide

A practical guide for building cross-platform applications with Flutter 3 and Dart. Focuses on proven patterns, state management, and performance optimization.

Quick Reference

Widget Patterns

Purpose	Component
State management (simple)	StateProvider + ConsumerWidget
State management (complex)	NotifierProvider / Bloc
Async data	FutureProvider / AsyncNotifierProvider
Real-time streams	StreamProvider
Navigation	GoRouter + context.go/push
Responsive layout	LayoutBuilder + breakpoints
List display	ListView.builder
Complex scrolling	CustomScrollView + Slivers
Hooks	HookWidget + useState/useEffect
Forms	Form + TextFormField + validation

Performance Patterns

Purpose	Solution
Prevent rebuilds	const constructors
Selective updates	ref.watch(provider.select(...))
Isolate repaints	RepaintBoundary
Lazy lists	ListView.builder
Heavy computation	compute() isolate
Image caching	cached_network_image

Core Principles

Widget Optimization

• Use const constructors wherever possible
• Extract static widgets to separate const classes
• Use Key for list items (ValueKey, ObjectKey)
• Prefer ConsumerWidget over StatefulWidget for state

State Management

• Riverpod for dependency injection and simple state
• Bloc/Cubit for event-driven workflows and complex logic
• Never mutate state directly (create new instances)
• Use select() to minimize rebuilds

Layout

• 8pt spacing increments (8, 16, 24, 32, 48)
• Responsive breakpoints: mobile (<650), tablet (650-1100), desktop (>1100)
• Support all screen sizes with flexible layouts
• Follow Material 3 / Cupertino design guidelines

Performance

• Profile with DevTools before optimizing
• Target <16ms frame time for 60fps
• Use RepaintBoundary for complex animations
• Offload heavy work with compute()

Checklist

Widget Best Practices

• const constructors on all static widgets
• Proper Key on list items
• ConsumerWidget for state-dependent widgets
• No widget building inside build() method
• Extract reusable widgets to separate files

State Management

• Immutable state objects
• select() for granular rebuilds
• Proper provider scoping
• Dispose controllers and subscriptions
• Handle loading/error states

Navigation

• GoRouter with typed routes
• Auth guards via redirect
• Deep linking support
• State preservation across routes

Performance

• Profile mode testing (flutter run --profile)
• <16ms frame rendering time
• No unnecessary rebuilds (DevTools check)
• Images cached and resized
• Heavy computation in isolates

Testing

• Widget tests for UI components
• Unit tests for business logic
• Integration tests for user flows
• Bloc tests with blocTest()

References

Topic	Reference
Widget patterns, const optimization, responsive layout	Widget Patterns
Riverpod providers, notifiers, async state	Riverpod State Management
Bloc, Cubit, event-driven state	Bloc State Management
GoRouter setup, routes, deep linking	GoRouter Navigation
Feature-based structure, dependencies	Project Structure
Profiling, const optimization, DevTools	Performance Optimization
Widget tests, integration tests, mocking	Testing Strategies
iOS/Android/Web specific implementations	Platform Integration
Implicit/explicit animations, Hero, transitions	Animations
Dio, interceptors, error handling, caching	Networking
Form validation, FormField, input formatters	Forms
i18n, flutter_localizations, intl	Localization

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Flutter, Dart, Material Design, and Cupertino are trademarks of Google LLC and Apple Inc. respectively. Riverpod, Bloc, and GoRouter are open-source packages by their respective maintainers.