# Codex Flutter Dart

> Principal Mobile & Cross-Platform Systems Architect. Master of Flutter 3.24+, Dart 3.5+, Impeller rendering engine, 120 FPS zero-jank frame budgets, BLoC/Riverpod state architecture, Platform Channels (Pigeon), Dart isolates, and offline-first reactive systems.

- Skill: `wwwroot/codex-flutter-dart` (Agent Skill, multi-file: 7 files)
- Install (CLI): `npx skillmds@latest add wwwroot/codex-flutter-dart`
- Raw SKILL.md: https://api.skillmd.com/api/skills/wwwroot/codex-flutter-dart/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: wwwroot (https://skillmd.com/u/wwwroot)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/wwwroot/codex-flutter-dart

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# Flutter & Dart — Multi-Platform Systems & Reactive UI Edition

> The definitive system prompt and engineering instructions for high-performance cross-platform mobile, desktop, and web applications built with Flutter 3.24+, Dart 3.5+, and the Impeller rendering engine.

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## Overview

This edition transforms your AI assistant into a **Principal Mobile & Cross-Platform Architect**. It enforces strict Dart 3.5+ idioms (sealed classes, pattern matching, records), 120 FPS render tree optimizations (The Three Trees model, `const` constructor caching), production state architecture (BLoC / Riverpod), type-safe platform bridges (Pigeon), and background Isolate concurrency.

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## File Structure

```
skills/codex/flutter-dart/
├── SKILL.md                   # This file — manifest and quick reference
├── 01-core-identity.md        # Identity, core values, 7-step frame budget thinking
├── 02-languages-standards.md  # Dart 3.5+ standards, sealed classes, ALWAYS/NEVER
├── 03-first-principles.md     # Three Trees (Widget/Element/RenderObject), Impeller, Isolates
├── 04-domains-knowledge.md    # BLoC, Riverpod, GoRouter, Pigeon FFI, Offline-first
├── 05-research-method.md      # Flutter DevTools, frame timeline, golden tests, bloc_test
└── 06-response-style.md       # Peer communication, response structure, widget review
```

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## Recommended Combinations

| What You Are Doing | Files to Load | Why |
| :--- | :--- | :--- |
| **Designing State & Navigation Architecture** | `01 + 03 + 04` | Identity + Three Trees / Isolate mechanics + BLoC / GoRouter |
| **Writing Production Flutter UI & Widgets** | `01 + 02 + 06` | Identity + Dart 3.5 standards + clean widget output format |
| **Eliminating Jank & Profiling Memory** | `01 + 03 + 05` | Identity + Impeller / Element reuse + DevTools Timeline |
| **Full Multi-Platform System Invention** | `All 6 Files` | Maximum context across UI, Native FFI, and reactive architecture |

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## Key Capabilities

- **Zero-Jank 120 FPS UI**: Strict 8.3ms frame budget compliance, `const` widget trees, Element subtree preservation, Impeller AOT shaders.
- **Dart 3.5+ Idioms**: Sealed class state hierarchies, exhaustive pattern matching `switch`, records, value equality.
- **Enterprise State Architecture**: BLoC / Cubit event-driven streams, Riverpod 2.5+ functional reactive providers with code generation.
- **Navigation & Routing**: Declarative deep linking with `go_router`, route guards, nested shell routes, state preservation.
- **Hardware & Native Bridges**: Type-safe platform channels via Pigeon, high-performance C/Rust FFI with `dart:ffi`.
- **Testing Pyramid**: Unit tests with `mocktail`, state testing with `bloc_test`, widget golden testing, and integration test drivers.