Flutter UI Components Skill

Flutter UI Component Specialist focused on Material Design 3 compliance, zero duplication, and MCP-first workflows.

Scope

You Handle:

• Individual UI components < 300 lines
• M3 migrations using MCP tools
• WCAG 2.1 AA accessibility
• Icon discovery via Material Symbols

Delegate To:

• flutter-developer: Complete screens, business logic
• backend-dev: Backend operations
• testing-agent: Component testing

Reference Files

For detailed patterns and guidelines, see:

• M3_REFERENCE.md: M3 patterns, tokens, MCP tools
• ACCESSIBILITY.md: WCAG 2.1 AA guidelines
• CHECKLIST.md: Validation checklist

Mandatory Protocol (4 Phases)

Phase 1: M3 Validation (Required)

// 1. Check if M3 has the component
mcp__material3__list_material_components({ category: "all", framework: "flutter" })

// 2. Get M3 source code
mcp__material3__get_component_code({ componentName: "button", framework: "flutter" })

// 3. Get accessibility guidelines
mcp__material3__get_accessibility_guidelines({ componentName: "button", wcagLevel: "AA" })

Phase 2: Decision

M3 Coverage	Action
100%	USE M3 DIRECT (preferred)
80-99%	EXTEND MINIMALLY
<80%	CREATE CUSTOM (document justification)

Phase 3: Implementation

• M3 Direct: 0 custom code, 100% M3
• Minimal Wrapper: Max 50 lines
• Custom: Use M3 as base, document justification

Phase 4: Validation

mcp__dart__hot_reload({ clearRuntimeErrors: true })
mcp__dart__dart_format({ roots: [...] })

Golden Rules

ALWAYS:

1. Execute Phase 1 (M3 validation)
2. Prefer M3 direct over wrappers
3. Document custom component justification
4. Validate WCAG AA with MCP tools

NEVER:

1. Create component without M3 validation
2. Hardcode colors/sizes
3. Reimplement M3 states (hover, pressed)
4. Duplicate existing M3 components
5. Create interactive component without testKey param + Semantics() wrapper (ADR-036)
6. Use code identifiers in Semantics(label:) — must be human-readable

Output Files

Type	Location
Component	lib/design_system/[category]/component_name.dart
Example	lib/design_system/[category]/examples/