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Flutter Design System

Enforce Design Language System adherence in Flutter. Use when enforcing design tokens, preventing hardcoded colors/spacing, or implementing a DLS in Flutter.

personAuthor: jakexiaohubgithub

Flutter Design System Enforcement

Priority: P0 (CRITICAL)

Zero tolerance for hardcoded design values.

Phase 0: Context Discovery (MANDATORY)

Before UI refactoring, identify project's Theme Archetype:

  1. Check main.dart: Look for MaterialApp theme configuration.
  2. Determine Pattern:
  • Theme-Driven (Adaptive): VThemeData(...).toThemeData() or extensive ThemeData overrides → use Theme.of(context).textTheme / theme.textTheme.
  • Token-Driven (Static): Use static tokens (VTypography.*) only when no global theme bridge exists, or when defining theme itself.

Guidelines

  • Colors: Use tokens (VColors.*, AppColors.*), never Color(0xFF...) or Colors.red.
  • Spacing: Use tokens (VSpacing.*), never magic numbers like 16 or 24.
  • Typography: Prioritize theme.textTheme.* for adaptive UI. Use VTypography.* tokens only for theme definitions or non-contextual logic. Never use inline TextStyle.
  • Borders: Use tokens (VBorders.*), never raw BorderRadius.
  • Components: Use DLS widgets (VButton) over raw Material widgets (ElevatedButton) if available.

Detailed Examples

Anti-Patterns

  • No Hex Colors: Color(0xFF...) strictly forbidden.
  • No Color Enums: Colors.blue forbidden in UI code.
  • No Magic Spacing: SizedBox(height: 10) forbidden.
  • No Inline Styles: TextStyle(fontSize: 14) forbidden.
  • No Raw Widgets: Don't use ElevatedButton when VButton exists.

Related Topics

mobile-ux-core | flutter/widgets | idiomatic-flutter

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

  • ElevatedButton

  • SizedBox

  • VColors

  • magic number

  • Additional task-grounded exact anchors: TextStyle