# Flutter > Flutter/Dart coding rules for this project — style, file size, and test coverage. Use when this capability is needed. - Skill: `tomevault-io/flutter-4` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/flutter-4` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/flutter-4/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/flutter-4 --- When writing or reviewing any Flutter/Dart code in this repository: 1. **Never hardcode style values.** Colors, font sizes, spacing, border radii, and icon sizes must come from `app_theme.dart` (`AppColors`, `AppText`, `AppLayout`, `AppIcons`). If a value is missing, add it there first. 2. **Keep files small and focused.** One widget family per file. If a file exceeds ~200 lines, split it. Extract private widget classes (`_SomeWidget`) instead of nesting logic inline inside `build`. 3. **Keep functions simple.** Build methods and helpers should be short. Deep nesting is a signal to extract a named widget. 4. **Cover with tests.** Every new widget needs at least one BDD widget test in `src/ui/test/`. Use fake API implementations (not mocks). Cover the golden path and key edge cases (empty, error, loading). Use `const Key('...')` on widgets so tests can target them reliably. --- > Source: [bsterligov/river](https://github.com/bsterligov/river) — distributed by [TomeVault](https://tomevault.io).