Dev Standards Skill

Dev Standards Skill - Code Quality & Architecture Management

A comprehensive skill for maintaining high code quality standards and project architecture awareness throughout development.

When to Use

• Starting any development task - Apply standards from the beginning
• Code review or refactoring - Ensure compliance with standards
• New conversation context - Quickly understand project architecture
• Adding new features - Check impact on existing architecture
• Debugging - Trace relationships between components

Core Principles

1. Modular & Component-Based Design

File Length Limits:

• Single file should not exceed 300 lines (excluding tests)
• Functions should not exceed 50 lines
• Classes should not exceed 200 lines

When to Split:

• Extract reusable logic into utility modules
• Separate concerns into different files
• Create shared components for common patterns
• Use composition over inheritance

Example Structure:

src/
├── features/           # Feature modules
│   └── user/
│       ├── index.ts    # Public API
│       ├── types.ts    # Type definitions
│       ├── utils.ts    # Feature-specific utilities
│       └── hooks.ts    # Feature-specific hooks
├── shared/             # Shared modules
│   ├── components/     # Reusable UI components
│   ├── utils/          # Common utilities
│   ├── hooks/          # Common hooks
│   └── types/          # Shared types
└── core/               # Core business logic
    ├── api/            # API layer
    ├── store/          # State management
    └── services/       # Business services

2. Low Coupling

Dependency Rules:

• Features should not depend on other features directly
• Use dependency injection for external dependencies
• Communicate through events/messages for loose coupling
• Define clear interfaces/contracts between modules

Anti-patterns to Avoid:

// ❌ Bad: Direct feature dependency
import { userService } from '../user/service';

// ✅ Good: Dependency injection
interface UserService {
  getUser(id: string): Promise<User>;
}

function createOrderService(userService: UserService) {
  // ...
}

3. Clean Comments

When to Comment:

• Complex algorithms that need explanation
• Non-obvious business logic or edge cases
• Workarounds for external library bugs
• Performance optimizations that look unusual

When NOT to Comment:

// ❌ Bad: Obvious comment
// Get user by id
function getUserById(id: string) { }

// ✅ Good: Self-documenting code
function getUserById(id: string) { }

// ✅ Good: Necessary comment
// Using setTimeout instead of requestIdleCallback due to Safari bug
// See: https://bugs.webkit.org/show_bug.cgi?id=12345
function scheduleWork(callback: () => void) {
  setTimeout(callback, 0);
}

Comment Style:

• Use JSDoc for public APIs
• Keep inline comments concise
• Explain "why", not "what"

4. No Auto-Generated Documentation

Prohibited:

• ❌ Auto-generating README after task completion
• ❌ Creating summary documents unprompted
• ❌ Writing changelog entries automatically

Allowed:

• ✅ Updating existing documentation when explicitly asked
• ✅ Adding JSDoc comments to public APIs
• ✅ Maintaining architecture graph (via scripts)

Architecture Graph System

Overview

The architecture graph maintains a machine-readable, LLM-friendly representation of your project's structure and relationships. This enables quick context understanding across conversation sessions.

Storage Location

<project-root>/
└── .arch/
    ├── graph.json          # Architecture graph data
    ├── modules.json        # Module definitions
    ├── dependencies.json   # Dependency relationships
    └── metadata.json       # Project metadata

Graph Format

The graph uses a simple, LLM-friendly JSON format:

{
  "modules": [
    {
      "id": "user-service",
      "name": "User Service",
      "path": "src/features/user/service.ts",
      "type": "service",
      "description": "Handles user authentication and profile management",
      "exports": ["UserService", "createUserService"],
      "responsibilities": [
        "User authentication",
        "Profile CRUD operations",
        "Session management"
      ]
    }
  ],
  "dependencies": [
    {
      "from": "order-service",
      "to": "user-service",
      "type": "uses",
      "description": "Validates user before creating order"
    }
  ],
  "dataFlow": [
    {
      "from": "api-handler",
      "to": "user-service",
      "data": "UserCredentials",
      "description": "Login request flow"
    }
  ]
}

Module Types

• service - Business logic services
• component - UI components
• utility - Helper functions
• type - Type definitions
• api - API endpoints
• store - State management
• hook - React hooks or similar
• middleware - Request/response processors

Relationship Types

• uses - Direct dependency
• extends - Inheritance
• implements - Interface implementation
• emits - Event emission
• listens - Event subscription
• calls - Function invocation

Scripts

Initialize Architecture System

bash scripts/init_arch.sh <project-root>

Creates .arch/ directory and initializes graph files.

Scan Project

bash scripts/scan_project.sh <project-root>

Automatically scans project and builds initial architecture graph by:

• Detecting file structure
• Parsing imports/exports
• Identifying module types
• Detecting common patterns

Add Module

bash scripts/add_module.sh <project-root> '<module-json>'

Example:

bash scripts/add_module.sh . '{
  "id": "auth-service",
  "name": "Authentication Service",
  "path": "src/core/auth/service.ts",
  "type": "service",
  "description": "Handles JWT token management",
  "exports": ["AuthService"],
  "responsibilities": ["Token generation", "Token validation"]
}'

Add Dependency

bash scripts/add_dependency.sh <project-root> '<dependency-json>'

Example:

bash scripts/add_dependency.sh . '{
  "from": "api-middleware",
  "to": "auth-service",
  "type": "uses",
  "description": "Validates JWT tokens on protected routes"
}'

Query Architecture

bash scripts/query_arch.sh <project-root> <query-type> [params]

Query types:

• module <module-id> - Get module details
• dependencies <module-id> - Get module dependencies
• dependents <module-id> - Get modules that depend on this
• path <file-path> - Get module by file path
• type <module-type> - Get all modules of type
• search <keyword> - Search modules by name/description

Show Architecture

bash scripts/show_arch.sh <project-root> [format]

Formats:

• summary - High-level overview (default)
• full - Complete graph
• mermaid - Mermaid diagram syntax
• tree - Tree structure

Validate Architecture

bash scripts/validate_arch.sh <project-root>

Checks for:

• Circular dependencies
• Missing modules
• Broken references
• Coupling violations

Workflow Integration

Starting a New Task

1. Load Architecture Context:

   bash scripts/show_arch.sh <project-root> summary
   

2. Query Relevant Modules:

   bash scripts/query_arch.sh <project-root> search "authentication"
   

3. Check Dependencies:

   bash scripts/query_arch.sh <project-root> dependencies auth-service
   

4. Apply Standards: Follow modular design principles

5. Update Graph: After creating new modules

   bash scripts/add_module.sh <project-root> '<module-json>'
   bash scripts/add_dependency.sh <project-root> '<dependency-json>'
   

Code Review Checklist

Before completing any task, verify:

• File length < 300 lines
• Function length < 50 lines
• No direct feature-to-feature dependencies
• Comments explain "why", not "what"
• Reusable logic extracted to shared modules
• Architecture graph updated
• No circular dependencies
• Clear module responsibilities

Auto-Apply Standards

When this skill is active, automatically:

1. Check File Length: Warn if file exceeds 300 lines
2. Suggest Splits: Recommend module extraction for long files
3. Detect Coupling: Identify direct feature dependencies
4. Review Comments: Flag obvious or unnecessary comments
5. Update Graph: Prompt to update architecture after changes

Best Practices

Naming Conventions

// Files: kebab-case
user-service.ts
auth-middleware.ts

// Functions: camelCase, verb prefix
getUserById()
validateToken()
createOrder()

// Classes: PascalCase, noun
class UserService {}
class OrderRepository {}

// Constants: UPPER_SNAKE_CASE
const MAX_RETRY_COUNT = 3;
const API_BASE_URL = '...';

// Types/Interfaces: PascalCase
interface User {}
type OrderStatus = 'pending' | 'completed';

Module Organization

// index.ts - Public API only
export { UserService } from './service';
export type { User, UserProfile } from './types';

// types.ts - Type definitions
export interface User {
  id: string;
  name: string;
}

// service.ts - Implementation
import type { User } from './types';
import { validateUser } from './utils';

export class UserService {
  // Implementation
}

// utils.ts - Internal utilities (not exported from index)
export function validateUser(user: User): boolean {
  // Validation logic
}

Dependency Management

// ✅ Good: Interface-based dependency
interface Logger {
  log(message: string): void;
}

class UserService {
  constructor(private logger: Logger) {}
}

// ✅ Good: Factory pattern
function createUserService(deps: {
  logger: Logger;
  db: Database;
}) {
  return new UserService(deps);
}

// ❌ Bad: Direct import of concrete implementation
import { ConsoleLogger } from '../logging/console-logger';
class UserService {
  private logger = new ConsoleLogger();
}

Integration with Dev Workflow Skill

This skill complements dev_workflow_skill:

• dev_workflow_skill: Manages tasks, testing, commits, deployment
• dev_standards_skill: Ensures code quality and maintains architecture

Use together:

1. Start task with /dev_workflow_skill
2. Apply standards from dev_standards_skill during development
3. Update architecture graph as you build
4. Complete task with workflow skill's CI/CD automation

Quick Reference

# Initialize
bash scripts/init_arch.sh .

# Scan existing project
bash scripts/scan_project.sh .

# Show architecture
bash scripts/show_arch.sh . summary

# Query specific module
bash scripts/query_arch.sh . module user-service

# Add new module
bash scripts/add_module.sh . '<module-json>'

# Add dependency
bash scripts/add_dependency.sh . '<dependency-json>'

# Validate
bash scripts/validate_arch.sh .

Language Support

Works with any language:

• TypeScript/JavaScript (Node.js, React, Vue, etc.)
• Python (Django, Flask, FastAPI, etc.)
• Go (standard library, frameworks)
• Rust (Cargo projects)
• Java/Kotlin (Maven, Gradle)
• C/C++ (CMake, Make)
• Ruby (Rails, Sinatra)
• PHP (Laravel, Symfony)
• And more...

Standards are language-agnostic:

• File length limits apply to all languages
• Modular design principles are universal
• Low coupling strategies work everywhere
• Comment guidelines adapt to language conventions

Dependencies

Automatic detection - scripts will use whichever is available:

1. jq (preferred) - Fast JSON processor
2. Python 3 (fallback) - Usually pre-installed
3. Python 2 (fallback) - Legacy support

No installation required if you have Python!

If neither is available:

# Install jq (recommended)
brew install jq              # macOS
sudo apt-get install jq      # Ubuntu
choco install jq             # Windows

# Or install Python
# https://www.python.org/downloads/

Getting Started

Quick Setup (3 commands)

# 1. Initialize
bash scripts/init_arch.sh .

# 2. Scan project (auto-detects language/framework)
bash scripts/scan_project.sh .

# 3. View architecture
bash scripts/show_arch.sh . summary

Add Your First Module

bash scripts/add_module.sh . '{
  "id": "user-service",
  "name": "User Service",
  "path": "src/features/user/service.ts",
  "type": "service",
  "description": "Handles user operations",
  "exports": ["UserService"],
  "responsibilities": ["User CRUD", "Authentication"]
}'

Important Notes

• Architecture graph is maintained by scripts, not manually edited
• Graph format is optimized for LLM understanding
• Works with any programming language
• Automatically uses jq or Python (no manual setup needed)
• Run scan_project.sh to auto-detect project type
• Update graph immediately after creating new modules
• Use validate_arch.sh to catch architectural issues early
• Standards are enforced during development, not after

References

Detailed guides in references/ directory (loaded on demand):

• modular-design.md - Module organization patterns
• low-coupling.md - Decoupling strategies
• clean-comments.md - Comment best practices
• architecture-graph.md - Graph system details
• quickstart.md - 5-minute tutorial
• examples.md - Real-world usage examples