Create Rule

Create Rules

This skill helps you develop effective Claude Code rules. Rules are markdown files in .claude/rules/ that provide persistent instructions Claude follows during a session.

Rule Basics

What Rules Are For

• Coding standards and conventions
• Project-specific guidelines
• Language or framework patterns
• Prohibited practices
• Style preferences

What Rules Are NOT For

• One-time instructions (just tell Claude directly)
• Dynamic content (use commands/skills instead)
• Tool configurations (use hooks)

Rule Structure

Basic Template

# Rule Name

Brief description of what this rule enforces.

## Section 1

Clear, actionable guidelines.

## Section 2

Examples showing good vs bad patterns.

## Checklist (optional)

- [ ] Quick verification items

Key Principles

1. Be Specific - Vague rules get ignored
2. Show Examples - Good vs bad patterns are clearer than descriptions
3. Stay Focused - One topic per rule file
4. Be Actionable - Rules should guide decisions

Rule Types

Standards Rules

Define coding standards for a language or framework:

# TypeScript Standards

## Naming Conventions

| Type | Convention | Example |
|------|------------|---------|
| Interfaces | PascalCase with I prefix | `IUserService` |
| Types | PascalCase | `UserResponse` |
| Constants | UPPER_SNAKE | `MAX_RETRIES` |

## Preferred Patterns

### Use type inference when obvious

```typescript
// Good - type is obvious
const count = 0;

// Bad - redundant
const count: number = 0;

### Prohibited Rules

List things to avoid:

```markdown
# Prohibited Patterns

## Never Use

### 1. any type

```typescript
// Bad
function process(data: any) { ... }

// Good
function process(data: unknown) { ... }

2. Non-null assertions without checks

// Bad
const name = user!.name;

// Good
if (user) {
  const name = user.name;
}

Quick Checklist

• No any types
• No ! assertions without guards
• No @ts-ignore without comments

### Style Rules

Define formatting and style preferences:

```markdown
# Code Style

## Imports

Order imports in these groups, separated by blank lines:
1. Node built-ins
2. External packages
3. Internal modules
4. Relative imports

## Comments

- Explain WHY, not WHAT
- No commented-out code in commits
- Use JSDoc for public APIs only

## Formatting

- Max line length: 100 characters
- Use trailing commas in multiline
- Prefer template literals over concatenation

Architecture Rules

Define structural patterns:

# Service Layer Architecture

## Structure

src/ services/ user/ user.service.ts # Business logic user.repository.ts # Data access user.types.ts # Types and interfaces index.ts # Public exports

## Patterns

### Services depend on repositories, never the reverse

```typescript
// Good
class UserService {
  constructor(private repo: UserRepository) {}
}

// Bad - repository importing service
class UserRepository {
  constructor(private service: UserService) {} // NO!
}

## Best Practices

### DO

- Use tables for quick reference
- Include code examples for every guideline
- Group related items together
- Provide a checklist at the end
- Keep rules under 200 lines

### DON'T

- Write walls of text
- Be vague ("write good code")
- Include too many topics in one file
- Repeat what's in other rules
- Use rules for documentation

## Adding Rules to Templates

To contribute a rule to rbw-claude-code:

1. Create the rule in `templates/rules/` or a subdirectory
2. Follow the structure of existing rules
3. Update the README in that directory
4. Test by symlinking to a project

### Directory Structure

templates/rules/ ├── python/ # Python-specific rules │ ├── README.md │ ├── asyncio.md │ └── ... ├── typescript/ # TypeScript rules (create if needed) │ └── ... ├── anti-slop.md # General rules at root └── README.md # Overview of all rules

## Testing Your Rule

1. Create the rule in your project's `.claude/rules/`
2. Start a new Claude Code session
3. Ask Claude to do something the rule addresses
4. Verify Claude follows the rule
5. Iterate on wording if needed

## Templates

Ready-to-use templates are available in:

${CLAUDE_PLUGIN_ROOT}/skills/create-rule/templates/

- `standards.md` - Coding standards template
- `prohibited.md` - Prohibited patterns template
- `style.md` - Style guide template