Project Conventions

This skill guides you in discovering and applying project-specific conventions. Every codebase has its own patterns and practices - your job is to find them and follow them.

Convention Discovery Process

Step 1: Project Configuration

Check these files for explicit conventions:

Code Style:

• .eslintrc*, eslint.config.* - JavaScript/TypeScript linting rules
• .prettierrc*, prettier.config.* - Formatting rules
• pyproject.toml, setup.cfg, .flake8 - Python config
• .editorconfig - Editor settings
• ruff.toml, .ruff.toml - Ruff linter config

Project Structure:

• tsconfig.json - TypeScript paths and settings
• package.json - Scripts, dependencies
• pyproject.toml - Python project config

Documentation:

• CONTRIBUTING.md - Contribution guidelines
• CLAUDE.md - AI coding guidelines
• README.md - Project overview
• docs/ - Extended documentation

Step 2: Existing Code Patterns

Study the codebase to find implicit conventions:

File Organization:

# Find how components are organized
ls -la src/components/

# Find test file patterns
find . -name "*.test.*" -o -name "*_test.*" -o -name "test_*"

# Find how utilities are organized
ls -la src/utils/ src/lib/ src/helpers/

Naming Patterns:

# Find function naming patterns
grep -r "^export function" src/ | head -20
grep -r "^def " src/ | head -20

# Find class naming patterns
grep -r "^export class" src/ | head -20
grep -r "^class " src/*.py | head -20

Import Patterns:

# Find import style (absolute vs relative)
grep -r "^import" src/ | head -30
grep -r "^from \." src/*.py | head -20

Step 3: Similar Features

Find features similar to what you're building:

1. Search for similar functionality:

   # If building a "user profile" feature
   grep -r "profile" src/
   find . -name "*profile*"

1. Study the implementation:

• How is it structured?
• What patterns does it use?
• How does it handle errors?
• How is it tested?

1. Note the patterns:

• Component structure
• State management approach
• API call patterns
• Validation approach

Common Convention Areas

Naming Conventions

Discover by example:

# Function names
grep -E "^(export )?(async )?function " src/**/*.ts

# Variable names
grep -E "^(const|let|var) " src/**/*.ts

# Component names
grep -E "^(export )?function [A-Z]" src/**/*.tsx

Common patterns:

• camelCase for functions/variables
• PascalCase for components/classes
• UPPER_SNAKE for constants
• kebab-case for file names (some projects)
• snake_case for file names (Python)

File Structure

Discover the pattern:

# Component structure
ls -la src/components/Button/

# Module structure
ls -la src/features/auth/

Common patterns:

Flat structure:

components/
  Button.tsx
  Button.test.tsx
  Button.styles.ts

Folder per component:

components/
  Button/
    index.ts
    Button.tsx
    Button.test.tsx
    Button.module.css

Feature-based:

features/
  auth/
    components/
    hooks/
    api.ts
    types.ts

Error Handling

Discover the pattern:

# Find try-catch patterns
grep -A5 "try {" src/**/*.ts

# Find error types
grep -r "extends Error" src/

# Find error handling in API
grep -r "catch" src/api/

Apply what you find:

• Use the same error types
• Follow the same handling pattern
• Match logging approach

Testing Patterns

Discover the pattern:

# Find test structure
head -50 src/**/*.test.ts

# Find test utilities
cat src/test/setup.ts
cat src/test/utils.ts

Match the patterns:

• Test file location (co-located vs separate)
• Naming convention (*.test.ts vs *.spec.ts)
• Setup and teardown approach
• Mocking strategy
• Assertion style

API Patterns

Discover the pattern:

# Find API call patterns
grep -r "fetch\|axios\|api\." src/

# Find API response handling
grep -A10 "async function fetch" src/api/

Match the patterns:

• How are endpoints defined?
• How is authentication handled?
• What's the error format?
• How are responses typed?

Convention Application Checklist

When implementing a feature, verify you're following conventions for:

Code Style

• [ ] Variable naming matches existing code
• [ ] Function naming matches existing code
• [ ] File naming follows project pattern
• [ ] Import style matches (absolute vs relative)

Structure

• [ ] File location follows project structure
• [ ] Component organization matches
• [ ] Export style matches (default vs named)

Patterns

• [ ] Error handling follows project patterns
• [ ] Async patterns match existing code
• [ ] State management follows project approach
• [ ] API calls follow established patterns

Testing

• [ ] Test file location is correct
• [ ] Test naming follows convention
• [ ] Test structure matches existing tests
• [ ] Mocking approach is consistent

Documentation

• [ ] Comments follow existing style
• [ ] JSDoc/docstrings match project
• [ ] README updates if needed

When Conventions Conflict

Sometimes you'll find inconsistent patterns:

1. Prefer newer code - Recent files often reflect current team preferences
2. Prefer maintained code - Active parts of the codebase reflect current practices
3. Prefer documented conventions - Explicit rules in configs override implicit patterns
4. Ask if unclear - When in doubt, ask the user which pattern to follow

Red Flags

Watch for these signs that you might be breaking conventions:

• Your code looks very different from surrounding code
• You're using a library/pattern not used elsewhere
• Your file structure doesn't match siblings
• Your naming feels inconsistent with the codebase
• Linting errors (the project has explicit rules you're breaking)

When you notice these, stop and investigate the existing conventions more carefully.