{folder}/
├── CLAUDE.md           # Context for this folder (100-200 lines)
└── subfolder/
    └── CLAUDE.md       # Context for subfolder (if needed)

# {Folder Name}

{One-sentence description of purpose}

## Overview

{2-3 sentences explaining what this folder contains and why}

## Structure

| Path | Purpose |
|------|---------|
| `file.py` | Description |
| `subfolder/` | Description |

## Key Concepts

- **Concept1**: Explanation
- **Concept2**: Explanation

## Entry Points

- `main_file.py` — Primary entry point
- `config.py` — Configuration

## Common Operations

### Operation 1
```bash
command example

## Type-Specific Sections

### Backend (Django/FastAPI/etc.)
```markdown
## Models
| Model | Purpose |
|-------|---------|
| **User** | User accounts |

## Services
| Service | Purpose |
|---------|---------|
| `create_user()` | Creates new user |

## API Endpoints
| Method | Path | Purpose |
|--------|------|---------|
| POST | `/api/users/` | Create user |

## Components
| Component | Purpose |
|-----------|---------|
| `Button` | Reusable button |

## State Management
- Store location: `src/store/`
- Pattern: Redux/Context/etc.

## Routing
| Route | Component | Purpose |
|-------|-----------|---------|
| `/home` | HomePage | Landing |

## Resources
| Resource | Purpose |
|----------|---------|
| `deployment.yaml` | App deployment |

## Environments
| Env | Description |
|-----|-------------|
| dev | Development |
| prod | Production |

## Commands
```bash
kubectl apply -f deployment.yaml

### Library/Package
```markdown
## Public API
| Function/Class | Purpose |
|----------------|---------|
| `parse()` | Parse input |

## Usage
```python
from package import parse
result = parse(data)

## Size Guidelines

- Target: 100-150 lines
- Maximum: 200 lines
- If larger needed → split to subfolders with own CLAUDE.md

## What to Include

- Purpose and context
- Key files and their roles
- Important concepts
- Common operations
- Dependencies

## What NOT to Include

- Full code listings (reference files instead)
- Duplicated parent context
- Temporary/generated files
- Obvious information

## Checklist

- [ ] Purpose clear in first 3 lines
- [ ] Structure table present
- [ ] Key concepts explained
- [ ] Entry points identified
- [ ] Line count within limits