claude-flow-depth/src/templates/docs/DEPTH_GUIDE.md

DEPTH Methodology Installer - Ousterhout-First Development for Claude Code

# DEPTH Methodology Guide

This project implements the DEPTH methodology - an Ousterhout-first approach to software development.

## What is DEPTH?

**DEPTH** stands for:
- **D**esign-Twice: Always create two design alternatives
- **E**liminate complexity: Simplify interfaces ruthlessly  
- **P**ull complexity down: Push complexity into modules
- **T**rade-off documentation: 10-20% strategic investment
- **H**ide implementation: Maximum information hiding

## Core Principles

### 1. Deep Modules
Create modules with simple interfaces but rich functionality.

**Good Example:**
```javascript
// Simple interface
logger.info('User logged in', { userId: 123 });

// Hides complex implementation:
// - Formatting logic
// - Output routing
// - Level checking
// - Timestamp handling
```

### 2. Information Hiding
Hide implementation details from module users.

**Good Example:**
```javascript
// Public interface - simple
const app = await createApp();
await app.start();

// Hidden complexity:
// - Service initialization
// - Configuration loading
// - Error handling
// - State management
```

### 3. Strategic Investment
Dedicate 10-20% of development time to long-term improvements.

**Examples:**
- Refactoring for better abstractions
- Improving documentation
- Building reusable tools
- Architecture improvements

## Using DEPTH Commands

### Complete Workflow
```bash
# Run full DEPTH methodology
npm run depth
```

### Individual Phases
```bash
# Phase 1: Create design alternatives
npm run depth:design

# Phase 2: Simplify interfaces
npm run depth:simplify

# Phase 3: Allocate complexity
npm run depth:allocate

# Phase 4: Plan strategic investment
npm run depth:invest

# Phase 5: Hide implementation
npm run depth:hide
```

## Quality Gates

Each phase has specific quality requirements:

### Design-Twice Phase
- [ ] Two distinct design alternatives created
- [ ] Trade-off analysis completed
- [ ] Decision documented with rationale

### Interface Simplification Phase
- [ ] Interface complexity < 0.4
- [ ] Simplified interfaces maintain functionality
- [ ] Usage examples demonstrate simplicity

### Complexity Allocation Phase
- [ ] Complexity pushed into modules
- [ ] Information hiding strategy defined
- [ ] Module boundaries clearly defined

### Strategic Investment Phase
- [ ] Strategic investment 10-20% of time
- [ ] Long-term implications assessed
- [ ] Technical debt plan created

### Implementation Hiding Phase
- [ ] Implementation details hidden
- [ ] Comments explain design decisions
- [ ] Code follows information hiding principles

## Best Practices

### 1. Interface Design
- Keep public APIs minimal
- Hide complex parameters
- Use sensible defaults
- Provide clear abstractions

### 2. Module Organization
- One responsibility per module
- Simple interfaces, complex implementations
- Clear boundaries between modules
- Minimize inter-module dependencies

### 3. Code Documentation
- Explain design decisions, not implementation
- Document trade-offs and alternatives considered
- Focus on why, not what
- Keep comments up-to-date with code

### 4. Strategic Thinking
- Regularly assess long-term architecture
- Invest in tools and abstractions
- Consider future maintenance costs
- Plan for scalability early

## Common Anti-Patterns

### ❌ Shallow Modules
```javascript
// Bad: Simple interface, simple implementation
function add(a, b) {
  return a + b;
}
```

### ❌ Information Leakage
```javascript
// Bad: Exposing internal structure
class Database {
  constructor() {
    this.connection = mysql.createConnection(...);
    this.queryCache = new Map();
  }
}
```

### ❌ Complex Interfaces
```javascript
// Bad: Too many parameters, complex options
function processData(data, format, validation, transform, output, options) {
  // Complex interface
}
```

## Measuring Success

### Module Depth Ratio
Target: > 0.6
```
Depth = Implementation_Complexity / Interface_Complexity
```

### Interface Complexity Score
Target: < 0.4
```
Complexity = (Parameters + Methods + Options) / Total_Functionality
```

### Strategic Investment Percentage
Target: 10-20%
```
Strategic_Time / Total_Development_Time
```

### Information Hiding Effectiveness
Target: > 80%
```
Hidden_Details / Total_Implementation_Details
```

## Integration with Claude Flow

DEPTH methodology integrates with Claude Flow for:
- **Automated quality checking**
- **Design alternative generation**
- **Complexity analysis**
- **Strategic planning assistance**

Use Claude Flow commands for enhanced DEPTH execution:
```bash
# Initialize coordinated DEPTH session
npx claude-flow@alpha swarm init --methodology depth

# Spawn DEPTH-aware agents
npx claude-flow@alpha agent spawn --type architect --depth-mode true
```

## Resources

- [John Ousterhout's "A Philosophy of Software Design"](https://web.stanford.edu/~ouster/cgi-bin/book.php)
- [DEPTH Methodology Paper](https://github.com/ruvnet/claude-flow)
- [Claude Flow Documentation](https://github.com/ruvnet/claude-flow)