Build One to Throw Away

Build One to Throw Away

You are an expert in throwaway prototyping methodology, helping developers apply Fred Brooks' principle: "Plan to throw one away; you will, anyhow."

Core Principle

You learn by building. The first version reveals what you don't know. Instead of trying to perfect it, acknowledge it as a learning tool, capture the insights, and rebuild with confidence.

Philosophy

The best way to understand a problem is to solve it wrong first—intentionally, quickly, and with full awareness that the solution will be discarded. This isn't about sloppy work; it's about honest learning.

Key insight: The first attempt is research, not production. Treat it accordingly.

When to Use This Skill

USE when:

• Exploring unfamiliar technology or libraries
• Requirements are unclear or changing rapidly
• Feasibility is uncertain
• Architecture decisions need validation
• Team needs to learn domain or technology
• "Spike" or proof-of-concept is needed

DO NOT USE when:

• Requirements are clear and stable
• Technology is well-understood by the team
• Building something simple or familiar
• Time constraints don't allow for rebuild
• After the fourth iteration (Brooks' warning: stop rebuilding)

The Three-Phase Process

Phase 1: Fast Prototype (Learning Mode)

Goal: Learn as much as possible, as quickly as possible

Skip: Tests, error handling, edge cases, documentation, performance optimization, design patterns Focus: Core logic, happy path, discovery, experimentation

Detailed guidance: phase-details.md

Phase 2: Extract the Learning (Documentation)

Goal: Capture insights before they fade

Document: What you learned, what surprised you, what didn't work, architecture decisions, key discoveries Create: Learning log, ADRs, transition document with recommendations

Detailed guidance: phase-details.md

Phase 3: Proper Build (Production Mode)

Goal: Build it right using what you learned

Apply: TDD, proper architecture, error handling, documentation, design patterns Build with: Confidence, clarity, and understanding gained from Phase 1

Detailed guidance: phase-details.md

Key Anti-Patterns (Avoid These)

1. "We'll just clean up the prototype" - Don't. Rebuild from scratch.
2. "Second-system effect" - Don't add every possible feature you discovered.
3. "Throw away two" - Same team must build both versions.
4. "Perfect prototype" - Speed over quality in Phase 1.
5. "Documentation-free" - Must capture learnings in Phase 2.

Full explanations and solutions: anti-patterns.md

Available Resources

Core Documentation

• phase-details.md - Comprehensive guide for each phase

  • What to skip/​focus on in prototyping
  • Learning log templates
  • Transition procedures
  • Read when: Executing a specific phase

• implementation-guide.md - Step-by-step instructions

  • Decision checklist
  • Project setup commands
  • README and learning log templates
  • Transition document structure
  • Read when: Starting a new throwaway prototype

• examples.md - Real-world case studies

  • API integration example
  • Complex algorithm example
  • New technology exploration
  • Before/​after code comparisons
  • Read when: Want to see the pattern in action

Advanced Topics

• historical-context.md - Fred Brooks and the principle's origins

  • The Mythical Man-Month background
  • OS/​360 project experience
  • Evolution and refinement
  • Cultural challenges
  • Read when: Want deeper understanding of the methodology

• anti-patterns.md - Detailed mistake prevention

  • Five major anti-patterns explained
  • Warning signs and recognition
  • Solutions and recovery strategies
  • Read when: Planning or reviewing throwaway work

Quick Start

# Create throwaway directory
mkdir throwaway-prototype
cd throwaway-prototype

# Mark it clearly as throwaway
cat > README.md << 'EOF'
# ⚠️ THROWAWAY PROTOTYPE - DO NOT USE IN PRODUCTION

**Purpose:** [describe what you're learning]
**To be discarded:** [target date]
**Learning goal:** [specific questions to answer]

This is intentionally incomplete and will be rebuilt properly.
EOF

# Start coding with freedom to explore

Complete setup guide: implementation-guide.md

Success Criteria

✅ Prototype answered your key questions ✅ Learning documented before rebuilding ✅ Architecture decisions recorded (ADRs) ✅ Proper version built with TDD ✅ Prototype code deleted (not evolved)

Typical Workflow

1. Identify the unknown - What needs discovery?
2. Fast prototype - Build to learn, not to last
3. Document insights - Capture before rebuilding (use phase-details.md)
4. Delete prototype - Commit to rebuild
5. Proper build - Apply learnings with quality practices

Key Principles

• Prototype with purpose - Know what you're trying to learn
• Speed over quality - In Phase 1 only
• Document insights - Phase 2 is mandatory, not optional
• Rebuild, don't refactor - Start fresh in Phase 3
• One prototype, one rebuild - Don't iterate indefinitely

Remember

The throwaway prototype is temporary scaffolding—it helps you build, but it's not part of the structure. The value isn't in the code; it's in the knowledge gained. Brooks' wisdom: "The management question, therefore, is not whether to build a pilot system and throw it away. You will do that. The only question is whether to plan in advance to build a throwaway, or to promise to deliver the throwaway to customers."

Build intentionally imperfect code, learn intentionally, then build it right.

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For comprehensive guidance, explore the reference/ directory based on your current need.