Extreme Programming (XP) Practices

<default_to_action> When applying XP practices:

1. START with practices that give immediate value
2. BUILD supporting practices gradually
3. ADAPT to your context
4. MEASURE results

Core XP Practices (Prioritized):

Practice	Start Here	Why First
TDD	✅ Yes	Foundation for everything
Continuous Integration	✅ Yes	Fast feedback
Pair Programming	✅ Yes	Knowledge sharing
Collective Ownership	After CI+TDD	Needs safety net
Small Releases	After CI	Infrastructure dependent

Pairing Quick Start:

Driver-Navigator (Classic):
- Driver: Writes code
- Navigator: Reviews, thinks ahead
- Rotate every 20-30 min

Ping-Pong (with TDD):
A: Write failing test
B: Make test pass + refactor
B: Write next failing test
A: Make test pass + refactor

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Quick Reference Card

The Five XP Values

Value	Meaning	Practice
Communication	Everyone knows what everyone does	Daily standups, pairing
Simplicity	Simplest thing that works	YAGNI, small design
Feedback	Get feedback early and often	TDD, CI, short iterations
Courage	Tell truth, adapt	Refactor, admit mistakes
Respect	Everyone contributes value	Sustainable pace, pairing

Core Practices

Practice	Description	Benefit
Pair Programming	Two devs, one workstation	Quality + knowledge sharing
TDD	Red-Green-Refactor	Confidence + design
CI	Integrate multiple times/day	Fast feedback
Collective Ownership	Anyone can change anything	No bottlenecks
Sustainable Pace	40-hour weeks	Long-term productivity
Small Releases	Ship frequently	Risk reduction

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Pair Programming

When to Pair

Context	Pair?	Why
Complex/risky code	✅ Always	Needs multiple perspectives
New technology	✅ Always	Learning accelerator
Onboarding	✅ Always	Knowledge transfer
Critical bugs	✅ Always	Two heads better
Simple tasks	❌ Skip	Not worth overhead
Research spikes	❌ Skip	Pair to discuss findings

Pairing Dos and Don'ts

Do:

• ✅ Switch roles every 20-30 min
• ✅ Take breaks together
• ✅ Think out loud
• ✅ Ask questions
• ✅ Keep sessions 2-4 hours max

Don't:

• ❌ Grab keyboard without asking
• ❌ Check phone while pairing
• ❌ Dominate conversation
• ❌ Pair all day (exhausting)

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Ensemble (Mob) Programming

Setup: 3+ developers, one screen, rotating driver

[Screen]
   ↓
[Driver] ← Directions from navigators
   ↑
[Navigator 1] [Navigator 2] [Navigator 3]

Rotation: Driver switches every 5-10 min

Best for:

• Complex problem solving
• Architectural decisions
• Learning new frameworks
• Resolving blockers

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Continuous Integration

CI Workflow:

1. Pull latest from main
2. Make small change (<2 hrs work)
3. Run tests locally (all pass)
4. Commit and push
5. CI runs tests automatically
6. If fail → fix immediately

Best Practices:

• Commit frequently (small changes)
• Keep build fast (<10 min)
• Fix broken builds immediately
• Never commit to broken build

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Four Rules of Simple Design

(In priority order)

1. Passes all tests - Works correctly
2. Reveals intention - Clear, expressive code
3. No duplication - DRY principle
4. Fewest elements - No speculative code

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Agent Integration

// Agent-human pair testing
const charter = "Test payment edge cases";
const tests = await Task("Generate Tests", { charter }, "qe-test-generator");
const reviewed = await human.review(tests);
await Task("Implement", { tests: reviewed }, "qe-test-generator");

// Continuous integration with agents
await Task("Risk Analysis", { prDiff }, "qe-regression-risk-analyzer");
await Task("Generate Tests", { changes: prDiff }, "qe-test-generator");
await Task("Execute Tests", { scope: 'affected' }, "qe-test-executor");

// Sustainable pace: agents handle grunt work
const agentWork = ['regression', 'data-generation', 'coverage-analysis'];
const humanWork = ['exploratory', 'risk-assessment', 'strategy'];

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Agent Coordination Hints

Memory Namespace

aqe/xp-practices/
├── pairing-sessions/*   - Pair/ensemble session logs
├── ci-metrics/*         - CI health metrics
├── velocity/*           - Team velocity data
└── retrospectives/*     - XP retrospective notes

Fleet Coordination

const xpFleet = await FleetManager.coordinate({
  strategy: 'xp-workflow',
  agents: [
    'qe-test-generator',   // TDD support
    'qe-test-executor',    // CI integration
    'qe-code-reviewer'     // Collective ownership
  ],
  topology: 'parallel'
});

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Common Objections

Objection	Response
"Pairing is 2x slower"	15% slower writing, 15% fewer bugs, net positive
"No time for TDD"	Debugging takes longer than testing
"CI is hard to setup"	Start simple: one action, one test
"Collective ownership = chaos"	Only without tests + CI

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Related Skills

• tdd-london-chicago - TDD deep dive
• refactoring-patterns - Safe refactoring
• pair-programming - AI-assisted pairing

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Remember

XP practices work as a system. Don't cherry-pick randomly:

• TDD enables collective ownership
• CI enables small releases
• Pairing enables collective ownership
• Sustainable pace enables everything

With Agents: Agents amplify XP. Pair humans with agents. Agents handle repetitive work, humans provide judgment and creativity.