• Key premise: Code churn patterns reveal developer archetypes with predictable quality outcomes
• Novel insight: AI coding assistants exhibit statistical twins of "rogue developer" patterns (r=0.92)
• Technical risk: This correlation suggests potential widespread defect introduction in AI-augmented teams

• Definition: Measure of how frequently a file changes over time (adds, modifications, deletions)
• Quality correlation: High relative churn strongly predicts defect density (~89% accuracy)
• Measurement: Most predictive as ratio of churned LOC to total LOC
• Research source: Microsoft studies demonstrating relative churn as superior defect predictor

Consistent developer pattern:

• ~25% active ratio spread evenly (e.g., Linus Torvalds, Guido van Rossum)
• <10% relative churn with strategic, minimal changes
• 4-5× fewer defects than project average
• Key metric: Low M1 (Churned LOC/Total LOC)

Average developer pattern:

• 15-20% active ratio (sprint-aligned)
• Moderate churn (10-20%) with balanced feature/maintenance focus
• Follows team workflows and standards
• Key metric: Mid-range values across M1-M8

Junior developer pattern:

• Sporadic commit patterns with frequent gaps
• High relative churn (~30%) approaching danger threshold
• Experimental approach with frequent complete rewrites
• Key metric: Elevated M7 (Churned LOC/Deleted LOC)

Rogue developer pattern:

• Night/weekend work bursts with low consistency
• Very high relative churn (>35%)
• Working in isolation, avoiding team integration
• Key metric: Extreme M6 (Lines/Weeks of churn)

AI developer pattern:

• Spontaneous productivity bursts with zero continuity
• Extremely high output volume per contribution
• Significant code rewrites with inconsistent styling
• Key metric: Off-scale M8 (Lines worked on/Churn count)
• Critical finding: Statistical twin of rogue developer pattern

Exponential vs. linear development approaches:

• Continuous improvement requires linear, incremental changes
• Massive code bursts create defect debt regardless of source (human or AI)

CI/CD considerations:

• High churn + weak testing = "cargo cult DevOps"
• Particularly dangerous with dynamic languages (Python)
• Continuous improvement should decrease defect rates over time

1. Treat AI-generated code with same scrutiny as rogue developer contributions
2. Limit AI-generated code volume to minimize churn
3. Implement incremental changes rather than complete rewrites
4. Establish relative churn thresholds as quality gates
5. Pair AI contributions with consistent developer reviews

The optimal application of AI coding tools should mimic consistent developer patterns: minimal, targeted changes with low relative churn - not massive spontaneous productivity bursts that introduce hidden technical debt.

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