# Track usage
tracker = SkillTracker("my-skill")
tracker.log_usage(task, result)

# Analyze failures
issues = tracker.analyze_failures()

# Polish and measure
improvement = measure_evolution(before_version, after_version)

CREATE (v1.0.0) → USE (track) → ANALYZE (failures) → 
POLISH (v1.1.0) → MEASURE (impact) → REPEAT

mkdir -p .claude/skills/my-skill

# Generate SKILL.md with skill-bootstrap
cat > .claude/skills/my-skill/SKILL.md << 'EOF'
---
name: my-skill
description: ...
---
# My Skill
[Initial implementation]
EOF

git add .claude/skills/my-skill
git commit -m "feat: add my-skill capability (v1.0.0)"

import json
from datetime import datetime

class SkillTracker:
    def __init__(self, skill_name):
        self.skill_name = skill_name
        self.log_file = f".claude/skills/{skill_name}/usage.json"
    
    def log_usage(self, task, success, issues=None, feedback=None):
        entry = {
            'timestamp': datetime.now().isoformat(),
            'task': task,
            'success': success,
            'issues': issues or [],
            'feedback': feedback
        }
        
        try:
            with open(self.log_file, 'r') as f:
                logs = json.load(f)
        except FileNotFoundError:
            logs = []
        
        logs.append(entry)
        
        with open(self.log_file, 'w') as f:
            json.dump(logs, f, indent=2)
    
    def get_consistency(self):
        try:
            with open(self.log_file, 'r') as f:
                logs = json.load(f)
            if not logs:
                return 0.0
            successes = sum(1 for log in logs if log['success'])
            return successes / len(logs)
        except FileNotFoundError:
            return 0.0

tracker = SkillTracker("csv-to-json")

# After each usage
tracker.log_usage(
    task="Transform users.csv to JSON",
    success=True,
    feedback="Worked perfectly"
)

# Or on failure
tracker.log_usage(
    task="Transform products.csv to JSON",
    success=False,
    issues=["encoding_error", "missing_fields"],
    feedback="Failed on UTF-16 encoding"
)

def analyze_failures(skill_name):
    tracker = SkillTracker(skill_name)
    
    with open(tracker.log_file, 'r') as f:
        logs = json.load(f)
    
    failures = [log for log in logs if not log['success']]
    
    # Group by issue type
    issues_by_type = {}
    for failure in failures:
        for issue in failure['issues']:
            if issue not in issues_by_type:
                issues_by_type[issue] = []
            issues_by_type[issue].append(failure)
    
    return issues_by_type

encoding_errors: 3 occurrences
missing_fields: 5 occurrences
malformed_csv: 2 occurrences

# Analyze
python analyze_skill.py csv-to-json
# → missing_fields: 5 occurrences (highest priority)

## Error Handling

### Missing Fields
Validate against schema and provide defaults:

```python
required_fields = ['id', 'name', 'email']
for field in required_fields:
    if field not in df.columns:
        df[field] = None

Commit as part of regular work:

```bash
git add .claude/skills/csv-to-json/SKILL.md
git commit -m "feat: add product import endpoint
- Implement import logic
- Update csv-to-json skill with missing field handling"

def measure_evolution(skill_name, before_ref, after_ref):
    """
    Compare skill performance before and after polishing
    """
    # Load logs from git history or separate tracking
    before_logs = load_logs(skill_name, before_ref)
    after_logs = load_logs(skill_name, after_ref)
    
    before_consistency = calculate_consistency(before_logs)
    after_consistency = calculate_consistency(after_logs)
    
    improvement = ((after_consistency - before_consistency) / 
                   before_consistency * 100)
    
    return {
        'before': before_consistency,
        'after': after_consistency,
        'improvement_percent': improvement
    }

# MAJOR: Breaking changes
git commit -m "feat!: change required fields (BREAKING)"
# Tag: my-skill-v2.0.0

# MINOR: New features, backwards compatible
git commit -m "feat: add Excel support"
# Tag: my-skill-v1.2.0

# PATCH: Bug fixes, polishing
git commit -m "fix: handle empty CSV files"
# Tag: my-skill-v1.1.1

name: csv-to-json
description: Transform CSV to JSON