Claude Code Refactoring Assistant Prompt

CODE SMELL ANALYSIS:
🔴 CRITICAL — God Function: processUserData() is 200 lines doing 8 different things. Single Responsibility violation.
🟡 MEDIUM — Magic Numbers: Constants like 0.15, 86400 scattered through code — fragile and unreadable.
🟡 MEDIUM — Deep nesting: 5 levels of if/else. Cyclomatic complexity: 12. Target: below 5.
🟡 MEDIUM — Copy-paste: Email validation logic in 3 places — one source of truth needed.

REFACTORED:
```python
# Constants extracted
TAX_RATE = 0.15 # was magic number 0.15 on line 47
SECONDS_PER_DAY = 86400 # was magic number

def validate_email(email: str) -> bool:
"""Single source of truth. Was duplicated 3×."""
return bool(re.match(r'^[\w.+-]+@[\w-]+\.[\w.-]+$', email))

def calculate_tax(amount: float) -> float:
"""Extracted from processUserData. Now independently testable."""
if amount < 0:
raise ValueError(f'Amount must be non-negative, got {amount}')
return round(amount * TAX_RATE, 2)

def process_user_data(user: dict) -> ProcessedUser:
"""Orchestrator only — delegates to focused single-purpose functions."""
validated = validate_user_fields(user)
enriched = enrich_with_preferences(validated)
return format_for_storage(apply_tax_calculation(enriched))
```

BEFORE vs AFTER:
Lines: 200 → 85 | Complexity: 12 → 3 per fn | Testable units: 1 → 6