CLAUDE: Extract rarity cost adjustment logic into data-driven function
This commit eliminates 150+ lines of duplicated, error-prone nested if/elif
logic by extracting rarity cost calculations into a lookup table and function.
## Changes Made
1. **Add RARITY_COST_ADJUSTMENTS lookup table** (creation_helpers.py)
- Maps (old_rarity, new_rarity) → (cost_adjustment, minimum_cost)
- Covers all 30 possible rarity transitions
- Self-documenting with comments for each rarity tier
- Single source of truth for all cost adjustments
2. **Add calculate_rarity_cost_adjustment() function** (creation_helpers.py)
- Takes old_rarity, new_rarity, old_cost
- Returns new cost with adjustments and minimums applied
- Includes comprehensive docstring with examples
- Handles edge cases (same rarity, undefined transitions)
- Logs warnings for undefined transitions
3. **Update batters/creation.py**
- Import calculate_rarity_cost_adjustment
- Replace 75-line nested if/elif block with 7-line function call
- Identical behavior, much cleaner code
4. **Update pitchers/creation.py**
- Import calculate_rarity_cost_adjustment
- Replace 75-line nested if/elif block with 7-line function call
- Eliminates duplication between batters and pitchers
5. **Add comprehensive tests** (tests/test_rarity_cost_adjustments.py)
- 22 tests covering all scenarios
- Tests individual transitions (Diamond→Gold, Common→Bronze, etc.)
- Tests all upward and downward transitions
- Tests minimum cost enforcement
- Tests edge cases (zero cost, very high cost, negative cost)
- Tests symmetry (up then down returns close to original)
## Impact
### Lines Eliminated
- **Batters:** 75 lines → 7 lines (89% reduction)
- **Pitchers:** 75 lines → 7 lines (89% reduction)
- **Total:** 150 lines of nested logic eliminated
### Benefits
✅ Eliminates 150+ lines of duplicated code
✅ Data-driven approach makes adjustments clear and modifiable
✅ Single source of truth prevents inconsistencies
✅ Independently testable business logic
✅ 22 comprehensive tests ensure correctness
✅ Easy to add new rarity tiers or modify costs
✅ Reduced risk of typos in magic numbers
## Test Results
✅ 22/22 new tests pass
✅ All existing tests still pass
✅ 100% backward compatible - identical behavior
## Files Modified
- creation_helpers.py: +104 lines (table + function + docs)
- batters/creation.py: -68 lines (replaced nested logic)
- pitchers/creation.py: -68 lines (replaced nested logic)
- tests/test_rarity_cost_adjustments.py: +174 lines (new tests)
**Net change:** 150+ lines of complex logic replaced with simple,
tested, data-driven approach.
Part of ongoing refactoring to reduce code fragility.
cb471d8057