# Changes Summary - Data Comparison Logic Fix

## Issues Fixed

### 1. Removed All-Sheet Functionality
- **Problem**: The tool was processing all sheets together, causing cross-sheet duplicate detection
- **Solution**: Completely removed all-sheet functionality, now only processes one sheet at a time
- **Changes**: 
  - Replaced `extract_kst_coordi_items()` with `extract_kst_coordi_items_for_sheet(sheet_name)`
  - Updated all comparison methods to work sheet-specifically

### 2. Fixed Duplicate Detection Logic
- **Problem**: Items appearing once on each side were incorrectly marked as duplicates
- **Solution**: Fixed `_find_duplicates_in_list()` to only return items that actually appear multiple times
- **Changes**: Used `Counter` to count occurrences and only return items with count > 1

### 3. Implemented Mixed Duplicate Priority
- **Problem**: Items showing as both pure duplicates and mixed duplicates
- **Solution**: Mixed duplicates (items in both datasets with duplicates on one side) now take priority
- **Changes**: Generate mixed duplicates first, then exclude those keys from pure duplicate lists

### 4. Sheet-Specific Analysis Only
- **Problem**: Cross-sheet contamination in duplicate detection
- **Solution**: All analysis now happens within a single sheet context
- **Changes**: 
  - `get_comparison_summary()` now requires sheet filter and defaults to first sheet
  - Removed old filtering methods, replaced with sheet-specific extraction

## BA Confirmed Cases - All Working ✅

### US URGENT Sheet
- ✅ `금수의 영역 - Episode 17` → Coordi duplicate
- ✅ `신결 - Episode 23` → Coordi duplicate  
- ✅ `트윈 가이드 - Episode 31` → Mixed duplicate (exists in both, duplicates in Coordi)
- ✅ No longer shows `트윈 가이드 - Episode 31` as pure Coordi duplicate

### TH URGENT Sheet
- ✅ `백라이트 - Episode 53-1x(휴재)` → KST duplicate (doesn't appear in Coordi)

## Code Changes Made

### data_comparator.py
1. **New Methods**:
   - `extract_kst_coordi_items_for_sheet(sheet_name)` - Sheet-specific extraction
   - `categorize_mismatches_for_sheet(sheet_data)` - Sheet-specific categorization
   - `generate_mismatch_details_for_sheet()` - Sheet-specific mismatch details with priority logic
   - `group_by_title_for_sheet()` - Sheet-specific grouping

2. **Updated Methods**:
   - `_find_duplicates_in_list()` - Fixed to only return actual duplicates
   - `get_comparison_summary()` - Now sheet-specific only
   - `print_comparison_summary()` - Added sheet name to output

3. **Removed Methods**:
   - `extract_kst_coordi_items()` - Replaced with sheet-specific version
   - `categorize_mismatches()` - Replaced with sheet-specific version
   - `generate_mismatch_details()` - Replaced with sheet-specific version
   - `group_by_title()` - Replaced with sheet-specific version
   - `filter_by_sheet()` - No longer needed
   - `filter_grouped_data_by_sheet()` - No longer needed
   - `calculate_filtered_counts()` - No longer needed

### web_gui.py
- Updated matched items extraction to use new grouped data structure
- Removed dependency on old `categorize_mismatches()` method

### Test Files
- `test_ba_confirmed_cases.py` - New test to verify BA confirmed expectations
- `test_sheet_filtering.py` - Updated to work with new sheet-specific logic

## Performance Improvements
- Faster analysis since no cross-sheet processing
- More accurate duplicate detection
- Cleaner separation of concerns between sheets

## Verification
All tests pass:
- ✅ Sheet filtering works correctly
- ✅ Duplicate detection is accurate
- ✅ BA confirmed cases match expectations
- ✅ Web interface works properly
- ✅ Mixed duplicates take priority over pure duplicates