## Security Fixes (Critical)
### 1. Settings file race condition fixed
- Added atomic write operation using temp file + os.replace()
- Prevents corruption if process crashes during settings save
- Uses proper cleanup on failure
### 2. CSV quoting protection implemented
- Added csv.QUOTE_MINIMAL to all CSV DictWriter operations
- Optimal efficiency while maintaining security
- Proper handling of special characters (quotes, commas, newlines)
### 3. Complete CSV field sanitization
- Fixed critical Date field sanitization gap
- Created specialized sanitize_date_text() preserving YYYY-MM-DD format
- All 7 CSV fields now properly sanitized before writing
- Added comprehensive input validation for user input vectors
## New Security Functions
- sanitize_csv_text(): Removes dangerous characters (=,+, -, @)
- sanitize_date_text(): Preserves date format while removing injection attempts
- sanitize_filename(): Path traversal protection
- sanitize_config_text(): JSON/configuration safety
- validate_input(): Centralized input validation with type-specific logic
## Enhanced Features
- Alternating row colors for visual time slot distinction
- Improved conflict resolution with clearer UI indicators
- Enhanced CSV error handling with line numbering
## Testing & Documentation
- Added comprehensive test suites (5 new test files)
- Created AGENTS.md development guide
- Updated TODO.md with staged improvement roadmap
- All tests passing with 100% backward compatibility
## Files Modified
- time_tracker.py: +280 lines (security functions + atomic operations)
- tests/: New security and feature test suites
- .gitignore: Updated to include documentation and tests
All critical vulnerabilities resolved while maintaining full functionality.
