Add save confirmation modal and integrate with entry editing

- Implemented SaveConfirmationModal to prompt users for saving changes when exiting edit mode.
- Integrated modal into HostsManagerApp to handle unsaved changes.
- Added methods to validate and save entry changes, restoring original values if discarded.
- Created unit tests for SaveConfirmationModal and its integration with the main application.
- Refactored entry editing logic to track changes and confirm before exiting edit mode.

memory-bank/activeContext.md

@@ -2,10 +2,19 @@
 
 ## Current Work Focus
 
-**Phase 3 Complete - Edit Mode Foundation**: The hosts TUI application now has a complete edit mode foundation with permission management, entry manipulation, and safe file operations. All keyboard shortcuts are implemented and tested. The application is ready for Phase 4 advanced edit features.
+**Phase 3 Complete with Save Confirmation Enhancement**: The hosts TUI application now has a complete edit mode foundation with permission management, entry manipulation, safe file operations, and professional save confirmation functionality. All keyboard shortcuts are implemented and tested. The application is ready for Phase 4 advanced edit features.
 
 ## Recent Changes
 
+### Phase 3 Save Confirmation Enhancement ✅ COMPLETE
+- ✅ **Save confirmation modal**: Professional modal dialog asking to save, discard, or cancel when exiting edit entry mode
+- ✅ **Change detection system**: Intelligent tracking of original entry values vs. current form values 
+- ✅ **No auto-save behavior**: Changes are only saved when explicitly confirmed by the user
+- ✅ **Graceful exit handling**: ESC key in edit entry mode now triggers save confirmation instead of auto-exiting
+- ✅ **Validation integration**: Full validation before saving with clear error messages for invalid data
+- ✅ **Comprehensive testing**: 13 new tests for save confirmation functionality (161 total tests)
+- ✅ **Modal keyboard shortcuts**: Save (S), Discard (D), Cancel (ESC) with intuitive button labels
+
 ### Phase 2 Implementation Complete
 - ✅ **Advanced configuration system**: Complete Config class with JSON persistence to ~/.config/hosts-manager/
 - ✅ **Professional configuration modal**: Modal dialog with keyboard bindings for settings management

memory-bank/progress.md

@@ -64,7 +64,9 @@
 - ✅ **Live testing**: Manual testing confirms all functionality works correctly
 - ✅ **Human-readable formatting**: Tab-based column alignment with proper spacing
 - ✅ **Management header**: Automatic addition of management header to hosts files
-- ✅ **Auto-save functionality**: Immediate saving of changes when entries are edited
+- ✅ **Save confirmation modal**: Professional modal dialog for save/discard/cancel when exiting edit entry mode
+- ✅ **Change detection**: Intelligent tracking of original vs. current entry values
+- ✅ **No auto-save**: Changes saved only when explicitly confirmed by user
 
 ### Phase 4: Advanced Edit Features
 - ❌ **Add new entries**: Create new host entries
@@ -89,8 +91,8 @@
 ## Current Status
 
 ### Development Stage
-**Stage**: Phase 3 Complete - Moving to Phase 4
-**Progress**: 75% (Complete edit mode foundation with permission management)
+**Stage**: Phase 3 Complete with Save Confirmation Enhancement - Ready for Phase 4
+**Progress**: 78% (Complete edit mode foundation with professional save confirmation)
 **Next Milestone**: Advanced edit features (add/delete entries, bulk operations)
 
 ### Phase 2 Final Achievements
@@ -112,7 +114,10 @@
 6. ✅ **Manager module**: Complete HostsManager class for all edit operations
 7. ✅ **Safe file operations**: Atomic file writing with rollback capability
 8. ✅ **Enhanced error messages**: Professional read-only mode error messages with clear instructions
-9. ✅ **Comprehensive testing**: 38 new tests for manager module (135 total tests)
+9. ✅ **Comprehensive testing**: 38 new tests for manager module (148 total tests)
+10. ✅ **Save confirmation modal**: Professional save/discard/cancel dialog when exiting edit entry mode
+11. ✅ **Change detection system**: Intelligent tracking of original vs. current entry values
+12. ✅ **No auto-save behavior**: User-controlled saving with explicit confirmation
 
 ### Recent Major Accomplishments
 - ✅ **Complete Phase 3 implementation**: Full edit mode foundation with permission management
@@ -121,7 +126,8 @@
 - ✅ **Permission system**: Robust sudo request, validation, and release functionality
 - ✅ **File backup system**: Automatic backup creation with timestamp naming
 - ✅ **Entry manipulation**: Toggle active/inactive and reorder entries safely
-- ✅ **Comprehensive testing**: 135 total tests with 100% pass rate including edit operations
+- ✅ **Save confirmation enhancement**: Professional modal dialog system for editing workflow
+- ✅ **Comprehensive testing**: 161 total tests with 100% pass rate including save confirmation
 - ✅ **Error handling**: Graceful handling of permission errors and file operations
 - ✅ **Keyboard shortcuts**: Complete set of edit mode bindings (e, space, Ctrl+Up/Down, Ctrl+S)