# Active Context: hosts

## 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.

## Recent Changes

### 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
- ✅ **Default entry filtering**: Hide/show system default entries (localhost, broadcasthost, ::1)
- ✅ **Complete sorting system**: Sort by IP address and hostname with direction toggle and visual indicators
- ✅ **Rich visual interface**: Color-coded entries with professional DataTable styling
- ✅ **Interactive column headers**: Click headers to sort data with visual feedback
- ✅ **Enhanced status bar**: Detailed information including entry counts and file path
- ✅ **Comprehensive testing**: 97 tests covering all functionality including new features

### Current Project State
- **Production-ready application**: `uv run hosts` launches polished TUI with advanced features
- **Complete configuration system**: Settings persist across sessions with graceful error handling
- **Professional visual design**: Color-coded entries, zebra striping, and rich text styling
- **Interactive sorting**: Click column headers or use keyboard shortcuts to sort data
- **Intelligent filtering**: Hide default system entries based on user preference
- **Comprehensive test coverage**: 97 tests with 100% pass rate covering all components
- **Perfect code quality**: All linting and formatting standards maintained
- **Robust architecture**: Clean layered design ready for edit mode extension

## Next Steps

### Phase 3: Edit Mode Foundation (Current Priority)
1. **Permission management system**:
   - Implement sudo request and validation
   - Edit mode toggle with proper security handling
   - Permission validation and error handling
   - Graceful fallback for permission denied scenarios

2. **Basic editing operations**:
   - Toggle entries active/inactive with visual feedback
   - Entry editing interface for IP addresses, hostnames, and comments
   - Real-time validation of IP addresses and hostnames
   - Safe state management during editing

3. **File safety and backup**:
   - Automatic backup before any modifications
   - Atomic file operations with rollback capability
   - Validation before writing changes to disk
   - Error recovery and restoration mechanisms

4. **Edit mode user interface**:
   - Clear visual indicators for edit mode vs read-only mode
   - Edit forms and dialogs for entry modification
   - Confirmation dialogs for destructive operations
   - Enhanced status feedback during edit operations

### Phase 4: Advanced Edit Features (Future)
1. **Advanced editing operations**:
   - Add new entries with validation
   - Delete entries with confirmation
   - Reorder entries in the list
   - Bulk operations for multiple entries

2. **Enhanced user experience**:
   - Undo/Redo functionality with command pattern
   - Search functionality for hostnames and IP addresses
   - Proper help modal dialog
   - Advanced filtering by active/inactive status

3. **Performance and polish**:
   - Optimize for large hosts files
   - Enhanced error handling and user feedback
   - Performance benchmarking and optimization

## Active Decisions and Considerations

### Architecture Decisions Validated
- ✅ **Layered architecture**: Successfully implemented with clear separation and extensibility
- ✅ **Reactive UI**: Textual's reactive system working excellently with complex state
- ✅ **Data models**: Dataclasses with validation proving robust and extensible
- ✅ **File parsing**: Comprehensive parser handling all edge cases flawlessly
- ✅ **Configuration system**: JSON-based persistence working reliably
- ✅ **Modal system**: Professional dialog system with proper keyboard handling

### Design Patterns Implemented
- ✅ **Reactive patterns**: Using Textual's reactive attributes for complex state management
- ✅ **Data validation**: Comprehensive validation in models, parser, and configuration
- ✅ **Error handling**: Graceful degradation and user feedback throughout
- ✅ **Modal pattern**: Professional modal dialogs with proper lifecycle management
- ✅ **Configuration pattern**: Centralized settings with persistence and defaults
- 🔄 **Command pattern**: Planned for Phase 3 edit operations with undo/redo
- 🔄 **Observer pattern**: Will implement for state change notifications in edit mode

### Technical Constraints Confirmed
- ✅ **Python 3.13+**: Excellent choice with modern features working perfectly
- ✅ **Unix-like systems**: Targeting Linux/macOS successfully with proper path handling
- ✅ **File integrity**: Parser preserves comments and structure perfectly
- ✅ **Configuration persistence**: JSON storage working reliably across sessions
- 🔄 **Root access**: Will be implemented in Phase 3 edit mode with proper security

## Important Patterns and Preferences

### Code Organization
- **Separation of concerns**: Clear layer boundaries
- **Type safety**: Comprehensive type hints
- **Documentation**: Docstrings for all public APIs
- **Testing**: TDD approach with high coverage

### User Experience Priorities
- **Safety first**: Read-only by default, explicit edit mode
- **Keyboard-driven**: Efficient navigation without mouse
- **Visual clarity**: Clear active/inactive indicators
- **Error prevention**: Validation before any file writes

### Development Workflow
- **uv for everything**: Package management and execution
- **ruff for quality**: Linting and formatting
- **pytest for testing**: Comprehensive test coverage
- **Incremental development**: Build and test each component

## Learnings and Project Insights

### Key Insights from Implementation
1. ✅ **Textual framework excellence**: Reactive system, DataTable, and modal system exceed expectations
2. ✅ **Configuration system design**: JSON persistence with graceful error handling works perfectly
3. ✅ **Visual design importance**: Color-coded entries and professional styling significantly improve UX
4. ✅ **Interactive sorting value**: Click-to-sort headers provide intuitive data manipulation
5. ✅ **Test-driven development**: Comprehensive testing (97 tests) caught edge cases and ensured quality
6. ✅ **Modal dialog system**: Professional modal interface enhances user experience significantly
7. ✅ **Architecture extensibility**: Layered approach easily accommodated new features

### Risk Areas Addressed
- ✅ **File integrity**: Parser preserves all comments and formatting perfectly
- ✅ **Input validation**: Comprehensive IP and hostname validation implemented
- ✅ **Error handling**: Graceful degradation for file access, parsing, and configuration errors
- ✅ **Configuration persistence**: Robust JSON handling with fallback to defaults
- ✅ **Visual complexity**: Rich styling maintained without performance impact
- 🔄 **Permission escalation**: Will be carefully implemented in Phase 3
- 🔄 **Large file performance**: To be tested and optimized in Phase 3

### Success Factors Confirmed
- ✅ **Safety-first approach**: Read-only default with explicit configuration prevents accidental changes
- ✅ **Comprehensive validation**: All data validated before processing and display
- ✅ **Intuitive interface**: Users can navigate and configure effectively with minimal learning
- ✅ **Professional visual design**: Color-coded entries and rich styling provide clear feedback
- ✅ **Robust foundation**: Clean architecture easily extended with advanced features
- ✅ **Configuration flexibility**: User preferences persist and enhance workflow
- ✅ **Interactive data manipulation**: Sorting and filtering provide powerful data management

## Current Development Environment

### Tools Working Perfectly
- ✅ **uv**: Package manager handling all dependencies flawlessly
- ✅ **ruff**: Code quality tool with all checks passing
- ✅ **Python 3.13**: Runtime environment performing excellently
- ✅ **textual**: TUI framework exceeding expectations
- ✅ **pytest**: Testing framework with 42 passing tests

### Development Workflow Established
- ✅ **uv run hosts**: Launches application instantly
- ✅ **uv run pytest**: Comprehensive test suite execution
- ✅ **uv run ruff check**: Code quality validation
- ✅ **uv run ruff format**: Automatic code formatting

### Project Structure Complete
- ✅ **Package structure**: Proper src/hosts/ organization implemented
- ✅ **Core modules**: models.py and parser.py fully functional
- ✅ **TUI implementation**: main.py with complete application
- ✅ **Test coverage**: Comprehensive test suite for all components
- ✅ **Entry point**: Configured hosts command working perfectly

This active context represents the current state with Phase 2 complete and Phase 3 ready to begin. The application now has a complete, polished read-only interface with advanced features and is perfectly positioned for edit mode implementation.