# Active Context: hosts

## Current Work Focus

**Phase 1 Complete - Foundation Established**: The hosts TUI application now has a fully functional foundation with comprehensive read-only functionality. The application successfully loads, parses, and displays hosts files in a modern two-pane TUI interface.

## Recent Changes

### Phase 1 Implementation Complete
- ✅ **Fully functional TUI application**: Complete two-pane interface with entry list and details
- ✅ **Robust hosts file parsing**: Handles comments, inactive entries, IPv4/IPv6 addresses
- ✅ **Comprehensive testing**: 42 passing tests covering all core functionality
- ✅ **Clean code quality**: All ruff linting checks passing
- ✅ **Proper project structure**: Well-organized package structure in src/hosts/

### Current Project State
- **Working application**: `uv run hosts` launches fully functional TUI
- **Complete dependencies**: textual, pytest, ruff properly configured
- **Comprehensive test suite**: 42 tests with 100% pass rate
- **Clean codebase**: All linting and formatting standards met
- **Robust architecture**: Layered design with clear separation of concerns

## Next Steps

### Phase 2: Enhanced Read-Only Features (Current Priority)
1. **Visual enhancements**:
   - Improve entry selection highlighting and visual feedback
   - Better status indicators for active/inactive entries
   - Enhanced color scheme and styling

2. **Data manipulation features**:
   - Sort entries by IP address, hostname, or status
   - Filter entries by active/inactive status
   - Search functionality for hostnames and IP addresses

3. **User experience improvements**:
   - Implement proper help modal dialog
   - Better keyboard shortcuts and navigation
   - Status bar enhancements with more detailed information

4. **Performance and polish**:
   - Optimize for large hosts files
   - Improve error handling and user feedback
   - Add configuration options

### Phase 3: Edit Mode Foundation (Next Major Phase)
1. **Permission management**:
   - Implement sudo request and management system
   - Edit mode toggle with proper security handling
   - Permission validation and error handling

2. **Basic editing operations**:
   - Toggle entries active/inactive
   - Reorder entries in the list
   - Edit IP addresses, hostnames, and comments
   - Add and delete entries

3. **File safety**:
   - Automatic backup before modifications
   - Atomic file operations
   - Validation before writing changes

## Active Decisions and Considerations

### Architecture Decisions Validated
- ✅ **Layered architecture**: Successfully implemented with clear separation
- ✅ **Reactive UI**: Textual's reactive system working excellently
- ✅ **Data models**: Dataclasses with validation proving robust
- ✅ **File parsing**: Comprehensive parser handling all edge cases
- ✅ **Permission model**: Read-only default working as intended

### Design Patterns Implemented
- ✅ **Reactive patterns**: Using Textual's reactive attributes effectively
- ✅ **Data validation**: Comprehensive validation in models and parser
- ✅ **Error handling**: Graceful degradation and user feedback
- 🔄 **Command pattern**: Planned for Phase 3 edit operations
- 🔄 **Observer pattern**: Will implement for state change notifications

### Technical Constraints Confirmed
- ✅ **Python 3.13+**: Excellent choice with modern features working well
- ✅ **Unix-like systems**: Targeting Linux/macOS successfully
- ✅ **File integrity**: Parser preserves comments and structure perfectly
- 🔄 **Root access**: Will be implemented in Phase 3 edit mode

## 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 and widgets exceed expectations
2. ✅ **File parsing complexity**: Real-world hosts files have many edge cases, all handled
3. ✅ **Test-driven development**: Comprehensive testing caught numerous edge cases early
4. ✅ **User experience focus**: Keyboard navigation and visual feedback crucial
5. ✅ **Architecture validation**: Layered approach proving maintainable and extensible

### 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 and parsing errors
- 🔄 **Permission escalation**: Will be carefully implemented in Phase 3
- 🔄 **Large file performance**: To be tested and optimized in Phase 2

### Success Factors Confirmed
- ✅ **Safety-first approach**: Read-only default prevents accidental changes
- ✅ **Comprehensive validation**: All data validated before processing
- ✅ **Intuitive interface**: Users can navigate effectively with minimal learning
- ✅ **Visual clarity**: Active/inactive states clearly distinguished
- ✅ **Robust foundation**: Clean architecture supports future enhancements

## 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 1 complete and Phase 2 ready to begin.