hosts-go/memory-bank/activeContext.md

Active Context: hosts-go

Current Work Focus

Status: Phase 2 In Progress - Basic TUI prototype implemented Priority: Expand Bubble Tea TUI with navigation and view features

Recent Changes

Phase 1: Core Functionality (COMPLETED) ✅

• ✅ Hosts file parser: Complete internal/core/parser.go implementation
• ✅ Intelligent formatting: Adaptive spacing and column alignment with GCD-based tab/space detection
• ✅ Comment handling: Disabled entries vs standalone comments with perfect preservation
• ✅ File operations: Safe backup system with timestamped backups in ~/.config/hosts-go/
• ✅ Error recovery: Malformed line handling with non-fatal warnings
• ✅ Format preservation: Round-trip parsing maintains original formatting while improving alignment
• ✅ Comprehensive testing: 54 comprehensive tests covering all parser functionality (100% passing)
• ✅ Demo application: Full showcase of parser capabilities with real-world examples

Parser Capabilities Achieved

• ✅ Standard entries: IPv4, IPv6, multiple aliases, inline comments
• ✅ Disabled entries: Commented lines with # IP hostname format detection
• ✅ Standalone comments: Header and section comments preserved separately
• ✅ Style detection: Automatic tab vs space detection with intelligent column widths
• ✅ Search functionality: Find entries by hostname or alias with O(1) performance
• ✅ Validation layers: IP address and hostname validation with clear error messages
• ✅ Atomic operations: Temporary files with rollback capability for safe writes

Safety Features Implemented

• ✅ Backup system: Timestamped backups before any modification
• ✅ Atomic writes: Temp file → atomic move to prevent corruption
• ✅ Warning system: Non-fatal issues reported without stopping parsing
• ✅ Format intelligence: Detect and preserve original formatting style
• ✅ Input validation: Comprehensive IP and hostname validation

Next Steps

Immediate (Phase 2 - Current Priority)

1. TUI Architecture Design ✅

   • Main Bubble Tea model with list and detail panes
   • State tracks selection and window size

2. Two-Pane Layout Implementation ✅

   • Left pane: entry list using Bubbles list component
   • Right pane: detail view of selected entry
   • Responsive sizing handled in update

3. Navigation System 🟡

   • Basic keyboard navigation via list component
   • Need scroll handling and pane switching

4. View Mode Implementation 🟡

   • Read-only display of /etc/hosts entries
   • Status bar and active/inactive indicators in list implemented
   • Further styling improvements pending

Medium-term (Phase 3)

1. Edit Mode Implementation

   • Explicit mode transition with visual indicators
   • Permission handling with sudo request
   • Entry modification forms with validation

2. File Integration

   • Connect TUI with existing parser functionality
   • Real-time display of actual /etc/hosts content
   • Live validation and formatting preview

3. Advanced Features

   • Entry toggle (activate/deactivate)
   • Add/edit/delete operations
   • Sorting and filtering capabilities

Active Decisions and Considerations

Architecture Decisions Finalized

• Layered architecture: TUI → Business Logic → System Interface (implemented and proven)
• Parser-first approach: Robust foundation before UI complexity (successfully completed)
• Test-driven development: 54 comprehensive tests proving approach effectiveness
• Safety-first design: Backup and atomic operations prevent data loss

Parser Design Patterns Implemented

• Intelligent formatting: GCD-based spacing detection preserves original style
• Warning system: Non-fatal errors allow graceful degradation
• Comment classification: Distinguish between disabled entries and standalone comments
• Round-trip consistency: Parse → format → parse maintains structural integrity

Technology Choices Validated

• Go standard library: Excellent for file operations and network validation
• String manipulation: Regex and string processing handle complex formatting
• Testing ecosystem: testify + table-driven tests provide excellent coverage
• File safety: Atomic operations with temp files prevent corruption

TUI Design Decisions (Ready to Implement)

• MVU pattern: Bubble Tea's Model-View-Update for predictable state management
• Component hierarchy: Main model coordinates list, detail, and modal components
• Keyboard-driven: Primary interaction method with mouse support as enhancement
• Mode-based interaction: Clear view/edit mode distinction for safety

Important Patterns and Preferences

Code Organization

• Use internal/ package for application-specific code
• Group related functionality in packages (tui/, core/, utils/)
• Keep main.go minimal - delegate to internal packages

Testing Strategy

• Write tests before implementation (TDD)
• Mock external dependencies (file system, network)
• Use table-driven tests for multiple scenarios
• Test both success and error cases

Error Handling

• Return errors explicitly, don't panic
• Provide clear error messages with context
• Implement graceful fallbacks where possible
• Log errors appropriately for debugging

UI/UX Principles

• Safety first: Default to read-only mode
• Clear feedback: Show operation status and results
• Keyboard-driven: Efficient navigation without mouse dependency
• Responsive: Sub-16ms update cycles for smooth interaction

Learnings and Project Insights

Development Environment Proven

• macOS compatibility: All file operations work seamlessly on macOS
• Go toolchain: Excellent development experience with built-in testing
• Terminal output: Rich formatting possible with careful Unicode handling

Parser Implementation Insights

• Format detection: GCD analysis effectively detects spacing patterns
• Comment parsing: Distinguishing disabled entries from comments requires careful regex work
• Error handling: Warning system allows processing to continue despite invalid lines
• Performance: String processing in Go handles large files efficiently

User Experience Learnings

1. Safety achieved: Backup system and atomic writes prevent corruption
2. Format preservation: Users expect their formatting style to be maintained
3. Clear feedback: Parsing warnings help users understand file issues
4. Predictable behavior: Round-trip parsing gives confidence in modifications

Technical Insights Gained

1. File operations: Atomic writes with temp files are essential for safety
2. Parsing complexity: Hosts files have many edge cases requiring careful handling
3. Testing approach: Table-driven tests excellent for covering format variations
4. Code organization: Clear separation between parsing and formatting logic
5. Validation layers: Multiple validation points catch issues early

Ready for TUI Implementation

• Solid foundation: Parser handles all hosts file variations reliably
• Proven patterns: Test-driven development approach validated
• Clear architecture: Well-defined interfaces ready for TUI integration
• Performance confidence: Parser handles large files without issues

Dependencies and Constraints

External Dependencies

• Bubble Tea ecosystem: Core framework and components
• System permissions: sudo access for editing hosts file
• File system: Atomic write operations and backup capability

Development Constraints

• No breaking changes: Must preserve existing hosts file format
• Backward compatibility: Work with various hosts file styles
• Minimal dependencies: Keep external dependencies focused and essential

Communication Preferences

Documentation Style

• Concrete examples: Show actual code snippets and command examples
• Clear structure: Use consistent heading hierarchy and formatting
• Actionable items: Specific next steps rather than vague suggestions

Progress Tracking

• Incremental development: Small, testable changes
• Regular updates: Update memory bank after significant milestones
• Clear status: Always know what's working, what's not, and what's next