hosts-go/memory-bank/activeContext.md

Active Context: hosts-go

Current Work Focus

Status: Foundation Complete - Ready for Phase 1 (Core Functionality) Priority: Implementing hosts file parser with format preservation

Recent Changes

Foundation Implementation (COMPLETED)

• ✅ Go module setup: Created go.mod with all required dependencies
• ✅ Project structure: Complete directory layout (cmd/, internal/, tests/)
• ✅ Core data models: Full HostEntry and HostsFile structs with validation
• ✅ Comprehensive testing: 44 test cases covering all model functionality
• ✅ Demo application: Working proof-of-concept showing foundation capabilities
• ✅ TDD implementation: Successfully proven test-driven development approach

Validation System Complete

• ✅ IP validation: IPv4/IPv6 support using Go's net.ParseIP
• ✅ Hostname validation: RFC-compliant with label-by-label checking
• ✅ Edge case handling: Hyphen restrictions, length limits, format validation
• ✅ Error messaging: Clear, specific error messages for all validation failures

Next Steps

Immediate (Phase 1 - Current Priority)

1. Hosts File Parser Implementation

   • Write comprehensive parser tests for various hosts file formats
   • Implement internal/core/parser.go for reading /etc/hosts
   • Handle comment preservation and formatting retention
   • Support active/inactive entry detection (commented lines)

2. File Operations

   • Add file reading with proper error handling
   • Implement round-trip parsing (read → parse → modify → write)
   • Test with real hosts file formats and edge cases

3. Integration Testing

   • Test parser with actual /etc/hosts file variations
   • Verify format preservation during round-trip operations
   • Handle malformed entries gracefully

Medium-term (Following sessions)

1. Core business logic

   • Implement hosts file parsing with comment preservation
   • Add validation for IP addresses and hostnames
   • Create entry manipulation functions (add, edit, delete, toggle)

2. Basic TUI foundation

   • Create main Bubble Tea model structure
   • Implement two-pane layout (list + detail)
   • Add basic navigation and selection

3. Permission handling

   • Implement view-mode by default
   • Add edit-mode transition with sudo handling
   • Test permission scenarios

Active Decisions and Considerations

Architecture Decisions Made

• Layered architecture: TUI → Business Logic → System Interface
• Repository pattern: Abstract file operations for testability
• Command pattern: Encapsulate edit operations for undo support
• Test-driven development: Write tests before implementation

Key Design Patterns

• MVU (Model-View-Update): Following Bubble Tea conventions
• Separation of concerns: Clear boundaries between UI, business logic, and system operations
• Graceful degradation: Handle permission issues without crashing

Technology Choices Confirmed

• Go 1.21+: Modern Go features and performance
• Bubble Tea: Mature, well-documented TUI framework
• Testify: Enhanced testing capabilities beyond stdlib
• golangci-lint: Code quality and consistency

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

• macOS focus: Primary development and testing platform
• Cross-platform awareness: Consider Linux compatibility from start
• Terminal compatibility: Test with multiple terminal applications

User Experience Priorities

1. Safety: Cannot accidentally corrupt hosts file
2. Speed: Faster than manual editing for common tasks
3. Clarity: Always know what mode you're in and what operations are available
4. Confidence: Validate changes before applying them

Technical Priorities

1. Reliability: Atomic file operations with backup/restore
2. Performance: Handle large hosts files efficiently
3. Maintainability: Clear code structure for future enhancements
4. Testability: Comprehensive test coverage for confidence in changes

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