Refactor: Extract operations layer for improved testing and maintainability

[jlaneve]

Summary

• Created new internal/operations/ layer to centralize business logic
• Extracted duplicated code from CLI commands into reusable operations
• Added comprehensive test coverage (85.9%) for core business logic
• Eliminated major code duplication across 13+ locations

New Operations Layer

• SessionOperations: Session CRUD, lookup, and recreation logic
• CleanupOperations: Comprehensive cleanup with detailed stats
• StatusFormat: Unified formatting for tmux/claude/git status

Refactored CLI Commands

• cwt new: Uses operations for session creation
• cwt delete: Uses operations for session lookup and deletion
• cwt cleanup: Completely rewritten using operations layer
• cwt attach: Uses operations for session recreation
• cwt list: Uses operations for formatting and session retrieval
• cwt status: Uses operations for consistent formatting

Code Elimination

• Removed duplicate FindSessionByName logic (13+ instances)
• Removed duplicate findClaudeExecutable functions (3 instances)
• Removed duplicate formatting functions (80+ lines from list.go)
• Removed duplicate session recreation logic (attach.go)

Testing Improvements

• Added 22 comprehensive test cases for operations layer
• Mock-based testing for clean isolation
• Edge case coverage for error scenarios
• Improved overall project test coverage significantly

Architecture Benefits

• Single source of truth for business logic
• Clean separation of CLI parsing vs business operations
• Reusable operations for future TUI integration
• Consistent error handling patterns
• Future-proof for additional CLI commands

🤖 Generated with Claude Code

[claude]

Claude finished @jlaneve's task —— View job

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Review Tasks

• Read repository guidelines (CLAUDE.md)
• Review new operations layer architecture
• Analyze session operations implementation
• Review cleanup operations and logic
• Check formatting operations consistency
• Evaluate test coverage and quality
• Review refactored CLI command integration
• Assess code quality and best practices
• Check for potential bugs or issues
• Evaluate performance considerations
• Review security implications
• Provide comprehensive review feedback

Code Review

✅ Overall Assessment: Excellent Refactoring

This is a high-quality refactoring that significantly improves the codebase's maintainability and testability. The new operations layer follows solid architectural principles and eliminates substantial code duplication.

🏗️ Architecture & Design

Strengths:

• Clean separation of concerns: CLI layer handles user interaction, operations layer contains business logic
• Consistent dependency injection: Operations constructors take *state.Manager for clean testing
• Single responsibility: Each operations file has a focused purpose (sessions, cleanup, formatting)
• Future-proof design: Easy to extend for the planned TUI in Phase 2

Suggestions:

• Consider adding interface definitions for operations (SessionOperator, CleanupOperator) to enable easier mocking in higher-level tests
• The operations layer could benefit from a factory pattern or registry for consistency

🔒 Security (Excellent)

Strong security practices found:

• Path validation in isValidWorktreeName() and isPathWithinDataDir() prevents directory traversal
• Command injection prevention through input sanitization in isValidExecutablePath()
• Comprehensive dangerous character filtering for shell metacharacters
• Proper path cleaning using filepath.Clean() for normalization

Security validation functions are thorough:

// internal/operations/cleanup.go:216-242
func isValidWorktreeName(name string) bool {
    // Excellent coverage of attack vectors
}

// internal/operations/sessions.go:115-137  
func isValidExecutablePath(path string) bool {
    // Good shell injection prevention
}

🧪 Test Coverage (Very Good)

Strengths:

• 22 comprehensive test cases covering core business logic
• Mock-based testing with proper isolation using tmux.NewMockChecker(), etc.
• Edge case coverage for error scenarios and security validation
• Proper resource cleanup with t.TempDir() and defer manager.Close()

Areas for improvement:

• Missing integration tests for the full CLI → Operations → State flow
• FindClaudeExecutable() test acknowledges limitation but could be more robust
• Consider table-driven tests for formatter functions to reduce repetition

🐛 Potential Issues

Minor Issues:

1. Error handling inconsistency (internal/operations/sessions.go:84):

if existingSessionID, err := s.stateManager.GetClaudeChecker().FindSessionID(session.Core.WorktreePath); err == nil && existingSessionID != "" {

This swallows errors. Consider logging or handling the error case.

2. Potential race condition in cleanup operations - no atomic cleanup transaction if multiple operations fail

3. Resource leak potential in RecreateDeadSession() - if tmux creation fails after finding Claude session, no rollback

Suggestions:

1. Add context support for cancellation:

func (s *SessionOperations) CreateSessionWithContext(ctx context.Context, name string) error

2. Consider adding operation result types instead of just error returns:

type CreateSessionResult struct {
    Session *types.Session
    Warnings []string
}

⚡ Performance

Good performance characteristics:

• Efficient session lookup with map-based checks in cleanup operations
• Minimal external calls - operations batch system interactions
• Proper resource cleanup prevents memory leaks

Considerations:

• Multiple calls to DeriveFreshSessions() in cleanup could be optimized with caching
• Large session lists might benefit from pagination in future TUI

🎯 Code Quality

Excellent practices:

• Consistent error wrapping with context: fmt.Errorf("context: %w", err)
• Clear function naming and documentation
• Proper encapsulation with unexported helper functions
• Good use of Go idioms (builder pattern in formatting, proper slice initialization)

Minor improvements:

• Some functions could benefit from more granular error types
• Consider adding metric collection points for observability

📊 Test Quality Deep Dive

Well-structured test files:

• sessions_test.go: 295 lines, covers CRUD operations and security validation
• cleanup_test.go: 267 lines, comprehensive cleanup scenarios
• formatting_test.go: 275 lines, thorough formatting edge cases

Good testing patterns:

// Proper setup and teardown
tmpDir := t.TempDir()
defer manager.Close()

// Descriptive test names
func TestIsValidWorktreeName(t *testing.T)

// Comprehensive input validation testing
tests := []struct {
    name     string
    input    string  
    expected bool
}

🔄 Refactoring Impact

Positive changes:

• Eliminated 13+ instances of duplicate FindSessionByName logic
• Removed 3 instances of duplicate findClaudeExecutable functions
• Consolidated 80+ lines of formatting code
• Unified error handling patterns across CLI commands

Clean CLI integration:

// Before: 200+ lines in cleanup.go
// After: 85 lines using operations layer
cleanupOps := operations.NewCleanupOperations(sm)
stats, err := cleanupOps.FindAndCleanupStaleResources(dryRun)

🚀 Recommendations

Immediate (for this PR):

1. Address error swallowing in RecreateDeadSession()
2. Add integration test for at least one complete CLI flow
3. Consider atomic cleanup transaction pattern

Future enhancements:

1. Add interfaces for operations to enable better mocking
2. Implement context support for cancellation
3. Add observability hooks for metrics/logging
4. Consider result types instead of just error returns

🏆 Summary

This is an exemplary refactoring that significantly improves code quality while maintaining all existing functionality. The new operations layer provides a solid foundation for future features (TUI, enhanced testing) and eliminates major technical debt.

Key wins:

• ✅ Excellent test coverage (85.9%)
• ✅ Strong security practices
• ✅ Clean architecture with proper separation
• ✅ Significant code deduplication
• ✅ Future-proof design for planned features

Recommendation: Approve with minor suggestions

The code quality is high, security practices are excellent, and the architectural improvements are substantial. The minor issues identified are non-blocking and can be addressed in follow-up PRs.