kilocode/refactor-plan

LLM-Powered TypeScript Refactoring: Implementation Plan

Overview

This project implements an LLM-powered TypeScript refactoring tool that uses TS Morph to perform code transformations. The tool allows for automated refactoring operations like renaming, moving, extracting, and more complex code changes through a well-defined DSL (Domain-Specific Language) that the LLM can generate.

Implementation Approach

We're taking a phased approach to implementation, focusing on incremental delivery of value while ensuring correctness, reliability, and maintainability. Each phase builds on the previous one, gradually increasing complexity and capabilities.

Phases Summary

Phase	Title	Duration	Status
0	Foundation Analysis & Architecture	1 week	Completed
1	Core Infrastructure & Safety	1 week	In Progress
2	Single-File Operations	1 week	Not Started
3	Multi-File Operations	2 weeks	Not Started
4	Complex Transformations	2 weeks	Not Started
5	Code Generation Operations	1 week	Not Started

Total Duration: 8-9 weeks

Phase Descriptions

Phase 0: Foundation Analysis & Architecture (1 week)

• Analyze existing refactoring code in the codebase
• Identify reusable components and patterns
• Design system architecture with clear component boundaries
• Create risk assessment and mitigation strategies
• Document findings and create implementation checklist

Phase 1: Core Infrastructure & Safety (1 week)

• Implement core refactoring engine architecture
• Create schema validation using Zod
• Build robust LLM response parser
• Develop transaction support for safe rollbacks
• Implement human review system for high-risk operations
• Establish comprehensive testing framework

Phase 2: Single-File Operations (1 week)

• Implement RENAME operation with full reference tracking (Priority #1)
• Implement REMOVE operation with safety checks
• Create symbol finder utility to locate TypeScript symbols across files
• Add comprehensive test coverage with real-world code examples
• Ensure operations work through the tool interface
• Validate through agent testing with real-world refactoring scenarios

Phase 3: Multi-File Operations (2 weeks)

• Implement MOVE operation with automatic import updates
• Create import management utility
• Add basic dependency analysis for operation ordering
• Test complex multi-file refactoring scenarios
• Handle file creation and cross-file references

Phase 4: Complex Transformations (2 weeks)

• Implement EXTRACT operation for functions and methods
• Implement REFACTOR (multi-step) operation
• Add advanced dependency analysis with semantic understanding
• Create code analysis utilities
• Test complex refactoring scenarios with rollback

Phase 5: Code Generation Operations (1 week)

• Implement ADD operation for new code elements
• Implement INLINE operation for optimization
• Create code generation utilities
• Add human review for all generative operations
• Test end-to-end workflows

Key Technical Concepts

TypeScript AST Manipulation

The refactoring tool uses TS Morph to manipulate TypeScript's Abstract Syntax Tree (AST), allowing for precise and safe code transformations. This approach maintains the semantic integrity of the code while making structural changes.

Schema Validation

We use Zod to validate the structure of refactoring operations, ensuring that the LLM's generated operations are well-formed and complete before execution. This provides robust error handling for LLM hallucinations or incomplete specifications.

Transaction Support

All refactoring operations are performed within a transaction, allowing for safe rollback if any part of the operation fails. This ensures that the codebase is never left in a partially refactored state.

Dependency Analysis

Complex refactorings with multiple steps require understanding dependencies between operations. The dependency analyzer ensures that operations are executed in the correct order, avoiding conflicts and maintaining code integrity.

Human Review

For high-risk operations (REMOVE, ADD) and complex refactorings, the tool requires human review before execution. This provides an additional safety layer and helps developers understand the changes being made.

Implementation Priorities

1. Correctness: Operations must maintain semantic equivalence and never introduce bugs
2. Reliability: Robust error handling and transaction support to prevent partial refactorings
3. Testability: Comprehensive test coverage to ensure operations work as expected
4. Maintainability: Clean, modular architecture that's easy to extend and maintain
5. Performance: Efficient operations that can handle large codebases

Success Criteria

• All refactoring operations pass snapshot tests
• Operations work correctly through the tool interface
• Environment parity is validated between test and production
• Error handling is comprehensive with clear messages
• Documentation is thorough and up-to-date
• The tool can handle real-world refactoring scenarios
• LLM can reliably generate valid refactoring operations

Supported Operations

When complete, the tool will support these operations:

1. RENAME: Change symbol names project-wide with reference tracking
2. MOVE: Relocate symbols between files with import management
3. REMOVE: Safely delete unused symbols with reference checking
4. EXTRACT: Extract code blocks into functions, methods, or classes
5. REFACTOR: Execute multi-step refactoring sequences
6. ADD: Add new code elements (functions, classes, methods, properties)
7. INLINE: Replace symbol references with their values
8. OPTIMIZE_IMPORTS: Clean up and organize import statements

Next Steps

1. ✅ Complete Phase 0: Architecture and analysis
2. 🔄 Finish Phase 1: Complete implementation of core infrastructure
3. ⏭️ Begin Phase 2: Implement RENAME operation first with comprehensive testing
4. 📝 Validate through agent testing with real TypeScript projects
5. ⏭️ Continue with remaining Phase 2 operations (REMOVE)
6. ⏭️ Proceed to Phase 3 for multi-file operations
7. ⏭️ Implement complex transformations in Phase 4
8. ⏭️ Complete with code generation operations in Phase 5

This phased approach allows for incremental delivery of value while managing complexity and ensuring quality at each step.