shunsukehayashi/miyabi

Overview

This skill refactor-helper automates and guides safe, systematic code refactoring for TypeScript projects. It focuses on improving code quality, performance, and maintainability while preserving behavior. Use it to modernize legacy code, break up large functions, and apply common refactoring patterns reliably.

How this skill works

refactor-helper inspects code for common smells (long functions, duplicate logic, complex conditionals, god classes, dead code) and proposes small, focused changes such as extract-function, replace-conditionals-with-polymorphism, and simplifications. It enforces a workflow: identify smells, add or verify tests, perform incremental refactors, and run verification steps (tests, lint, typechecks). It also suggests tooling commands and concrete code examples tailored to TypeScript.

When to use it

• Modernizing legacy TypeScript code to newer syntax or patterns
• Breaking up large functions or classes to improve readability
• Removing dead code and unused dependencies safely
• Consolidating duplicated logic or simplifying complex conditionals
• Preparing code for performance or maintainability improvements

Best practices

• Make one small refactor per commit to keep changes reviewable
• Ensure tests exist and pass before starting any refactor
• Run tests, lint, and type checks after each incremental change
• Preserve external behavior — refactor structure, not logic
• Use automated tools (ts-prune, depcheck) to find dead code and unused deps

Example use cases

• Extracting validation and calculation helpers from a long order-processing function
• Replacing switch-based pricing logic with strategy classes to enable extension
• Simplifying nested user checks using optional chaining and array includes
• Removing unused exports and dependencies discovered by automated scans
• Adding focused unit tests before refactoring a critical module