TypeScript AST Refactor uses ts-morph to programmatically manipulate TypeScript abstract syntax trees for large-scale codebase transformations. It supports extract-function refactoring by analyzing variable scope and closure dependencies, rename-symbol operations that propagate across import/export boundaries, and dead code elimination by tracing reachability from entry points. The tool leverages the TypeScript Compiler API diagnostics to validate transformations before writing, ensuring type safety is preserved. It handles complex scenarios like generic type parameter inference, conditional types, and mapped types. Batch mode processes entire directories with configurable glob patterns, and a dry-run mode generates unified diffs for review. Integration with ESLint auto-fix rules ensures code style consistency after transformation.