ast-grep-cli

Automate AST-based code searches, rewrites, and rule testing via YAML rules.

1|Updated Mar 15, 2026

Search Tags:#refactoring #cli #yaml #ast #pattern-matching #code-search #rule-testing

Ready to run

npx skills add https://github.com/hafley66/claude-research --skill ast-grep-cli

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: ast-grep-cli
Source: https://github.com/hafley66/claude-research/tree/main/skills/ast-grep-cli
Command: npx skills add https://github.com/hafley66/claude-research --skill ast-grep-cli

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

AST-driven code search, rewrite, and rule testing can be verbose and error-prone when done manually. This skill provides a cohesive CLI to locate patterns, apply safe transformations, and validate rules against codebases.

Core Features & Use Cases

Run one-off searches and rewrites using AST patterns to automate refactoring.
Manage projects with sgconfig.yml to organize rule directories and tests.
Scan codebases and validate rules with snapshot tests to ensure stability.
Debug pattern parsing and tune queries with advanced options to improve accuracy.

Quick Start

Run a sample search with a pattern to locate matches in your codebase.

Frequently Asked Questions about ast-grep-cli

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I use AST pattern matching for code search and refactoring?▼

AST pattern matching for code search and refactoring uses YAML-defined rules to locate and rewrite code structures safely. This approach leverages abstract syntax trees to automate transformations across JavaScript and TypeScript codebases via a CLI.

How do I validate and test custom code rewrite rules against a codebase?▼

Validating and testing custom code rewrite rules uses snapshot-based validation to ensure rule stability. You define test cases in your project configuration to scan the codebase and verify that pattern matches and transformations produce expected results.

Can I use YAML rules to search JavaScript and TypeScript code?▼

Yes, you can use YAML rules to search JavaScript and TypeScript code effectively. The system applies these YAML-defined rules through the ast-grep CLI to execute structured abstract syntax tree searches across your project files.

What is the best way to organize AST code search rules in a project?▼

Organizing AST code search rules in a project uses an sgconfig.yml file to define and manage rule directories. This configuration establishes a cohesive project setup that enables the CLI to locate and apply your custom pattern-matching rules accurately.

Why do manual AST-driven code rewrites fail when refactoring large codebases?▼

Manual AST-driven code rewrites fail when refactoring large codebases because they are verbose and error-prone without a cohesive CLI. Automating searches and applying safe transformations through snapshot validation prevents structural errors during execution.