How do I install the Ast Grep skill?

Run npx skillmds@latest add masih-0x3/ast-grep in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Ast Grep safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Ast Grep?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Ast Grep free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Ast Grep?

Masih-0x3 (@masih-0x3) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Ast Grep by masih-0x3 — Agent Skill

Name: Ast Grep
Author: Masih-0x3

File contents

AST Grep

Use AST-aware search when the question is about code shape, not just text. rg remains the default for plain strings; ast-grep is for syntax.

When To Use

Use this skill when:

Finding call sites by syntactic shape.
Searching for imports, JSX props, function calls, decorators, object patterns, assignments, or API usage.
Planning or applying a mechanical codemod.
Refactoring repeated code structures across files.
Avoiding false positives from comments, strings, generated files, or unrelated identifiers.

Skip this skill when:

A simple rg or rg --files query answers the question.
The language is unsupported or the repo lacks enough files for AST matching to pay off.
The task needs semantic call flow or impact analysis; use codegraph first when available.

Workflow

Define the code shape in words before writing the pattern.
Start with rg or rg --files if needed to identify languages and candidate directories.
Choose the language/parser explicitly when the tool requires it.
Test the AST pattern on a small scope first.
Inspect matches before changing files.
For codemods:
- run a dry run or JSON/listing mode first.
- apply changes to the narrowest safe file set.
- inspect the diff.
- run tests/typecheck/lint relevant to the changed language.

Pattern Discipline

Prefer concrete syntax over broad wildcards.
Exclude generated/build/vendor directories.
Avoid matching comments and strings unless that is the target.
Keep replacement patterns minimal.
If the pattern is brittle, stop and use manual edits or CodeGraph-assisted navigation.

Tool Notes

Common command shapes:

ast-grep --lang ts -p '<pattern>' <path>
ast-grep --lang tsx -p '<pattern>' <path>
ast-grep --lang js -p '<pattern>' <path>

Use the installed tool's help output for exact flags. Some versions differ on JSON, rewrite, and update flags.

Guardrails

Do not apply a codemod without inspecting candidate matches.
Do not run broad rewrites over the whole home directory or unrelated workspaces.
Do not treat a clean AST search as proof of runtime behavior.
Preserve unrelated user changes.

Closeout

AST-grep:
- Shape searched:
- Scope:
- Matches:
- Changes applied:
- Validation:

---name: ast-grepdescription: Use for AST-aware code search, syntax-shaped matching, codemods, API migrations, repeated structured edits, or refactors where text grep may overmatch or miss language structure.---# AST GrepUse AST-aware search when the question is about code shape, not just text. `rg` remains the default for plain strings; `ast-grep` is for syntax.## When To UseUse this skill when:- Finding call sites by syntactic shape.- Searching for imports, JSX props, function calls, decorators, object patterns, assignments, or API usage.- Planning or applying a mechanical codemod.- Refactoring repeated code structures across files.- Avoiding false positives from comments, strings, generated files, or unrelated identifiers.Skip this skill when:- A simple `rg` or `rg --files` query answers the question.- The language is unsupported or the repo lacks enough files for AST matching to pay off.- The task needs semantic call flow or impact analysis; use `codegraph` first when available.## Workflow1. Define the code shape in words before writing the pattern.2. Start with `rg` or `rg --files` if needed to identify languages and candidate directories.3. Choose the language/parser explicitly when the tool requires it.4. Test the AST pattern on a small scope first.5. Inspect matches before changing files.6. For codemods: - run a dry run or JSON/listing mode first. - apply changes to the narrowest safe file set. - inspect the diff. - run tests/typecheck/lint relevant to the changed language.## Pattern Discipline- Prefer concrete syntax over broad wildcards.- Exclude generated/build/vendor directories.- Avoid matching comments and strings unless that is the target.- Keep replacement patterns minimal.- If the pattern is brittle, stop and use manual edits or CodeGraph-assisted navigation.## Tool NotesCommon command shapes:```bashast-grep --lang ts -p '<pattern>' <path>ast-grep --lang tsx -p '<pattern>' <path>ast-grep --lang js -p '<pattern>' <path>```Use the installed tool's help output for exact flags. Some versions differ on JSON, rewrite, and update flags.## Guardrails- Do not apply a codemod without inspecting candidate matches.- Do not run broad rewrites over the whole home directory or unrelated workspaces.- Do not treat a clean AST search as proof of runtime behavior.- Preserve unrelated user changes.## Closeout```textAST-grep:- Shape searched:- Scope:- Matches:- Changes applied:- Validation:```

Frequently asked questions

Ast Grep