Structural Code Search with ast-grep

What it does

When your agent uses it

• Finding every async function without error handling across a codebase
• Locating calls to a function with particular arguments
• Writing and debugging a new ast-grep rule in YAML
• Code queries that plain text search cannot express

Example prompts

• “Find all async functions in src that use await but have no try/catch.”
• “Write an ast-grep rule for React components that call useEffect without a dependency array.”
• “Test this ast-grep rule against my example file and tighten it until it matches only the intended code.”

Requirements

• The ast-grep CLI

Workflow steps

5 steps, taken from the step headings in SKILL.md.

1. 1Understand the Query
2. 2Create Example Code
3. 3Write the ast-grep Rule
4. 4Test the Rule
5. 5Search the Codebase

What it can do on your machine

Read from SKILL.md and the folder at commit 34ad57e. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are bash, yaml and javascript).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Structural Code Search with ast-grep loads about 2.4k tokens when it runs, and up to ~5k if it reads all its reference files. Until then it costs about 120 tokens; SKILL.md has 835 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~120

When it runs · the whole SKILL.md, loaded when a task matches

~2.4k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from warp-drive-data/warp-drive at commit 34ad57e, republished under its MIT licence (© warp-drive-data). 835 words, ~2,370 tokens.

name

ast-grep

description

Guide for writing ast-grep rules to perform structural code search and analysis. Use when users need to search codebases using Abstract Syntax Tree (AST) patterns, find specific code structures, write new rules, working with @ast-grep/napi or perform complex code queries that go beyond simple text search. This skill should be used when users ask to search for code patterns, find specific language constructs, or locate code with particular structural characteristics.

// test_example.js
async function example() {
  const result = await fetchData();
  return result;
}

id: async-with-await
language: javascript
rule:
  kind: function_declaration
  has:
    pattern: await $EXPR
    stopBy: end

echo "async function test() { await fetch(); }" | ast-grep scan --inline-rules "id: test
language: javascript
rule:
  kind: function_declaration
  has:
    pattern: await \$EXPR
    stopBy: end" --stdin

ast-grep scan --rule test_rule.yml test_example.js

ast-grep run --pattern 'console.log($ARG)' --lang javascript /path/to/project

ast-grep scan --rule my_rule.yml /path/to/project

ast-grep scan --inline-rules "id: my-rule
language: javascript
rule:
  pattern: \$PATTERN" /path/to/project

ast-grep run --pattern 'async function example() { await fetch(); }' \
  --lang javascript \
  --debug-query=cst

# See the structure of your target code
ast-grep run --pattern 'class User { constructor() {} }' \
  --lang javascript \
  --debug-query=cst

# See how ast-grep interprets your pattern
ast-grep run --pattern 'class $NAME { $$$BODY }' \
  --lang javascript \
  --debug-query=pattern

echo "const x = await fetch();" | ast-grep scan --inline-rules "id: test
language: javascript
rule:
  pattern: await \$EXPR" --stdin

echo "const x = await fetch();" | ast-grep scan --inline-rules "..." --stdin --json

# Basic pattern search
ast-grep run --pattern 'console.log($ARG)' --lang javascript .

# Search specific files
ast-grep run --pattern 'class $NAME' --lang python /path/to/project

# JSON output for programmatic use
ast-grep run --pattern 'function $NAME($$$)' --lang javascript --json .

# With rule file
ast-grep scan --rule my_rule.yml /path/to/project

# With inline rules
ast-grep scan --inline-rules "id: find-async
language: javascript
rule:
  kind: function_declaration
  has:
    pattern: await \$EXPR
    stopBy: end" /path/to/project

# JSON output
ast-grep scan --rule my_rule.yml --json /path/to/project

has:
  pattern: await $EXPR
  stopBy: end

# Correct: escaped $
ast-grep scan --inline-rules "rule: {pattern: 'console.log(\$ARG)'}" .

# Or use single quotes
ast-grep scan --inline-rules 'rule: {pattern: "console.log($ARG)"}' .

ast-grep scan --inline-rules "id: async-await
language: javascript
rule:
  all:
    - kind: function_declaration
    - has:
        pattern: await \$EXPR
        stopBy: end" /path/to/project

ast-grep scan --inline-rules "id: console-in-class
language: javascript
rule:
  pattern: console.log(\$\$\$)
  inside:
    kind: method_definition
    stopBy: end" /path/to/project

ast-grep scan --inline-rules "id: async-no-trycatch
language: javascript
rule:
  all:
    - kind: function_declaration
    - has:
        pattern: await \$EXPR
        stopBy: end
    - not:
        has:
          pattern: try { \$\$\$ } catch (\$E) { \$\$\$ }
          stopBy: end" /path/to/project

© warp-drive-data, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in .claude/skills/ast-grep of warp-drive-data/warp-drive.

• SKILL.md
• references/rule_reference.md

Open the folder on GitHubat commit 34ad57e

Used in 5 other repositories

We found 5 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 5 other GitHub owners. This page covers the copy in warp-drive-data/warp-drive, which our catalogue first saw on October 7, 2026.

• JanDeDobbeleer/oh-my-posh.agents/skills/ast-grep
• nodetool-ai/nodetool.agents/skills/ast-grep
• ast-grep/agent-skillast-grep/skills/ast-grep
• archibate/dotfiles-opencodeskills/ast-grep
• coleam00/skills.claude/skills/ast-grep