hai-ast-grep

ast-grep uses tree-sitter to parse code into AST, enabling precise pattern matching. Reach for it whenever a search or refactor depends on syntax structure: one-off searches and rewrites run straight from the CLI, reusable lint/codemod rules are written in YAML. Either way the job is not "write a pattern" — it is to ship a pattern or rule validated against a positive AND a negative case, so it catches what it should and nothing it shouldn't.

Project Configuration

Project-level batch scanning via ast-grep scan requires an sgconfig.yml config file; one-off pattern tests via ast-grep run -p '<pattern>' do not.

# sgconfig.yml (project root)
ruleDirs:
  - rules          # rule directory; recursively loads all .yml files

Typical project structure: