ast-grep / agent-skill

The named skill, ast-grep, teaches an agent to write ast-grep rules -- metavariables, relational queries, composite AND/OR/NOT logic -- so it can search a codebase by code structure instead of plain text: functions missing error handling, a call made with too many arguments, a hook used inside another hook, that kind of pattern. It needs the ast-grep binary itself already on the machine, installed through Homebrew, npm, or cargo, since the skill is a guide to a command-line tool rather than a self-contained capability.

This is for someone doing a large or unfamiliar-codebase refactor or audit who wants AST-aware search instead of grep, and specifically someone using Claude Code, since the package ships as a Claude Code plugin marketplace rather than a plain skill folder; the README is explicit that Claude will not reach for this skill on its own and has to be told to use ast-grep by name.

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A second skill lives in the repository with no README mention at all. ast-grep-outline gives an agent a cheap structural map of a codebase's files, directories, imports, exports, and top-level members before it reads full source -- a distinct job from the rule-writing skill above -- but nothing in the README's installation steps, usage notes, or file listing names it; we found it only by reading the skill files directly.

Both skills share the same one dependency. Neither needs an account or a network call; both assume only that the ast-grep CLI is already installed and on PATH, so the entire package's cost to start is that one command-line tool.