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ast-grep

ast-grep is a skill for Codex from OutlineDriven/odin-claude-plugin. It costs 40 tokens per session (1,219 once invoked), scanned A, original, Apache-2.0.

A tool and workflow for searching, checking, and rewriting code by its structure rather than by matching text. An abstract syntax tree is the parsed structure of code, so formatting and whitespace do not affect the match.

In plain words
What is it for?
Use it to find particular function calls, rename variables, change function signatures, convert code patterns, enforce custom rules, and inspect code across supported languages.
Why use it?
It avoids fragile search-and-replace edits that can change the wrong text or miss equivalent code written differently. It supports structural checks and dry runs before rewriting.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Part of the odin-code plugin — 60 skills shipped together

not rated 35repo changed 3d ago A scan SkillSpector: pass 40 tokens original Apache-2.0

Good fit Use it to find particular function calls, rename variables, change function signatures, convert code patterns, enforce custom rules, and inspect code across supported languages.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/outlinedriven/odin-claude-plugin/ast-grep
View source ↗ OutlineDriven/odin-claude-plugin outlinedriven.github.io
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add OutlineDriven/odin-claude-plugin --skill ast-grep
Clone the repo
git clone --depth 1 https://github.com/OutlineDriven/odin-claude-plugin

Made for: Codex.

Or install odin-code, the plugin that ships this one along with the rest of its 60 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for ast-grep

README.md
[![agentmods](https://agentmods.dev/badge/skills/outlinedriven/odin-claude-plugin/ast-grep/github.svg)](https://agentmods.dev/skills/outlinedriven/odin-claude-plugin/ast-grep)
Your own site
<a href="https://agentmods.dev/skills/outlinedriven/odin-claude-plugin/ast-grep"><img src="https://agentmods.dev/badge/skills/outlinedriven/odin-claude-plugin/ast-grep/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for ast-grep

Your own site · 80×15
<a href="https://agentmods.dev/skills/outlinedriven/odin-claude-plugin/ast-grep"><img src="https://agentmods.dev/badge/skills/outlinedriven/odin-claude-plugin/ast-grep.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,219 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00040 $0.01219
Opus 5 $0.00020 $0.00609
Sonnet 5 $0.00008 $0.00244
Haiku 4.5 $0.00004 $0.00122

Measured 3d ago against content hash 83937c99021c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

ast-grep scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/ast_grep_helper.py, tests/smoke.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/odin-code/skills/ast-grep/SKILL.md · 51 lines

How it starts

The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ast-grep

Contract

Field Bound contract
Trigger AST-based modification, structural search, lint, or replacement too fragile for regex.
Authority Reversible local: writes only VCS-tracked source files (search is read-only; rewrites apply only through the helper after dry-run review); rollback is version control. No remote mutation.
Side effect Local file writes through the helper two-pass validate/dry-run/apply flow; no remote, credential, or published mutation.
Done Pattern validated and blast radius reviewed; any rewrite landed at the correct scope (search/lint-only runs are valid).

Inputs

  • An ast-grep pattern, single-quoted in the shell so $VAR reaches ast-grep unexpanded.
  • A language (--lang) or a single target path whose extension auto-detects it; required for stdin patterns.
  • For rewrites: a rewrite template and one or more target paths (defaults to the current directory).
  • Optional: include/exclude globs (repeatable, prefix ! to exclude), context lines, JSON output mode.

Procedure

  1. Confirm the task is structural (call, function, class, or import shaped like a pattern), not text/regex/filename matching (use grep) or semantic type/reference lookup (use LSP or the compiler). ast-grep matches syntax, not bytes. Done when: the task is confirmed structural.
  2. Validate the pattern before searching: python3 scripts/ast_grep_helper.py validate '<pattern>' --lang <L>. Exit 0 means ast-grep parses it cleanly; exit 2 means malformed (the helper prints the parsed pattern tree showing the ERROR node). Fix and re-validate. Done when: validate exits 0.
  3. For a rewrite, run the dry-run: python3 scripts/ast_grep_helper.py replace '<pattern>' '<rewrite>' --lang <L> <paths>. Read the diff and the N matches across M files count. If the blast radius is wrong, stop and refine the pattern (tighten meta-variables, add --lang, add context); re-run the dry-run. Done when: the dry-run diff and match count are correct.
  4. Apply only after the dry-run diff is correct: python3 scripts/ast_grep_helper.py replace '<pattern>' '<rewrite>' --lang <L> <paths> --apply. The helper writes via a separate --update-all pass. Done when: files are updated via --update-all.
  5. Invoke ast-grep, never sg: sg collides with the setgroups binary on many systems. Done when: ast-grep is invoked, not sg.

Read the full file on GitHub · 51 lines

Files

What ships with it

13 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago Changed · -17 tokens per session 83937c99021c
  2. 6d ago Changed · -120 lines · +18 tokens per session ff045ffe3959
  3. 10d ago First seen · 171 lines · 39 tokens per session scan A 178fcf62fcc8

Subscribe to this mod's changes

ast-grep is a skill published in the GitHub repository OutlineDriven/odin-claude-plugin (35 stars, last pushed today), licensed Apache-2.0. It adds 40 tokens to every session and 1,219 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Claude CodeDebuggingclaude-code-pluginclaude-code-pluginsclaude-marketplaceclaude-pluginsoutline-driven-development
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