jscpd Code Migration Tracker
kucherenko/jscpd
Measures a code port between languages or frameworks with jscpd's function-level comparison, porting tests before code and tracking what is left unmatched.
Use ast-grep for Python structural code exploration, mechanical codemods, and rule maintenance in this repo.
Install Ast Grep
$ npx skills add banteg/crimson --skill ast-grep -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install banteg/crimson ast-grep --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/banteg/crimson.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.codex/skills/ast-grep .claude/skills/ast-grep && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "ast-grep" agent skill from https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grep into .claude/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grepType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add banteg/crimson --skill ast-grep -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install banteg/crimson ast-grep --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/banteg/crimson.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.codex/skills/ast-grep .agents/skills/ast-grep && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "ast-grep" agent skill from https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grep into .agents/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add banteg/crimson --skill ast-grep -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install banteg/crimson ast-grep --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/banteg/crimson.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.codex/skills/ast-grep .cursor/skills/ast-grep && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "ast-grep" agent skill from https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grep into .cursor/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/banteg/crimson.git --path .codex/skills/ast-grep--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add banteg/crimson --skill ast-grep -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install banteg/crimson ast-grep --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/banteg/crimson.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.codex/skills/ast-grep .gemini/skills/ast-grep && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "ast-grep" agent skill from https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grep into .gemini/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install banteg/crimson ast-grepInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add banteg/crimson --skill ast-grep -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/banteg/crimson.git skills-src && mkdir -p .github/skills && cp -r skills-src/.codex/skills/ast-grep .github/skills/ast-grep && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "ast-grep" agent skill from https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grep into .github/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add banteg/crimson --skill ast-grep -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install banteg/crimson ast-grep --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/banteg/crimson.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.codex/skills/ast-grep .opencode/skills/ast-grep && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "ast-grep" agent skill from https://github.com/banteg/crimson/tree/master/.codex/skills/ast-grep into .opencode/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
ast-grep- GitHub stars
- 184
- Token cost
- ~541 tokens
- SKILL.md length
- 183 words
- Files
- 2
- Skills in repo
- 2
- Repo updated
- First seen
- Licence
- None found
At a glance
Use ast-grep for Python structural code exploration, mechanical codemods, and rule maintenance in this repo.
- Works in 3 steps: Start narrow (single directory or file… → Prototype match/rewrite → Apply intentionally
- Tasks that involve Code migrations
- SKILL.md covers Quick Start, Structural Exploration, Mechanical Codemods and Repo Rule Layout, plus 2 more sections
- Calls just and git
What it does
Ast Grep is an agent skill from banteg/crimson. Use ast-grep for Python structural code exploration, mechanical codemods, and rule maintenance in this repo. Use this when you need syntax-aware search/replace (instead of regex), to add/update ast-grep rules in tools/ast-grep/, or to verify rule behavior with ast-grep scan and ast-grep test.
Its SKILL.md is about 540 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files (for example `agents/openai.yaml`).
It sits in Development, covering Code migrations. It works with Python. The repository describes itself as: a faithful rewrite of crimsonland 1.9.93 from 2003.
When your agent uses it
- Tasks that involve Code migrations
Example prompts
- “/ast-grep”
Requirements
- Python 3
Workflow steps
3 steps, taken from the first numbered list in SKILL.md.
- Start narrow (single directory or file set).
- Prototype match/rewrite
- Apply intentionally
What it can do on your machine
Read from SKILL.md and the folder at commit 8bd33b5. 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
Shell commands in SKILL.md call:
justgit
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md. Its commands use git, which can reach the network depending on how they are called.
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
Ast Grep loads about 541 tokens when it runs. Until then it costs about 77 tokens; SKILL.md has 183 words of instructions outside code blocks.
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
Auto-check passed
The automated check found no risky patterns in SKILL.md.
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
Without a licence we can't republish the file, so here is its outline and opening line. It has 183 words (~541 tokens).
“Prefer ast-grep for structural exploration and mechanical rewrites in Python code.”
- name
- ast-grep
Files
SKILL.md and 1 other file in .codex/skills/ast-grep of banteg/crimson.
- SKILL.md
- agents/openai.yaml
Open the folder on GitHubat commit 8bd33b5
Compare with similar skills
Ast Grep next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Ast Grep this skillbanteg/crimson | 184 | — | ~541 | Automated safety check: Pass | None | |
| jscpd Code Migration Trackerkucherenko/jscpd | 6.4k | — | ~5k | Automated safety check: Pass | MIT | |
| RustPython Stdlib UpgradeRustPython/RustPython | 22k | — | ~876 | Automated safety check: Pass | MIT | |
| Code Migrationanthropics/code-migration-kit-with-claude-code | 743 | — | ~983 | Automated safety check: Pass | Custom licence | |
| Saleor Port Changessaleor/saleor | 23k | — | ~969 | Automated safety check: Pass | BSD-3-Clause | |
| Frappe Ops UpgradesImpertio-Studio/Frappe_Claude_Skill_Package | 187 | — | ~3.3k | Automated safety check: Notes | MIT |
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RustPython Stdlib Upgrade
RustPython/RustPython
Upgrades a Python standard library module from CPython into RustPython with update_lib, then triages and marks the tests that still fail.
- Official
Code Migration
anthropics/code-migration-kit-with-claude-code
Run a large-scale language migration with the six-step process: create the map and the rules, stress-test the rules, translate everything, compile, run it, match behavior.
Saleor Port Changes
saleor/saleor
Forward-ports or backports a single PR or branch onto the currently checked-out Saleor branch, handling GraphQL version markers and migration numbering along the way.
Frappe Ops Upgrades
Impertio-Studio/Frappe_Claude_Skill_Package
A skill your agent uses when upgrading Frappe/ERPNext between major versions (v14 to v15, v15 to v16), troubleshooting failed migrations, or planning rollback.
Documenso Upgrade Migration
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Questions about Ast Grep
What does Ast Grep do?
Use ast-grep for Python structural code exploration, mechanical codemods, and rule maintenance in this repo. Ast Grep is an agent skill from banteg/crimson. Use ast-grep for Python structural code exploration, mechanical codemods, and rule maintenance in this repo.
When should I use Ast Grep?
Ast Grep fits situations like: tasks that involve Code migrations.
How do I install Ast Grep in Claude Code?
Run `npx skills add banteg/crimson --skill ast-grep -a claude-code`. Or copy the skill folder (.codex/skills/ast-grep in banteg/crimson) into .claude/skills/ast-grep in your project. Claude Code loads it when a task matches its description.
How do I install Ast Grep in Codex?
Run `npx skills add banteg/crimson --skill ast-grep -a codex`. Or copy the skill folder (.codex/skills/ast-grep in banteg/crimson) into .agents/skills/ast-grep in your project. Codex loads it when a task matches its description.
Can I use Ast Grep in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add banteg/crimson --skill ast-grep -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ast-grep, .gemini/skills/ast-grep, .github/skills/ast-grep and .opencode/skills/ast-grep in your project.
What does Ast Grep need to run?
Going by SKILL.md and its folder, Ast Grep needs the command-line tools its instructions call (just and git). Our summary lists: Python 3.
Does Ast Grep access the network?
SKILL.md contains no URLs. Its commands use git, which can reach the network depending on how they are called. This is read from the text; nothing was executed.
Is Ast Grep safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Ast Grep use?
No licence was found for Ast Grep or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.
How many tokens does Ast Grep use?
About 541 tokens (SKILL.md is roughly 2.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Ast Grep?
Skills that share tags, products or a category with Ast Grep: jscpd Code Migration Tracker (kucherenko/jscpd, 6.4k stars), RustPython Stdlib Upgrade (RustPython/RustPython, 22k stars), Code Migration (anthropics/code-migration-kit-with-claude-code, 743 stars) and Saleor Port Changes (saleor/saleor, 23k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Ast Grep?
banteg (a GitHub user) maintains it in banteg/crimson, which has 184 GitHub stars. The repository holds 2 skills in this directory. The repository was last updated on October 8, 2026.
Source: banteg/crimson on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.