What is cairn?
cairn is a Claude Code mod by jmgirard that milestone-driven development workflow and tracking system for Claude Code projects: a language-agnostic core with per-repo toolchain profiles (R, Python, Claude Code plugin, Docker image,. It is listed under Security and has 4 GitHub stars.
| Type | Claude code mod |
|---|---|
| Author | jmgirard |
| Repository | jmgirard/cairn |
| Popularity | 4 GitHub stars |
| Category | Security |
| Security | Review before installing (72/100) |
| Rank | #737 of 5,272 Claude Code mods; #102 in Security |
| License | MIT |
| Last commit | 2026-10-18 |
| Hooks | 10 events |
| Sees | Edit calls, MultiEdit calls, Write calls, classic hooks, every prompt, every skill |
| Draws on | Pane, AbovePrompt |
Is cairn safe to install?
cairn scores 72/100 on the MCPMods security check: Review before installing. Things to review: starts processes outside the sandbox; watches every prompt or event. It passed 5 of 8 checks.
Mod footprints come from claude plugin validate, which lists every event a mod hooks and every API call it makes without running it.
| Check | Result |
|---|---|
| No network access | Pass |
| Starts processes outside the sandbox | Review |
| Writes no files or config | Pass |
| Doesn't read environment variables | Pass |
| Watches every prompt or event | Review |
| Doesn't drive Claude | Pass |
| Validator reported problems | Note |
| Has an open-source license | Pass |
API calls in its code
| Call | What it means |
|---|---|
$.command.register | |
$.command.run | drives Claude |
$.fs.list | reads files |
$.fs.read | reads files |
$.fs.stat | reads files |
$.process.run | runs processes |
$.prompt.fill | writes the prompt box |
$.session.cwd | |
$.session.root | |
$.state.get | |
$.state.set | |
$.store.get | keeps its own state |
$.store.set | keeps its own state |
$.ui.close | draws interface |
$.ui.invalidate | draws interface |
$.ui.open | draws interface |
$.ui.panes | draws interface |
$.ui.resolve | draws interface |
$.ui.toast | draws interface |
How do I install cairn?
- Check your Claude Code version. Mods need Claude Code 2.1.287 or later and are on by default.
claude --version
- Read its footprint. This lists every event it hooks and every API call it makes, without running it.
git clone https://github.com/jmgirard/cairn claude plugin validate ./cairn/.
- Install it. Run this in your terminal, then /reload-plugins in an open session.
claude plugin marketplace add jmgirard/cairn && claude plugin install cairn@cairn
Or ask Claude to set it up
Paste this into Claude Code and it installs cairn for you:
Install the "cairn" Claude Code mod from https://github.com/jmgirard/cairn. Run claude plugin validate on it first and show me what it can access before you enable it.