What is redpen?
redpen is a Claude Code mod by joonhyukyim that line-by-line review pane: comment on what Claude changed, then send every comment back as one prompt. It is listed under Interface and has 4 GitHub stars.
| Type | Claude code mod |
|---|---|
| Author | joonhyukyim |
| Repository | joonhyukyim/redpen |
| Popularity | 4 GitHub stars |
| Category | Interface |
| Security | Low risk (84/100) |
| Rank | #738 of 5,272 Claude Code mods; #273 in Interface |
| License | MIT |
| Last commit | 2026-10-11 |
| Hooks | 8 events |
| Sees | Edit calls, NotebookEdit calls, Write calls |
| Draws on | Pane |
Is redpen safe to install?
redpen scores 84/100 on the MCPMods security check: Low risk. Things to review: reads environment variables. It passed 6 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 no processes | Pass |
| Writes no files or config | Pass |
| Reads environment variables | Review |
| Only sees the events it hooks | Pass |
| Drives Claude (model calls, prompts) | Note |
| Passes claude plugin validate | Pass |
| Has an open-source license | Pass |
API calls in its code
| Call | What it means |
|---|---|
$.clock.now | |
$.clock.sleep | |
$.command.register | |
$.env.get | reads env vars |
$.fs.list | reads files |
$.fs.read | reads files |
$.fs.stat | reads files |
$.prompt.submit | drives Claude |
$.session.cwd | |
$.session.messages | reads the transcript |
$.state.get | |
$.state.set | |
$.ui.focus | draws interface |
$.ui.invalidate | draws interface |
$.ui.open | draws interface |
$.ui.resolve | draws interface |
$.ui.toast | draws interface |
How do I install redpen?
- 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/joonhyukyim/redpen claude plugin validate ./redpen/.
- Install it. Run this in your terminal, then /reload-plugins in an open session.
claude plugin marketplace add joonhyukyim/redpen && claude plugin install redpen@redpen
Or ask Claude to set it up
Paste this into Claude Code and it installs redpen for you:
Install the "redpen" Claude Code mod from https://github.com/joonhyukyim/redpen. Run claude plugin validate on it first and show me what it can access before you enable it.