How to set up the free sealmd plugin in Claude Code, Cursor, or Copilot

Installing sealmd takes two commands in Claude Code and needs nothing but Node.js 18+ — no account, no API key, zero dependencies. The plugin is the free, open-source, MIT-licensed half of Seal: it lets your AI agent run a Google-Docs-style review pass over any local Markdown file — anchored comments, suggested edits with an Accept button, role-tailored summaries — without the document ever leaving your machine. Here’s the full setup, from install to your first review.

What do I need before installing sealmd?

Node.js 18 or newer. That’s the whole list — the plugin has zero dependencies. A git repo is optional but recommended, because sharing review state with collaborators is just commit and push. The gh CLI is only required if you want the plugin to open GitHub pull requests for you; everything else works without it.

How do I install sealmd in Claude Code?

Two commands inside a Claude Code session:

/plugin marketplace add jonyster/sealmd
/plugin install sealmd@sealmd

The first adds the marketplace from the jonyster/sealmd repo; the second installs the plugin. After that, /sealmd, /seal-new, /seal-open, and /seal-role are available in every project.

How do I use sealmd from Cursor, Codex, or Copilot?

Through rules files that ship in the repo and point each agent at the same CLI engine. Cursor reads .cursor/rules/seal-review.mdc; OpenAI Codex and GitHub Copilot read .github/copilot-instructions.md. Drop the relevant file into your project and that agent can start, open, and drive reviews exactly like Claude Code does. Same files on disk, same review page, no separate install per agent.

How do I run my first review?

Point the one command at any Markdown file:

/sealmd <doc.md>

It auto-detects what to do. If a review already exists for that file, it opens it. Otherwise it runs a guided setup — confirm the doc, name the owner, pick your reviewer role — and opens the review page. Use /seal-new to force fresh setup, /seal-open to skip questions, or /seal-role to add a role-tailored summary (a ~90-second digest written for a specific reviewer role).

What files does sealmd create?

Two, next to your document. doc.seal.md is the sidecar holding comments, suggestions, and resolve state — commit it, since git is the transport and collaborators pull it to see review state. doc.review.html is the derived, self-contained review page and is auto-gitignored. Your doc.md stays canonical and untouched: Seal isn’t an editor — accepted suggestions apply the edit to the source file, but your agent or editor remains the thing that writes it.

Where does the review page open?

Live at http://127.0.0.1:<port> — loopback-only and token-authed, so nothing is exposed beyond your machine — or as the static, offline doc.review.html you can send as a file or zip bundle. Both render the same page, with dark and light themes.

How do I update the plugin?

Run:

/plugin marketplace update sealmd

then open /plugin, choose sealmd → Update, and restart Claude Code.

Do I need an account or API key to use sealmd?

No. The sealmd plugin is free, MIT-licensed, and open source, and it runs entirely on your machine. There is no account, no API key, and nothing to sign up for. Your AI agent (Claude Code, Cursor, Codex, or Copilot) does the AI work; the plugin itself has zero dependencies beyond Node.js 18+.

Does sealmd work outside Claude Code?

Yes. Claude Code gets the native /plugin install, and the repo includes rules files for the others: .cursor/rules/seal-review.mdc wires in Cursor, and .github/copilot-instructions.md wires in OpenAI Codex and GitHub Copilot. All of them drive the same CLI engine, so the review files and commands are identical whichever agent you use.

Does the plugin do approvals?

No, deliberately. The local plugin covers comments, suggestions, role summaries, and resolve/reopen. Sign-off is a normal GitHub PR — run seal pr or click the Open PR button, which shells to gh pr create — and git history is the audit trail. If you need identity-verified approval bound to the exact wording, that lives in the hosted tier at www.sealmd.net.

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