Understand · Improve · Recheck

Know what your AI built.
Make it better.

Use reusable Guides to understand your app, ask your coding agent for changes, and check what improved.

Free for VS Code Claude Code & Codex CLIYour code stays local

How it works

From understanding to real changes.

1

Understand

Run a Guide to review your project.

2

Improve

Comment, or ask your agent to fix something.

3

Recheck

Run again to see what changed.

Guides

Reusable reviews for your project.

A Guide is a Markdown page that tells your coding agent what to examine. Pick a built-in one or write your own.

Product Understanding

What your app really does, and for whom.

Architecture and Runtime

How the parts really fit together.

Security and Privacy

Permissions, secrets, data leaks, what the agent may reach.

Stubs and Placeholders

Code that only pretends to work.

AI Change Review

What your latest AI changes actually did.

Run any Guide again to see what changed. Fix findings with your agent and check the result.

Not checked again? Never counted as fixed.

The Pen

Point your pen. Comment. Improve.

Change the content Change my code Ask your agent Just a comment

Select text on any Markdown page. Tell your agent what to do, or simply leave a comment.

Your wiki

Your documents. Your living wiki.

Keep editable Markdown pages locally. Work with your AI on any page, whether it is connected to code or not.

Know when a code-related page needs another review.

Pen Wiki for Teams

Your team comments. Your agent makes the changes.

Share your pages as a web wiki. Teammates and clients comment in their browser. Their feedback syncs to your editor, where you decide what changes.

Your wiki. Your AI. Your choice.

Free in VS Code. Use your existing coding agent. Keep your code local and share pages only when you choose.