Codex Plugin Starter

A thoughtful starting point for your next Codex plugin.

A working local MCP plugin with React, TypeScript, the official OpenAI Apps SDK UI, and a small notebook to make the pieces tangible. Start with the layout. Make the behavior your own.

Try it

Use this template to create your own repository, then:

npm ci
npm run dev

Open the local URL printed by Vite. Create a note, search, save a favorite, or switch appearance. The preview starts with sample notes, saves changes in this browser, and needs no API key.

Build your own plugin walks through identity, tools, UI, installation, and release. For a domain change, try the reading-list exercise.

Related MCP server: mcp-knowledge-base

Work on a note with Codex

Each note has a Work on this with Codex button. In a compatible host it sends the selected note to the app's current conversation and asks Codex to propose a plan. Continue there to refine the plan or ask Codex to save a new draft using Notebook's tools. The button leaves the original note unchanged. If a note saved from the conversation is not visible in the panel, use Refresh notes to fetch the current server state.

The browser preview and hosts without text-message support show the exact prompt with a Copy prompt action. They do not run AI. The plugin uses the host's conversation, so it needs no separate OpenAI API key. A successful handoff means the host accepted the message, not that the AI finished working.

Where notes are saved

The installed plugin stores notes in SQLite, outside the plugin directory. Notes survive app restarts and plugin updates. The browser preview uses separate local storage, so refreshing the page keeps its notes too.

See storage and privacy for database paths, backups, and removal.

What is included

• An elegant responsive sample with a sidebar, searchable notes, favorites, and an accessible editor.

• OpenAI UI buttons, inputs, textarea, badges, and icons; host theme and safe-area support.

• Four MCP tools with validated inputs and structured results, usable with or without the UI.

• A sidebar entrypoint, portable plugin manifest, compatibility manifest, and a marketplace.

• A browser preview, model tests, real stdio smoke test, and official AppBridge browser test.

• Self-contained packaging, dependency notices, checksums, and a release workflow.

Build and install locally

Node.js 22.13+ and npm are required.

npm run check
npm run package
codex plugin marketplace add ./artifacts/plugin
codex plugin add notebook@codex-plugin-starter

Open Notebook from the Codex sidebar in a current desktop app, or ask Codex to open Notebook. The package includes its UI and runtime dependencies; the receiving computer needs Node, not a source checkout. See installation and compatibility.

Development commands

Understand the pieces

Architecture · Build your plugin · Install and update · Release · Privacy

This is an independent community starter, not an official OpenAI product. It uses the official OpenAI UI library and MCP Extensions SDK.

MIT licensed. Bundled dependencies retain their own licenses; packaging includes third-party notices.