Agent Skills

coss-particles

coss.com is the new holding company of cal.com, the pioneers of open source scheduling infrastructure and cal.com continues to be the 'google search' of our alphabet.

Installation
CLI
npx skills add https://github.com/cosscom/coss --skill coss-particles

Install this skill with the CLI and start using the SKILL.md workflow in your workspace.

Last updated 4/22/2026

coss.com

coss.com (formerly Origin UI)

The everything but AI company.

About the Project

coss.com is the new holding company of cal.com, the pioneers of open source scheduling infrastructure. Our mission is to build a home for amazing open source projects, giving them the support they need to grow and succeed.

We're building the coss stack, a one line npm install @coss package that includes everything you need to build your application, from email, SMS, calendar APIs, scheduling, video conferencing, notifications and more.

Repository Overview

This repository contains multiple products and applications that make up the coss.com ecosystem:

Apps and Packages

  • apps/www/ - Main coss.com website
  • apps/ui/ - coss ui component library and documentation
  • apps/origin/ - Legacy Origin UI components (pre-acquisition)
  • packages/ui/ - Shared UI components package
  • packages/typescript-config/ - TypeScript configurations
  • biome.json - Shared Biome configuration for linting and formatting

Each package/app is 100% TypeScript.

Environment Variables

This monorepo contains multiple Next.js applications that are designed to link to each other. For the navigation to work correctly, you must set up environment variables for both local development and production deployments.

Local Development

For local development, create a .env.local file in each of the app directories with the corresponding variables.

  1. www app

    This app needs to know the URLs of the other apps. Create a file at apps/www/.env.local:

    # apps/www/.env.local
NEXT_PUBLIC_APP_URL=http://localhost:3000
NEXT_PUBLIC_COSS_UI_URL=http://localhost:4000/ui

  2. ui app

    This app needs to know the URLs of the other apps. Create a file at apps/ui/.env.local:

    # apps/ui/.env.local
NEXT_PUBLIC_APP_URL=http://localhost:4000/ui
NEXT_PUBLIC_COSS_URL=http://localhost:3000
NEXT_PUBLIC_ORIGIN_URL=http://localhost:4001

  3. origin app

    This app needs to know the URLs of the other apps. Create a file at apps/origin/.env.local:

    # apps/origin/.env.local
NEXT_PUBLIC_APP_URL=http://localhost:4001/origin
NEXT_PUBLIC_COSS_URL=http://localhost:3000
NEXT_PUBLIC_COSS_UI_URL=http://localhost:4000/ui

[!NOTE]
Turborepo is configured to watch for changes in .env* files, so it will automatically invalidate the cache when these variables change.

Development

This Turborepo has some additional tools already setup for you:

Build

To build all apps and packages:

bun run build

To build a specific app:

bun run build --filter=www
bun run build --filter=ui
bun run build --filter=origin

Develop

To develop all apps and packages:

bun run dev

To develop a specific app:

bun run dev --filter=www
bun run dev --filter=ui
bun run dev --filter=origin

coss ui

coss ui is a collection of beautifully designed, accessible, and composable components for your React apps. Built on top of Base UI and styled with Tailwind CSS, it's designed for you to copy, paste, and own.

We think Base UI is the best foundation for modern web applications. We've taken its powerful, unstyled primitives and given them a design system that's ready to go, right out of the box.

This is the component library we'll be progressively adopting for cal.com. We're building it in the open for anyone who wants to create beautiful, reliable user interfaces.

Origin UI Acquisition

This repository also includes the Origin UI components as a legacy snapshot. Origin UI was a pre-acquisition collection of Radix-based, shadcn-style components that remains available for use, but with limited support and maintenance. Active development now focuses on the new Particles components built on the coss ui primitives.

Contributing to coss ui

We're always looking for contributors to help improve our UI components. Whether it's a bug report, a new feature, or a documentation update, we appreciate your help.

Please see our Contributing Guidelines for more information on how to get involved.

Licensing

This repository uses a mixed licensing approach. The default license for this project is AGPLv3.0.

  • MIT: The apps/origin/ and apps/ui/ directories are licensed under their original MIT license
  • AGPLv3: All other directories are licensed under the GNU Affero General Public License v3.0

For detailed information, see our Licensing documentation.

Acknowledgements

Special thanks to:

  • Tailwind CSS - For the utility-first CSS framework that powers our design system
  • Base UI - For providing the robust, accessible primitives that form the foundation of our components
  • shadcn/ui - For inspiring our copy-paste approach and component philosophy
  • Fumadocs - For providing the documentation framework that powers our component docs