DeepSeek Harness (DSH) EXPLAINED | Everything Is a Plugin

In this video we take a deep dive into DeepSeek Harness (DSH), DeepSeek's open-source agent harness, built on the Cordis plugin system around one idea: everything is a plugin, including the agent loop, the tools, and even the system prompt. We start with a quick tour of the new Electron desktop application, then break down the architecture of DSH and the history and design of Cordis, the plugin system that powers it. We look at how plugins provide services, how dependency injection and events connect every part of the application, and how Cordis tracks registrations to clean up plugins safely when they unmount. Then we go hands-on: we write real plugins in code, run `dsh web --patch` with a custom `cordis.patch.yml`, watch three plugins (a greet tool, a bash guard, and a hello plugin) load and fire inside the app, and finish by loading the plugins into the desktop application via npm packages and the `.dsh` user configuration. By the end, you'll understand how the composability of DSH works and how to create and load your own plugins, including a custom agent loop that never calls a model. --- 🔗 *Links* - DeepSeek Harness GitHub repository: https://github.com/deepseek-ai/deepseek-harness - Cordis GitHub repository: https://github.com/cordiverse/cordis - Cordis design paper: https://arxiv.org/abs/2608.25512 - DeepSeek Harness website: https://www.deepseek.com/en/harness/ --- 🤓 *Topics Covered* - The DSH agent harness architecture and desktop app - How the Cordis plugin system powers everything - Building and loading your own DSH plugins --- ⏱️ *Timestamps* 0:00 Intro 1:00 App Demo 5:57 What Is DSH 8:22 History of Cordis 10:59 What Is Cordis 15:04 Cordis Context 20:02 Events 24:00 Plugins Code Demo 28:54 Loading the Plugins 👋 *Connect with me* - My website: https://alejandro-ao.com/ - X (Twitter): https://x.com/_alejandroao - LinkedIn: https://www.linkedin.com/in/alejandro-ao/