DeepSeek Harness (dsh) is an open-source agent harness developed by DeepSeek AI. The README describes it as an architecture where "everything is a plugin" and says it is powered by Cordis, which is presented as the underlying composability framework.
The project is currently in developer preview, and the README explicitly warns that compatibility-breaking changes may still happen. Users can run it locally from npm with `npx @deepseek-ai/dsh web`, which starts a Web UI on `http://127.0.0.1:3080` by default, or build and run it from a repository checkout with pnpm.
The repository also includes detailed documentation and runnable examples covering architecture, development, APIs, workflows, and interface patterns. That makes the project useful for developers who want to experiment with agent harness concepts, understand the plugin model, or adapt the harness to custom tooling and runtime setups.