The one-sentence definition
DeepSeek Harness is an open-source Agent harness developed by DeepSeek AI. It runs locally, connects a model to tools and a workspace, records the session, applies permission policy, and can present the whole workflow through a browser UI.
Why “Everything is a Plugin” matters
| Token | Role | Check |
|---|---|---|
| Model adapter | Connects a model provider to the shared runtime | Can be replaced through configuration |
| Tool registry | Exposes controlled capabilities to the Agent | Execution passes through policy and lifecycle events |
| Session log | Stores durable messages, steps, and tool events | Reload, resume, and replay derive from recorded facts |
| Web UI | Renders sessions, workspace controls, and settings | It is another composed part of the plugin tree |
Profiles assemble a usable product
- 01
Choose a profile
The official distribution includes web and headless templates. A profile defines which ordered bundles and external plugins start together.
- 02
Choose a workspace
The Agent works against a selected project directory. That boundary matters because tools can read files, edit code, and run commands there.
- 03
Apply permission policy
The Web UI asks before operations that require approval under the active policy. A Harness is useful precisely because model output is not treated as automatic authority.
- 04
Run a recorded session
Messages, model steps, and tool results become session events, so the interface can resume and explain what happened.
Where visual themes fit
The official Web Client exposes a reversible ThemeRuntime token override. DSH Themes uses that narrow surface for Simple Themes. Full Skin is a stricter DSH Themes publishing protocol built on official Cordis and Web mechanisms; it is not an official native DeepSeek Harness skin format.
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Compare published artifacts or return to the installation documentation.