DeepSeek Harness (dsh)

DeepSeek Harness (dsh) is DeepSeek AI's open-source agent harness. Agent = Model + Harness, and every capability inside it is a swappable plugin.

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2026/08/14
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What is DeepSeek Harness?

DeepSeek Harness (dsh) is DeepSeek AI's open-source agent harness: it gives a model a workspace, a tool registry, sandbox and approval policy, an append-only session log and a loop that keeps work moving. It is built for teams that want to own their agent runtime, plugin authors publishing capabilities under the dsh-plugin topic, and anyone who needs to swap a model adapter, sandbox or storage backend by configuration. What sets it apart is that every capability — models, tools, skills, sessions, sandboxes, storage, loops, scheduling and the UI — is a plugin mounted on the Cordis kernel, so you extend dsh by adding a plugin rather than patching a core.

Key features

Everything is a plugin
The model adapter, tool registry, session log, agent loop and browser UI are all plugins, so any part is replaceable from configuration and no privileged core needs patching.
Cordis kernel underneath
Cordis mounts, unmounts and reconnects plugins and tracks their dependencies, and registrations unwind automatically when their plugin unloads.
Patch-layer composition
A running instance is a plugin tree composed from ordered layers — bundle patches, the profile's own patch file, the machine-level patch and command-line overlays — where later layers win per row.
Four agent presets on one core
Standard gives the full toolset, Code exposes tools through the Code Mode SDK, Minimal keeps only persistent bash and str_replace_editor, and Creator adds runtime inspection and preset-authoring guidance.
Append-only session log
System prompts, reasoning, tool calls and results, subagent scheduling and context injections are all logged, and resume, fork, search and replay operate on that single event stream.
Sandbox and permission modes
File-effect confinement for spawned processes offers read-only, workspace-write and danger-full-access modes across Linux, macOS and Windows backends.
Swappable model providers
DeepSeek, catalog providers such as Anthropic and OpenAI, and custom OpenAI-compatible endpoints all arrive through the same adapter interface.

How to use DeepSeek Harness

  1. Install Node.js 22.19 or newer, or version 24 and above.
  2. Run npx @deepseek-ai/dsh web. The command starts the Web UI, served at http://127.0.0.1:3080 by default. A source checkout instead needs a clone, pnpm install, pnpm run build and pnpm dsh web from the repository root.
  3. Open Settings, then Models, add a model key and save it. The model route becomes usable immediately without restarting.
  4. Choose a workspace directory, since the session composer stays unavailable until one is selected.
  5. Inspect and extend the runtime: dsh web --dump-config prints the composed plugin tree your machine boots, and dsh plugin installs out-of-tree plugins into a profile by forwarding pnpm verbs to the profile directory.

Use cases

  • Teams that want to own their agent runtime instead of consuming a closed one.
  • Plugin authors building and publishing capabilities under the dsh-plugin topic on GitHub.
  • Model evaluation that needs a stable, minimal tool surface across runs — Minimal mode limits the agent to persistent bash and a file editor.
  • Internal platforms embedding an inspectable agent loop behind their own UI, since the browser client, HTTP server and client modules ship as bundles.
  • Anyone who needs to swap a model adapter, sandbox or storage backend by configuration rather than by code, or point the filesystem and subprocess at a remote sandbox with one swap.

Pricing

The official website does not list pricing or paid plans for DeepSeek Harness; the project is published under the MIT license and is in developer preview, so check the official site for current details.

FAQ

Is DeepSeek Harness the same project as the Python deepseek-harness package?

No. Two unrelated projects use the name DeepSeek Harness. The official one from DeepSeek AI is TypeScript, runs on Node.js and is installed with npx @deepseek-ai/dsh web, while the community project is a Python client library for the DeepSeek V4-Pro and V4-Flash APIs installed with pip. They have different authors, source trees, languages and version lines, and neither is a fork or successor of the other.

What do I need installed to run DeepSeek Harness?

DeepSeek Harness needs Node.js 22.19 or newer, or 24 and above. Running the published CLI needs nothing else, while building from a source checkout also requires Corepack-enabled pnpm 11.7.0 and Git 2.26 or newer. At least one model provider must be configured.

Which model providers can DeepSeek Harness use?

It accepts a DeepSeek API key, a catalog provider such as Anthropic or OpenAI, or a custom OpenAI-compatible endpoint. Bedrock, Vertex, Azure and Codex need their native credentials rather than an API-key field. DeepSeek Harness ships no weights and calls whichever provider you configure.

What are the four modes in DeepSeek Harness?

Standard mode is a full coding agent with file editing, shell, file and web search, skills, planning, goals, subagents and workflows. Code mode adds the Code Mode SDK so the model can combine multi-step operations into one TypeScript program, Minimal mode keeps only persistent bash and str_replace_editor for benchmarking, and Creator mode adds runtime inspection and preset-authoring guidance on top of Standard.

Is DeepSeek Harness ready for production use?

Not for deployments that need API stability today: DeepSeek Harness is in developer preview and compatibility-breaking changes are expected, with core plugins and APIs still changing. It is also software you run yourself rather than a hosted or managed service.

Can DeepSeek Harness be served to a network?

The CLI accepts --host and --port, but --host 0.0.0.0 is intentionally not supported yet and exits with a usage error. The Web UI is meant to be served locally, at http://127.0.0.1:3080 by default.

DeepSeek Harness (dsh)

DeepSeek Harness (dsh) is DeepSeek AI's open-source agent harness. Agent = Model + Harness, and every capability inside it is a swappable plugin.

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