DeepSeek Harness developer preview · 0.1.2-rc.1

Download DeepSeek Harness Everything is a plugin

Every capability is a plugin that can be swapped or recomposed: models, tools, skills, sessions, sandboxes, storage, loops, scheduling, and the UI.

Run the local Web UI at 127.0.0.1:3080 with npx @deepseek-ai/dsh web. MIT license. Node.js ^22.19.0 or >=24. CLI unpacked 43 KB on 0.1.2-rc.1.

Download for Windows Run with Node.js

View features Trust and safety

$ npx @deepseek-ai/dsh web

$ git clone https://github.com/deepseek-ai/deepseek-harness.git
$ cd deepseek-harness
$ pnpm install
$ pnpm run build
$ pnpm dsh web

model tools skills session sandbox storage loop schedule ui

Agent + model = Harness

HARNESS

keeps agents working in real-world environments

The model is the soul of an agent.

A harness lets an agent understand its environment, use tools, and keep working in real-world settings.

Cordis kernel

The Cordis kernel manages plugins: installing, uninstalling, and dependencies. Agent capabilities live in these plugins.

Capabilities as plugins

Plugins provide every agent capability, including models, tools, skills, sessions, sandboxes, storage, loops, scheduling, and the UI. Cordis services and events let the plugins work together.

Compose with configuration

Developers can select, swap, or extend any capability in configuration without changing the DeepSeek Harness source code.

Design approach

Everything is a plugin

DeepSeek Harness is built on Cordis. Plugins provide models, tools, skills, sessions, sandboxes, storage, loops, scheduling, and the UI. Developers select or extend a capability in configuration instead of forking the tree. The official Settings frame lists 159 installed rows.

Every run is traceable

Everything the model sees is recorded in an append-only session log: system prompts, reasoning, tool calls and results, subagent scheduling, and every context injection. Resume, fork, search, and replay use the same event stream.

Trajectory view details

DeepSeek Harness Settings Plugins list with 159 plugins including llm, session, and api-gateway — Settings → Plugins. Click to enlarge.

Every run is traceable

Everything the model sees is recorded in an append-only session log: system prompts, reasoning, tool calls and results, subagent scheduling, and every context injection. In the Trajectory view, you can inspect these records by source. Resume, fork, search, and replay all operate on the same event stream.

Trajectory view details

Multiple runtime modes

Standard mode includes the full toolset. Code / PTC mode uses model-generated code to orchestrate multiple rounds of tool calls. Minimal mode keeps only a shell tool and a file editor for benchmarking models in a thin environment. Creator mode lets you inspect the current runtime, test Cordis plugins in memory, and combine them into new modes.

Full mode table

Describe what you want to build

Get started

Try it now or install from source

Quick start

Install Node.js ^22.19.0 or >=24.0.0, then launch the local Web UI with npx.

$ npx @deepseek-ai/dsh web

Install from source

Clone the published source and follow the setup commands in the repository. Shown as text, not an outbound link.

$ git clone https://github.com/deepseek-ai/deepseek-harness

Who actually runs dsh

Agent runtime authors swap model, tool, and sandbox plugins without editing the DeepSeek Harness source.
Coding-agent operators pin @deepseek-ai/[email protected] and keep a disposable workspace under workspace-write plus ask.
Eval teams use Minimal mode (persistent bash + str_replace_editor) when they want a thin tool surface.
Preset builders use Creator mode to test Cordis plugins in memory before writing a Profile.

DeepSeek Harness vs Claude Code, Codex, and OpenCode

Comparison of public facts for this category. DeepSeek Harness is a developer preview with compatibility-breaking changes.

Criterion	DeepSeek Harness	Claude Code	Codex	OpenCode
Distribution	npm CLI + source. npx @deepseek-ai/dsh web	Vendor CLI / IDE surface	Vendor CLI / IDE surface	Community open-source agent
License	MIT on 0.1.x	Proprietary product terms	Proprietary product terms	Open-source project license
Plugin model	Cordis plugins for models, tools, skills, session, sandbox, UI	Closed product with extension hooks	Closed product with extension hooks	Community plugins, not Cordis
Session trace	Append-only log + Trajectory resume / fork / replay	Vendor session UI	Vendor session UI	Varies by build
Runtime modes	Standard, Code / PTC, Minimal, Creator	Single product mode	Single product mode	Configurable, not these four names
Production claim	Developer preview. Not security-audited.	Generally available product	Generally available product	Community-supported

Source you can read

MIT-licensed repository and npm package @deepseek-ai/dsh. npm signatures and shasums are published per version. Commands on this site are shown as text, not outbound links.

Honest preview status

The README states there will be compatibility-breaking changes. GitHub Issues are closed; reports go to Discussions. Do not treat sandbox prompts as a containment guarantee. Read the legal usage policy.

Integrity checks

0.1.2-rc.1 shasum fef213043313affc36ca2226d2637ad483b5e3f6. 0.1.1-rc.2 shasum 1a5112369f1c46b13a6e6f21de8af5e6afd45074. Full notes on the download integrity section.

Field notes

Notes from people who already ran it

From discussions after real installs. Not marketing quotes.

Swapped the model plugin without touching the DeepSeek Harness tree. Cordis composition is the reason I stayed.

Discussion note · runtime author

Trajectory showed the exact bash payload that listed my workspace. Resume from that event worked. The UI still hiccups on very long streamed turns.

Discussion note · eval engineer

On Windows 11, C:\Windows\Temp plus windows-acl made every sandboxed pwsh call die with SandboxUnavailableError. Moving TEMP off the system temp dir fixed it.

Discussion note · Windows 11 Pro 25H2

npx brought the Web UI up in one command. Port 3080 was already reserved by Hyper-V, so I had to pick another port. That is in the port 3080 guide.

Discussion note · desktop lab

Creator mode is the only place I could inspect plugins in memory before writing a Profile. Token use on a multi-hour coding loop was higher than I budgeted.

Discussion note · preset builder

I pinned 0.1.1-rc.2 after an unpinned npx pull changed behavior overnight. The README warning is not decorative.

Discussion note · platform ops

Swapped the model plugin without touching the DeepSeek Harness tree. Cordis composition is the reason I stayed.

Discussion note · runtime author

Trajectory showed the exact bash payload that listed my workspace. Resume from that event worked. The UI still hiccups on very long streamed turns.

Discussion note · eval engineer

On Windows 11, C:\Windows\Temp plus windows-acl made every sandboxed pwsh call die with SandboxUnavailableError. Moving TEMP off the system temp dir fixed it.

Discussion note · Windows 11 Pro 25H2

npx brought the Web UI up in one command. Port 3080 was already reserved by Hyper-V, so I had to pick another port. That is in the port 3080 guide.

Discussion note · desktop lab

Creator mode is the only place I could inspect plugins in memory before writing a Profile. Token use on a multi-hour coding loop was higher than I budgeted.

Discussion note · preset builder

I pinned 0.1.1-rc.2 after an unpinned npx pull changed behavior overnight. The README warning is not decorative.

Discussion note · platform ops

Short FAQ

Is DeepSeek Harness free?+

Yes. DeepSeek Harness is published under the MIT License as a developer preview. You can inspect, modify, and self-host it. Early 0.0.1-rc packages used BSD-3-Clause; current 0.1.x packages are MIT.

Does DeepSeek Harness work on Windows 11?+

Yes, if Node.js is ^22.19.0 or >=24.0.0. The Windows sandbox uses an ACL restricted-token backend. Known issues include C:\Windows\Temp ACL lockouts, workspaces owned by BUILTIN\Administrators, and port 3080 reserved by Hyper-V, WSL2, or Docker.

Is DeepSeek Harness a model?+

No. DeepSeek Harness is the agent runtime around models. It supplies plugins for tools, sessions, sandboxes, storage, loops, scheduling, and the Web UI. Model IDs and API prices are separate releases.

Why might antivirus flag dsh?+

dsh is an npm CLI, not a Windows installer. Heuristic scanners sometimes flag Node processes that spawn shells. Check the published shasum for the version you pinned, such as fef213043313affc36ca2226d2637ad483b5e3f6 for 0.1.2-rc.1.

Open the full FAQ

Get the preview

Download DeepSeek Harness

Windows 10/11, macOS, and Linux through Node.js. Buttons on the download page are ready for your package URLs.

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