DeepSeek Harness Installation Tutorial: Understanding the New Agent Mode in One Article

DeepSeek V4 Pro was just released, by our own company. Agent The product followed, and it was called DeepSeek Harness.

Many people will be confused at first glance, thinking it's similar to Codex.Claude Local programming with the same code Agent After installation, run the webpage and type commands in the browser to... AI I'll help you modify the code.

Learn about DeepSeek Harness

In fact, DeepSeek is not "yet another" AI It's not an "editor," but rather an infrastructure layer.

Agent = Model + Harness

The model is the soul, responsible for thinking and decision-making; Harness is the hands, feet, and nervous system, responsible for understanding the environment, using tools, and continuously working in real-world scenarios. Without Harness, even the smartest model can only stare blankly.

Codex、Cursor Agent、Claude The code is essentially a pre-packaged Harness by the vendor. Tools, sandboxes, session management, and UI are all hidden away. The only things you can modify are Skills and MCPs.

DeepSeek Harness is different. Its core concept is:Everything is a plugin。

Model integration is a plugin, file editing is a plugin, web page search is a plugin, and this web interface itself is also a UI plugin. In other words, like the modular phones of yesteryear, you could replace, add, or disassemble whatever you wanted, assembling it all yourself.

Install Node.js

Visit the official Node.js website: https://nodejs.org, select the version suitable for your computer system, and download and install it.

One-clickstart up

Open a terminal command prompt and enter the following installation command:

npx @deepseek-ai/dsh web

Continue typing in the terminal yA local URL will pop up.

Copy the address to your browser, and the interface will appear.

You can use what's already on your computer. AI Agent（Cursor、Claude To install (either Code or WorkBuddy), simply create a shortcut on your desktop.

The first time you open it, a pop-up window will ask you to fill in a DeepSeek API Key. If you don't have one, you can apply for one on the DeepSeek Open Platform.

API Open Platform URL：https://platform.deepseek.com/

After filling in the information and saving, you will officially enter Harness.

The entire page consists of two parts: the left side is the workspace and conversation list, and the middle is the chat area.

DeepSeek Harness does not have a "Create New Project" button.

Harness requires a local folder to be bound as a "workspace" to function. Click "Select Workspace" and specify your project directory.Agent Only then can you read files, run commands, and modify code inside.

Harness gave them four sets directly.Agent Preset is like giving the same brain four different bodies.

• Standard modeThe most comprehensive file editing, shell execution, web search, skill invocation, task planning, and sub-system functions. Agent Collaboration, it's all there. First time using it? Choose this one.
• PTC modePTC stands for Programmatic Tool Calling. The biggest difference between PTC and the standard mode is:AI Instead of manually calling tools step by step, it directly generates a piece of TypeScript code that orchestrates, chains, and even executes multiple operations in parallel, completing them all at once. For example, if you need to read 10 files in batches, search for information, summarize, and write to a new file, the standard mode would require dozens of rounds of dialogue, while the PTC mode accomplishes it all with a single piece of code, making it much faster and saving on tokens.
• Minimalist modeOnly provide bash and a file editor; everything else is removed. Suitable for purely testing the model's coding capabilities or for specific tasks.SimpleThere's no need to equip a full set of gear.
• Creative ModeThis model is the most "nested": it makes... AI Help you create a new one Agent Preset. You could say, "Make me a dedicated code reviewer." Agent", it willautomaticGenerate configuration filePrompt wordsThe tool set can be saved and used directly in the mode list.

Harness has three levels of permissions, which can be switched using the shield icon in the lower left corner:

• Read OnlySuitable for code review and logic analysis; absolutely safe.
• Workspace Write（recommend）It can read and write the current workspace folder, but cannot access other parts of the system. It is the first choice for daily development.
• Full Access: Fully permitted, allowing the execution of any system command.

if Agent If you are about to perform an operation that exceeds your current permissions, a pop-up window will ask you to confirm.

• /planEnter planning mode.AI List out a plan first, and only start working on it after you confirm it, to prevent unnecessary changes.
• /goalSet an overall goal for a long task.AI It will remember and continue to move towards the goal, and will correct itself if it goes astray along the way.
• /compactCompressing early conversation history makes room for context and is a lifesaver when long conversations get stuck.
• /permission：fastSwitch permission levels.
• /model: Temporarily switch the model used in the current dialogue.

DeepSeek Harness is not yet another one. AI Programming tools areopen sourcePluggable and self-evolving Agent Framework: The model, tools, UI, and behavioral logic are all broken down into plugins, and dynamic composition and side effect reversal are implemented based on the Cordis kernel.

It's currently in developer preview and it iterates very quickly. But if you want to experience...Agent "What does the underlying structure look like?" or "Do you want to build one yourself that perfectly matches your workflow?" AI This assistant is worth installing and trying right now.