DeepSeek opens agent platform where you build plugins by chatting with it

DeepSeek has launched Harness, an open source agent platform that the company itself describes as being in public preview. An agent is an AI program that doesn't just answer questions but also carries out tasks on its own. According to DeepSeek, Harness can be used for everyday tasks, coding, research and background automation. It runs both as a desktop app and in a web interface.

Build your own add-on in the chat

One of the most eye-catching features is Creator mode. It lets users create plugins, meaning small add-ons, through an ordinary chat. The plugins can extend the platform's tools, skills and user interface. DeepSeek's own example is a Pomodoro timer, built simply by describing it.

According to two guides and reviews that don't come from DeepSeek itself, Creator mode asks clarifying questions, builds the plugin and installs it automatically in the same session. According to the tech site DataCamp, the mode can also be used to inspect the running system, test plugins in memory and combine them into new modes.

Everything is a plugin

Harness is built on the Cordis plugin framework. According to DataCamp, nearly everything in the system is swappable: the model adapter, tools, sessions, sandbox and even the agent loop itself, which governs how the agent works step by step.

Creator is only one of several modes. Standard offers full functionality with file editing, shell, search, skills and planning. PTC lets the model write programs against a generated SDK, a set of programming tools. Minimal includes only a persistent shell and file editing with text replacement. PTC was previously called Code mode.

Early stage and security risks

According to a third-party guide on DEV Community, version 0.1 of the developer preview was released on August 13, 2026. It is an early stage: the repository, meaning the project's code folder, warns that compatibility-breaking changes will come. One API has already changed, when Code mode was renamed PTC mode.

DeepSeek's security notice also states that no audit has been carried out, meaning an independent security review. The tool can edit files, run commands and load third-party plugins, and according to the notice, this poses real security risks.

For ordinary users, this means that Harness is for now a tool for those who want to experiment, and that you should be careful about what it gets access to. Community plugins are available on GitHub, and there is developer documentation for those who want to build further.