DeepSeek Harness Developer Preview (v0.1) is now available for testing by Harness developers worldwide, and it is also open-sourced under the MIT license. As an early preview version, DeepSeek Harness adopts a "everything is a plugin" design approach, building Agent Harness through a plugin-based architecture. Capabilities such as models, tools, skills, sessions, sandboxes, storage, loops, scheduling, and UI are all combined in the form of plugins, allowing independent replacement and flexible recombination.
DeepSeek Harness is mainly built based on the Cordis plugin system. The Cordis meta-framework only handles plugin loading, unloading, and dependency management. The specific components of Agent Harness are implemented by different Cordis plugins, which collaborate through service and event mechanisms. Developers can independently select, replace, or extend any capability at the configuration level without modifying the DeepSeek Harness source code.
For different scenarios, DeepSeek Harness provides four modes: standard, PTC (programmatic tool call), minimal, and creative. In PTC mode, the model generates code to combine multiple rounds of tool calls; the minimal mode retains only the Shell and file editing tools, used for model benchmark testing in minimal environments; the creative mode supports checking the runtime, experimenting with Cordis plugins in memory, and combining new modes. Currently, systems with the Node.js development toolchain can quickly start its Web UI via npx.
