DeepSeek Open-Sources Harness: A Fully Plugin-Based Agent Framework

机器之心 · wechat · 2026-08-13

DeepSeek has released the developer preview of DeepSeekHarness, an agent SDK and application framework. Rather than being a simple API client, it is built on a microkernel with an "everything is a plugin" philosophy, aiming to provide a foundational way to assemble AI agents.

Core Architecture & Design:

Layered Plugins: Strictly separates interfaces, implementations, and consumers. Capabilities like file systems, terminals, LSP, and the AgentLoop itself are independent packages, allowing easy replacement of local shells with remote containers or custom tools.
AgentLoop Traffic Rules: Breaks down conversations into strict Turn and Step lifecycles. Tool calls pass through a pipeline of safety guards, concurrent scheduling, and context management, supporting parallel read-only tasks and exclusive execution for state-modifying tasks.
SessionLog as Source of Truth: Mandates that everything the model sees can be reconstructed from logs. It records requests, streaming outputs, and tool results as event streams, ensuring consistency between UI, state recovery, and playback for robust debugging.
Multi-Agent & Workflows: Features built-in sub-agent delegation and workflow orchestration with strict context isolation. It also introduces collaborative state components like goals, plans, and to-do lists across different lifecycles.

Product Modes:

The framework supports WebUI, TUI, and Headless entry points. The WebUI offers four preset modes: the fully-featured Standard Mode; PTC Mode (lets the model write TypeScript to combine multi-step operations); Minimal Mode (reduced toolset for lower context burden); and Creative Mode (allows the agent to explore and recombine its own runtime to create new presets).

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DeepSeek Open-Sources Harness: A Fully Plugin-Based Agent Framework

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