DEEPSEEK HARNESS · PRACTICAL GUIDE

What is DeepSeek Harness? From installation to a working DeepSeek API

DeepSeek's upgraded open-source agent harness can use the latest V4 Flash Vision model for multimodal workflows alongside tools, skills, sessions, sandboxes, filesystems, and orchestration. This guide shows where OK-API fits in the model connection layer.

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MIT

Open-source license

dsh

Command-line entry point

All

Everything is a plugin

Vision

Multimodal model

Run it now

npx @deepseek-ai/dsh web

More than a chat interface

Harness gives a model a controlled environment in which it can select context, call tools, maintain sessions, and advance a task. Its plugin architecture lets teams replace models, tools, or execution environments without rebuilding the entire agent application.

Models, tools, skills, sessions, and sandboxes are plugins
The dsh process serves the local Web UI
Designed for coding agents and multi-step tool workflows

OK-API provides the model connection layer

Harness runs the agent; OK-API supplies the model endpoint. After adding one custom provider, the same user API key can discover and call DeepSeek V4 Flash Vision, Flash, and Pro.

Base URL: https://api.ok-api.net/v1
Use a scoped user key instead of exposing an upstream credential
Supports streaming, tools, and DeepSeek thinking controls

Give Harness image understanding

Select deepseek-v4-flash-vision-exp when a Harness workflow must inspect screenshots, diagrams, or other visual inputs. The model supports image understanding with tools and file inputs; it is not an image-generation model.

Declare image in the model's input capabilities
Keep text-only Flash and Pro available as fallback choices
Validate image and tool workflows after each Harness upgrade

Why start with V4 Flash

Flash is a practical first model for validating installation, authentication, model discovery, and the tool loop. You can move complex tasks to Pro without changing application authentication or rebuilding the provider.

Verify /v1/models first
Run a minimal tool-enabled session
Confirm reasoning content survives multi-turn requests

A safe boundary for the preview

DeepSeek labels Harness as a Developer Preview and warns that compatibility-breaking changes can occur. Pin versions in production, record configuration changes, and replay critical agent workflows before upgrading.

Pin the @deepseek-ai/dsh version
Regression-test tools and long sessions before upgrades
Track the official repository and this integration guide

FAQ

Frequently asked questions

Is DeepSeek Harness an official DeepSeek project?+

Yes. The official repository is deepseek-ai/deepseek-harness. It is MIT licensed and currently marked as a Developer Preview.

Do I need a separate DeepSeek API key when I use OK-API?+

No. Create a scoped OK-API user key and point the Harness custom provider to the OK-API /v1 endpoint.

How is Harness different from the OpenAI SDK?+

An SDK sends API requests. Harness also manages tools, sessions, context, execution loops, sandboxes, and a user interface—the runtime around the model.

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