How to Install / Upgrade: DeepSeek Harness launches as open source rival to Claude Code, alongside V4-Pro on…

What happened

DeepSeek, the Chinese AI lab, on Thursday launched the official version of DeepSeek-V4-Pro, an updated flagship model focused heavily on agentic workloads, and put it on the API with higher prices. Alongside that model it launched DeepSeek Harness v0.1, a new open-source agent harness that gives developers an alternative to Claude Code. The release moves DeepSeek beyond the model layer and into the software developers use to put AI agents to work.

The technical detail

To upgrade, point agent workloads at the official DeepSeek-V4-Pro API instead of whatever prior DeepSeek flagship you were calling, and account for the higher API prices before you cut traffic over. Install DeepSeek Harness v0.1 as the open-source agent harness and run your agentic jobs through that harness if you want the Claude Code alternative DeepSeek shipped with this release. Keep the model upgrade and the harness install together so V4-Pro’s agentic focus is actually exercised through Harness v0.1 rather than only through raw API calls.

Market and competitive context

Watch the higher DeepSeek-V4-Pro API prices and the fact that Harness is v0.1, a first official harness release rather than a drop-in clone of Claude Code. After the change, confirm you are on the official DeepSeek-V4-Pro and on DeepSeek Harness v0.1, then run a real agentic workload through the harness and verify it completes as the agent runtime instead of Claude Code. If the job still hits the old model or the old harness, you have not finished the upgrade.