DeepSeek is inviting open-source developers into beta tests for DeepSeek Harness, software meant to turn language models into multi-step agents, the South China Morning Post reported. Harness lead Cui Tianyi, hired in March from quant trading, posted the call as the firm pushes agent tooling beside its cheap V4 Flash model. Agentic harnesses became a competitive front after Anthropic's Claude Code showed demand for coded workflows. Why it matters: Hangzhou labs are contesting the agent control plane, not only token prices. Caveat: no release date was given, and the harness group remains short-staffed.