DeepSeek releases open-source agent harness with plugin architecture

DeepSeek AI released DeepSeek Harness v0.1, an MIT-licensed agent harness in developer preview where every capability is implemented as a plugin. It supports four runtime modes, append-only session logs, and provider-agnostic model routing, meaning it isn't locked to DeepSeek's own models.

Why it matters: DeepSeek expanding from model releases into agent tooling puts it in more direct competition with harnesses like Claude Code and OpenAI's agent frameworks, and an MIT-licensed, provider-agnostic design could make it attractive to developers wary of vendor lock-in. It's part of a broader trend of labs building out the agent-harness layer around their models, not just the models themselves.