DeepSeek Harness

DeepSeek Harness is an open-source agent harness, released as a developer preview, built on the equation its own page states: an agent is a model plus a harness. Everything on the harness side — the model interface, tools, skills, sessions, sandboxes, storage, the control loop, scheduling, even the UI — is a plugin that can be replaced and recombined.

That is a considered architectural position rather than a feature list. Most agent frameworks commit early: this is how sessions work, this is where memory lives, this is the loop. Those commitments are what make them productive and also what make them awkward the moment your requirement differs, and the usual outcome is a fork or a rewrite. A harness where every part is a plugin is an explicit bet that the parts will keep changing and that the seams matter more than the defaults. The honest caveat is that developer previews are previews: the plugin interfaces are the thing most likely to move, so anything built against them now should expect to be rebuilt. The MIT licence at least makes that rebuilding permissible.