What DeepSeek Harness is
DeepSeek Harness (dsh) is an open-source agent harness developed by DeepSeek AI. Upstream, it is described as built around a plugin architecture — “everything is a plugin” — and is licensed MIT. It is currently in developer preview, and the upstream project warns that compatibility-breaking changes are expected during that preview.
What HarnessRouter added
HarnessRouter Community Edition tagged v0.8.0 on 20 August 2026 and added DeepSeek Harness as a version-pinned, developer-preview backend. The tag's conformance commit reports a Full-class UHP run with 52/52 checks executed through a DeepSeek Harness harness, with task checks run on claude-haiku-4.5 via the dsh backend's pi-ai route.
Conformance evidence through DeepSeek Harness
The v0.8.0 evidence is a published Full-class 52/52 UHP conformance report executed through the DeepSeek Harness integration. It demonstrates that HarnessRouter's dsh path satisfies the same Full-class behavioral expectations as its other backends. It does not, by itself, expand the UHP conformance suite beyond 52 checks.
Upstream status to keep in mind
Because DeepSeek Harness is in developer preview with expected compatibility-breaking changes, integration behavior may shift as upstream evolves. Treat the v0.8.0 integration and its conformance run as a point-in-time result, not a permanent guarantee of the upstream API surface.
What is not proven
Why the distinction matters
A reference implementation can adapt an existing harness without that harness vendor changing its own API. Native adoption would be a stronger ecosystem signal: it would mean a vendor, tool or independent runtime exposes or consumes UHP directly, reducing dependence on one adapter implementation.
Related pages
Read HarnessRouter Community Edition, conformance, the adoption tracker, the ecosystem map, and the other harness pages: Codex, Claude Code, Hermes, and Pi.