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UHPUHPDeveloper Guide
Independent resource · Not affiliated with HarnessRouter · Site data checked 4 Oct 2026

Reference implementation

HarnessRouter Community Edition

What belongs to UHP, what is specific to HarnessRouter, and what the current self-hosted reference implementation supports.

Verified: Protocol: 2026-09-28Release: v0.29.0

HarnessRouter Community Edition is the self-hosted reference implementation of UHP. Reference implementation behavior is not automatically normative UHP behavior.

Current implementation snapshot

Section titled “Current implementation snapshot”
CoordinateCurrent state
Stable releasev0.29.0, published 4 Oct 2026 at 00:33:05 UTC
Stable commit2826cf633b0588fa494da20fdf2828deacfb7e79
Upstream mainSame commit at this cutoff
UHP protocol2026-09-28 Draft
Conformance package2026.9.28.post3
Executable checks85
Released backends20

Release train highlights

Section titled “Release train highlights”
  • v0.24.0 / PR #266: introduces Runtime Plugins, starting with a Browser service connected once per workspace and included explicitly per harness.
  • v0.25.0 / PR #264: adds CheetahClaws 3.5.88 as backend sixteen.
  • v0.26.x: implements UHP Environments, including builds, versions, read-only session mounts, capability discovery and conformance coverage.
  • v0.26.18 / PRs #350-#351: adds Claude Sonnet 5.5 across the applicable model catalogue and removes the separate per-organization Runtime Plugin availability gate. The default was already open to every organization, so existing default instances do not change behavior.
  • v0.27.0 / PR #343: adds a Microsoft 365 Runtime Plugin using each organization’s own Entra application. Delegated mode executes as the signed-in workspace member instead of borrowing another member’s identity.
  • v0.28.6 / PR #368: hardens public artifact sharing with sandboxed response headers and durable revocation revalidation on the next read.
  • v0.28.7 / PR #369: adds GPT-6.1 Sol to every harness base that carries GPT-6 Sol, with the release recording connection-specific measured coverage and explicit refusal notes where a channel does not serve the model.
  • v0.29.0 / PR #373: adds Kilo CLI 7.8.1, MiniMax Code 0.5.4, Grok Build 1.0.41 and Agent Zero v2.13 as four new bases. The same release hardens relay failure/retry handling and keeps credential-bearing harness configuration out of checkpoints/workspace repositories.

None of these later product/model changes revise the UHP protocol version.

Runtime Plugins are not UHP Harness Plugins

Section titled “Runtime Plugins are not UHP Harness Plugins”

HarnessRouter Runtime Plugins are workspace-connected runtime services. Browser and Microsoft 365 are current implementation examples.

UHP Harness Plugins are protocol-level Agent Plugins packages carried on harness objects. The two concepts have different ownership, transport and lifecycle boundaries.

Backend set

Section titled “Backend set”

The released backend set is now 20:

Claude Code, Codex, Hermes, Pi, DeepSeek Harness, OpenCode, Qwen Code, Cline, Gemini CLI, Oh My Pi, Goose, Kimi Code CLI, Aider, OpenHands, System One, CheetahClaws, Kilo CLI, MiniMax Code, Grok Build and Agent Zero.

Adapter support does not establish native UHP adoption by the upstream project.

Environments

Section titled “Environments”

HarnessRouter is the reference implementation for UHP 2026-09-28 Environments. Task override behavior follows metadata.environment per PR #331, schema, conformance and gateway implementation.

The current Tasks prose table still carries one stale top-level environment row; that documentation drift is not treated as a second implemented wire form.

Primary sources

Section titled “Primary sources”