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UHPUHPDeveloper Guide
Independent developer guide. Not affiliated with HarnessRouter or the official UHP project.

UHP adoption tracker

Backend support is not native adoption. This page keeps protocol implementation, adapter support and upstream endorsement separate.

Page reviewed 8 Nov 2026 Source and review policy

Protocol: 2026-10-19HarnessRouter: v0.38.2

Current adoption status

Section titled “Current adoption status”
ClaimStatusEvidence
UHP specification existsVerifiedCurrent protocol is 2026-10-04 Draft.
HarnessRouter CE implements UHPVerifiedStable v0.38.5 / 52c929f1cf30; separately checked main is the same commit the tag was cut from. From v0.36.0 CE also implements and advertises the optional input_history capability of UHP 2026-10-19 Tasks §2.1, so that optional capability is now established in the reference implementation; the optional memories and harness_retirement capabilities are still not advertised. v0.35.1 changes relay, SQL, media and driver behavior, not the UHP version or backend-adoption classification.
Current conformance sourceVerified104 executable checks, package 2026.10.19.post5.
HarnessRouter released backend supportVerified implementation30 offered backends; the runner’s BACKENDS registry holds the same 30 entries, so every registered base is now offered (re-read at v0.38.5 on 8 November 2026). v0.37.0 adds Mistral Vibe, Docker Agent, fast-agent and Deep Agents Code, and removes the Gajae-Code entry the previous stable implemented but did not offer. v0.33.0 added MiMo Code, jcode, OpenSquilla, nanobot and Qoder Cloud Agent.
HarnessRouter Runtime PluginsVerified implementationBrowser from PR #266 / v0.24.0; Microsoft 365 from PR #343 / v0.27.0; not a UHP protocol feature.
UHP EnvironmentsVerified protocol + reference implementationUHP 2026-09-28, PR #321; task override patched by PR #331.

Classify new evidence before changing an adoption label

Section titled “Classify new evidence before changing an adoption label”

System One now provides a useful positive native example: its own v0.4.0 README documents s1 serve, and its checked-in report records 40 passed / 0 failed / 0 skipped / 0 errored, highest class Core, protocol 2026-09-12, suite 2026.9.12.post1. The report was generated 19 September against loopback, implementation 0.1.0; it is project-authored evidence, not this site’s rerun or current Full certification. Read the System One guide for its separate adapter role.

New evidenceSupported labelWhat would upgrade the claim
Server adds a backend adapterAdapter/integration supportUpstream’s own UHP implementation/documentation
Upstream exposes UHP endpointNative protocol implementationIdentified runtime interoperability and suite report
Project publishes exact-class reportMeasured at named revision/classA newer scoped report, never an inferred denominator refresh
Community directory lists a projectListed implementationSource inspection and reproducible measurement
Client supports UHP transportClient implementationPublished endpoint/version matrix for operational claims

Apply the labels per role and version. SuperQode’s client and server are two claims; a client-only project should not inherit a server’s conformance class. The conformance guide explains why a newer suite requires a new measured result. For other HarnessRouter backends, retain native adoption not established unless the upstream project supplies comparable direct evidence.

Native-adoption boundary

Section titled “Native-adoption boundary”

HarnessRouter can integrate a harness without the upstream project implementing or endorsing UHP. CheetahClaws becoming backend sixteen, and Kilo CLI, MiniMax Code, Grok Build and Agent Zero joining in v0.29.0, are HarnessRouter implementation evidence, not native UHP adoption by those upstream projects.

The same rule applies to the other HarnessRouter backends unless the upstream project itself names and implements UHP. HarnessRouter model support for Claude Sonnet 5.5 or GPT-6.1 Sol is implementation/provider compatibility evidence, not native UHP adoption by a model vendor.

Conformance does not automatically transfer

Section titled “Conformance does not automatically transfer”

A reference-server result, adapter test, provider matrix or backend-specific integration test is not evidence that an upstream harness is independently UHP conformant.

Section titled “Related reading”

Compare the independent uhp-go server evidence with the UHP client inventory. Read conformance before interpreting a report or badge.

Primary sources

Section titled “Primary sources”