What is UHP?
Understand the problem UHP addresses, what an agent harness is, and what the protocol standardizes.
Current state: 15 August 2026
UHP is new. HarnessRouter publicly open-sourced the protocol and its Community Edition implementation on 14 August 2026. The current published protocol version in the official repository is 2026-08-11.
The protocol specifies a common HTTP contract for selecting configured harnesses, executing work, streaming progress, continuing sessions, moving files and artifacts, cancelling work, returning machine-readable errors, and reporting results. The current reference implementation supports Codex, Claude Code and Hermes as harness backends.
Important distinction: support in HarnessRouter Community Edition is not the same thing as native UHP adoption by OpenAI, Anthropic or Nous Research. This site tracks those claims separately.
Why this site exists
The official specification is the authority for normative behavior. This independent guide focuses on the questions developers ask around it: where UHP sits in the agent stack, how it differs from MCP and other harness projects, what conformance means in practice, and whether independent adoption is actually happening.
Explore the guide
| Topic | Best page | Question answered |
|---|---|---|
| Basics | What is UHP? | What does the protocol actually standardize? |
| System model | Architecture | How do client, server and harness relate? |
| Normative rules | Specification guide | What is in version 2026-08-11? |
| Verification | Conformance | What does “UHP conformant” mean? |
| Tool interoperability | UHP vs MCP | Are the protocols competitors or complements? |
| Harnesses | Codex, Claude Code, Hermes | What is verified about each backend? |
| Market signal | Adoption tracker | Who has actually implemented or endorsed UHP? |
Editorial principles
Pages distinguish protocol requirements from implementation behavior. Claims about vendor adoption require a primary source. Early announcements are dated. Where evidence is missing, the page says so instead of turning inference into fact.