Core project
| Component | Current role |
|---|---|
| UHP specification | Normative protocol contract; current published version 2026-08-11. |
| HarnessRouter Community Edition | Self-hosted reference implementation. |
| Conformance suite | Behavioral verification across Core, Extended and Full classes. |
| Schema artifacts | OpenAPI 3.1 and JSON Schema 2020-12 representations. |
Supported backends in the reference implementation
The current HarnessRouter repository lists Codex, Claude Code and Hermes. They are installed on first run rather than redistributed in the image, reflecting their separate licensing and packaging.
Adjacent projects worth distinguishing
- MCP: context and tool interoperability at a different boundary.
- Harness Protocol: portable harness configuration through
harness.yaml. - Agent Harness Protocol (AHP): a separate supervision/policy-oriented protocol project using JSON-RPC event and decision flows.
- Vercel AI SDK HarnessAgent: a separate unified programming abstraction for harnesses such as Claude Code and Codex; not the same protocol.
What would count as ecosystem growth?
- An independent UHP server passes the conformance suite.
- A product client supports more than one UHP server implementation.
- A harness vendor publishes native UHP support.
- SDKs appear that are maintained outside the reference project.
- Interoperability testing happens across independently maintained implementations.
Avoid false ecosystem inflation
A press-release syndication count is not adoption. A GitHub mention is not implementation. A wrapper around HarnessRouter is not necessarily an independent UHP server. This site records stronger evidence separately in the adoption tracker.