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Reference

UHP glossary

Short definitions for the terms used across the Unified Harness Protocol specification and this independent guide.

Verified: 11 Sep 2026Protocol: 2026-08-11Static SSG

Core UHP terms

Agent harness

A complete agent runtime around a model, including its execution loop, tools and session state.

Base

A stable identifier for a harness family, such as codex, claude-code or hermes.

Configured harness

A harness base plus runtime configuration such as model defaults, instructions, restrictions, skills, MCP servers and budgets.

Client

The application speaking UHP to request work.

Server

The UHP implementation that accepts tasks and drives one or more harnesses.

Response

One atomic unit of work: a task request and its resulting state/output.

Session

A chain of responses sharing conversation context, workspace and configured harness.

Container

The file namespace associated with a session.

Artifact

A file produced by agent work and made available through the protocol.

Event

A streamed fact describing progress, delivered through the event stream.

Conformance class

Core, Extended or Full; each class defines a cumulative set of mandatory server capabilities.

Capability discovery

The server document at GET /v1/uhp describing versions, conformance class and supported features.

Adjacent terms

MCP

Model Context Protocol, an open protocol for connecting AI applications to tools, resources and prompts. It addresses a different boundary from UHP. The 2026-07-28 release also formalizes opt-in extensions, including the released Tasks extension for asynchronous long-running operations.

Skills over MCP

An MCP Working Group effort to distribute and discover Agent Skills through MCP primitives. On 11 September 2026 the official SEP-2640 proposal branch moved to Final after recording SDK reference implementations and conformance coverage. PR #2640 nevertheless remains open and unmerged into MCP core main, and the official ext-skills Working Group repository remains explicitly experimental. Final SEP lifecycle status is therefore distinct from a merged core-main change or a universally shipped MCP capability. Skills Over MCP is also distinct from Agent Plugins packaging and is not a UHP feature.

AI Catalog

An emerging common catalog/trust envelope for heterogeneous AI artifacts. The working draft uses application/ai-catalog+json, identifies native artifacts by media type, supports nested catalogs, and can attach an optional Trust Manifest for identity, attestations and provenance without redefining the underlying artifact format. The project is maintained in a temporary Linux Foundation working repository by contributors from MCP, A2A and other ecosystems; its own adoption plan says MCP and A2A steering committees would vote after finalization, so it is not treated here as already adopted by either protocol.

AIP (Agent Identity Protocol)

An overloaded name currently used by multiple independent agent-identity proposals rather than one canonical standard. Current active Internet-Drafts include Cao/Arango’s registry-and-enforcement-proxy model, Singla’s decentralized DID/delegation model, Prakash’s Invocation-Bound Capability Token model for attenuating single- or multi-hop authority, and the qualified OpenA2A AIP identity/capability/trust model. The IETF Datatracker states that these individual Internet-Drafts are not IETF-endorsed standards. Use the author/project or exact draft identifier when referring to AIP. These identity/authorization layers are distinct from UHP’s complete-harness execution contract. See UHP vs AIP.

ARD (Agentic Resource Discovery)

A pre-invocation federated-discovery specification whose current published version is v0.91, status Proposal, dated 26 Aug 2026. v0.91 defines a distinct JSON-LD ARD entry and self-contained ARD conformance while retaining compatibility with catalog entries. Consumers resolving a domain MUST fetch /.well-known/ard.json and honour rel="ard"; the predecessor /.well-known/ai-catalog.json / rel="ai-catalog" names are optional compatibility lookups (MAY), not required fallbacks. The specification repository also publishes schemas, OpenAPI and a zero-dependency conformance CLI. ARD stops at discovery and hands execution/authentication to the resource’s native protocol. See UHP vs ARD.

AGNTCY

A Linux Foundation-hosted open-source infrastructure stack for cross-framework agent discovery, capability description, identity/access, secure messaging and observability. Its components include Agent Directory Service, OASF, SLIM and Identity; they evolve independently rather than sharing one AGNTCY protocol version. AGNTCY is adjacent infrastructure, not UHP’s client↔server↔complete-harness execution contract. See UHP vs AGNTCY.

ATIF (Agent Trajectory Interchange Format)

An Active Harbor RFC for portable JSON records of complete agent trajectories. The current changelog is v1.7; the schema can represent messages, reasoning, tool calls, observations, metrics, continuation data and embedded subagent trajectories. ATIF is used for debugging, replay, evaluation and training-oriented workflows rather than live harness control. NVIDIA NeMo Relay documents an ATIF v1.7 exporter. See UHP vs ATIF.

Agent Skills

A lightweight, open format for reusable agent capabilities. A skill is a folder centered on SKILL.md, with metadata and instructions plus optional scripts, references, assets and other resources. Agent Plugins uses Agent Skills as one of its portable component types; Agent Skills itself is not a UHP feature.

Agent Plugins

An open, vendor-neutral package standard for distributing reusable components that extend AI agents. The published 1.0.0 format uses a root plugin.json manifest and can package Agent Skills under skills/ plus MCP server configuration in mcp.json; 1.1.0 is a working draft. It standardizes plugin packaging/discovery rather than UHP’s client/server harness-execution contract.

Harness Protocol (harnessprotocol.io)

A separate open specification for portable harness configuration using harness.yaml. Its current changelog records specification release v1.1.0 on 27 Jul 2026: the v1 Schema layer remains the configuration contract, HEP-7’s signed consent-first Exchange layer is Accepted/shipped, and Registry HEP-8 remains in Review and unreleased. See UHP vs Harness Protocol.

Harness Protocol v1 (SuperQode)

A separate SuperQode-internal control-plane contract using the same generic name. It normalizes session, event and evidence behavior across SuperQode Core, direct Python harnesses and an ACP adapter. It is not the harnessprotocol.io specification and is separate from SuperQode’s UHP client implementation.

AHP (Agent Host Protocol)

Microsoft’s synchronized multi-client state protocol for authoritative agent-host sessions. It coordinates shared host/session state and can layer over ACP, but it does not replace UHP’s complete-harness execution contract. See UHP vs Agent Host Protocol.

AHP (Agentic Hypercall Protocol)

An unrelated active individual Internet-Draft, draft-campbell-agentic-market-00, for agents to discover, invoke, pay for and rate tools over HTTPS. It proposes /.well-known/ahp.json discovery, OpenAPI tool descriptions, HTTP 402 payment, optional blind settlement and signed transaction/reputation evidence. It is not an RFC or IETF-endorsed standard. See UHP vs Agentic Hypercall Protocol.

An upstream agent harness integrated by HarnessRouter Community Edition as a backend (v0.7.0). HarnessRouter also installs an MCP adapter for this path. Pi integration is a HarnessRouter implementation fact, not proof that the Pi project adopted UHP natively.

DeepSeek Harness

An upstream open-source agent harness from DeepSeek AI (developer preview, MIT licensed) integrated by HarnessRouter Community Edition as the dsh backend (v0.8.0). Integration is not proof of native UHP adoption by DeepSeek.

LLMTR

A Turkey-hosted model gateway added by HarnessRouter v0.6.0 as a provider. It is a HarnessRouter provider integration, not a UHP protocol feature.

Core UHP terms

Adjacent terms

Primary sources