HarnessRouter standardizes agent runs via one protocol

Building an agent product usually starts with a small adapter that launches a process and reads its output. That works until the product needs live progress, session continuity, file uploads and downloads, access rules, and a defined cancellation path. Errors also have to be structured enough to separate provider failures, permission denials, time limits, missing files, and cancelled tasks. Adding a second harness beside the first means rebuilding and maintaining all of those mappings again — the reason UHP defines one task lifecycle both integrations can follow.

UHP draws a line between two kinds of routing. Model routing happens inside the inference layer, choosing an endpoint based on price, latency, context length, availability, or measured quality, while the application or harness still owns the agent loop. Harness routing selects the runtime that owns the task, which can change the tools, skills, workspace, permissions, and event stream. A product may use both layers: in UHP, the model field chooses the model while metadata.harness_id chooses the configured harness.

HarnessRouter is a self-hosted UHP server that reads the Harness ID and starts the selected runtime, recording output as UHP events, responses, sessions, files, and errors. Its Docker image carries a Console, a Gateway, and a Runner, with a named /data volume and only the Console port published. The self-hosting guide lists backends including Codex, Claude Code, Hermes, DeepSeek Harness, Gemini CLI, OpenCode, Qwen Code, Cline, and Goose. The protocol standardizes the task lifecycle but does not make the harnesses behave the same, so the practical question for a team is whether one shared way to submit work and inspect results is enough to cover the runtimes it wants to offer, and whether the local isolation model — separate operating-system users and workspaces rather than separate containers — fits how it deploys agents. The project is Apache 2.0 licensed and ships its spec, schemas, and conformance tests.