HarnessRouter Offers Unified Interface for Agent Harnesses
Akshay Pachaar describes HarnessRouter, an open-source layer that runs multiple agent harnesses, including Codex, Claude Code, Hermes and Jev's System One, under one interface via the Unified Harness Protocol. He links to the repository and a related article.
Original post · 1 min read
(including System One by Jev)
Devs just open-sourced a plug-and-play infrastructure layer that lets you run any harness under a single interface, like:
- Codex
- Hermes
- Claude code
- DeepSeek Harness
- System One, powered by Jev
- And 9 more agent harnesses
This means you can bring Jev into the same product that already uses Codex, Claude Code, or another supported harness, without writing another implementation for sessions, streaming, files, cancellation, and failure handling.
Here's the repo: github.com/HarnessRouter/harnessrouter
(don't forget to star it ⭐ )
The harnesses run locally, and the Unified Harness Protocol (UHP) defines the common task interface with an OpenAI Responses-compatible API.
If you want to dive deeper, my recent article explains why model routing is not the same as harness routing, and what it takes to support multiple harnesses.
It also covers UHP, the full local setup, a working API call, and how sessions and files work.
Read it below.
Akshay 🚀 @akshay_pachaarRun Any Agent Harness Under One Interface — How UHP and HarnessRouter standardize agent execution across Codex, Claude Code, Hermes, and other runtimes.
When an agent product integrates one harness directly, its backend starts depending on