Agent Harness Engineering

Unreal Agent is an async-first agent harness from Unreal Labs: a Go library, a runner binary, and a Harbor-compatible benchmark runner, MIT licensed, first released on 22 September 2026. When the model issues a tool call, the harness immediately appends an event-log record in the in-progress state, lets the model keep working, and appends the real result when the tool finishes. It is not Epic’s Unreal Engine. It is also not Inworld’s Unreal Engine AI toolkit, which Inworld launched as the “Unreal AI Runtime” — two unrelated products already occupy that name. ...

A self-evolving agent harness is the layer of prompts, memory, skills, tools, and control logic that lets an AI agent improve its own behavior over time. Proteus is an open-source, MIT-licensed research-preview framework that lets you plug in any agent harness, evolve it across episodes, and measure exactly what changed. Instead of chasing a single benchmark score, Proteus asks what a self-evolving harness actually does and whether an initial condition leaves a permanent mark. ...