AutoHarness is a CLI-driven application for automated benchmark harness optimization. It implements an iterative workflow where proposals (code/config changes) are generated via LLMs or templates, applied to a target harness, evaluated using benchmark adapters (Tau2/Bench, HAL, Harbor, etc.), and promoted based on statistical validation. The system manages workspaces, tracks, campaigns, and iterations with persistent state stored under .autoharness/. Key features include proposal generators (Codex/Claude assistants, OpenAI Responses, failure-driven), benchmark adapters with staging isolation, configuration composition, and extensible plugin architecture for search strategies and preflight checks. The tool supports both interactive and non-interactive modes with configurable autonomy levels (proposal/bounded/full) and provides comprehensive inspection/export capabilities for auditability.