TL;DR Wrapping coding agent harnesses in a repeated plan-develop-QA loop boosts multi-day autonomous software development performance by an average of 52%. Title: Harness-of-Harness: Multi-Day Autonomous Software Development with Continual Improvement URL: Points 🔁 It leaves existing harnesses like Codex CLI and OpenCode untouched, adding an iterative improvement layer on top 🧭 Splits work into Planner, Developer, and QA Tester roles, carrying verified evidence forward into each new loop 📊 Improved across all 3 benchmarks and 3 model configs, e.g. GameCraft-Bench score jumping from 49.58 to 71.52 💰 Beats plain repeated Vanilla passes even at the same pass count, and is more token-efficient too 🎮 A 70-iteration, multi-day case study built a fully playable FPS game from scratch 🧩 Ablations confirm every piece matters: dropping plan updates, evidence feedback, or warm-start each hurts performance What stands out to me is the philosophy: not just running longer, but iterating smartly by accumulating verified knowledge. #AIAgents# #SoftwareEngineering#