"Harness^2: Recursive Agent Harnessing for an Open World" Harness optimization would usually struggle to adapt to new tasks without ground-truth feedback, and improvements made for one task rarely transfer to others too. So Google's Harness² introduces two levels of recursive self-improvement: it proposes, tests, and combines changes to an agent's prompts, tools, and workflows for the current task, then stores lessons from those experiments to improve future harness modifications. Across…