offline harness optimization ships one shared harness that can overfit and cannot react mid-run, while online evolvers must reason from scratch or need verifier feedback that is unavailable at test time. Meta² learns a reusable textual Meta-Skill offline — by contrasting rollouts with no evolver, with an evolver, and with an evolver given privileged verifier information — and an online evolver then uses it to decide whether to keep the harness or make a task-local edit as evidence emerges.