The Pokémon article you linked is basically about benchmarking. In that context, the harness functions as part of the benchmark setup: the controlled environment around the model, the available inputs, tools, and assistance.

The current usage of “harness,” at least in the agent engineering discussion, seems closer to a lower-level runtime layer, almost like an OS around the agent.

So I see this as a transition: from “harness” as a narrower benchmark/control-variable layer to “harness” as the broader operating environment of the agent.

That does not mean I think your point is wrong. With topics like this, the interpretation depends on which part of the lineage one emphasizes. The first appearance of the idea may go back to 2022 or earlier, while the usage that looks closer to the current meaning may have emerged at a different point.

I am probably giving more weight to the SIG article, while you are giving more weight to a different point in the lineage. Both seem reasonable to me.