Stanford's WHALE paper alternates tuning LLM weights and harness, raising reward-hacking fears

teortaxesTex · x · 2026-09-13

A new Stanford paper tackles a common blind spot in LLM evaluation and tuning: practitioners either burn compute fine-tuning weights with a frozen harness, or hand-craft agent scaffolds around a black-box model — and the two bottleneck each other. Better weights can't fix retrieval logic that misses documents, and clever control flow is useless if the base model isn't sharp enough.

The authors propose WHALE, which alternates between the two: tuning weights against the current harness via rejection sampling, then iterating the harness against the updated weights, so model and scaffold co-evolve.

Commentator teortaxesTex flags a worrying direction for anyone concerned about reward hacking: you may end up with both a slop model and a slop harness optimized to look good together.

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