Operon-S1 moved a biomedical agent's judgement calls out of the reasoning loop and onto a local model
AspireAI community · arXiv (cs.AI, cs.LG)
Language-model agents doing long biology work make judgements about conventions, skills, errors, evidence and stopping inside the reasoning that does the work, where they cannot be measured, replaced or improved on their own. Operon-S1 is a fast decision system that separates judging from doing: a decision harness poses the agent's recurring judgements as closed questions at 13 decision points and acts only through fixed messages that never contain an answer, so any model that can answer can serve as the judge. Across seven life-science benchmarks a local decision model took over these judgements in 0.6 seconds at the median for an in-loop request on CPU at no request cost, with no measurable change in the agent's score on five of six benchmarks, while the general model driving the agent accounted for 8.0 to 35.2 percent of task cost. Every decision is recorded with its consequence, and a new version enters service only through a promotion gate. The underlying labels come from task construction and verifiers rather than human annotation, and task-level results use the public checkpoint.
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Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.