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An agent that treats one athlete as N-of-1 science sealed 20 predictions before the fact, and its safety officer vetoed it twice in three weeks

AspireAI community · arXiv
Personal-health agents read wearable data and recommend, but do not learn about an individual in a way that can be audited or falsified. This system treats one cross-country mountain biker as the subject of accountable N-of-1 science, with every claim living in an evidence-gated hypothesis registry that must issue a probabilistic prediction about a future session before it occurs. In a live prospective phase covering the first three weeks the ledger sealed 20 predictions and scored 14; the descent forecast calibrated after one correction, the climb forecast was pessimistic as the athlete improved, and the safety officer vetoed the agent twice. Over 104 stop-free descents on eight segments the fit estimates one hour less sleep slows a descent by 2.2 percent, with a 90 percent interval of -0.2 to plus 4.7 percent, and wet conditions showed no effect. The limitation is inherent to N-of-1 work: it is one person, one season, and the replay benchmark shows the digital twin beats standard forecasters on heart rate but not on segment time.
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One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
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.
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