Agents & InferenceSimon Willison

Jev introduces a new shape of LLM - System One, aka Decision Models

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Summary A

Jev outputs typed probabilistic decisions (category scores, yes/no, ratings with confidence) instead of tokens, charges only for input at $0.042/M tokens with free output, and evaluates many parallel questions against one document in roughly single-question latency. This makes it dramatically cheaper and faster than a generative LLM for classification, prioritization, and reranking (e.g. scoring 100 BM25 candidates for relevance), but you get zero explanation—just a float—so build heavy evals and bias testing into your pipeline and never use it for anything like ranking job applicants.