ResearchResearch paperLarge Language Models1 source · Oct 18, 2026

Narrow Decision Models: A System-1 Architecture for Calibrated, Typed Decisions

System One models, introduced with TypeSafe's Jev, answer typed questions about a state with calibrated probabilities instead of generated text: choosing among options described in natural language (Choice), placing the state on an ordered scale (Score), or judging a yes/no statement (Noul).

Key points

  • Jev is general-purpose: one set of weights, served as an API and adapted to a domain only through the request.
  • A Narrow Decision Model (NDM) offers the same interface but is trained for the decisions of one organization, is small enough to run on its own infrastructure, and has an open architecture whose properties can be stated and tested.
  • The architecture serializes a request as a prefix tree (the state, then each question, then each option) and runs a bidirectional encoder under a block attention mask with logical positions, so that each answer is, by construction, invariant to the order of its options and independent of the other questions asked.
  • A minimal validation on public and fictitious data shows that the invariances hold to rounding in a trained model, that a small instance routes on organization charts it has never seen well above lexical retrieval, and that, at equal compute, the block architecture reaches a lower loss than a pairwise cross-encoder.

Sources (1)

  • [1]Narrow Decision Models: A System-1 Architecture for Calibrated, Typed Decisions
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 18, 09:49 PM
    System One models, introduced with TypeSafe's Jev, answer typed questions about a state with calibrated probabilities instead of generated text: choosing among options described in natural language (Choice), placing the state on an ordered scale (Score), or judging a yes/no statement (Noul).
    Jev is general-purpose: one set of weights, served as an API and adapted to a domain only through the request.

Extractive summary: sentences quoted from the sources.

Before this

  1. Oct 18, 2026System X: An LLM Decision Model That Replies from Its Own KV Cache
  2. Oct 17, 202620 Jev Alternatives: The Decision Models Taking On TypeSafe in 2026
  3. Oct 17, 2026Good Judgment, Bad Advice: Decision-Model Controllers Raise Agent Cost Without Improving Success
  4. Oct 16, 2026SPIDES: Information-Flow Control for Browser Agents
  5. Oct 16, 2026Monitor-Validity Failures: LLM Safety Evidence Paths at Evolving Framework Boundaries
  6. Oct 16, 2026Liquid AI Releases d1-ultra: A Multimodal Decision Model That Scores 65 on the AA Decision Index

Related