PostHog/jeeves

Jeeves – Reasoning improves Jev-like decision models

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A Jev-style classifier that reasons when it is unsure, with a diffusion drafter, trained on public data. Inspired by Kev. Jev-like models give calibrated decision probabilities, but at low accuracy. A lot of pipelines therefore rely on a reasoning model as a fallback. Jeeves trains a Jev-like Qwen3.5-9B (LoRA and a pointer head) to reason before it decides when it is unsure. This results in better performance on out of domain tasks, and outperforms Jev in JevBench hard (public). Jeeves v2 and v1 answer directly when their calibrated confidence is at least 0.9 and otherwise reason first (nothinkthreshold 0.9, greedy, 2,560-token cap); the percentage is the share of questions that reasoned. JevK5 (v0.3) does not reason; we ran it ourselves on the same items. The Kev-9B and Jev columns are the numbers Kev publishes. \ No Kev-9B JevBench result is published. These are Kev-8B (Qwen3). All JevBench numbers are on…

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Inside the original README — Document outline
  1. Jeeves – Reasoning improves Jev-like decision models
  2. Acknowledgements
  3. Highlights
  4. Problem
  5. Results
  6. Quickstart
  7. Python
  8. Options
  9. How it works
  10. Training
  11. Diffusion drafter
  12. Reproduce

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Jeeves – Reasoning improves Jev-like decision models

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Owner
PostHog
Primary language
Python
Stars
411
Forks
21
Open issues + pull requests
5
License
MIT
Archived
No
Default branch
master
Created
2026-09-29T09:56:47.000Z
Last push
2026-10-01T16:47:45.000Z

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