What it is
A drop-in replacement for deepagents SkillsMiddleware that selects only the SKILL.md skills needed for each user turn, keeping a large catalog out of the prompt. For developers building agents with hundreds of skills.
How it uses Jev
Jev ranks the skill catalog against the request and recent conversation, and answers whether a skill is needed. It verifies top candidates by reading their SKILL.md. Probabilities are compared to thresholds to load, offer, or skip skills.
Primitives:choicescore
Technique worth stealing
Use calibrated probabilities to gate skill loading, with a fallback to the full catalog on judge failure.
Try it
pip install "langchain-skill-router[jev]", set TYPESAFE_API_KEY, and use JevJudge in SkillRouterMiddleware.
Evidence
Each line is one question put to Jev about the README. ≥ 0.60 reads as yes, ≤ 0.40 as no; in between Jev is not making a call.
- Jev-centricno0.11
- Shows a System One patternyes0.86
- Handles uncertaintyno0.06
- Measuredyes0.97
- Runnableyes0.95
- Worth recommendingno0.39
- Model replicano0.21
- Problem scopescore on a 0–2 scale1.15
- About Jevyes0.79
Signals by Jev jev-1.13.0, card written by DeepSeek V4.1 Flash from the README on 23 Sept 2026.