What it is
jev-router is a developer tool that adds automatic per-turn model routing to Claude Code and OpenAI Codex. It launches the real upstream CLI and uses Jev to send simple work to a fast tier and difficult work to a strong tier.
How it uses Jev
One Jev call per fresh user turn selects a shared abstract tier (Fast, Balanced, Strong, Long) from the user's prompt. The chosen tier maps to a concrete model, and the proxy rewrites the request to that model. Tool-loop continuations keep the tier chosen at the start of the turn.
Primitives:choice
Technique worth stealing
Use a loopback proxy to rewrite the model per turn while preserving the CLI's native interface, tools, sessions, permissions, and authentication.
Try it
npm install -g jev-router, set JEV_API_KEY, then run jev-claude or jev-codex.
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-centricyes0.83
- Shows a System One patternunclear0.58
- Handles uncertaintyno0.07
- Measuredno0.05
- Runnableyes0.97
- Worth recommendingunclear0.40
- Model replicano0.08
- Problem scopescore on a 0–2 scale1.04
- About Jevyes0.97
Signals by Jev jev-1.13.0, card written by DeepSeek V4.1 Flash from the README on 20 Sept 2026.