jev-router

jev-router

Automatic per-turn model routing for Claude Code and OpenAI Codex. Jev sends simple work to
the fast tier and difficult work to the strong tier, while preserving each CLI's native
interface, tools, sessions, permissions, and authentication.
Both commands launch the real upstream CLI. Jev only chooses the model for a fresh user turn.

Quick start

Requires Node.js 20.12+ and at least one supported CLI:
Claude Code or
OpenAI Codex.

1. npm package



2. Local repository



On Windows PowerShell:



Get a key from TypeSafe. Then launch either interface from any
repository:



No Anthropic or OpenAI API key is required when the corresponding CLI is already logged in
with a subscription. Every CLI argument is forwarded:



For a local checkout, npm link installs both commands. Without it, run
node bin/jev-claude.mjs or node bin/jev-codex.mjs.

Claude Code interface



jev-claude launches Claude Code with Jev Router selected in /model. Selecting another
model pauses routing; selecting Jev Router resumes it.

The injected status line shows the model used for the last turn:



Claude Code otherwise remains unchanged, including its keybindings, tools, permission prompts,
/compact, /resume, and session handling. An existing custom statusLine is preserved;
set JEV_NO_STATUSLINE=1 to disable Jev's status line.

The explanation skill is bundled with the npm package and loaded automatically: run
/jev-explain in jev-claude, or $jev-explain in jev-codex, to see the factors behind
the last routing decision:



The report is rendered locally from the exact prompt, System One request, and System One
response saved when routing occurred. Recent decisions are retained per CLI session; invoking
the explanation skill…