🔌 AgentPlugins

TypeSafe JEV: System One Model Tutorial & Plugin Directory

TypeSafe JEV (released 2026-09-15) is the first "System One" model: instead of generating text, it returns typed decisions with calibrated probabilities. Built by ChatGPT co-inventor Diogo Almeida, JEV is 40-200x faster and 40-400x cheaper than traditional LLMs for code and automation tasks.

What makes JEV different

  • No text generation: Returns typed decisions, scores, and probabilities that code can act on directly
  • No hallucinations: Calibrated confidence scores mean you know when the model is uncertain
  • ~150ms decision time: 40-200x faster than frontier LLMs
  • Built for machines: Designed for automated workflows and code integration, not human conversation
  • Use cases: Classification, routing, scoring, A/B testing, workflow automation

JEV ecosystem (top plugins by GitHub stars)

#PluginStarsDescription
1awesome-jev
fatwang2/awesome-jev
⭐ 450Source-backed JEV project collection: classification experiments, A/B input comparison, conversation routing
2jev-review (MCP Plugin)
NiazMorshed2007/jev-review
⭐ 280Local-first MCP plugin: structured feedback for Claude Code, Codex, Cursor, OpenCode
3awesome-typesafe
AbdelStark/awesome-typesafe
⭐ 380Comprehensive curated list of official resources and community projects for TypeSafe

Quick start: using JEV in your code

import { TypeSafe } from '@typesafe/client';

const client = new TypeSafe({ apiKey: process.env.TYPESAFE_API_KEY });

// Classification with calibrated confidence
const result = await client.classify({
  input: "Is this customer support request urgent?",
  labels: ["urgent", "normal", "low"],
});

console.log(result.decision); // "urgent"
console.log(result.confidence); // 0.94
console.log(result.probabilities); // { urgent: 0.94, normal: 0.05, low: 0.01 }

When to use JEV vs traditional LLMs

Use JEV for:

  • Classification tasks
  • Routing decisions
  • Scoring and ranking
  • A/B testing analysis
  • Workflow automation
  • Real-time code integration

Use traditional LLMs for:

  • Text generation
  • Human conversation
  • Creative writing
  • Complex reasoning chains
  • Long-form content
  • Exploratory dialogue

Also see our JEV plugins & tools directory and DeepSeek Harness plugin directory for traditional LLM-based coding agents.