swift-jev

Swift library and CLI for Jev with enum-typed Choice, Noul and Score questions, plus an agent skill for coding agents.

CLIproductionMIT

Overview

swift-jev is a Swift library and command-line tool for TypeSafe's Jev. In the library, Choice questions are typed by Swift enums that conform to JevChoiceOptions with option descriptions, Noul questions can describe what true and false mean, and Score questions take ordered levels. A result builder sends all questions in one request; responses are read with require(question) returning the enum value or probability, plus confidence, per-option probabilities and an estimated cost. It needs Swift 6.2, supports Apple platforms (Linux is declared but not covered by CI), and has no dependencies.

The CLI takes a JSON request on a file or stdin and writes only the JSON response to stdout, validating questions before sending and accepting the key from the environment or a key file, never from arguments. A bundled Jev skill teaches coding agents (Codex, Claude Code, Cursor, GitHub Copilot and others) how to prepare a request and interpret the response, installable with npx skills add. Custom compatible endpoints are supported.

What the decision model decides

Type	Question	Answers
Choice	Which team should handle this customer inquiry?	billing · technical · sales · account
Yes / no	Does this inquiry need to be handled today?	—
Score	How frustrated is the customer?	Calm and factual · Visibly annoyed · Angry, threatening to leave

How it works

Declare questions with Swift types
client.evaluate(state:) with a result builder
Read typed answers, confidence and cost
Or call the jev CLI with JSON from a script or agent

Strengths

Compile-time typed options via enums
No dependencies
CLI and agent skill for coding agents

Caveats

Linux untested
Requires Swift 6.2

Getting started

.package(url: "https://github.com/d-date/swift-jev", from: "1.0.0"), or swift run jev --input request.json with TYPESAFE_API_KEY set.

At a glance

Type: CLI
Status: production
Language: Swift
Runtime: Swift library + CLI
Has code: yes
Has tests: yes
License: MIT

Use cases and integrations

Infra / SDKs / Integrations537

How curated lists describe it

A Swift client for TypeSafe AI's Jev — typed judgements, not text
logicrw/awesome-jev-projects
A Swift client for TypeSafe AI's Jev — typed judgements, not text.
hellogumbo/awesome-jev
Swift library and CLI for the three primitives.
MrJev/awesome-jev

Frequently asked questions

How are choices typed?

As Swift enums conforming to JevChoiceOptions, so answers come back as enum values.

Can coding agents use it?

Yes, via the CLI and a bundled Jev skill.

Where does the key come from?

TYPESAFE_API_KEY or a key file, never from arguments or request JSON.

Related projects

askjev
Unofficial hosted or local Jev MCP server giving agents a quick second opinion: it picks yes/no, scale or choice and returns probabilities.
MCP serverbetaTypeScript
jev-mcp (blakestone-x)
Python MCP server wrapping Jev as classify, score, check, match and screen tools with confidence on every answer.
MCP serverbetaPython
openrouter-jev-mcp
Python decision gateway and stdio MCP server exposing Jev via OpenRouter's alpha Decisions endpoint to Claude Code, Codex and Cursor.
MCP serverbetaPython
prompt2jev
Agent skill and CLI that converts plain requirements, LLM prompts or prompt-calling code into a typed Jev request and runnable script.
Agent skillbetaPython
jev-mcp (freepik-company)
Go MCP server giving any client typed Jev decisions via OpenRouter or TypeSafe, with validated answers and no paid retries.
MCP serverproductionGo
System One Connector
Go CLI and single-binary MCP server giving Claude Code, Codex, Hermes and pi an evaluate tool backed by Jev, d1, CLM or Laya.
MCP serverbetaGo