jev-repl
Terminal REPL for shaping System One requests before writing code, with lessons, a sketch editor, conversation turns and offline simulation.
Overview
jev-repl is a terminal REPL for experimenting with TypeSafe System One requests before writing code. You set a state, add named noul, choice and score questions with short commands, and press Enter to see typed answers with their distributions. With a TypeSafe key the answers are live; without one they are simulated locally so the request shapes can be learned offline.
It includes an eleven-step lesson track from what a noul is to what a call costs and how to take a session out as code; a sketch view (Ctrl-K) that edits the whole request as one page of text and previews the JSON, simulated answers, equivalent TypeScript or estimated cost; a turn command that grows the state into a conversation while questions stay fixed; and a trend command that re-asks every question after each turn and draws how each answer moved, naming the turns where it changed. Presets such as a triage session are built in.
What the decision model decides
| Type | Question | Answers |
|---|---|---|
| Yes / no | is_urgent: the message conveys urgency | yes · no |
| Choice | department: which team should handle this | billing · technical |
| Score | frustration: how frustrated the customer appears | Calm · Frustrated but civil · Very angry |
How it works
- Run npx jev-repl
- Set a state and add typed questions
- Send to see answers (live or simulated)
- Grow a conversation with :turn and watch :trend
- Export the request as code
Strengths
- Learn the API offline with simulated answers
- Shows how answers change over a conversation
- Previews code and cost before writing anything
Caveats
- Simulated answers are not real model output
- Live use requires a TypeSafe key
Getting started
npx jev-replAt a glance
- Type
- Service
- Status
- beta
- Language
- TypeScript
- Runtime
- Terminal REPL (Node)
- Has code
- yes
Use cases and integrations
How curated lists describe it
Terminal REPL for shaping System One requests before writing code. Simulates answers when no API key is set.
MrJev/awesome-jev
Frequently asked questions
Do I need a key?
No. Without TYPESAFE_API_KEY answers are simulated locally.
What does :trend show?
How each question's answer changes as a conversation grows, turn by turn.
Can I turn a session into code?
Yes. The sketch view previews the request as TypeScript.
Related projects
Server behind api.typesafe.pro, a free anonymous System One-compatible endpoint that forwards to TypeSafe on the operator's key.
ServiceproductionBrowser form for building Jev requests from pasted text without hand-writing JSON, then rerunning to see how steady the answers are.
ProjectbetaJavaScriptNushell module for TypeSafe's System One API: pipe content in, ask noul, choice and score questions, and filter on the numbers.
ServicebetaNushellOne-page playground and test bench for Jev with TypeSafe, OpenRouter, LLM-baseline and mock backends behind one /v1/systemone contract.
ServiceprototypeTypeScriptStatic browser interface for making structured Jev decisions through the Pollinations API, with multilingual READMEs.
ServiceprototypeJavaScriptDesktop GUI and CLI for asking Jev Noul, Choice and Score questions by hand and reading the probabilities.
ProjectprototypePython