What does Jev State actually build?

Conversational state machines: you define states, entry criteria, replies, and allowed transitions, and Jev proposes the typed next-state choice that validation and your confidence threshold accept or reject.

Do I need a Jev key to explore the studio?

No. Simulation mode works without a provider account; entering a TypeSafe key under Connect Jev switches the Try view to Live Jev, and reply generation optionally uses OpenAI's Responses API.

How do I run the studio locally?

Clone the repository, run npm ci, copy .env.example to .env.local, then npm run dev and open localhost:5173; it needs Node.js 22 and npm, and no database or account.

What comes in the downloaded code project?

A ZIP with workflow.json, workflow.ts and lib/ (the same execution engine), example.ts, evaluate.ts with CI exit codes, a GitHub Actions check workflow, validation.json, and a bundled coding-agent skill for integration.

What does each inspected decision show?

The actual input, the question, the probabilities, the threshold decision, the resolved model, latency, and token usage, so a wrong transition can be explained rather than guessed at.

What are the state-machine limits?

Current workflows are flat state machines: nested states, parallel regions, arbitrary executable guards, and XState machine import are not supported, and the studio is an opinionated subset of XState.

Does passing simulation mean live behavior is validated?

No. Validation.json separates simulation and live runs, a simulation pass never marks live behavior as validated, and changed criteria or cases invalidate earlier evidence; live tests cost provider tokens.

CommunityJev Tools & CLIs

Jev State

A local-first studio for building and regression-testing Jev-powered conversational state machines: define states visually, watch Jev's typed choice meet your threshold, and export runnable TypeScript.

See highlights

Open github.com

Stars: 8
Language: TypeScript
License: MIT
Published by: Community
Author: priyankark
Last verified: Oct 2026

priyankark/jev-state

User repository on GitHub

View on GitHub

Build and regression-test conversational state machines powered by Jev. Inspect decisions, capture failing conversations as tests, and export runnable TypeScript for your app.

Forks: 0
Last pushed: Updated Sep 2026

Repo stats from the GitHub API, cached Oct 2026.Homepage

Tagscommunity typescript state-machine testing xstate

Works forJev for Classification Jev for Decision gating Jev for Evaluation

Used inJev for Software & DevTools Jev for Customer Support

Languages: TypeScript
Platforms: Vercel AI Gateway
Capabilities: Open sourceSelf-hostedRuns locally

Highlights

Answers whether an agent changes state when it should, and whether a change broke another conversation.
Jev proposes a typed next-state choice; validation, your confidence threshold, and declared XState transitions decide.
Get code exports a runnable ZIP: workflow.json, the execution engine, a regression runner, and a GitHub Actions check.
Decision inspection shows the input, question, probabilities, threshold decision, resolved model, latency, and tokens.
No account, database, or paywall; the workspace lives in the browser and simulation runs need no provider key.

Watch out

Opinionated studio, not a full XState implementation: workflows are flat state machines, so nested states, parallel regions, executable guards, and XState import are out. A simulation pass never counts as live validation, and live runs use your provider keys and are billed there.

Questions about this entry

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X: Jevspresso: XState sets the options, Jev picks the next move at an espresso bar.

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