“The customer says they were charged twice for their monthly subscription and wants one duplicate charge refunded.”
Names the event, product context, and requested outcome.BEGINNER TUTORIAL · LIVE MODEL
How to Use Jev
Jev is not a chatbot. Give it a situation, a specific decision, and the allowed kind of answer. Jev returns a bounded decision with probabilities your software can inspect.
YOUR FIRST RUNNo setupNo TypeSafe accountReal Jev result
- 01LOADStart with a complete example
- 02RUNSend it to the real Jev model
- 03UNDERSTANDRead the decision and probabilities
- 04EDITChange one fact and compare
01 / RUN YOUR FIRST DECISION
Your first Jev decision is ready
The Support Routing example is already loaded. Its State describes a duplicate subscription charge. Its Choice question asks which team should handle the request, with four allowed answers. No setup. No TypeSafe account. Example ready.
The example is already filled in. Click Run Jev first. You do not need to change anything.
1 Confirm Support Routing is selected.2 Press Run Jev.3 Read the returned decision and probability bars.
CHOOSE AN EXAMPLE — READY TO RUN
OUTPUTTypeSafe Jev
Your Jev decision will appear here.
Your Jev decision will appear here.
Give Jev a state and a typed question.
Run it to see the decision and probabilities.
State + QuestionJevDecision + Probability
Run the loaded example, then edit the inputs or choose another example to experiment.
What just happened?
The Playground sent the visible State and typed Question to the real Jev model. Jev selected one of the four choices and returned its probability distribution. The result panel renders that live response; this tutorial does not predict or hard-code the answer. Actual probabilities can vary between evaluations.
02 / WRITE THE STATE
State is the evidence Jev can use
State describes the situation at decision time. Include the facts that separate one answer from another. Clear evidence matters more than length; you do not need prompting tricks or a long persona.
- Customer message
- Incident report
- Document
- Agent status
- Browser page description
“A customer has a problem. Think carefully and act as an expert support manager.”
Adds a role, but leaves out the evidence needed to route the request.03 / ASK ONE DECISION
Make the Question bounded and specific
A good Question has a decision your application recognizes. Ask what you need to choose, verify, or score—not for an essay about the situation.
“Which team should handle this customer request?”
One decision, paired with Billing, Technical, Sales, and Other.“Tell me what you think.”
Combines classification and response writing without a bounded answer.04 / CHOOSE THE ANSWER TYPE
Boolean, Choice, or Score
How likely is this true?
Use for a proposition such as “Was a refund issued?” The result is P(true), shown as Yes and No probabilities.
Which allowed option fits?
Use for routing or classification. You define 2–10 distinct choices; Jev selects one and may return probabilities for them.
Where is it on this scale?
Use an ordered rubric. This Playground uses five named levels, from 0 to 4; Jev may return a fractional score between them.
Which type should I use?True or false proposition? BooleanNamed alternatives? ChoiceOrdered severity or quality? Score
05 / READ PROBABILITIES
A lead can be clear or close
Probabilities show Jev’s distribution over the allowed answers. They express its estimated preference among those answers; they are not a guarantee of correctness. Your application decides when to act, ask for review, or gather more evidence based on its own risk, costs, and evaluation results.
Illustrative distributions for reading the interface; they are not saved Jev results or recommended universal thresholds.
06 / TRY YOUR OWN INPUT
Try a controlled comparison
Return to the live Playground, keep Support Routing selected, and replace the State and Question below. Run it again, then compare the returned choice and distribution with your first run.
PASTE THIS STATE
“My account is locked and I cannot sign in.”
- Change the Question
- Which team should handle this?
- Keep the Choices
- Billing · Technical · Sales · Other
Changing one fact at a time makes the comparison easier to understand. The exercise does not prescribe which option Jev must select.
NEXT / TRY THE OTHER PRESETS
Run Boolean and Score next
Refund Verification
Evaluates how likely it is that the supplied state says a refund was issued.
Incident Urgency
Places an incident on an ordered rubric from No urgency to Critical.
Both presets are already available above. Select one, read its State and Question, then run it as-is before editing.
07 / ASK MORE THAN ONE QUESTION
Reuse one State for focused decisions
In the Playground, choose Multiple questions and load Agent Action Gate. The preset sends one shared State with three independent questions: whether important data is at risk, whether confirmation is required, and which next action to choose.
One shared State
BooleanBooleanChoice
Your app combines the answersOne answer is not automatically used as context for another. Your software combines the returned decisions under its own policy. See the browser agent worked example for a complete decision boundary.
08 / JEV DECIDES. SOFTWARE ACTS.
Jev decides; software acts
Chooses Billing
YOUR SOFTWAREAssigns the ticket after checking queue rules.
Returns a high P(true) for refund issued
YOUR SOFTWAREShows the status or requests review; it does not issue money.
Returns CLICK e3
BROWSER CODEValidates the current page and performs the click.
09 / COMMON MISTAKES
Eight mistakes to avoid
- Using Jev like a chatbotAsk for one bounded decision instead of an open-ended reply.
- Asking an open-ended questionName the exact choice, claim, or scale you need evaluated.
- Using overlapping choicesMake each Choice option lead to a distinct meaning or action.
- Leaving important facts out of StatePut the evidence needed for the decision in State.
- Treating a 100% display as guaranteed correctnessProbability is Jev’s distribution over the allowed answers, not proof.
- Asking Jev to perform the actionKeep permissions, side effects, and enforcement in your software.
- Using Score for unordered categoriesUse Choice when the allowed answers have no lowest-to-highest order.
- Adding many questions too earlyUnderstand one focused question before combining several.
30-SECOND CHEAT SHEET
Use Jev in seven parts
- STATEWhat Jev knows.
- QUESTIONWhat Jev must decide.
- CHOICEPick one option.
- BOOLEANProbability a statement is true.
- SCOREPosition on an ordered scale.
- PROBABILITYHow strongly the model favors an answer.
- APPLICATIONWhat actually performs the action.
BEGINNER FAQ
Questions about using Jev
Is Jev a chatbot?
No. Jev evaluates supplied state against typed questions and returns bounded answers with probabilities. Read the What Is Jev guide for the model-level explanation. What is Jev?
Do I need a TypeSafe account?
No. The live tutorial is ready to run without a TypeSafe account or signup.
Can I use Jev for free here?
Yes, within this independent Playground’s usage limits. The pricing page explains the separate published API rate for people building their own applications. See Jev pricing.
What is State?
State is the information Jev reads before deciding, such as a customer message, incident report, record, agent status, or page description.
What is the difference between Choice and Boolean?
Choice selects one answer from a list you provide. Boolean returns the probability that one proposition is true, displayed here as Yes = P(true) and No = 1 − P(true).
What does a 100% display mean?
It means the displayed distribution strongly favors that answer after rounding. It is not a guarantee that the answer is correct.
Can I ask several questions about the same state?
Yes. Multiple Questions mode sends focused questions with one shared state. Jev evaluates each question independently; your application decides how to combine the answers. See the browser agent example.
Can Jev take actions for me?
Jev returns decisions. Your software validates permissions and policy, chooses any threshold or review path, and performs the action.
Where do developers find the API?
The Jev API guide covers installation, server-side authentication, request contracts, response handling, and errors. Open the Jev API guide.
READY TO BUILD?
Move the same decision pattern into your application.
The API guide covers the real request contract, server-side key handling, response shapes, and failure states.
Read the Jev API guide