Jev knowledge base·verified Sep 22, 2026

jev evals in failproof ai

Jev evals are live for Failproof beta users. See how typed judgments fit session evidence, results, audits and recurring findings.

the short answer

Yes. Jev evals and policies are live in Failproof AI for beta users. Failproof connects completed agent-session evidence with typed Jev evaluation results, audits and recurring findings, then supports the path from measured failures to runtime policies. Email nikita@befailproof.ai for access or help getting started.

Availability
Live for beta users as of September 22, 2026
Access
nikita@befailproof.ai
Jev role
Typed semantic evaluator
Failproof role
Trace-linked results, audits, findings and policy lifecycle

Jev Evals and Policies Are Live in Failproof

Jev evals and Jev policies are live for Failproof beta users. Email nikita@befailproof.ai if you need access or help getting started.

Where a Jev Result Fits in the Failproof Evidence Loop

Failproof’s value is not replacing a Jev API call. It is preserving the chain from session evidence to a measurable result and then to recurring operational work. A playground can answer one question; a reliability system must show which sessions failed, how the criterion changed, whether the pattern recurs and what happened after intervention.

01SessionAgent messages, tool calls, results and relevant environment evidence.
02ProjectionA versioned subset becomes Jev state for one criterion.
03Jev resultTyped answer, full distribution, resolved model and usage.
04AuditRepeated results and trace evidence are analyzed together.
05FindingA recurring failure pattern becomes owned reliability work.
06PolicyOnly validated patterns may graduate into observed or enforced controls.
A Jev answer becomes useful when it remains attached to the production evidence and follow-through.

Start with a Small Portfolio of Independent Evals

One broad “session quality” score hides which system component needs repair. Independent evals can point to routing, prompting, tool descriptions, retrieval, recovery logic or final communication. The trajectory guide defines the evidence boundary, while tool-call evaluation separates intent, authorization, execution and outcome.

EvaluatorJev shapeEvidence neededWhat it reveals
Task completionNoulUser goal, final response and completion-bearing tool resultsThe agent claimed or achieved the requested outcome
Primary failure typeChoiceRelevant trace events plus a stable failure taxonomyWhere recurring remediation work belongs
Recovery qualityScoreError, subsequent attempts and final stateWhether the agent recovered, stalled or made the failure worse
Tool appropriatenessNoul or ChoicePre-call state, permitted tools and proposed callWhether the selected action matched intent at decision time
Claim supportOne Noul per claim-evidence pairAtomic claim and cited tool or retrieval evidenceWhether the response overstates what the trace proves

Store an Evaluation Result as a Versioned Measurement

Do not store only a Boolean. A Noul of 0.51 and 0.99 may both pass a 0.5 rule while representing different evidence. The Jev eval guide covers primitive semantics; calibration explains how distributions become validated operating points.

FieldWhy it matters
Session and evidence referencesReviewer can inspect the exact supporting trace
Primitive and full distributionPreserves uncertainty and future threshold replay
Resolved model and providerSeparates alias/provider changes from traffic drift
Question, criteria and state-projection versionsDefines the measurement instrument
Derived pass/review/fail and thresholdExplains how probability became workflow state
Human label, override and eventual outcomeSupports calibration and incident review

Design the First Beta Evaluator Narrowly

Good first criteria include whether the requested task was completed, whether a cited claim is supported by supplied evidence, or whether a tool matched the user’s stated intent. Counts, schemas, permissions and arithmetic remain deterministic checks. The question-writing guide gives rewrite patterns.

  1. Select one recurring failure with clear trace evidence and operational ownership.
  2. Write one atomic criterion and define positive, negative and unscorable examples.
  3. Project only the messages, tool arguments/results and outcome fields needed.
  4. Label a representative set without seeing Jev’s result.
  5. Measure errors, calibration, latency, cost and missing-evidence coverage.
  6. Run in observation mode before using the result for alerts or policy work.

Turn Individual Results into Recurring Failure Evidence

A failed eval is evidence, not yet a diagnosis. Ten task-completion failures may share one missing tool capability, or they may be unrelated. Grouping should retain links to original sessions and the evaluator version so a team can distinguish a recurring mechanism from coincidental labels. The drift guide covers production slices and delayed outcomes.

01ResultOne versioned Jev judgment remains linked to its session evidence.
02SliceResults are grouped by agent, release, tool, tenant, language or failure type.
03AuditRepresentative failures and apparent passes are reviewed against labels and outcomes.
04FindingRepeated evidence becomes one named, owned reliability problem.
05FixPrompt, tool, retrieval, code or workflow changes target the observed mechanism.
06VerifyRegression replay and current traffic show whether the fix reduced the failure.
The operational value appears after the model call.

Direct Jev Calls and Failproof Solve Different Layers

A direct harness remains useful for local experiments and model comparison. A reliability platform becomes valuable when results must stay connected to production traces, repeated failures and remediation. The evaluation-platform comparison shows how direct API runners, LangSmith, Vercel tooling and Failproof differ by layer rather than treating them as interchangeable model hosts.

NeedDirect Jev harnessFailproof workflow
Run a bounded judgmentCall the TypeSafe SDK or APIJev supplies the same kind of typed judgment inside an evaluation workflow
Attach production evidenceBuild trace ingestion and identifiersConnect evaluation results with captured agent sessions
Find recurring patternsBuild grouping, queries and review operationsUse audits and findings around repeated evidence
Track remediationBuild ownership and follow-throughConnect findings with ongoing reliability work
Move toward preventionBuild and operate the runtime control pathUse the Jev policy lifecycle available in beta

An Eval Result Is Not Automatically a Policy

An evaluation normally measures completed behavior. A policy runs at a lifecycle point where it can alter an action. Moving a question earlier changes available evidence, latency constraints and the cost of errors. Backtest the pre-action version on recorded evidence, define outage and review behavior, then observe before enforcing.

The eval-versus-policy guide explains that promotion path. Jev policies are live for Failproof beta users. Email nikita@befailproof.ai if you need access or help getting started.

FAQ

How do I get access to Jev evals in Failproof?

Email nikita@befailproof.ai. Jev evals are live for beta users as of September 22, 2026.

How do I get started with Jev in Failproof?

Email nikita@befailproof.ai for beta access and onboarding help.

Does Failproof replace TypeSafe?

No. Jev supplies the model judgment; Failproof connects evaluation results with traces, audits, findings and policy operations.

Can the same Jev question become a policy?

Potentially, but moving it pre-action changes evidence and failure costs. Backtest, choose thresholds and observe it before enforcement.

Sources

Checked against the sources below on September 22, 2026. Model versions, prices and limits change.

  1. Failproof AI docs: Evaluations overview
  2. Failproof AI docs: Policies overview
  3. Failproof AI PR #570: Jev evals and policies announcement
  4. TypeSafe AI docs: Primitives
  5. TypeSafe AI docs: State
  6. TypeSafe AI docs: Jev 1.13 jaggedness