building-with-jev

building-with-jev is a skill for Claude Code from notque/vexjoy-agent. It costs 27 tokens per session (11,152 once invoked), scanned A, original, MIT.

A development guide for programs that call Jev, a judgment model that answers independently defined questions about one shared state and returns probabilities for the possible answers.

In plain words
What is it for?
Use it to design Jev questions and answer choices, prepare the input state, connect calls to hooks or scripts, and diagnose incorrect responses.
Why use it?
It helps keep decision logic, calculations, and ordered steps in code while using Jev only for the judgments it is suited to make.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it to design Jev questions and answer choices, prepare the input state, connect calls to hooks or scripts, and diagnose incorrect responses.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/notque/vexjoy-agent/building-with-jev
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add notque/vexjoy-agent --skill building-with-jev
Clone the repo
git clone --depth 1 https://github.com/notque/vexjoy-agent

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for building-with-jev

README.md
[![agentmods](https://agentmods.dev/badge/skills/notque/vexjoy-agent/building-with-jev/github.svg)](https://agentmods.dev/skills/notque/vexjoy-agent/building-with-jev)
Your own site
<a href="https://agentmods.dev/skills/notque/vexjoy-agent/building-with-jev"><img src="https://agentmods.dev/badge/skills/notque/vexjoy-agent/building-with-jev/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for building-with-jev

Your own site · 80×15
<a href="https://agentmods.dev/skills/notque/vexjoy-agent/building-with-jev"><img src="https://agentmods.dev/badge/skills/notque/vexjoy-agent/building-with-jev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 11,152 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00027 $0.11152
Opus 5.5 $0.00011 $0.04461
Sonnet 5.5 $0.00005 $0.02230
Haiku 4.5 $0.00003 $0.01115

Measured today against content hash 76b52547a94b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

building-with-jev scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/meta/building-with-jev/SKILL.md · 375 lines

How it starts

The opening of the file, as written. The whole thing — 375 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Building with Jev

Jev reads one state, answers every question in the request independently and in parallel, and returns a probability distribution over answers you defined. A head cannot read another head's answer: parallel heads share evidence, not reasoning. For one state, maximize independent heads that can change a decision or action, subject to their token cost and the 64,000-token request budget; omit noise heads. Code owns control flow, arithmetic, policy, and every serial dependency; Jev owns the snap judgment. It does not reason in steps, count, do arithmetic, or generate text. Use this skill to design the questions, fit the state, compose answers in code, wire the call into a hook or script, and fix a call that answers wrong.

Before writing or changing any Jev request, apply Jev production rules and tick its pre-ship checklist. It sets request size (2.5–4k tokens via Gateway until measured), per-run budget (~50k tokens), screen-then-detail above ~50 items, sending each stage at once with an instance cap of floor(0.25 × 250,000 / tokens_per_request), retries by status code, eval pacing, caching, logging, and the order to measure failures. The rest of this skill is the method for designing questions; those rules govern how requests are sent. Its four facts come first: use Vercel AI Gateway; too much context is the most common failure, so split an oversized request into as many small requests as it takes (the toolkit transports do this automatically); a small request is the first diagnostic; rate limits are normal, so retry them.

Prefer direct judgments over supplied evidence. Bounded action selection is valid when candidates and decision evidence are supplied. If answering requires an intermediate result that changes later evidence or candidates, code must resolve that dependency before a later Jev request.

Reference Loading Table

Signal Load These Files Why
request or response shape, instruction objects, criteria objects, reading score/probabilities/confidence references/primitives.md Full API shape and answer semantics
writing or rewriting instructions, criteria, levels, options, examples references/question-design.md Question rules with before/after pairs
max_tokens_exceeded, large inputs, batching, truncation, untrusted text in state references/state-and-budget.md Fitting stages, batching, bounds, adversarial state
any production Jev call: request size, run budget, parallelism, retries, caching, logging, failure diagnosis skills/shared-patterns/jev-production-lessons.md The concrete rules and checklist; read before shipping
429, 529, Gateway 503, rate limits, tokens per second, concurrency, fan-out size, retries, eval pacing, "works locally but fails in production" references/state-and-budget.md (Rate limits), references/improve-and-calibrate.md (Service failure or wrong design) Per-second pricing, pacing, backoff numbers, and the diagnosis order
model alias, jev-latest, jev-preview, pin a version, deprecation, long context, status codes, retry headers, SDK, official TypeSafe skill references/models-and-limits.md Aliases, limits, danger-zone headers, errors, retry rules
cookbook technique: beam search, parent fallback, uncertain band, rerank, guardrails, memory gate, entity match, feature discovery, argmax, smoothing references/cookbook-techniques.md One row per documented technique, with the shape and the numbers
fan-out, confidence gates, composite scores, taxonomy walks, cascades, second requests, long horizon, multi-step, agent loop, beam, branching, checkpoint references/composition-patterns.md Docs patterns plus ours, with script paths as worked examples
hooks, reader/storage/action, fail modes, persistence, calibration store references/integration-lifecycle.md Where a call lives and what happens when Jev is down
wrong answers, low confidence, clustered scores, revision discipline, known debt, baseline, OOD, holdout references/improve-and-calibrate.md Symptom table and labeled-example loop
dissolving a skill, replacing an LLM with Jev, three-tier classification references/dissolving-a-skill.md Method, phase table, worked example
decision surface, card, gate design, threshold, what numbers mean, failure behavior, versions references/decision-card.md Decision card template: fields every gate must define before code ships
position of a judgment, operand, gate, post-judge, selector, verifier, logical operators, dissolve a skill phase references/composition-positions.md 11 positions a judgment can occupy relative to a function, mapped to our scripts, with the walk-the-positions procedure
image, screenshot, rendered frame, reference picture, Box question, JevImage references/images.md Send images through the transport: limits, preparation, token cost, visual hill-climb anchors
iteratively improve a skill, rubric, prompt, policy, or other artifact with broad Jev feedback references/iteration-with-jev.md Controlled A/B iteration, wide independent question batteries, variance checks, stopping rules, and avoiding optimization artifacts
model limitations, version changes, or a failure-mode audit references/question-design.md, references/state-and-budget.md, references/primitives.md, references/improve-and-calibrate.md Literal wording, arithmetic and dates, indirection, state filtering, hostile state, structural invariants, generation boundaries, and labeled retesting

Read the full file on GitHub · 375 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. today Changed · +39 lines 76b52547a94b
  2. 20d ago Changed c486e15480db
  3. 23d ago Changed · +26 lines 07c47c8ea563
  4. 25d ago Changed · +221 lines · -6 tokens per session 37f570c9163c
  5. 26d ago Changed · -216 lines · +6 tokens per session 7d1e440b2059
  6. 27d ago First seen · 305 lines · 27 tokens per session scan A 9991071cbf1e

Subscribe to this mod's changes

building-with-jev is a skill published in the GitHub repository notque/vexjoy-agent (442 stars, last pushed today), licensed MIT. It adds 27 tokens to every session and 11,152 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-20.

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