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.
npx skills add notque/vexjoy-agent --skill building-with-jevgit clone --depth 1 https://github.com/notque/vexjoy-agentWrote 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.
[](https://agentmods.dev/skills/notque/vexjoy-agent/building-with-jev)<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.
<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>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.
| Model | Per session | Once 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 |
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.
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 |
What ships with it
13 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/composition-patterns.md 15 KB
- references/composition-positions.md 3.1 KB
- references/cookbook-techniques.md 6.4 KB
- references/decision-card.md 2.6 KB
- references/dissolving-a-skill.md 4.7 KB
- references/images.md 9.9 KB
- references/improve-and-calibrate.md 11 KB
- references/integration-lifecycle.md 7.2 KB
- references/iteration-with-jev.md 3.9 KB
- references/models-and-limits.md 6.1 KB
- references/primitives.md 9.7 KB
- references/question-design.md 12 KB
- references/state-and-budget.md 12 KB
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.
- today Changed · +39 lines 76b52547a94b
- 20d ago Changed c486e15480db
- 23d ago Changed · +26 lines 07c47c8ea563
- 25d ago Changed · +221 lines · -6 tokens per session 37f570c9163c
- 26d ago Changed · -216 lines · +6 tokens per session 7d1e440b2059
- 27d ago First seen · 305 lines · 27 tokens per session scan A 9991071cbf1e
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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