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TypeSafe (Jev) Provider Guide

The only provider that serves decide rather than generate/stream — it returns typed, calibrated judgments and emits no text at all.

Overview​

TypeSafe's Jev is a "System One" model. You send one state plus a map of named, typed questions; it returns one typed answer per question, all evaluated in a single parallel pass. Nothing has to be parsed back out of prose, and every choice/score answer carries a calibrated confidence rather than a self-reported one.

Because it emits no text, generate() and stream() are not available and getAISDKModel() throws — the same shape Voyage and Jina already use for embedding-only providers. Its descriptor declares inferenceKinds: ["decide"], which keeps it out of auto-select and the health sweep, so those throws are unreachable in normal use.

This is not neurolink.evaluate(), which scores an already-generated response with RAGAS scorers. Different feature, different word.

Key Facts​

  • Provider id: typesafe (aliases: jev, typesafe-ai)
  • Inference kinds: decide only — the single provider of the 40 that does
  • Tool calling: none (toolSupport: "none") — a decision model calls nothing
  • Health check: env-only; it is never probed with a live generation
  • Default decide timeout: 5000 ms (timeouts.decideMs)
  • Latency: flat in question count — 1 question ~393 ms, 400 questions ~465 ms. Concurrent requests queue instead, so batch every question into one call rather than fanning out.
  • Cost: ~$0.042 per million input tokens, output billed at zero — about $0.00002 per decision. Output tokens are reported — measured 21 for a single question, converging to ~17.5 per question in a batch of eight — they are simply not charged.
  • Accuracy is the trade: 67.8% on TypeSafe's own 711-case benchmark against Opus 5's 73.1%. Right for decisions that are gated and reversible; wrong for final answers.

Quick Start​

1. Get an API key​

Create one at console.typesafe.ai/keys.

2. Configure​

export TYPESAFE_API_KEY=apikey_...      # the only switch
export TYPESAFE_MODEL=jev-latest        # optional
export TYPESAFE_BASE_URL=https://api.typesafe.ai  # optional

3. Use it​

import { NeuroLink, readDecisionChoice } from "@juspay/neurolink";

const neurolink = new NeuroLink();

const result = await neurolink.tryDecide({
  state: ticketText, // a string OR structured JSON
  questions: {
    team: {
      type: "choice",
      instructions: "Which team should handle this?",
      criteria: {
        billing: "Payments, invoicing, refunds",
        technical: "Bugs, outages, integrations",
        sales: "Pricing, upgrades, new accounts",
      },
    },
    urgent: { type: "boolean", instructions: "Does this express urgency?" },
  },
});

const team = result && readDecisionChoice(result.answers, "team");
if (team && team.confidence >= 0.7) {
  assignTo(team.choice);
} else {
  assignToHumanTriage(); // low confidence is a signal, not an error
}

tryDecide() returns null on any failure. Use decide() when you want the failure to surface; it throws a ProviderError whose cause carries a typed kind.

The degradation contract​

Setting the key is the entire switch, and removing it is a complete undo. Every internal consumer of decide fails open: with no decision provider configured, model routing, context budgeting, relevance compaction, tool routing and RAG planning all behave exactly as they did before. There is no configuration in which a missing, invalid, slow or unreachable decision model changes NeuroLink's observable behaviour.

A credential the service does not accept disables that provider instance rather than paying a round trip on every later call to be told so again.

Two transports​

The same model is reachable two ways, and the choice is made once in the constructor.

DirectVercel AI Gateway
KeyTYPESAFE_API_KEYAI_GATEWAY_API_KEY
Endpointapi.typesafe.aiai-gateway.vercel.sh/v4/ai/evaluation-model
Model named inrequest bodyai-model-id header
Question vocabularynoulboolean
confidenceon each answeron providerMetadata
Billed byTypeSafeVercel

Holding both keys keeps the direct transport, so the confidence figures a host already sees do not shift underneath it when a second key appears. Force one with TYPESAFE_TRANSPORT=direct|gateway or credentials.typesafe.transport.

⚠️ The gateway refuses every request — free credits included — until the Vercel team has a credit card on file, returning 403 customer_verification_required. That is an account state, not a bad key, and it arrives before the model id is validated.

Full detail, including the measured error table and why the distribution peak is not a substitute for the reported confidence, is in The decide inference type.

AreaWhat the decision replaces
Model routingdifficulty + capabilities + risk + model pick in one round trip
Model catalogueone choice over the registry ranks all N candidates at once
Context budgeta rubric-placed scope reading lowers the compaction threshold
Relevance compactionper-message keep/drop, plus a gate on the generated summary
Tool / MCP routingone boolean per server, replacing a 15s LLM call at ~400 ms
RAG retrievalper-query topK / hybrid / graph / rerank planning

Limits and gotchas​

  • Two input ceilings, both enforced by the service: state plus the longest single question ≈ 33,000 tokens, and state plus all questions ≈ 64,000. Exceeding either returns max_tokens_exceeded with no message at all — the provider supplies a real sentence in its place.
  • Batch, never fan out. Latency is flat in question count but concurrent requests queue, so a second round trip costs far more than a hundred extra questions.
  • A boolean carries no confidence of its own. Use decisionBooleanConfidence(p) — distance from a coin flip, so 0.5 → 0 and 0/1 → 1.
  • 403 vs 401 are inverted on the direct API, and from TypeSafe's own docs: a missing Authorization header returns 403, an invalid key returns 401. The gateway does not share this quirk.

Troubleshooting​

SymptomCauseFix
tryDecide() always returns nullNo key, or the key was rejected once and the instance disabled itselfCheck TYPESAFE_API_KEY; construct a new instance after fixing it
max_tokens_exceededOne of the two input ceilingsShorten state, or split questions across calls — but prefer shrinking state
403 customer_verification_requiredGateway transport, no card on the Vercel teamAdd a payment method, or use the direct transport
Routing never changesA modelPool is configured, which owns selection outrightSee Provider Orchestration

See also​