Vercel AI Gateway

huncho/gateway calls Jev through Vercel AI Gateway, for when your models are routed and billed there. Same decision, different import line, nothing else changes.

import { huncho, noul } from "huncho";
import { gateway } from "huncho/gateway";

const route = huncho("support.route", { model: gateway() })
  .ask({ urgent: noul("Does this need a human within the hour?") })
  .when((a) => a.urgent.p, { enter: 0.8, exit: 0.6 }, "page")
  .else("wait");

Key

gateway() reads AI_GATEWAY_API_KEY the first time it is called; importing the entry reads nothing. To take the key from somewhere else, build the provider yourself:

import { createGateway } from "huncho/gateway";

const gateway = createGateway({ apiKey: process.env.MY_GATEWAY_KEY });

apiKey may be undefined or empty, in which case the variable is read instead. No key at all is a ConfigError on the first call: gateway: set AI_GATEWAY_API_KEY or pass apiKey to createGateway. A key the gateway rejects is a ProviderError with status 401 or 403 and retryable: false. Keys and Errors have the general rules.

Defaults


Entry	`huncho/gateway`
Factory	`createGateway(options)`
Ready-made instance	`gateway`
Key from	`AI_GATEWAY_API_KEY`
URL	`https://ai-gateway.vercel.sh/v4/ai/evaluation-model`
Model id	`typesafe-ai/jev`
Wire	`gateway`

gateway() is the default model; gateway("typesafe-ai/some-id") is another. The gateway names models vendor/model.

Options

createGateway(options) takes the core options every provider shares, apiKey, url, defaultModel, fetch and retries, plus:

Option	Meaning
`headers`	Extra request headers, merged under the auth and protocol headers.

const gateway = createGateway({
  apiKey: await vault.read("gateway"),
  retries: 2,
  headers: { "X-Team": "support" },
});

On the wire

gateway has a wire of its own, the Vercel AI Gateway evaluation dialect. The model id travels in the Ai-Model-Id header rather than the body, alongside the protocol and specification version headers; a noul question is sent as boolean and decoded back to noul; a choice’s confidence comes from providerMetadata.typesafe.confidence, and when that is missing it is the gap between the top two probabilities; the request id is the x-vercel-id response header. The fixtures under fixtures/wires/gateway/ pin every one of those, described in Wire fixtures. Transport retries 408, 429, 500, 502, 503 and 529 with backoff and fails any other status on first sight.