Providers, models and API keys

A provider package turns a model name into a model object. It reads the provider's API key from an environment variable when the model is called.

import { generateText } from "ai";
import { openai } from "@ai-sdk/openai";

const model = openai("gpt-4.1-mini");
console.log(model.provider, model.modelId);

try {
  await generateText({ model, prompt: "Say hello." });
} catch (error) {
  console.log(error.name);
  console.log(error.message);
}

npx tsx keys.ts

openai("gpt-4.1-mini") creates the model without contacting OpenAI. The key is loaded when generateText calls it, and without OPENAI_API_KEY the call fails with AI_LoadAPIKeyError before any request is sent. openai.responses shows this provider uses OpenAI's Responses API.

A plain string as model goes through Vercel's AI Gateway, one key for many providers. The course never sends a request there; the stand-in model from lesson 4 goes where these would.