CopilotKit

npm install @copilotkit/runtime @copilotkit/react-core @copilotkit/react-ui @ai-sdk/openai

// app/api/copilotkit/route.ts
import { createOpenAI } from "@ai-sdk/openai";
import {
  CopilotRuntime,
  OpenAIAdapter,
  copilotRuntimeNextJSAppRouterEndpoint,
} from "@copilotkit/runtime";

// Unset, createOpenAI would fall back to OPENAI_API_KEY and send that key here.
const apiKey = process.env.OP_API_KEY;
if (!apiKey) throw new Error("OP_API_KEY is not set");

// OpenAIAdapter calls the Responses API, which is not served here.
// This override makes it call chat completions instead.
class OPInferenceAdapter extends OpenAIAdapter {
  override getLanguageModel() {
    return createOpenAI({
      baseURL: "https://api.opinference.com/v1",
      apiKey,
    }).chat(this.model);
  }
}

export async function POST(req: Request) {
  const { handleRequest } = copilotRuntimeNextJSAppRouterEndpoint({
    runtime: new CopilotRuntime(),
    serviceAdapter: new OPInferenceAdapter({ model: "openai/gpt-oss-120b" }),
    endpoint: "/api/copilotkit",
  });
  return handleRequest(req);
}