src/lib/langfuse.ts

import { LangfuseClient } from "@langfuse/client";

// Ensure this is never imported on the client
if (typeof window !== "undefined") {
  throw new Error("`langfuse` must only be used on the server side.");
}

declare global {
  // eslint-disable-next-line no-var
  var __langfuse__: LangfuseClient | undefined;
}

export const langfuse = globalThis.__langfuse__ ?? new LangfuseClient({
  publicKey: process.env.LANGFUSE_PUBLIC_KEY,
  secretKey: process.env.LANGFUSE_SECRET_KEY,
  baseUrl: process.env.LANGFUSE_BASE_URL || "https://cloud.langfuse.com",
});

if (!globalThis.__langfuse__) globalThis.__langfuse__ = langfuse;