04 Streaming

import { createFileRoute } from "@tanstack/react-router";
import { supportAgent } from "~/ai/support-agent";

type SupportStreamRequest = {
  message?: string;
};

export const Route = createFileRoute("/api/support/stream")({
  server: {
    handlers: {
      POST: async ({ request }) => {
        const body = (await request.json()) as SupportStreamRequest;
        const message = body.message?.trim();

        if (!message) {
          return Response.json(
            { error: { code: "bad_request", message: "message is required" } },
            { status: 400 },
          );
        }

        return new Response(supportAgent.prompt(message).readableStream(), {
          headers: {
            "Content-Type": "application/x-ndjson",
            "Cache-Control": "no-cache",
          },
        });
      },
    },
  },
});

const response = await fetch("/api/support/stream", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ message: "Draft a support reply." }),
});

const reader = response.body?.getReader();
const decoder = new TextDecoder();

while (reader) {
  const next = await reader.read();
  if (next.done) break;

  for (const line of decoder.decode(next.value).split("\n")) {
    if (line.trim()) console.log(JSON.parse(line));
  }
}