04 Streaming

import type { RequestHandler } from "@sveltejs/kit";
import { z } from "zod";
import { supportAgent } from "$lib/server/ai/support-agent";

const SupportStreamRequest = z.object({
  message: z.string().trim().min(1, "message is required"),
});

export const POST: RequestHandler = async ({ request }) => {
  const parsed = SupportStreamRequest.safeParse(await request.json());

  if (!parsed.success) {
    return Response.json(
      { error: { code: "bad_request", message: parsed.error.issues[0]?.message } },
      { status: 400 },
    );
  }

  return new Response(supportAgent.prompt(parsed.data.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 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));
  }
}