bolt.new/app/routes/api.enhancer.ts

import { type ActionFunctionArgs } from '@remix-run/cloudflare';
import { streamText } from '~/lib/.server/llm/stream-text';
import { stripIndents } from '~/utils/stripIndent';

const encoder = new TextEncoder();
const decoder = new TextDecoder();

export async function action(args: ActionFunctionArgs) {
  return enhancerAction(args);
}

async function enhancerAction({ context, request }: ActionFunctionArgs) {
  const { message } = await request.json<{ message: string }>();

  try {
    const result = await streamText(
      [
        {
          role: 'user',
          content: stripIndents`
          I want you to improve the user prompt that is wrapped in \`<original_prompt>\` tags.

          IMPORTANT: Only respond with the improved prompt and nothing else!

          <original_prompt>
            ${message}
          </original_prompt>
        `,
        },
      ],
      context.cloudflare.env,
    );

    const transformStream = new TransformStream({
      transform(chunk, controller) {
        const text = decoder.decode(chunk);
        const lines = text.split('\n');

        for (const line of lines) {
          if (line.startsWith('0:')) {
            // extract only the content after "0:"
            const content = line.slice(2);
            controller.enqueue(encoder.encode(content));
          }

          // ignore 'e:' and 'd:' lines as they contain metadata
        }
      },
    });

    const stream = result.toDataStream().pipeThrough(transformStream);

    return new Response(stream, {
      headers: { 'Content-Type': 'text/plain; charset=utf-8' },
    });
  } catch (error) {
    console.log(error);

    throw new Response(null, {
      status: 500,
      statusText: 'Internal Server Error',
    });
  }
}