import { TextEncoder } from "node:util"; /** * Convert an async iterable of strings into a ReadableStream. * @param iterable - Async iterable of strings. * @returns ReadableStream of Uint8Array chunks. */export const streamAsyncStrings = (iterable: AsyncIterable<string>): ReadableStream<Uint8Array> => {  const encoder = new TextEncoder();  const iterator = iterable[Symbol.asyncIterator]();  return new ReadableStream<Uint8Array>({    async pull(controller): Promise<void> {      const { value, done } = await iterator.next();      if (done) {        controller.close();        return;      }      controller.enqueue(encoder.encode(value));    },    async cancel(): Promise<void> {      if (iterator.return) {        await iterator.return();      }    },  });}; /** * Build SSE headers for streaming responses. * @param extra - Additional headers. * @returns Headers object. */export const buildSseHeaders = (extra: Record<string, string> = {}): Record<string, string> => ({  "Content-Type": "text/event-stream",  "Cache-Control": "no-cache, no-transform",  Connection: "keep-alive",  "X-Accel-Buffering": "no",  ...extra,});