Function downloadAndSaveAttachment

src/runtime/adapters/attachment-utils.ts:64–106

(
  rootDir: string,
  channelId: string,
  url: string,
  filename: string,
  mimeType?: string,
  headers?: Record<string, string>,
)

 * Download a file from a URL and save it as an attachment.
 */
export async function downloadAndSaveAttachment(
  rootDir: string,
  channelId: string,
  url: string,
  filename: string,
  mimeType?: string,
  headers?: Record<string, string>,
): Promise<ChannelAttachment> {
  const dir = getAttachmentDir(rootDir, channelId);
  fs.mkdirSync(dir, { recursive: true });

  const ts = Date.now();
  const safeName = sanitizeFilename(filename);
  const storedName = `${ts}-${safeName}`;
  const fullPath = path.join(dir, storedName);

  const response = await fetch(url, { headers });
  if (!response.ok) {
    throw new Error(
      `Failed to download attachment from ${url}: ${response.status} ${response.statusText}`,
    );
  }

  const body = response.body;
  if (!body) {
    throw new Error(`Empty response body when downloading ${url}`);
  }

  const nodeStream = Readable.fromWeb(body as any);
  const writeStream = fs.createWriteStream(fullPath);
  await pipeline(nodeStream, writeStream);

  const stats = fs.statSync(fullPath);
  const detectedMime =
    mimeType || response.headers.get("content-type")?.split(";")[0] || undefined;

  return {
    filename,
    localPath: fullPath,
    mimeType: detectedMime,
    size: stats.size,
  };
}

// ---------------------------------------------------------------------------
// Formatting helpers