Function isCoverFileName

packages/core/src/sync/sync-naming.ts:70–76

(fileName: string)

/** Heuristic: file is a cover if its extension is a known image format. */
export function isCoverFileName(fileName: string): boolean {
  const dot = fileName.lastIndexOf(".");
  if (dot < 0) return false;
  const ext = fileName.slice(dot + 1).toLowerCase();
  if (!ext) return false;
  return COVER_EXTENSIONS.has(ext);
}