curl --request POST \
  --url https://prod.featherhq.com/api/v1/knowledge-base/collection/{collectionId}/files/bulk-add \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '
{
  "fileIds": [
    "<string>"
  ]
}
'

{
  "total": 123,
  "successful": 123,
  "failed": 123,
  "results": [
    {
      "fileId": "<string>",
      "success": true,
      "error": "<string>"
    }
  ]
}