Attachment

attachment = await client.api.create_attachment(
    thread_id="<THREAD_UUID>",
    step_id="<STEP_UUID>"
    name="my_attachment",
    content_type="text/plain",
    content="Hello world",
)

const thread = await client.thread().upsert();

const fileStream = createReadStream('PATH_TO_FILE');
const mime = 'image/png';

const { objectKey } = await client.api.uploadFile({
  threadId: thread.id,
  content: fileStream,
  mime
});

const attachment = new Attachment({
  name: 'test',
  objectKey,
  mime
});

const finalStep = await thread
  .step({
    name: 'Assistant',
    type: 'assistant_message',
    output: "Here is the generated image!",
    attachments: [attachment]
  })
  .send();