Upload a file to xAI's storage. Returns the file's metadata. Files can be referenced by ID anywhere a `file_id` is accepted (e.g. chat attachments). Maximum file size: 50 MB. Files are kept until you delete them, or until `expires_after` elapses if set at upload time.

The size of the file, in bytes.

The Unix timestamp (in seconds) for file creation time.

The Unix timestamp (in seconds) for file expiry time. null if file does not expire.

The name of the file.

The file identifier, which can be used in other API requests.

The object type, which is always file. Only included for compatability.

Public URL for the file. Only present when the file has an active public URL.

Unix timestamp (seconds) when the public URL expires. Only present when the public URL has an independent expiry.

The intended purpose of the uploaded file. Only included for OAI compatability.