There was a mistake in the API method name. We've corrected the mistake and apologize for any inconvenience caused by this error.
The LIFF SDK keeps a permanent link for the current page. We'll publish the documentation of the API that handles this permanent link.
These APIs are already included in the latest LIFF SDK, so the LIFF SDK version doesn't change.
For more information on how to get a permanent link, see Get a permanent link for the current page in the LIFF documentation.