It's not completely seamless, but it should work adequately well. The
workbook (aka client) inserts the workbook version into the http request
body. The server code compares that version number against its minimum
supported client version.
If the client is too old, an error message is sent back to the client.
When the client receives the "Obsolete" error message, it launches the
https://<server>:<port>/template URL in the default browser, which
enables the user to save the downloaded new workbook file.
