It’s a bit complicated to make the Author/Category into databases, because the readwise API does not report them as uniquely identifiable entities (just text strings).
It’s a shame we don’t have Single select field options as level in smart folders
It is possible to choose whether the field is text or single-select at the time you initially configure the fields (the default is text, but you can choose single-select if you prefer).
But I will roll a change to make single-select the default choice for the
- author
- category
- source
- highlight color
fields.
(Tags should automatically default to a multi-select type)