As part of the support for category adaptation (T188605), we want to better communicate the cases where there are no categories and encourage users to add new categories.
The general idea is to show a message inside the category box (using base30, #72777D) to show a message. The message will be different depending on the circumstances.
For the list of categories in the source article, the message will be "No categories", and it will be only shown when there are no categories for the source article (i.e., the source category box is empty).
For the list of categories in the translation, there default message will be "No categories. Consider adding some to better classify the topic." However, we want to provide some more clarity for the case where the source article has some categories but none of them could be adapted. In such case the message will be: "The original categories don’t exist in this language. Explore more categories to better describe the topic."
A mockup below shown the expected messages in different circumstances: