Yes, I think there could be arguments for different behaviors, but I suspect the expected behavior should be the same as when you select the link by other methods, such as starting a region at one end and then jumping to the beginning or end of the line with move-beginning-of-line or move-end-of-line. When killing the line or region after that movement, the entire text (URL, description, all brackets) is killed.
Also, when emphasis markers are hidden (org-hide-emphasis-markers t), and the same experiment is performed on a word at the beginning of a line that is emphasized , for example "/italicized/", all of the hidden slash characters are successfully killed. So I think that is another indication that the expected behavior would be to kill all of the characters, hidden or not.
I think the fact that it is only some, perhaps underused, methods of selecting the text--arrow keys or mouse-dragging--that result in this unusual behavior, also points to the behavior not being intended.
>
> Org Mode will turn the above text into a clickable link called "link".
>
> Now, select the link either by clicking and dragging the mouse from the end of the word "link" to the beginning of the word, or by starting a region at either the beginning or end of the word (or on the next line) and then using the arrow keys to move point to either the "l" or "k" in "link".
>
> Your region should now encompass "link" and nothing else.
>
> Now, kill the line or region.
>
> You will see immediately that the full text was not killed. Instead, the link description is killed, along with, depending on where point was, possibly some of the brackets, leaving behind the opening brackets, the link URL, the URL closing bracket, and in some cases the final two brackets.
Well. Part of the link text is indeed hidden, causing all kinds of
unexpected behaviours depending on the point move direction.
I am not sure what can be done here. I am not even sure what is the
expected behaviour.
--
Ihor Radchenko // yantar92,
Org mode contributor,