Formatting code like below doesn't change it:

a =
    String.reverse ("""first line
              second line""" ++ ".")

• the call's first argument isn't moved to the next line
• the operator ++ does not get its own line
• the closing paren isn't moved to the next line

A simple solution would be checking whether the range of the multiline string starts and ends on the same line
and considering it multi vs single-line based on that.

I assume the current behavior is to some part intentional because it enables a kind of string interpolation syntax.
If yes, I think making an exception for multi-line strings with just ++ seems okay, while still considering the whole ++ chain as multi-line.

Thanks <3