I assume that the snake parts that are outside the grid are included in the totals given for those rows. This fits with my understanding of the rules, but my initial assumption was that they are outside the grid and therefore not counted.
actually I agree with you but I prefer this type of puzzles without giving infomation about the direction of the squares next to the head or tail, so I was forced to develop the puzzle the way it is. I considered the option to put the numbers right next to the rows (without a gap) but in my opinion that would become less clear
I guess for future puzzles one way to make it clearer is to put a "1" below the columns that contain only the head or tail (just to indicate that the head and tail are counted)
That's a good idea - I think that would make it unambiguous.
Another way would be to include the other cells in the relevant rows/columns, either as black cells or with a leaf already in them. However, I'm aware this will make the puzzle visually less appealing.