> outputs 3 chars

You mean codepoints or maybe grapheme clusters?

Anyways yeah it’s a little more complicated but the principle of being able to truncate a string without splitting a codepoint in O(1) is still useful

Yah, I was using char interchangeably with code point. I also used byte instead of code unit.

> truncate a string without splitting a codepoint in O(1) is still useful

Agreed!