textutil

func Truncate ¶

func Truncate(s string, limit int, tail string) string

Truncate shortens s to at most limit runes, appending tail when it does.

It exists because the obvious form, s[:limit] + tail, slices BYTES. Any multi-byte character straddling the cut is split in half, leaving a dangling byte and invalid UTF-8 — which corrupts terminal layout (the renderer and the terminal disagree on the width), HTML, and any text handed to a model. Titles routinely carry a "·", an accent or an emoji, so this is not a rare case.

limit counts runes, not columns: callers here are bounding text size, not laying out a terminal. For width-sensitive rendering use ansi.Truncate, which accounts for double-width characters.

A limit at or below the length of tail returns the leading runes alone, so the result never grows past the caller's budget.