package tools

import "unicode/utf8"

// CutUTF8 按字节上限截断，并回退到完整 rune，避免切开 UTF-8。
func CutUTF8(s string, maxBytes int) string {
	if maxBytes <= 0 || len(s) <= maxBytes {
		return s
	}
	end := maxBytes
	for end > 0 && !utf8.ValidString(s[:end]) {
		end--
	}
	return s[:end]
}