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internal/termout/width.go

@@ -0,0 +1,73 @@
+package termout
+
+import (
+	"regexp"
+	"strings"
+	"unicode/utf8"
+
+	"golang.org/x/text/width"
+)
+
+var ansiEscapeRe = regexp.MustCompile(`\x1b\[[0-9;]*m`)
+
+// displayWidth returns the terminal display width of text, ignoring ANSI codes.
+func displayWidth(text string) int {
+	plain := ansiEscapeRe.ReplaceAllString(text, "")
+	w := 0
+	for _, r := range plain {
+		w += runeDisplayWidth(r)
+	}
+	return w
+}
+
+func runeDisplayWidth(r rune) int {
+	if r == utf8.RuneError {
+		return 0
+	}
+	// Most emoji / symbols render as double-width in modern terminals.
+	if isEmojiLikeRune(r) {
+		return 2
+	}
+	switch width.LookupRune(r).Kind() {
+	case width.EastAsianWide, width.EastAsianFullwidth:
+		return 2
+	default:
+		return 1
+	}
+}
+
+func isEmojiLikeRune(r rune) bool {
+	switch {
+	case r >= 0x1F300 && r <= 0x1FAFF: // pictographs / emoji
+		return true
+	case r >= 0x2600 && r <= 0x27BF: // misc symbols
+		return true
+	case r >= 0x2300 && r <= 0x23FF: // misc technical (⌚ etc.)
+		return true
+	case r >= 0x2B50 && r <= 0x2B55:
+		return true
+	default:
+		return false
+	}
+}
+
+func padRightDisplay(text string, target int) string {
+	if target <= 0 {
+		return ""
+	}
+	gap := target - displayWidth(text)
+	if gap <= 0 {
+		return text
+	}
+	return text + strings.Repeat(" ", gap)
+}
+
+func maxDisplayWidth(rows ...string) int {
+	max := 0
+	for _, row := range rows {
+		if w := displayWidth(row); w > max {
+			max = w
+		}
+	}
+	return max
+}