Extend prompt execution contract

internal/promptexec/copy.go

@@ -78,3 +78,15 @@ func boundText(value string, limit int) string {
 	}
 	return value
 }
+
+func boundCodePoints(value string, limit int) string {
+	if limit <= 0 || value == "" {
+		return ""
+	}
+	value = strings.ToValidUTF8(value, "<22>")
+	runes := []rune(value)
+	if len(runes) <= limit {
+		return value
+	}
+	return string(runes[:limit])
+}