final String language = locale.getLanguage();
        if ("en".equals(language)) {
            return StringUtil.EMPTY;
        }
        return "IMPORTANT: You MUST respond in " + locale.getDisplayLanguage(Locale.ENGLISH) + ".";
    }

    /**
     * Resolves the {{languageInstruction}} placeholder in a prompt.
     *
     * @param prompt the prompt template