# MTranServerUnavailableException.java

    package com.yumu.noveltranslator.exception;

    /**
     * Thrown when the MTranServer circuit breaker is open or the service is unavailable.
     * Enables upstream round-robin logic (UserLevelThrottledTranslationClient) to switch to the Python fallback service.
     */
    public class MTranServerUnavailableException extends RuntimeException {

        public MTranServerUnavailableException(String message) {
            super(message);
        }

        public MTranServerUnavailableException(String message, Throwable cause) {
            super(message, cause);
        }
    }