check

printing/apps.py

@@ -1,5 +1,8 @@
+import logging
 from django.apps import AppConfig
 
+logger = logging.getLogger(__name__)
+
 
 class PrintingConfig(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
@@ -16,4 +19,9 @@ class PrintingConfig(AppConfig):
         process_completed.connect(
             handlers.on_printing_job_process_completed,
             sender=PrintingJob
+        )
+        
+        logger.info(
+            f'[printing.apps] 已注册 process_completed 信号处理器, '
+            f'sender={PrintingJob}, handler={handlers.on_printing_job_process_completed}'
         )