Namespace of another "login"-type plugin to run fresh before every single call to this one (never a cached session) — mirrors legacy's exec_login_plugin (~/LANraragi/lib/LANraragi/Model/Plugins.pm:107-135). Omit entirely for a plugin that needs no login, or that is itself a "login"-type plugin (which never chases another login). A failed login attempt only logs a warning; this plugin's own call still goes ahead, just without hostArgs.user_agent_cookies populated.