Design a comprehensive meta-prompt framework for planning the backend logic of a SaaS application. This framework should guide the generation of detailed prompts to address specific aspects of backend architecture, including database design, API endpoints, data processing workflows, security considerations, and scalability.  The output should be a structured outline that incorporates prompts for each of these areas.  The prompts should be detailed enough to elicit specific technical requirements and design choices from an AI assistant, but flexible enough to adapt to various application contexts. Consider including examples of prompts for specific scenarios, such as handling user authentication, managing payment processing, and implementing data backups.  The generated meta-prompt framework should be adaptable to different technology stacks (e.g., Node.js, Python/Django, Ruby on Rails) and scaling strategies (e.g., microservices, serverless).  The success of this meta-prompt will be measured by its ability to generate detailed and actionable prompts that, when answered by an AI assistant, result in a complete and well-documented backend architecture design.  The final output should be a structured document with sections for each aspect of backend logic, each section containing several detailed prompts relevant to that area.  Include examples of prompt outputs for a few key areas like user authentication and payment processing.