Designing the BFF (Backend-for-Frontend) contract with request aggregation and client-specific shaping is a smart way to keep frontends lean while improving performance and maintainability. By aggregating multiple backend calls into a single, tailored response, the BFF reduces network overhead and simplifies client logic. At the same time, shaping responses specifically for each client (web, mobile, etc.) ensures that only relevant data is delivered, improving efficiency and user experience. When done well, this approach creates a clean separation of concerns, allowing backend services to remain generic while the BFF adapts outputs to meet diverse frontend needs.

BFF patterns are underappreciated in the API design world. The request aggregation approach you describe is exactly what I implement when building automation dashboards — the frontend needs very specific data shapes that don't map cleanly to individual microservice responses. One pattern I've found useful: versioning BFF contracts independently from backend services, so mobile and web clients can evolve at different speeds without breaking each other. The caching layer at the BFF level is also a game changer for reducing downstream load.