Rails accelerates web development with its convention-over-configuration principle and MVC pattern. But as your app grows, that simplicity can turn into tangled complexity, making it harder to maintain and extend. The second edition of Layered Design for Ruby on Rails Applications helps tackle this challenge head on, guiding you toward a more scalable and maintainable architecture. Written by a seasoned software engineer and open source contributor to Ruby on Rails, this updated edition refines the proven techniques from the first edition and introduces timely new topics that reflect today’s development challenges. You’ll dive deeper into state machines and workflows, learning how to identify, embed, and eventually isolate them for clarity and resilience. You’ll also explore the exciting frontier of abstractions in the AI era, treating LLMs as APIs, structuring agent layers, and integrating third-party libraries to keep your AI features organized and testable. By embracing layered abstractions, you’ll not only reduce complexity but also improve your ability to adapt to change - whether adding new features, scaling systems, or weaving AI capabilities into your applications. By the end of the book, you’ll be equipped to design clean, extensible, and future-ready Rails applications. *Email sign-up and proof of purchase required