The 6th SOLID Principle?

I've been writing about the SOLID principles for over a decade. I built InversifyJS because of them, I wrote about implementing them with the onion architecture , and just recently, I argued that they are universal design principles that show up far beyond the world of object-oriented programming. But I've always felt something was missing — not from the principles themselves, but from the conversation around them. SOLID tells you how to write good components. It doesn't tell you how to compose them into a system that can change shape. Let me explain. The gap Imagine you have a perfectly SOLID codebase. Your UserRepository depends on an abstraction. Your EmailService has a single responsibility. Your OrderProcessor is open for extension but closed for modification. Everything is beautiful. You followed the five principles to the letter. Now your CTO walks in and says: "We need to split the user management into its own microservice." What happens? You start ripping things apart. You cre