Kotlin Multiplatform: the migration I wish I'd planned

We started moving a shared business layer to Kotlin Multiplatform, and it's going well — but I'd do a few things differently.

What I'd plan first:

• A clear boundary between shared logic and platform UI (we blurred it early)
• Dependency injection that works on both sides from day one
• A test strategy before the first shared module

The wins are real: one place for models, serialization, and validation. The trap is thinking "shared" means "everything."

Next milestone is sharing some of the state management. If you've done KMP on a real app, I'd like to hear what bit you.