14  lib/ Architecture

Let me explain the recommended Flutter production structure with inline explanations:

14.2 Architecture Flow Explanation

User Interaction
       ↓
Presentation Layer (UI)
       ↓
Domain Layer (Business Logic)
       ↓
Data Layer (External Sources)
       ↓
Backend Services (Firebase, APIs)

Data Flow: User taps button → Presentation calls UseCase → UseCase calls Repository → Repository calls DataSource → DataSource hits Firebase/API → Response flows back up the chain → UI updates

14.3 Key Benefits for Your Background

Python Similarity: The domain layer works like pure Python modules - no framework dependencies, just business logic. You can test these independently, similar to testing Python functions.

JavaScript Comparison: The presentation layer manages state like React components, but with Flutter’s reactive widget system. State flows down, events flow up.

Separation of Concerns: Each layer has one job, making debugging easier. If there’s a UI bug, check presentation. If business logic fails, check domain. If data doesn’t load, check data layer.

Testing Strategy: You can unit test domain logic without UI, integration test data layer without business logic, and widget test presentation without backend calls.

This structure scales well as your app grows and makes it easy to add new features like “medical_imaging” or “patient_reports” following the same three-layer pattern within the features directory.