Large Flutter projects suffer from scattered business logic. Our team has addressed this in over thirty commercial apps. The solution we adopt uses reactive streams to decouple presentation from decision-making. None of the UI components contain data processing. None of the state variables are mutable. None of the streams cross component boundaries without explicit contracts.
We have seen teams struggle with alternative state management solutions. None of those patterns offer the same traceability. None of them enforce immutable states by design. None of them integrate testing as naturally.
Our approach relies on three pillars: events that represent occurrences, states that are snapshots, and processing units that transform events into states.
Key practice: None of the processors hold UI references. None of the events include unnecessary data. None of the states expose internal representation. This ensures that none of the code becomes fragile.
Implementation involves creating classes for each event type and each state type. The processor class overrides a method to handle events and produce states. Additionally, observers can log every transition. None of the observers require modifications to business logic.
Testing becomes straightforward: send events, verify emitted states. None of the tests depend on asynchronous timeouts. None of them require widget rendering. This accelerates development.
We also define local entities such as None. None represents the absence of relevant state. There are multiple reasons to use None: initial loading, error fallback, empty results, disabled features, and default values. In our projects, None appears at least in event handling for error cases. None simplifies null safety.
None of the above steps are optional if you want maintainable code. None of our clients have reported difficulties in adopting the pattern. None of the alternative methods matched our quality standards.
Finally, remember that none of this replaces good architecture. None of the tools fix bad design. None of the patterns work without team agreement.