A Modern Kotlin-Based MVI Architecture

Zsolt Kocsi from Badoo reveals how their chat module kept losing first messages despite a full Clean Architecture rewrite. The culprit? Uncontrolled state mutations in a massively asynchronous app.

Badoo's engineering team open-sourced MVICore, their Kotlin-based MVI framework, after traditional architecture patterns failed to solve race conditions and edge cases in their chat feature. This deep dive explains how they moved beyond simple state reducers to build a production-ready solution.

Key Takeaways

• Single immutable State object eliminates race conditions from parallel async operations
• Feature component encapsulates business logic with Wish, State, and News parameters
• Built-in middleware enables logging and time-travel debugging out of the box
• A/B tests showed message-sending gaps even after Clean Architecture rewrite

The article breaks down optional components like Actor, NewsPublisher, and Bootstrapper that handle the messy real-world scenarios reducers alone can't solve.