Introducing Trio | Part II
Article Summary
Airbnb's Android team just solved one of mobile architecture's hardest problems: navigation in massive, modularized apps. Their solution? Store navigation state right in the ViewModel.
In Part II of their Trio framework series, Airbnb engineers Eli Hart, Ben Schwab, and Yvonne Wong reveal how they built a Compose-based navigation system that works across 2000+ modules. This isn't your typical navigation library.
Key Takeaways
- Navigation stack lives in ViewModel State, enabling atomic updates with business logic
- Custom Router system with compile-time validation ensures type safety across modules
- ViewModels get Activity access via Flow to handle intents without leaking references
- Fragment interop allows gradual migration during years-long Compose transition
- KSP processor validates Router-to-Trio mappings at compile time preventing runtime errors
Critical Insight
Airbnb's Trio framework treats navigation as state, making complex screen flows testable, type-safe, and perfectly suited for large modularized codebases.
