Before Compose: A Case Study in Building Fast Android UI Preview

Meta’s Android codebase works as a monorepo. Before our area was ready for Compose, teams still had to solve the same daily problem: slow builds made UI iteration painful.

This talk is a case study in building fast preview tooling for Litho, Meta’s declarative Android UI framework. During 2023, we started from a single goal — “change UI code and see the result quickly inside Android Studio” — and split one big problem into a chain of technical challenges: compiling changed Java/Kotlin code, spinning up a dedicated local server, sending payloads to a sandboxed mobile activity, and rendering the result back through an IDE plugin. The resulting solution reduced preview time from minutes to seconds.

Attendees will learn how web-stack development techniques can be adapted for mobile tooling, and how to stitch compiler, server, app, and IDE pieces into one practical developer workflow.