After adding German and Spanish to our Flutter app, release builds showed raw keys like checkout.pay_button instead of text. The new translation files were declared as assets only on one laptop, never in the repository. How we found it, fixed the declarations and moved to compile-time localizations.
Our Flutter app grew from five screens to sixty, and every change touched widgets, API calls and state in the same file. The structure we moved to: feature-first folders, with UI, state, repository and service layers whose dependencies point one way, and how each layer is tested.
A security review found refresh tokens sitting in plain text in our Flutter app's preferences file. This guide sorts local data into three buckets, explains what shared_preferences, Hive (and its maintained hive_ce fork) and flutter_secure_storage actually do on each platform, and covers the uninstall and backup traps.
Our Flutter app gained about 9 MB of Dart heap every time a user opened and closed the order details screen, until older Android phones killed it. DevTools showed dozens of retained State objects held alive by a stream subscription and an AnimationController that were never disposed.
A new Android Studio with JDK 21 forced a Gradle upgrade, the Gradle upgrade pulled in AGP 8, and AGP 8 rejected two old Flutter plugins with Namespace not specified. How we untangled the Gradle, AGP, Kotlin and JDK chain.