KMP AGP 9.0 Migration

Android Gradle Plugin 9.0 makes the Android application and library plugins incompatible with the Kotlin Multiplatform plugin in the same module. This skill guides you through the migration.

Step 0: Analyze the Project

Before making any changes, understand the project structure:

1. Read settings.gradle.kts (or .gradle) to find all modules
2. For each module, read its build.gradle.kts to identify which plugins are applied
3. Check if the project uses a Gradle version catalog (gradle/libs.versions.toml). If it exists, read it for current AGP/Gradle/Kotlin versions. If not, find versions directly in build.gradle.kts files (typically in the root buildscript {} or plugins {} block). Adapt all examples in this guide accordingly — version catalog examples use alias(libs.plugins.xxx) while direct usage uses id("plugin.id") version "x.y.z"
4. Read gradle/wrapper/gradle-wrapper.properties for the Gradle version
5. Check gradle.properties for any existing workarounds (android.enableLegacyVariantApi)
6. Check for org.jetbrains.kotlin.android plugin usage — AGP 9.0 has built-in Kotlin and this plugin must be removed