platform upgrades

android/.gitignore

@@ -11,3 +11,4 @@ GeneratedPluginRegistrant.java
 key.properties
 **/*.keystore
 **/*.jks
+.kotlin/

android/app/build.gradle

@@ -33,10 +33,6 @@ android {
         coreLibraryDesugaringEnabled true
     }
 
-    kotlinOptions {
-        jvmTarget = '17'
-    }
-
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
     }
@@ -47,7 +43,6 @@ android {
         targetSdkVersion flutter.targetSdkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
-        multiDexEnabled true
     }
 
     buildTypes {
@@ -59,12 +54,17 @@ android {
     }
 }
 
+kotlin {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+    }
+}
+
 flutter {
     source '../..'
 }
 
 dependencies {
-    implementation 'com.android.support:multidex:2.0.1'
     // Same version as workmanager_android pins — needed to enqueue its
     // BackgroundWorker from native widget code (the plugin uses
     // `implementation`, so androidx.work is not exposed transitively).

android/app/src/main/java/io/flutter/app/FlutterMultiDexApplication.java

@@ -1,25 +0,0 @@
-// Generated file.
-//
-// If you wish to remove Flutter's multidex support, delete this entire file.
-//
-// Modifications to this file should be done in a copy under a different name
-// as this file may be regenerated.
-
-package io.flutter.app;
-
-import android.app.Application;
-import android.content.Context;
-import androidx.annotation.CallSuper;
-import androidx.multidex.MultiDex;
-
-/**
- * Extension of {@link android.app.Application}, adding multidex support.
- */
-public class FlutterMultiDexApplication extends Application {
-  @Override
-  @CallSuper
-  protected void attachBaseContext(Context base) {
-    super.attachBaseContext(base);
-    MultiDex.install(this);
-  }
-}

android/build.gradle

@@ -5,10 +5,25 @@ allprojects {
     }
 }
 
-rootProject.buildDir = '../build'
+rootProject.layout.buildDirectory = file('../build')
 subprojects {
-    project.buildDir = "${rootProject.buildDir}/${project.name}"
+    project.layout.buildDirectory = rootProject.layout.buildDirectory.dir(project.name)
 }
+// AGP 9 enables built-in Kotlin, but Flutter's migrator pins
+// android.builtInKotlin=false while the plugin ecosystem catches up. Most
+// plugins honour that flag and fall back to KGP themselves; file_picker and
+// background_downloader only check the AGP major version and silently skip
+// applying KGP, which leaves their Kotlin sources uncompiled (missing
+// FilePickerPlugin/BackgroundDownloaderPlugin at link time). Apply KGP for
+// them as soon as AGP is on the project, i.e. before their android {} block
+// runs. Drop this once both plugins ship a builtInKotlin-aware build script.
+gradle.beforeProject { sub ->
+    if (!(sub.name in ['file_picker', 'background_downloader'])) return
+    sub.plugins.withId('com.android.library') {
+        sub.pluginManager.apply('org.jetbrains.kotlin.android')
+    }
+}
+
 // Pin every Android subproject to JVM 17 so plugins that ship Kotlin sources
 // compiled with a higher target (e.g. receive_sharing_intent at 21) or stale
 // Java compatibility (e.g. home_widget at 1.8) don't break the build under
@@ -42,5 +57,5 @@ subprojects {
 }
 
 tasks.register("clean", Delete) {
-    delete rootProject.buildDir
+    delete rootProject.layout.buildDirectory
 }

android/gradle.properties

@@ -1,10 +1,6 @@
 org.gradle.jvmargs=-Xmx4G
 android.useAndroidX=true
-android.enableJetifier=true
-android.defaults.buildfeatures.buildconfig=true
-android.nonTransitiveRClass=false
-android.nonFinalResIds=false
-# This builtInKotlin flag was added automatically by Flutter migrator
-android.builtInKotlin=false
 # This newDsl flag was added automatically by Flutter migrator
 android.newDsl=false
+# This builtInKotlin flag was added automatically by Flutter migrator
+android.builtInKotlin=false

android/gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.3.1-all.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME

android/settings.gradle

@@ -19,9 +19,9 @@ pluginManagement {
 
 plugins {
     id "dev.flutter.flutter-plugin-loader" version "1.0.0"
-    id "com.android.application" version '8.13.2' apply false
-    id "com.android.library" version '8.13.2' apply false
-    id "org.jetbrains.kotlin.android" version "2.2.20" apply false
+    id "com.android.application" version '9.1.0' apply false
+    id "com.android.library" version '9.1.0' apply false
+    id "org.jetbrains.kotlin.android" version "2.4.0" apply false
     id 'org.gradle.toolchains.foojay-resolver-convention' version '0.10.0'
 }