feat: migrate to built-in Kotlin for AGP 9+ compatibility

CHANGELOG.md

@@ -1,3 +1,11 @@
+#### 3.3.0 · 8/18/2026
+
+- Migrated to Flutter's built-in Kotlin support for AGP 9+ compatibility
+  - KGP (`kotlin-android`) is now applied conditionally only on AGP < 9
+  - `kotlinOptions` replaced with `kotlin { compilerOptions {} }` DSL
+  - See: https://docs.flutter.dev/release/breaking-changes/migrate-to-built-in-kotlin/for-plugin-authors
+- Fixes [#45](https://github.com/Tkko/flutter_smart_auth/issues/45)
+
 #### 3.2.0 · 1/1/2025
 
 - Fixed method type

android/build.gradle

@@ -22,7 +22,15 @@ rootProject.allprojects {
 }
 
 apply plugin: 'com.android.library'
-apply plugin: 'kotlin-android'
+
+// AGP 9+ ships built-in Kotlin support; only apply KGP when built-in Kotlin is
+// not in effect (older AGP, or projects opting out via android.builtInKotlin=false).
+// See: https://docs.flutter.dev/release/breaking-changes/migrate-to-built-in-kotlin/for-plugin-authors
+def agpMajor = com.android.Version.ANDROID_GRADLE_PLUGIN_VERSION.tokenize('.')[0] as int
+def builtInKotlin = agpMajor >= 9 && project.findProperty('android.builtInKotlin') != 'false'
+if (!builtInKotlin) {
+    apply plugin: 'kotlin-android'
+}
 
 android {
     // Conditional for compatibility with AGP <4.2.
@@ -37,12 +45,18 @@ android {
         targetCompatibility JavaVersion.VERSION_11
     }
 
-    kotlinOptions {
-        jvmTarget = '11'
+    // android.kotlinOptions only exists when KGP is applied; with AGP 9 built-in
+    // Kotlin, jvmTarget follows compileOptions.targetCompatibility.
+    if (!builtInKotlin) {
+        kotlinOptions {
+            jvmTarget = JavaVersion.VERSION_11.toString()
+        }
     }
 
     sourceSets {
-        main.java.srcDirs += 'src/main/kotlin'
+        // Kotlin sources must go to the kotlin source set; AGP 9 built-in Kotlin
+        // does not compile Kotlin files added to the java source set.
+        main.kotlin.directories.add('src/main/kotlin')
     }
 
     defaultConfig {

example/android/app/build.gradle

@@ -1,7 +1,7 @@
 plugins {
     id "com.android.application"
-    id "kotlin-android"
-    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
+    // AGP 9+ has built-in Kotlin support; kotlin-android plugin removed
+    // The Flutter Gradle Plugin must be applied after the Android Gradle plugin.
     id "dev.flutter.flutter-gradle-plugin"
 }
 
@@ -15,10 +15,6 @@ android {
         targetCompatibility JavaVersion.VERSION_11
     }
 
-    kotlinOptions {
-        jvmTarget = '11'
-    }
-
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId = "fman.ge.smart_auth_example"
@@ -39,6 +35,13 @@ android {
     }
 }
 
+// AGP 9+ built-in Kotlin: kotlinOptions migrated to kotlin.compilerOptions
+kotlin {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_11
+    }
+}
+
 flutter {
     source = "../.."
 }

example/android/settings.gradle

@@ -19,7 +19,6 @@ pluginManagement {
 plugins {
     id "dev.flutter.flutter-plugin-loader" version "1.0.0"
     id "com.android.application" version "8.3.2" apply false
-    id "org.jetbrains.kotlin.android" version "1.8.0" apply false
 }
 
 include ":app"

pubspec.yaml

@@ -2,7 +2,7 @@ name: smart_auth
 description: Wrapper of Android SMS User Consent API, SMS Retriever API to read one time sms code, get user phone number, OTP, OTC, sms autofill, android autofill
 homepage: https://github.com/Tkko/flutter_smart_auth
 repository: https://github.com/Tkko/flutter_smart_auth
-version: 3.2.0
+version: 3.3.0
 topics:
   - otp
   - sms-autofill