Support AGP 9 built-in Kotlin and the KMP android library plugin#543
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AGP 9 enables built-in Kotlin by default and rejects org.jetbrains.kotlin.android, so the plugin never saw its only Android trigger and silently configured nothing on AGP 9 projects. - React to com.android.base when the built-in `kotlin` extension is present, in addition to org.jetbrains.kotlin.android; a flag prevents double configuration on AGP 8 where both fire - Fall back to testImplementation when testApi does not exist (AGP 9 removed it) - Codec auto-detection selects protobuf-javalite for Android projects detected via com.android.base, not just via the KGP android plugin - Tolerate a missing <target>Test KotlinSourceSet: the AGP KMP android target (com.android.kotlin.multiplatform.library) has androidHostTest/androidDeviceTest instead of androidTest - Fall back to the base generateProto/generateTestProto tasks for JVM-like KMP targets whose Gradle source sets don't exist (the AGP KMP android target creates none) - Order ArtProfile tasks after generateProto: AGP derives baselineProfiles directories as siblings of Kotlin source directories, which lands inside generateProto's output and otherwise trips Gradle's implicit-dependency validation - Integration tests: AGP version is overridable via -Dandroid-integration.version; android-test-fixtures applies the KGP android plugin only on AGP < 9; new multiplatform-android module exercises the KMP android target and is included only on AGP 9+ - CI: new integration-agp9 job runs the integration suite with AGP 9.2.1 on all three OSes, with and without the configuration cache
Replaces the source-set-srcDir approach for com.android.kotlin.multiplatform.library with the variant API. Generated sources are registered per component with addGeneratedSourceDirectory via a sync task, so source sets correspond exactly to compilations: androidMain gets main protos, androidHostTest gets test protos when host tests are enabled. Device tests are not wired. - New AndroidKmpLibrary object handles the target; ProtoktBuild dispatches to it and no longer needs the generateProto task-name fallback or optional test source sets - protokt-gradle-plugin adds a compileOnly dependency on com.android.tools.build:gradle-api; runtime classes load only when the AGP KMP library plugin is present - ArtProfile ordering constraint kept: commonMain's generated srcDir still participates in the android compilation, so AGP still derives a baselineProfiles sibling inside generateProto's output - multiplatform-android integration module enables host tests and exercises main and test protos in them
addGeneratedSourceDirectory relocates the wired DirectoryProperty into an AGP-managed location, which forced a sync task to copy generateProto output. Add the generated directories to the androidMain and androidHostTest Kotlin source sets directly, with explicit compile-task dependencies, matching how every other source-set-less KMP target is wired. Drops the sync task and the compileOnly dependency on com.android.tools.build:gradle-api.
- Replace the androidConfigured flag with a hasPlugin check: the com.android.base callback runs after the plugins block, so checking for org.jetbrains.kotlin.android there is race-free on AGP 8 - Use the<KotlinMultiplatformExtension>() in AndroidKmpLibrary - Construct messages directly in multiplatform-android tests instead of through a commonMain factory - android-test-fixtures: compileSdk 31 -> 36. Platform 31 is not preinstalled on GitHub runners and its on-demand download corrupts intermittently, failing random integration matrix rows
ogolberg
approved these changes
Jul 7, 2026
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AGP 9 enables built-in Kotlin by default and fails the build if
org.jetbrains.kotlin.androidis applied. That plugin id was protokt's only Android trigger, so on AGP 9 protokt configured nothing.Single-platform Android
com.android.basewhen the built-inkotlinextension is present and the KGP android plugin is not (avoiding double configuration on AGP 8).testApitotestImplementationsince AGP 9 removedtestApi.optimal()codec detection selectsprotobuf-javalitefor these projects, matchingkotlin("android")behavior.KMP android target (
com.android.kotlin.multiplatform.library)Previously failed at apply time. Protokt now wires it like other source-set-less KMP targets, with source sets mapping exactly to compilations:
src/main/proto→androidMain;src/test/proto→androidHostTestwhen host tests are enabled. Device tests are not wired.ArtProfiletasks are ordered aftergenerateProto: AGP derivesbaselineProfilesdirectories as siblings of Kotlin source directories, which lands insidegenerateProto's output and otherwise trips Gradle's implicit-dependency validation. Bit of an annoyance.Tests and CI
-Dandroid-integration.versionoverrides AGP in the integration suite;android-test-fixturescovers the legacy path on AGP 8 and built-in Kotlin on 9.multiplatform-androidmodule (AGP 9+ only) exercises the KMP android target, including host tests.integration-agp9CI job runs the suite with AGP 9.2.1 on all three OSes, with and without the configuration cache. Separate job because AGP 9 forces KGP 2.2.10+ onto the buildscript classpath, which would invalidate the older-Kotlin matrix rows.android-test-fixturescompileSdk bumped 31 → 36; platform 31 is not preinstalled on runners and its download corrupts intermittently.