diff --git a/test_runner/src/main/kotlin/ftl/args/ArgsHelper.kt b/test_runner/src/main/kotlin/ftl/args/ArgsHelper.kt
index b0e1317f7f..745caf2cd1 100644
--- a/test_runner/src/main/kotlin/ftl/args/ArgsHelper.kt
+++ b/test_runner/src/main/kotlin/ftl/args/ArgsHelper.kt
@@ -223,6 +223,7 @@ object ArgsHelper {
 
         val shardCount = Shard.shardCountByTime(filteredTests, oldTestResult, args)
 
+        // TODO: manual sharding must be limited to 1..50 tests per shard
         val shards = Shard.createShardsByShardCount(filteredTests, oldTestResult, args, shardCount)
 
         return testMethodsAlwaysRun(shards.stringShards(), args)
diff --git a/test_runner/src/main/kotlin/ftl/gc/GcAndroidTestMatrix.kt b/test_runner/src/main/kotlin/ftl/gc/GcAndroidTestMatrix.kt
index 0b4bdfb228..59c7cc777a 100644
--- a/test_runner/src/main/kotlin/ftl/gc/GcAndroidTestMatrix.kt
+++ b/test_runner/src/main/kotlin/ftl/gc/GcAndroidTestMatrix.kt
@@ -1,20 +1,7 @@
 package ftl.gc
 
 import com.google.api.services.testing.Testing
-import com.google.api.services.testing.model.Account
-import com.google.api.services.testing.model.AndroidDeviceList
-import com.google.api.services.testing.model.AndroidInstrumentationTest
-import com.google.api.services.testing.model.ClientInfo
-import com.google.api.services.testing.model.EnvironmentMatrix
-import com.google.api.services.testing.model.EnvironmentVariable
-import com.google.api.services.testing.model.FileReference
-import com.google.api.services.testing.model.GoogleAuto
-import com.google.api.services.testing.model.GoogleCloudStorage
-import com.google.api.services.testing.model.ResultStorage
-import com.google.api.services.testing.model.TestMatrix
-import com.google.api.services.testing.model.TestSetup
-import com.google.api.services.testing.model.TestSpecification
-import com.google.api.services.testing.model.ToolResultsHistory
+import com.google.api.services.testing.model.*
 import ftl.args.AndroidArgs
 import ftl.util.ShardCounter
 import ftl.util.Utils.fatalError
@@ -33,7 +20,7 @@ object GcAndroidTestMatrix {
         testApkGcsPath: String,
         runGcsPath: String,
         androidDeviceList: AndroidDeviceList,
-        testTargets: List<String>,
+        testTargets: List<List<String>>,
         args: AndroidArgs,
         shardCounter: ShardCounter,
         toolResultsHistory: ToolResultsHistory
@@ -44,9 +31,17 @@ object GcAndroidTestMatrix {
 
         val matrixGcsPath = join(args.resultsBucket, runGcsPath, shardCounter.next())
 
+        // ShardingOption().setUniformSharding(UniformSharding().setNumShards())
+        val testTargetsForShard: List<TestTargetsForShard> = testTargets.map {
+            TestTargetsForShard().setTestTargets(it)
+        }
+        val manualSharding = ManualSharding().setTestTargetsForShard(testTargetsForShard)
+        val shardingOption = ShardingOption().setManualSharding(manualSharding)
+
         val androidInstrumentation = AndroidInstrumentationTest()
             .setAppApk(FileReference().setGcsPath(appApkGcsPath))
             .setTestApk(FileReference().setGcsPath(testApkGcsPath))
+            .setShardingOption(shardingOption)
 
         if (args.testRunnerClass != null) {
             androidInstrumentation.testRunnerClass = args.testRunnerClass
@@ -56,8 +51,6 @@ object GcAndroidTestMatrix {
             androidInstrumentation.orchestratorOption = "USE_ORCHESTRATOR"
         }
 
-        androidInstrumentation.testTargets = testTargets
-
         // --auto-google-login
         // https://cloud.google.com/sdk/gcloud/reference/firebase/test/android/run
         // https://github.com/bootstraponline/gcloud_cli/blob/e4b5e01610abad2e31d8a6edb20b17b2f84c5395/google-cloud-sdk/lib/googlecloudsdk/api_lib/firebase/test/android/matrix_creator.py#L174
diff --git a/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt b/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt
index 6e29262316..f51a9edf8c 100644
--- a/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt
+++ b/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt
@@ -38,21 +38,19 @@ object AndroidTestRunner {
             val testShardChunks = AndroidTestShard.getTestShardChunks(androidArgs, apk.test)
             allTestShardChunks += testShardChunks
             repeat(runCount) {
-                testShardChunks.forEach { testTargets ->
-                    // specify dispatcher to avoid inheriting main runBlocking context that runs in the main thread
-                    // https://kotlinlang.org/docs/reference/coroutines/coroutine-context-and-dispatchers.html
-                    jobs += async(Dispatchers.IO) {
-                        GcAndroidTestMatrix.build(
-                            appApkGcsPath = apk.app ?: androidArgs.appApk,
-                            testApkGcsPath = apk.test,
-                            runGcsPath = runGcsPath,
-                            androidDeviceList = androidDeviceList,
-                            testTargets = testTargets,
-                            args = androidArgs,
-                            shardCounter = shardCounter,
-                            toolResultsHistory = history
-                        ).executeWithRetry()
-                    }
+                // specify dispatcher to avoid inheriting main runBlocking context that runs in the main thread
+                // https://kotlinlang.org/docs/reference/coroutines/coroutine-context-and-dispatchers.html
+                jobs += async(Dispatchers.IO) {
+                    GcAndroidTestMatrix.build(
+                        appApkGcsPath = apk.app ?: androidArgs.appApk,
+                        testApkGcsPath = apk.test,
+                        runGcsPath = runGcsPath,
+                        androidDeviceList = androidDeviceList,
+                        testTargets = testShardChunks,
+                        args = androidArgs,
+                        shardCounter = shardCounter,
+                        toolResultsHistory = history
+                    ).executeWithRetry()
                 }
             }
         }
@@ -73,7 +71,8 @@ object AndroidTestRunner {
         val result = mutableListOf<AppTestPair>()
 
         appTestApks.forEach { apks ->
-            val appApkGcsPath = async(Dispatchers.IO) { GcStorage.upload(apks.app ?: args.appApk, gcsBucket, runGcsPath) }
+            val appApkGcsPath =
+                async(Dispatchers.IO) { GcStorage.upload(apks.app ?: args.appApk, gcsBucket, runGcsPath) }
             val testApkGcsPath = async(Dispatchers.IO) { GcStorage.upload(apks.test, gcsBucket, runGcsPath) }
 
             result.add(
diff --git a/test_runner/src/test/kotlin/ftl/gc/GcAndroidTestMatrixTest.kt b/test_runner/src/test/kotlin/ftl/gc/GcAndroidTestMatrixTest.kt
index ff8a243a0b..18a1ab0eb0 100644
--- a/test_runner/src/test/kotlin/ftl/gc/GcAndroidTestMatrixTest.kt
+++ b/test_runner/src/test/kotlin/ftl/gc/GcAndroidTestMatrixTest.kt
@@ -37,7 +37,7 @@ class GcAndroidTestMatrixTest {
             testApkGcsPath = "",
             runGcsPath = "",
             androidDeviceList = AndroidDeviceList(),
-            testTargets = listOf(""),
+            testTargets = listOf(listOf("")),
             args = androidArgs,
             shardCounter = ShardCounter(),
             toolResultsHistory = createToolResultsHistory(androidArgs)