Route calls through an entry point the native stack can implement

Adds the seam a native MatrixRTC call stack plugs into, with nothing behind it
yet, so that the stack itself lands as a self-contained change.

`FeatureFlags.NativeCall` is off by default and unfinished.
`features/callnative/api` declares `NativeCallEntryPoint`, and
`features/callnative/impl` provides a default that logs and does nothing:
turning the flag on today gets no call and a line in the log. That is the
honest outcome, where falling back to the WebView would make the flag look
broken rather than unimplemented.

`DefaultElementCallEntryPoint` forks on the flag. The read is asynchronous
because the flag is storage-backed, and caching it in an eagerly started
StateFlow would race a call placed just after app start onto the default
value.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

features/call/impl/build.gradle.kts

@@ -86,6 +86,7 @@ dependencies {
     implementation(libs.coil.compose)
     implementation(libs.serialization.json)
     implementation(libs.element.call.embedded)
+    implementation(projects.features.callnative.api)
     api(projects.features.call.api)
 
     testCommonDependencies(libs, true)

features/call/impl/src/main/kotlin/io/element/android/features/call/impl/DefaultElementCallEntryPoint.kt

@@ -16,14 +16,24 @@ import io.element.android.features.call.api.ElementCallEntryPoint
 import io.element.android.features.call.impl.notifications.CallNotificationData
 import io.element.android.features.call.impl.utils.ActiveCallManager
 import io.element.android.features.call.impl.utils.IntentProvider
+import io.element.android.features.callnative.api.NativeCallEntryPoint
+import io.element.android.libraries.di.annotations.AppCoroutineScope
 import io.element.android.libraries.di.annotations.ApplicationContext
+import io.element.android.libraries.featureflag.api.FeatureFlagService
+import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.UserId
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.launch
+import timber.log.Timber
 
 @ContributesBinding(AppScope::class)
 class DefaultElementCallEntryPoint(
     @ApplicationContext private val context: Context,
     private val activeCallManager: ActiveCallManager,
+    private val nativeCallEntryPoint: NativeCallEntryPoint,
+    private val featureFlagService: FeatureFlagService,
+    @AppCoroutineScope private val appCoroutineScope: CoroutineScope,
 ) : ElementCallEntryPoint {
     companion object {
         const val EXTRA_CALL_TYPE = "EXTRA_CALL_TYPE"
@@ -31,7 +41,18 @@ class DefaultElementCallEntryPoint(
     }
 
     override fun startCall(callData: CallData) {
-        context.startActivity(IntentProvider.createIntent(context, callData))
+        // The flag is backed by storage, so it has to be read asynchronously. Caching it in an
+        // eagerly started StateFlow would race: a call placed just after app start could be routed
+        // on the default value before the real one arrived.
+        appCoroutineScope.launch {
+            val useNativeCall = featureFlagService.isFeatureEnabled(FeatureFlags.NativeCall)
+            Timber.i("startCall: roomId=${callData.roomId}, nativeCall=$useNativeCall")
+            if (useNativeCall) {
+                nativeCallEntryPoint.startCall(callData)
+            } else {
+                context.startActivity(IntentProvider.createIntent(context, callData))
+            }
+        }
     }
 
     override suspend fun handleIncomingCall(

features/call/impl/src/test/kotlin/io/element/android/features/call/DefaultElementCallEntryPointTest.kt

@@ -16,15 +16,21 @@ import io.element.android.features.call.impl.DefaultElementCallEntryPoint
 import io.element.android.features.call.impl.notifications.CallNotificationData
 import io.element.android.features.call.impl.ui.ElementCallActivity
 import io.element.android.features.call.utils.FakeActiveCallManager
+import io.element.android.features.call.utils.FakeNativeCallEntryPoint
+import io.element.android.features.callnative.api.NativeCallEntryPoint
+import io.element.android.libraries.featureflag.api.FeatureFlags
+import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.matrix.test.AN_EVENT_ID
 import io.element.android.libraries.matrix.test.A_ROOM_ID
 import io.element.android.libraries.matrix.test.A_SESSION_ID
 import io.element.android.libraries.matrix.test.A_USER_ID_2
 import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
 import io.element.android.tests.testutils.robolectric.RobolectricTest
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.TestScope
 import kotlinx.coroutines.test.advanceTimeBy
+import kotlinx.coroutines.test.advanceUntilIdle
 import kotlinx.coroutines.test.runTest
 import org.junit.Test
 import org.robolectric.RuntimeEnvironment
@@ -32,10 +38,13 @@ import org.robolectric.Shadows.shadowOf
 import kotlin.time.Duration.Companion.seconds
 
 class DefaultElementCallEntryPointTest : RobolectricTest() {
+    @OptIn(ExperimentalCoroutinesApi::class)
     @Test
     fun `startCall - starts ElementCallActivity setup with the needed extras`() = runTest {
         val entryPoint = createEntryPoint()
         entryPoint.startCall(CallData(A_SESSION_ID, A_ROOM_ID, isAudioCall = false))
+        // The flag is read asynchronously before routing.
+        advanceUntilIdle()
 
         val expectedIntent = Intent(InstrumentationRegistry.getInstrumentation().targetContext, ElementCallActivity::class.java)
         val intent = shadowOf(RuntimeEnvironment.getApplication()).nextStartedActivity
@@ -43,6 +52,24 @@ class DefaultElementCallEntryPointTest : RobolectricTest() {
         assertThat(intent.extras?.containsKey("EXTRA_CALL_TYPE")).isTrue()
     }
 
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @Test
+    fun `startCall - routes to the native call stack when the feature flag is on`() = runTest {
+        val startNativeCallLambda = lambdaRecorder<CallData, Unit> {}
+        val entryPoint = createEntryPoint(
+            nativeCallEntryPoint = FakeNativeCallEntryPoint(startNativeCallLambda),
+            isNativeCallEnabled = true,
+        )
+        val callData = CallData(A_SESSION_ID, A_ROOM_ID, isAudioCall = true)
+
+        entryPoint.startCall(callData)
+        advanceUntilIdle()
+
+        startNativeCallLambda.assertions().isCalledOnce().with(value(callData))
+        // The WebView Activity must not also be launched.
+        assertThat(shadowOf(RuntimeEnvironment.getApplication()).nextStartedActivity).isNull()
+    }
+
     @OptIn(ExperimentalCoroutinesApi::class)
     @Test
     fun `handleIncomingCall - registers the incoming call using ActiveCallManager`() = runTest {
@@ -70,8 +97,15 @@ class DefaultElementCallEntryPointTest : RobolectricTest() {
 
     private fun TestScope.createEntryPoint(
         activeCallManager: FakeActiveCallManager = FakeActiveCallManager(),
+        nativeCallEntryPoint: NativeCallEntryPoint = FakeNativeCallEntryPoint(),
+        isNativeCallEnabled: Boolean = false,
     ) = DefaultElementCallEntryPoint(
         context = InstrumentationRegistry.getInstrumentation().targetContext,
         activeCallManager = activeCallManager,
+        nativeCallEntryPoint = nativeCallEntryPoint,
+        featureFlagService = FakeFeatureFlagService(
+            initialState = mapOf(FeatureFlags.NativeCall.key to isNativeCallEnabled),
+        ),
+        appCoroutineScope = this,
     )
 }

features/call/impl/src/test/kotlin/io/element/android/features/call/utils/FakeNativeCallEntryPoint.kt

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.features.call.utils
+
+import io.element.android.features.call.api.CallData
+import io.element.android.features.callnative.api.NativeCallEntryPoint
+
+class FakeNativeCallEntryPoint(
+    private val startCallLambda: (CallData) -> Unit = {},
+) : NativeCallEntryPoint {
+    override fun startCall(callData: CallData) = startCallLambda(callData)
+}