Give the native call component its view of Matrix

The factory lives in libraries/matrix/impl because that is the only module compiled against the Rust SDK, and is app-scoped because a call is started for whichever account it belongs to rather than the one on screen.

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

features/callnative/api/build.gradle.kts

@@ -13,8 +13,18 @@ android {
     namespace = "io.element.android.features.callnative.api"
 }
 
+// Temporary: `-PelementCallLocalVersion` points this at a locally published build of
+// element-call-android. Goes with the repositories in settings.gradle.kts.
+val elementCallVersion: String = providers.gradleProperty("elementCallLocalVersion")
+    .getOrElse(libs.versions.element.call.get())
+
 dependencies {
-    // api, not implementation: CallData is part of NativeCallEntryPoint's signature.
+    // api, not implementation: ElementCallMatrixTransport is part of ElementCallTransportFactory's
+    // signature, and CallData of NativeCallEntryPoint's.
+    // api, so that consumers of this module inherit the versions the BOM pins - the artifact
+    // below is declared without one.
+    api(platform("io.element.android:element-call-bom:$elementCallVersion"))
+    api(libs.element.call.api)
     api(projects.features.call.api)
     implementation(projects.libraries.architecture)
     implementation(projects.libraries.matrix.api)

features/callnative/api/src/main/kotlin/io/element/android/features/callnative/api/ElementCallTransportFactory.kt

@@ -0,0 +1,26 @@
+/*
+ * 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.callnative.api
+
+import io.element.android.call.api.matrix.ElementCallMatrixTransport
+import io.element.android.libraries.matrix.api.MatrixClient
+
+/**
+ * Makes the native call's view of Matrix for a session.
+ *
+ * The component's turnkey transport is built over a raw Rust SDK client, and only
+ * `libraries/matrix/impl` is compiled against the SDK. This is the seam that keeps it that way: the
+ * implementation lives there, everything else takes a [MatrixClient] and asks.
+ *
+ * A factory rather than a binding for the transport itself, because the call is started from app scope
+ * - a call can be placed for an account that is not the one on screen - and the session it belongs to
+ * is known only as an id until a client is fetched for it.
+ */
+fun interface ElementCallTransportFactory {
+    fun create(client: MatrixClient): ElementCallMatrixTransport
+}

libraries/matrix/impl/build.gradle.kts

@@ -20,16 +20,47 @@ android {
 
 setupDependencyInjection()
 
+// Temporary: `-PelementCallLocalVersion` points this at a locally published build of
+// element-call-android, because the library has no remote repository yet. Goes with the mavenLocal
+// block in settings.gradle.kts. Only the BOM carries a version; every other artifact follows it.
+val elementCallVersion: String = providers.gradleProperty("elementCallLocalVersion")
+    .getOrElse(libs.versions.element.call.get())
+
+val usesLocalRustSdk = file("${rootDir.path}/libraries/rustsdk/matrix-rust-sdk.aar").exists()
+
+if (usesLocalRustSdk) {
+    // element-call-matrix declares the Rust SDK as an ordinary Maven dependency, so with the local
+    // AAR in place a debug classpath would carry two copies of org.matrix.rustcomponents.sdk.
+    // Point the library's dependency at the same local AAR the app is using.
+    configurations.matching { it.name.startsWith("debug") }.configureEach {
+        resolutionStrategy.dependencySubstitution {
+            substitute(module("org.matrix.rustcomponents:sdk-android"))
+                .using(project(":libraries:rustsdk"))
+                .because("the local Rust SDK AAR replaces the published one on debug builds")
+        }
+    }
+}
+
 dependencies {
     releaseImplementation(libs.matrix.sdk)
-    if (file("${rootDir.path}/libraries/rustsdk/matrix-rust-sdk.aar").exists()) {
-        println("\nNote: Using local binary of the Rust SDK.\n")
+    if (usesLocalRustSdk) {
+        println(
+            "\nNote: Using local binary of the Rust SDK." +
+                "\n      element-call-matrix is substituted onto it as well, so the native call runs" +
+                "\n      against this SDK rather than the one it was published against.\n"
+        )
         debugImplementation(projects.libraries.rustsdk)
     } else {
         debugImplementation(libs.matrix.sdk)
     }
     implementation(variantOf(libs.rustls.platform.verifier) { artifactType("aar") })
 
+    // The native call's Matrix transport. Only this module may hand it a raw SDK client.
+    implementation(platform("io.element.android:element-call-bom:$elementCallVersion"))
+    implementation(libs.element.call.api)
+    implementation(projects.features.callnative.api)
+    implementation(libs.element.call.matrix)
+
     implementation(projects.appconfig)
     implementation(projects.features.enterprise.api)
     implementation(projects.libraries.androidutils)

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/di/DefaultElementCallTransportFactory.kt

@@ -0,0 +1,38 @@
+/*
+ * 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.libraries.matrix.impl.di
+
+import dev.zacsweers.metro.AppScope
+import dev.zacsweers.metro.ContributesBinding
+import io.element.android.call.api.matrix.ElementCallMatrixTransport
+import io.element.android.call.matrix.ElementCallSdkTransport
+import io.element.android.features.callnative.api.ElementCallTransportFactory
+import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.impl.RustMatrixClient
+
+/**
+ * Gives the native call component its view of Matrix.
+ *
+ * Here because this is the only module in the app compiled against the Rust SDK, and the component's
+ * turnkey transport needs a raw SDK client. No feature module ever sees the SDK, the rule that no
+ * feature depends on `libraries/matrix/impl` still holds, and the SDK version contract is checked where
+ * the app's own SDK pin lives.
+ *
+ * The transport is built on the client's own coroutine scope, which is what ties it to the session: the
+ * component has no shutdown of its own, so cancelling that scope at logout is the only thing that stops
+ * the RTC core and its to-device subscription.
+ */
+@ContributesBinding(AppScope::class)
+class DefaultElementCallTransportFactory : ElementCallTransportFactory {
+    override fun create(client: MatrixClient): ElementCallMatrixTransport {
+        return ElementCallSdkTransport(
+            client = (client as RustMatrixClient).innerClient,
+            sessionScope = client.sessionCoroutineScope,
+        )
+    }
+}