[Link new device] Handle split steps in the SDK

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/linknewdevice/ContinuationMessageSender.kt

@@ -0,0 +1,13 @@
+/*
+ * 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.api.linknewdevice
+
+interface ContinuationMessageSender {
+    suspend fun cancel(): Result<Unit>
+    suspend fun confirm(): Result<Unit>
+}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/linknewdevice/LinkDesktopHandler.kt

@@ -18,8 +18,10 @@ interface LinkDesktopHandler {
 sealed interface LinkDesktopStep {
     data object Uninitialized : LinkDesktopStep
     data object Starting : LinkDesktopStep
+
     data class WaitingForAuth(
         val verificationUri: String,
+        val continuationMessageSender: ContinuationMessageSender,
     ) : LinkDesktopStep
 
     data class EstablishingSecureChannel(

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/linknewdevice/LinkMobileHandler.kt

@@ -22,7 +22,12 @@ sealed interface LinkMobileStep {
     data object Starting : LinkMobileStep
     data class QrReady(val data: String) : LinkMobileStep
     data object QrRotating : LinkMobileStep
-    data class WaitingForAuth(val verificationUri: String) : LinkMobileStep
+
+    data class WaitingForAuth(
+        val verificationUri: String,
+        val continuationMessageSender: ContinuationMessageSender,
+    ) : LinkMobileStep
+
     data class QrScanned(val checkCodeSender: CheckCodeSender) : LinkMobileStep
     data class Error(val errorType: ErrorType) : LinkMobileStep
     data object SyncingSecrets : LinkMobileStep