Merge pull request #6013 from element-hq/feature/bma/importSession

[POC] Signin with Element Classic
2026-01-15 17:21:16 +01:00
parent b6e5daee71 caf5ab1085
commit f62b2b7ae6
16 changed files with 747 additions and 1 deletions
--- a/features/login/impl/src/main/AndroidManifest.xml
+++ b/features/login/impl/src/main/AndroidManifest.xml
@@ -15,4 +15,6 @@
        </intent>
    </queries>

+    <!-- Permission to read data from Element classic -->
+    <uses-permission android:name="im.vector.app.READ_DATA" />
 </manifest>
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/di/LoginModule.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/di/LoginModule.kt
@@ -14,6 +14,8 @@ import dev.zacsweers.metro.Binds
 import dev.zacsweers.metro.ContributesTo
 import io.element.android.features.login.impl.changeserver.ChangeServerPresenter
 import io.element.android.features.login.impl.changeserver.ChangeServerState
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicPresenter
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicState
 import io.element.android.libraries.architecture.Presenter

@ContributesTo(AppScope::class)
@@ -21,4 +23,7 @@ import io.element.android.libraries.architecture.Presenter
 interface LoginModule {
    @Binds
    fun bindChangeServerPresenter(presenter: ChangeServerPresenter): Presenter<ChangeServerState>
+
+    @Binds
+    fun bindLoginWithClassicPresenter(presenter: LoginWithClassicPresenter): Presenter<LoginWithClassicState>
 }
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingPresenter.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingPresenter.kt
@@ -26,6 +26,7 @@ import io.element.android.features.enterprise.api.canConnectToAnyHomeserver
 import io.element.android.features.login.impl.accesscontrol.DefaultAccountProviderAccessControl
 import io.element.android.features.login.impl.accountprovider.AccountProviderDataSource
 import io.element.android.features.login.impl.login.LoginHelper
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicState
 import io.element.android.features.rageshake.api.RageshakeFeatureAvailability
 import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.core.meta.BuildMeta
@@ -44,6 +45,7 @@ class OnBoardingPresenter(
    private val onBoardingLogoResIdProvider: OnBoardingLogoResIdProvider,
    private val sessionStore: SessionStore,
    private val accountProviderDataSource: AccountProviderDataSource,
+    private val loginWithClassicPresenter: Presenter<LoginWithClassicState>,
 ) : Presenter<OnBoardingState> {
    @AssistedFactory
    interface Factory {
@@ -99,6 +101,8 @@ class OnBoardingPresenter(

        val loginMode by loginHelper.collectLoginMode()

+        val loginWithClassicState = loginWithClassicPresenter.present()
+
        fun handleEvent(event: OnBoardingEvents) {
            when (event) {
                is OnBoardingEvents.OnSignIn -> localCoroutineScope.launch {
@@ -132,6 +136,7 @@ class OnBoardingPresenter(
            loginMode = loginMode,
            version = buildMeta.versionName,
            onBoardingLogoResId = onBoardingLogoResId,
+            loginWithClassicState = loginWithClassicState,
            eventSink = ::handleEvent,
        )
    }
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingState.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingState.kt
@@ -10,6 +10,7 @@ package io.element.android.features.login.impl.screens.onboarding

 import androidx.annotation.DrawableRes
 import io.element.android.features.login.impl.login.LoginMode
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicState
 import io.element.android.libraries.architecture.AsyncData

 data class OnBoardingState(
@@ -24,6 +25,7 @@ data class OnBoardingState(
    @DrawableRes
    val onBoardingLogoResId: Int?,
    val loginMode: AsyncData<LoginMode>,
+    val loginWithClassicState: LoginWithClassicState,
    val eventSink: (OnBoardingEvents) -> Unit,
 ) {
    val submitEnabled: Boolean
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingStateProvider.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingStateProvider.kt
@@ -11,6 +11,8 @@ package io.element.android.features.login.impl.screens.onboarding
 import androidx.annotation.DrawableRes
 import androidx.compose.ui.tooling.preview.PreviewParameterProvider
 import io.element.android.features.login.impl.login.LoginMode
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicState
+import io.element.android.features.login.impl.screens.onboarding.classic.aLoginWithClassicState
 import io.element.android.libraries.architecture.AsyncData
 import io.element.android.libraries.designsystem.R

@@ -44,6 +46,7 @@ fun anOnBoardingState(
    @DrawableRes
    customLogoResId: Int? = null,
    loginMode: AsyncData<LoginMode> = AsyncData.Uninitialized,
+    loginWithClassicState: LoginWithClassicState = aLoginWithClassicState(),
    eventSink: (OnBoardingEvents) -> Unit = {},
 ) = OnBoardingState(
    isAddingAccount = isAddingAccount,
@@ -56,5 +59,6 @@ fun anOnBoardingState(
    version = version,
    loginMode = loginMode,
    onBoardingLogoResId = customLogoResId,
+    loginWithClassicState = loginWithClassicState,
    eventSink = eventSink,
 )
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingView.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingView.kt
@@ -31,10 +31,15 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.PreviewParameter
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.compose.LifecycleEventEffect
 import io.element.android.compound.theme.ElementTheme
 import io.element.android.compound.tokens.generated.CompoundIcons
 import io.element.android.features.login.impl.R
 import io.element.android.features.login.impl.login.LoginModeView
+import io.element.android.features.login.impl.screens.onboarding.classic.ConfirmingLoginWithElementClassic
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicEvent
+import io.element.android.features.login.impl.screens.onboarding.classic.LoginWithClassicState
 import io.element.android.libraries.architecture.AsyncData
 import io.element.android.libraries.designsystem.atomic.atoms.ElementLogoAtom
 import io.element.android.libraries.designsystem.atomic.atoms.ElementLogoAtomSize
@@ -42,6 +47,8 @@ import io.element.android.libraries.designsystem.atomic.molecules.ButtonColumnMo
 import io.element.android.libraries.designsystem.atomic.pages.FlowStepPage
 import io.element.android.libraries.designsystem.atomic.pages.OnBoardingPage
 import io.element.android.libraries.designsystem.components.BigIcon
+import io.element.android.libraries.designsystem.components.async.AsyncActionView
+import io.element.android.libraries.designsystem.components.dialogs.ConfirmationDialog
 import io.element.android.libraries.designsystem.preview.ElementPreview
 import io.element.android.libraries.designsystem.preview.PreviewsDayNight
 import io.element.android.libraries.designsystem.theme.components.Button
@@ -109,6 +116,43 @@ fun OnBoardingView(
            buttons = buttons,
        )
    }
+
+    LoginWithElementClassicView(
+        state = state.loginWithClassicState,
+    )
+}
+
+@Composable
+private fun LoginWithElementClassicView(
+    state: LoginWithClassicState,
+) {
+    LifecycleEventEffect(Lifecycle.Event.ON_RESUME) {
+        state.eventSink(LoginWithClassicEvent.RefreshData)
+    }
+    AsyncActionView(
+        async = state.loginWithClassicAction,
+        confirmationDialog = { confirming ->
+            when (confirming) {
+                is ConfirmingLoginWithElementClassic -> {
+                    // TODO i18n
+                    ConfirmationDialog(
+                        title = "Sign in with Element Classic",
+                        content = "You are signing in as ${confirming.userId} on Element Classic." +
+                            " Your existing session on Element Classic will not be signed out. Do you want to continue?",
+                        submitText = stringResource(CommonStrings.action_continue),
+                        onSubmitClick = { state.eventSink(LoginWithClassicEvent.DoLoginWithClassic) },
+                        onDismiss = { state.eventSink(LoginWithClassicEvent.CloseDialog) },
+                    )
+                }
+            }
+        },
+        onErrorDismiss = {
+            state.eventSink(LoginWithClassicEvent.CloseDialog)
+        },
+        onSuccess = {
+            // noop, the view will be closed
+        }
+    )
 }

@Composable
@@ -239,6 +283,18 @@ private fun OnBoardingButtons(
        } else {
            CommonStrings.action_continue
        }
+        if (state.loginWithClassicState.canLoginWithClassic) {
+            Button(
+                text = "Sign in with Element Classic",
+                leadingIcon = IconSource.Vector(CompoundIcons.Mobile()),
+                onClick = {
+                    state.loginWithClassicState.eventSink(
+                        LoginWithClassicEvent.StartLoginWithClassic
+                    )
+                },
+                modifier = Modifier.fillMaxWidth(),
+            )
+        }
        if (state.canLoginWithQrCode) {
            Button(
                text = stringResource(id = R.string.screen_onboarding_sign_in_with_qr_code),
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/ConfirmingLoginWithElementClassic.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/ConfirmingLoginWithElementClassic.kt
@@ -0,0 +1,15 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+import io.element.android.libraries.architecture.AsyncAction
+import io.element.android.libraries.matrix.api.core.UserId
+
+class ConfirmingLoginWithElementClassic(
+    val userId: UserId,
+) : AsyncAction.Confirming
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/ElementClassicConnection.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/ElementClassicConnection.kt
@@ -0,0 +1,249 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+import android.content.ComponentName
+import android.content.Context
+import android.content.Context.BIND_AUTO_CREATE
+import android.content.Intent
+import android.content.ServiceConnection
+import android.os.Bundle
+import android.os.Handler
+import android.os.IBinder
+import android.os.Message
+import android.os.Messenger
+import android.os.RemoteException
+import dev.zacsweers.metro.AppScope
+import dev.zacsweers.metro.ContributesBinding
+import io.element.android.libraries.core.log.logger.LoggerTag
+import io.element.android.libraries.core.meta.BuildMeta
+import io.element.android.libraries.core.meta.BuildType
+import io.element.android.libraries.di.annotations.AppCoroutineScope
+import io.element.android.libraries.di.annotations.ApplicationContext
+import io.element.android.libraries.matrix.api.core.UserId
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
+import timber.log.Timber
+
+interface ElementClassicConnection {
+    fun start()
+    fun stop()
+    fun requestData()
+    val stateFlow: StateFlow<ElementClassicConnectionState>
+}
+
+sealed interface ElementClassicConnectionState {
+    object Idle : ElementClassicConnectionState
+    object ElementClassicNotFound : ElementClassicConnectionState
+    object ElementClassicReadyNoSession : ElementClassicConnectionState
+    data class ElementClassicReady(val userId: UserId) : ElementClassicConnectionState
+    data class Error(val error: String) : ElementClassicConnectionState
+}
+
+private val loggerTag = LoggerTag("ECConnection")
+
+@ContributesBinding(AppScope::class)
+class DefaultElementClassicConnection(
+    @ApplicationContext
+    private val context: Context,
+    @AppCoroutineScope
+    private val coroutineScope: CoroutineScope,
+    private val buildMeta: BuildMeta,
+) : ElementClassicConnection {
+    // Messenger for communicating with the service.
+    private var messenger: Messenger? = null
+
+    // Target we publish for external service to send messages to IncomingHandler.
+    private val incomingMessenger: Messenger = Messenger(IncomingHandler())
+
+    // Flag indicating whether we have called bind on the service.
+    private var bound: Boolean = false
+
+    /**
+     * Class for interacting with the main interface of the service.
+     */
+    private val serviceConnection = object : ServiceConnection {
+        override fun onServiceConnected(className: ComponentName, service: IBinder) {
+            Timber.tag(loggerTag.value).d("onServiceConnected")
+            // This is called when the connection with the service has been
+            // established, giving us the object we can use to
+            // interact with the service. We are communicating with the
+            // service using a Messenger, so here we get a client-side
+            // representation of that from the raw IBinder object.
+            messenger = Messenger(service)
+            bound = true
+            // Request the data as soon as possible
+            requestData()
+        }
+
+        override fun onServiceDisconnected(className: ComponentName) {
+            Timber.tag(loggerTag.value).d("onServiceDisconnected")
+            // This is called when the connection with the service has been
+            // unexpectedly disconnected&mdash;that is, its process crashed.
+            messenger = null
+            bound = false
+        }
+    }
+
+    override fun start() {
+        Timber.tag(loggerTag.value).w("start()")
+        coroutineScope.launch {
+            // Establish a connection with the service. We use an explicit
+            // class name because there is no reason to be able to let other
+            // applications replace our component.
+            try {
+                val intentService = Intent()
+                intentService.setComponent(getElementClassicComponent(buildMeta))
+                if (context.bindService(intentService, serviceConnection, BIND_AUTO_CREATE)) {
+                    Timber.tag(loggerTag.value).d("Binding returned true")
+                } else {
+                    // This happen when the app is not installed
+                    Timber.tag(loggerTag.value).d("Binding returned false")
+                    mutableStateFlow.emit(ElementClassicConnectionState.ElementClassicNotFound)
+                }
+            } catch (e: SecurityException) {
+                Timber.tag(loggerTag.value).e(e, "Can't bind to Service")
+                mutableStateFlow.emit(ElementClassicConnectionState.Error(e.localizedMessage.orEmpty()))
+            }
+        }
+    }
+
+    override fun stop() {
+        Timber.tag(loggerTag.value).w("stop(): Unbinding (bound=$bound)")
+        if (bound) {
+            // Detach our existing connection.
+            context.unbindService(serviceConnection)
+            bound = false
+        }
+        coroutineScope.launch {
+            mutableStateFlow.emit(ElementClassicConnectionState.Idle)
+        }
+    }
+
+    override fun requestData() {
+        Timber.tag(loggerTag.value).w("requestData()")
+        coroutineScope.launch {
+            val finalMessenger = messenger
+            if (finalMessenger == null) {
+                Timber.tag(loggerTag.value).w("The messenger is null, can't request data")
+                mutableStateFlow.emit(ElementClassicConnectionState.Error("The messenger is null, can't request data"))
+            } else {
+                try {
+                    // Get the data
+                    val msg = Message.obtain(null, MSG_GET_DATA)
+                    msg.replyTo = incomingMessenger
+                    finalMessenger.send(msg)
+                } catch (e: RemoteException) {
+                    // In this case the service has crashed before we could even
+                    // do anything with it; we can count on soon being
+                    // disconnected (and then reconnected if it can be restarted)
+                    // so there is no need to do anything here.
+                    Timber.tag(loggerTag.value).e(e, "RemoteException")
+                    mutableStateFlow.emit(ElementClassicConnectionState.Error(e.localizedMessage.orEmpty()))
+                }
+            }
+        }
+    }
+
+    private val mutableStateFlow = MutableStateFlow<ElementClassicConnectionState>(ElementClassicConnectionState.Idle)
+    override val stateFlow = mutableStateFlow.asStateFlow()
+
+    /**
+     * Handler of incoming messages from service.
+     */
+    @Suppress("DEPRECATION")
+    inner class IncomingHandler : Handler() {
+        override fun handleMessage(msg: Message) {
+            Timber.tag(loggerTag.value).d("IncomingHandler handling message ${msg.what}")
+            when (msg.what) {
+                MSG_GET_DATA -> {
+                    // The data must be extracted from the bundle before we launch the coroutine, else the bundle will be emptied
+                    val state = msg.data.toElementClassicConnectionState()
+                    emitElementClassicState(state)
+                }
+                else -> {
+                    super.handleMessage(msg)
+                }
+            }
+        }
+    }
+
+    private fun emitElementClassicState(state: ElementClassicConnectionState) = coroutineScope.launch {
+        when (state) {
+            is ElementClassicConnectionState.Error -> {
+                Timber.tag(loggerTag.value).w("Received error from Element Classic: %s", state.error)
+                mutableStateFlow.emit(state)
+            }
+            is ElementClassicConnectionState.ElementClassicReady -> {
+                Timber.tag(loggerTag.value).d("Received userId from Element Classic: %s", state.userId)
+                mutableStateFlow.emit(state)
+            }
+            ElementClassicConnectionState.ElementClassicReadyNoSession -> {
+                Timber.tag(loggerTag.value).d("Received no session from Element Classic")
+                mutableStateFlow.emit(state)
+            }
+            else -> {
+                // Should not happen
+                Timber.tag(loggerTag.value).w("Received unexpected state from Element Classic: %s", state)
+                mutableStateFlow.emit(ElementClassicConnectionState.Idle)
+            }
+        }
+    }
+
+    private fun getElementClassicComponent(buildMeta: BuildMeta) = ComponentName(
+        buildString {
+            append(ELEMENT_CLASSIC_APP_ID)
+            append(
+                when (buildMeta.buildType) {
+                    BuildType.DEBUG -> ELEMENT_CLASSIC_APP_ID_DEBUG_SUFFIX
+                    BuildType.NIGHTLY -> ELEMENT_CLASSIC_APP_ID_NIGHTLY_SUFFIX
+                    BuildType.RELEASE -> ELEMENT_CLASSIC_APP_ID_RELEASE_SUFFIX
+                }
+            )
+        },
+        ELEMENT_CLASSIC_SERVICE_FULL_CLASS_NAME,
+    )
+
+    private fun Bundle?.toElementClassicConnectionState(): ElementClassicConnectionState {
+        return if (this == null) {
+            ElementClassicConnectionState.Error("No data received from Element Classic")
+        } else {
+            val error = getString(KEY_ERROR_STR)
+            if (error != null) {
+                ElementClassicConnectionState.Error(error)
+            } else {
+                val userId = getString(KEY_USER_ID_STR)?.let(::UserId)
+                if (userId != null) {
+                    ElementClassicConnectionState.ElementClassicReady(userId)
+                } else {
+                    ElementClassicConnectionState.ElementClassicReadyNoSession
+                }
+            }
+        }
+    }
+
+    // Everything in this companion object must match what is defined in Element Classic
+    private companion object {
+        // Command to the service to get the data.
+        const val MSG_GET_DATA = 1
+
+        const val ELEMENT_CLASSIC_APP_ID = "im.vector.app"
+        const val ELEMENT_CLASSIC_APP_ID_DEBUG_SUFFIX = ".debug"
+        const val ELEMENT_CLASSIC_APP_ID_NIGHTLY_SUFFIX = ".nightly"
+        const val ELEMENT_CLASSIC_APP_ID_RELEASE_SUFFIX = ""
+
+        const val ELEMENT_CLASSIC_SERVICE_FULL_CLASS_NAME = "im.vector.app.features.importer.ImporterService"
+
+        // Keys for the bundle returned from the service
+        const val KEY_ERROR_STR = "error"
+        const val KEY_USER_ID_STR = "userId"
+    }
+}
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicEvent.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicEvent.kt
@@ -0,0 +1,15 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+sealed interface LoginWithClassicEvent {
+    data object RefreshData : LoginWithClassicEvent
+    data object StartLoginWithClassic : LoginWithClassicEvent
+    data object DoLoginWithClassic : LoginWithClassicEvent
+    data object CloseDialog : LoginWithClassicEvent
+}
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicPresenter.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicPresenter.kt
@@ -0,0 +1,103 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import dev.zacsweers.metro.Inject
+import io.element.android.libraries.architecture.AsyncAction
+import io.element.android.libraries.architecture.Presenter
+import io.element.android.libraries.featureflag.api.FeatureFlagService
+import io.element.android.libraries.featureflag.api.FeatureFlags
+import io.element.android.libraries.sessionstorage.api.SessionStore
+import io.element.android.libraries.sessionstorage.api.toUserListFlow
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+
+@Inject
+class LoginWithClassicPresenter(
+    private val elementClassicConnection: ElementClassicConnection,
+    private val sessionStore: SessionStore,
+    private val featureFlagService: FeatureFlagService,
+) : Presenter<LoginWithClassicState> {
+    @Composable
+    override fun present(): LoginWithClassicState {
+        val coroutineScope = rememberCoroutineScope()
+
+        val isSignInWithClassicEnabled by remember {
+            featureFlagService.isFeatureEnabledFlow(FeatureFlags.SignInWithClassic)
+        }.collectAsState(initial = false)
+
+        if (isSignInWithClassicEnabled) {
+            DisposableEffect(Unit) {
+                elementClassicConnection.start()
+                onDispose {
+                    elementClassicConnection.stop()
+                }
+            }
+        }
+
+        val state by elementClassicConnection.stateFlow.collectAsState()
+        val loginWithClassicAction = remember { mutableStateOf<AsyncAction<Unit>>(AsyncAction.Uninitialized) }
+
+        val existingSession by remember {
+            sessionStore.sessionsFlow().toUserListFlow()
+        }.collectAsState(emptyList())
+
+        val canLoginWithClassic by remember {
+            derivedStateOf {
+                when (val finalState = state) {
+                    is ElementClassicConnectionState.ElementClassicReady -> {
+                        // Ensure there is no existing session with the same Id.
+                        finalState.userId.value !in existingSession && isSignInWithClassicEnabled
+                    }
+                    else -> false
+                }
+            }
+        }
+
+        fun handleEvent(event: LoginWithClassicEvent) {
+            when (event) {
+                LoginWithClassicEvent.RefreshData -> {
+                    elementClassicConnection.requestData()
+                }
+                LoginWithClassicEvent.StartLoginWithClassic -> {
+                    val currentState = elementClassicConnection.stateFlow.value
+                    if (currentState is ElementClassicConnectionState.ElementClassicReady) {
+                        loginWithClassicAction.value = ConfirmingLoginWithElementClassic(
+                            userId = currentState.userId,
+                        )
+                    } else {
+                        loginWithClassicAction.value = AsyncAction.Failure(IllegalStateException("Element Classic is not ready"))
+                    }
+                }
+                LoginWithClassicEvent.DoLoginWithClassic -> coroutineScope.launch {
+                    // TODO Implement real login logic here
+                    loginWithClassicAction.value = AsyncAction.Loading
+                    delay(1000)
+                    loginWithClassicAction.value = AsyncAction.Success(Unit)
+                }
+                LoginWithClassicEvent.CloseDialog -> {
+                    loginWithClassicAction.value = AsyncAction.Uninitialized
+                }
+            }
+        }
+
+        return LoginWithClassicState(
+            canLoginWithClassic = canLoginWithClassic,
+            loginWithClassicAction = loginWithClassicAction.value,
+            eventSink = ::handleEvent,
+        )
+    }
+}
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicState.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicState.kt
@@ -0,0 +1,16 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+import io.element.android.libraries.architecture.AsyncAction
+
+data class LoginWithClassicState(
+    val canLoginWithClassic: Boolean,
+    val loginWithClassicAction: AsyncAction<Unit>,
+    val eventSink: (LoginWithClassicEvent) -> Unit,
+)
--- a/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicStateProvider.kt
+++ b/features/login/impl/src/main/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicStateProvider.kt
@@ -0,0 +1,20 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+import io.element.android.libraries.architecture.AsyncAction
+
+fun aLoginWithClassicState(
+    canLoginWithClassic: Boolean = false,
+    loginWithClassicAction: AsyncAction<Unit> = AsyncAction.Uninitialized,
+    eventSink: (LoginWithClassicEvent) -> Unit = {},
+) = LoginWithClassicState(
+    canLoginWithClassic = canLoginWithClassic,
+    loginWithClassicAction = loginWithClassicAction,
+    eventSink = eventSink,
+)
--- a/features/login/impl/src/test/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingPresenterTest.kt
+++ b/features/login/impl/src/test/kotlin/io/element/android/features/login/impl/screens/onboarding/OnBoardingPresenterTest.kt
@@ -16,6 +16,7 @@ import io.element.android.features.enterprise.test.FakeEnterpriseService
 import io.element.android.features.login.impl.accesscontrol.DefaultAccountProviderAccessControl
 import io.element.android.features.login.impl.accountprovider.AccountProviderDataSource
 import io.element.android.features.login.impl.login.LoginHelper
+import io.element.android.features.login.impl.screens.onboarding.classic.aLoginWithClassicState
 import io.element.android.features.login.impl.web.FakeWebClientUrlForAuthenticationRetriever
 import io.element.android.features.login.impl.web.WebClientUrlForAuthenticationRetriever
 import io.element.android.features.wellknown.test.FakeWellknownRetriever
@@ -88,7 +89,10 @@ class OnBoardingPresenterTest {
            assertThat(initialState.canCreateAccount).isEqualTo(OnBoardingConfig.CAN_CREATE_ACCOUNT)
            assertThat(initialState.canReportBug).isFalse()
            assertThat(initialState.isAddingAccount).isFalse()
-            assertThat(awaitItem().canLoginWithQrCode).isTrue()
+            assertThat(initialState.loginWithClassicState.canLoginWithClassic).isFalse()
+            val finalState = awaitItem()
+            assertThat(finalState.canLoginWithQrCode).isTrue()
+            assertThat(finalState.loginWithClassicState.canLoginWithClassic).isFalse()
        }
    }

@@ -283,6 +287,7 @@ private fun createPresenter(
    onBoardingLogoResIdProvider = onBoardingLogoResIdProvider,
    sessionStore = sessionStore,
    accountProviderDataSource = accountProviderDataSource,
+    loginWithClassicPresenter = { aLoginWithClassicState() },
 )

 fun createLoginHelper(
--- a/features/login/impl/src/test/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/FakeElementClassicConnection.kt
+++ b/features/login/impl/src/test/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/FakeElementClassicConnection.kt
@@ -0,0 +1,29 @@
+/*
+ * 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.login.impl.screens.onboarding.classic
+
+import io.element.android.tests.testutils.lambda.lambdaError
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+class FakeElementClassicConnection(
+    private val startResult: () -> Unit = { lambdaError() },
+    private val stopResult: () -> Unit = { lambdaError() },
+    private val requestDataResult: () -> Unit = { lambdaError() },
+    initialState: ElementClassicConnectionState = ElementClassicConnectionState.Idle
+) : ElementClassicConnection {
+    override fun start() = startResult()
+    override fun stop() = stopResult()
+    override fun requestData() = requestDataResult()
+    private val mutableStateFlow = MutableStateFlow(initialState)
+    override val stateFlow: StateFlow<ElementClassicConnectionState> = mutableStateFlow.asStateFlow()
+    suspend fun emitState(state: ElementClassicConnectionState) {
+        mutableStateFlow.emit(state)
+    }
+}
--- a/features/login/impl/src/test/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicPresenterTest.kt
+++ b/features/login/impl/src/test/kotlin/io/element/android/features/login/impl/screens/onboarding/classic/LoginWithClassicPresenterTest.kt
@@ -0,0 +1,213 @@
+/*
+ * 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.
+ */
+
+@file:OptIn(ExperimentalCoroutinesApi::class)
+
+package io.element.android.features.login.impl.screens.onboarding.classic
+
+import com.google.common.truth.Truth.assertThat
+import io.element.android.libraries.featureflag.api.FeatureFlagService
+import io.element.android.libraries.featureflag.api.FeatureFlags
+import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
+import io.element.android.libraries.matrix.test.A_USER_ID
+import io.element.android.libraries.sessionstorage.api.SessionStore
+import io.element.android.libraries.sessionstorage.test.InMemorySessionStore
+import io.element.android.libraries.sessionstorage.test.aSessionData
+import io.element.android.tests.testutils.WarmUpRule
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.test
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.runTest
+import org.junit.Rule
+import org.junit.Test
+
+class LoginWithClassicPresenterTest {
+    @get:Rule
+    val warmUpRule = WarmUpRule()
+
+    @Test
+    fun `present - initial state - feature disabled - start is not invoked`() = runTest {
+        val presenter = createPresenter(
+            elementClassicConnection = FakeElementClassicConnection(
+                startResult = {
+                    error("start should not be invoked when feature is disabled")
+                },
+            )
+        )
+        presenter.test {
+            val initialState = awaitItem()
+            assertThat(initialState.canLoginWithClassic).isFalse()
+            assertThat(initialState.loginWithClassicAction.isUninitialized()).isTrue()
+        }
+    }
+
+    @Test
+    fun `present - feature enabled - start is invoked`() = runTest {
+        val startResult = lambdaRecorder<Unit> {}
+        val presenter = createPresenter(
+            elementClassicConnection = FakeElementClassicConnection(
+                startResult = startResult,
+            ),
+            isFeatureEnabled = true,
+        )
+        presenter.test {
+            val initialState = awaitItem()
+            assertThat(initialState.canLoginWithClassic).isFalse()
+            assertThat(initialState.loginWithClassicAction.isUninitialized()).isTrue()
+            val finalState = awaitItem()
+            assertThat(finalState.canLoginWithClassic).isFalse()
+        }
+        startResult.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `present - emit request data invokes the expected method`() = runTest {
+        val requestDataResult = lambdaRecorder<Unit> {}
+        val presenter = createPresenter(
+            elementClassicConnection = FakeElementClassicConnection(
+                startResult = {},
+                requestDataResult = requestDataResult,
+            ),
+            isFeatureEnabled = true,
+        )
+        presenter.test {
+            val initialState = awaitItem()
+            assertThat(initialState.canLoginWithClassic).isFalse()
+            assertThat(initialState.loginWithClassicAction.isUninitialized()).isTrue()
+            val nextState = awaitItem()
+            assertThat(nextState.canLoginWithClassic).isFalse()
+            nextState.eventSink(LoginWithClassicEvent.RefreshData)
+        }
+        requestDataResult.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `present - start login with wrong state emits an error`() = runTest {
+        val presenter = createPresenter(
+            elementClassicConnection = FakeElementClassicConnection(
+                startResult = {},
+            ),
+            isFeatureEnabled = true,
+        )
+        presenter.test {
+            skipItems(1)
+            val state = awaitItem()
+            state.eventSink(LoginWithClassicEvent.StartLoginWithClassic)
+            val errorState = awaitItem()
+            assertThat(errorState.loginWithClassicAction.isFailure()).isTrue()
+        }
+    }
+
+    @Test
+    fun `present - start login with correct state - user cancel`() = runTest {
+        val elementClassicConnection = FakeElementClassicConnection(
+            startResult = {},
+        )
+        val presenter = createPresenter(
+            elementClassicConnection = elementClassicConnection,
+            isFeatureEnabled = true,
+        )
+        presenter.test {
+            skipItems(2)
+            elementClassicConnection.emitState(
+                ElementClassicConnectionState.ElementClassicReady(userId = A_USER_ID)
+            )
+            val readyState = awaitItem()
+            assertThat(readyState.canLoginWithClassic).isTrue()
+            readyState.eventSink(LoginWithClassicEvent.StartLoginWithClassic)
+            val confirmingState = awaitItem()
+            assertThat(confirmingState.loginWithClassicAction.isConfirming()).isTrue()
+            assertThat((confirmingState.loginWithClassicAction as ConfirmingLoginWithElementClassic).userId).isEqualTo(A_USER_ID)
+            confirmingState.eventSink(LoginWithClassicEvent.CloseDialog)
+            val finalState = awaitItem()
+            assertThat(finalState.loginWithClassicAction.isUninitialized()).isTrue()
+        }
+    }
+
+    @Test
+    fun `present - start login with correct state - user confirms`() = runTest {
+        val elementClassicConnection = FakeElementClassicConnection(
+            startResult = {},
+        )
+        val presenter = createPresenter(
+            elementClassicConnection = elementClassicConnection,
+            isFeatureEnabled = true,
+        )
+        presenter.test {
+            skipItems(2)
+            elementClassicConnection.emitState(
+                ElementClassicConnectionState.ElementClassicReady(userId = A_USER_ID)
+            )
+            val readyState = awaitItem()
+            assertThat(readyState.canLoginWithClassic).isTrue()
+            readyState.eventSink(LoginWithClassicEvent.StartLoginWithClassic)
+            val confirmingState = awaitItem()
+            assertThat(confirmingState.loginWithClassicAction.isConfirming()).isTrue()
+            assertThat((confirmingState.loginWithClassicAction as ConfirmingLoginWithElementClassic).userId).isEqualTo(A_USER_ID)
+            confirmingState.eventSink(LoginWithClassicEvent.DoLoginWithClassic)
+            val loadingState = awaitItem()
+            assertThat(loadingState.loginWithClassicAction.isLoading()).isTrue()
+            val finalState = awaitItem()
+            assertThat(finalState.loginWithClassicAction.isSuccess()).isTrue()
+        }
+    }
+
+    @Test
+    fun `present - cannot sign in if a session with the same account already exists`() = runTest {
+        val elementClassicConnection = FakeElementClassicConnection(
+            startResult = {},
+        )
+        val presenter = createPresenter(
+            elementClassicConnection = elementClassicConnection,
+            isFeatureEnabled = true,
+            sessionStore = InMemorySessionStore(
+                initialList = listOf(
+                    aSessionData(
+                        sessionId = A_USER_ID.value,
+                    )
+                )
+            ),
+        )
+        presenter.test {
+            skipItems(2)
+            elementClassicConnection.emitState(
+                ElementClassicConnectionState.ElementClassicReady(userId = A_USER_ID)
+            )
+            // No new item, because canLoginWithClassic is still false
+        }
+    }
+
+    @Test
+    fun `present - cannot sign in if the feature is disabled`() = runTest {
+        val elementClassicConnection = FakeElementClassicConnection()
+        val presenter = createPresenter(
+            elementClassicConnection = elementClassicConnection,
+            isFeatureEnabled = false,
+        )
+        presenter.test {
+            skipItems(1)
+            // Note: it should not happen IRL
+            elementClassicConnection.emitState(
+                ElementClassicConnectionState.ElementClassicReady(userId = A_USER_ID)
+            )
+            // No new item, because canLoginWithClassic is still false
+        }
+    }
+}
+
+private fun createPresenter(
+    elementClassicConnection: ElementClassicConnection = FakeElementClassicConnection(),
+    sessionStore: SessionStore = InMemorySessionStore(),
+    isFeatureEnabled: Boolean = false,
+    featureFlagService: FeatureFlagService = FakeFeatureFlagService(
+        initialState = mapOf(FeatureFlags.SignInWithClassic.key to isFeatureEnabled)
+    ),
+) = LoginWithClassicPresenter(
+    elementClassicConnection = elementClassicConnection,
+    sessionStore = sessionStore,
+    featureFlagService = featureFlagService,
+)
--- a/libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt
+++ b/libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt
@@ -133,4 +133,11 @@ enum class FeatureFlags(
        defaultValue = { false },
        isFinished = false,
    ),
+    SignInWithClassic(
+        key = "feature.signin_with_classic",
+        title = "Sign in with Element Classic",
+        description = "Allow the application to sign in to the current Element Classic account.",
+        defaultValue = { false },
+        isFinished = false,
+    ),
 }