Timeline : initial multi-select state

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesPresenter.kt

@@ -402,6 +402,10 @@ class MessagesPresenter(
             TimelineItemAction.Unpin -> handleUnpinAction(targetEvent)
             TimelineItemAction.ViewInTimeline -> Unit
             TimelineItemAction.RetrySending -> handleRetrySending(targetEvent)
+            TimelineItemAction.Select -> {
+                val eventId = targetEvent.eventId ?: return@launch
+                timelineState.eventSink(TimelineEvent.EnterSelectionMode(eventId))
+            }
         }
     }
 

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesView.kt

@@ -10,6 +10,8 @@ package io.element.android.features.messages.impl
 
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.expandVertically
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
 import androidx.compose.animation.shrinkVertically
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
@@ -89,12 +91,15 @@ import io.element.android.features.messages.impl.timeline.components.reactionsum
 import io.element.android.features.messages.impl.timeline.components.reactionsummary.ReactionSummaryView
 import io.element.android.features.messages.impl.timeline.components.receipt.bottomsheet.ReadReceiptBottomSheet
 import io.element.android.features.messages.impl.timeline.components.receipt.bottomsheet.ReadReceiptBottomSheetEvent
+import io.element.android.features.messages.impl.timeline.isSelectionModeActive
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.TimelineItemGroupPosition
 import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemStateEventContent
 import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemTextContent
+import io.element.android.features.messages.impl.timeline.selectedCount
 import io.element.android.features.messages.impl.timeline.sendfailure.SendFailureDialogView
 import io.element.android.features.messages.impl.topbars.MessagesViewTopBar
+import io.element.android.features.messages.impl.topbars.SelectionModeTopBar
 import io.element.android.features.messages.impl.topbars.ThreadTopBar
 import io.element.android.features.messages.impl.voicemessages.composer.VoiceMessagePermissionRationaleDialog
 import io.element.android.features.messages.impl.voicemessages.composer.VoiceMessageSendingFailedDialog
@@ -177,6 +182,14 @@ fun MessagesView(
         block()
     }
 
+    // Entering selection mode collapses the composer, so dismiss the keyboard too. hideKeyboard
+    // triggers the IME hide animation, keeping it in sync with the composer collapse.
+    LaunchedEffect(state.timelineState.isSelectionModeActive) {
+        if (state.timelineState.isSelectionModeActive) {
+            localView.hideKeyboard()
+        }
+    }
+
     fun onContentClick(event: TimelineItem.Event) {
         Timber.v("onMessageClick= ${event.id}")
         val eventId = event.eventId
@@ -233,34 +246,45 @@ fun MessagesView(
             Scaffold(
                 contentWindowInsets = scaffoldScrollableContentInsets,
                 topBar = {
-                    if (state.timelineState.timelineMode is Timeline.Mode.Thread) {
+                    when {
-                        ThreadTopBar(
+                        state.timelineState.isSelectionModeActive -> {
-                            roomName = state.roomName,
+                            SelectionModeTopBar(
-                            roomAvatarData = state.roomAvatar,
+                                selectedCount = state.timelineState.selectedCount,
-                            heroes = state.heroes,
+                                onCancelClick = {
-                            isTombstoned = state.isTombstoned,
+                                    state.timelineState.eventSink(TimelineEvent.ExitSelectionMode)
-                            onBackClick = onBackClick,
+                                },
-                        )
+                            )
-                    } else {
+                        }
-                        MessagesViewTopBar(
+                        state.timelineState.timelineMode is Timeline.Mode.Thread -> {
-                            roomName = state.roomName,
+                            ThreadTopBar(
-                            roomAvatar = state.roomAvatar,
+                                roomName = state.roomName,
-                            isTombstoned = state.isTombstoned,
+                                roomAvatarData = state.roomAvatar,
-                            heroes = state.heroes,
+                                heroes = state.heroes,
-                            dmUserIdentityState = state.dmUserVerificationState,
+                                isTombstoned = state.isTombstoned,
-                            sharedHistoryIcon = state.topBarSharedHistoryIcon,
+                                onBackClick = onBackClick,
-                            dmUserStatus = state.dmUserStatus,
+                            )
-                            onBackClick = { hidingKeyboard { onBackClick() } },
+                        }
-                            onRoomDetailsClick = { hidingKeyboard { onRoomDetailsClick() } },
+                        else -> {
-                            menuActions = {
+                            MessagesViewTopBar(
-                                MessagesMenuActions(
+                                roomName = state.roomName,
-                                    displayThreads = state.timelineState.timelineMode !is Timeline.Mode.Thread && state.threads.hasThreads,
+                                roomAvatar = state.roomAvatar,
-                                    roomCallState = state.roomCallState,
+                                isTombstoned = state.isTombstoned,
-                                    onJoinCallClick = onJoinCallClick,
+                                heroes = state.heroes,
-                                    onThreadsListClick = onThreadsListClick
+                                dmUserIdentityState = state.dmUserVerificationState,
-                                )
+                                sharedHistoryIcon = state.topBarSharedHistoryIcon,
-                            }
+                                dmUserStatus = state.dmUserStatus,
-                        )
+                                onBackClick = { hidingKeyboard { onBackClick() } },
+                                onRoomDetailsClick = { hidingKeyboard { onRoomDetailsClick() } },
+                                menuActions = {
+                                    MessagesMenuActions(
+                                        displayThreads = state.timelineState.timelineMode !is Timeline.Mode.Thread && state.threads.hasThreads,
+                                        roomCallState = state.roomCallState,
+                                        onJoinCallClick = onJoinCallClick,
+                                        onThreadsListClick = onThreadsListClick
+                                    )
+                                }
+                            )
+                        }
                     }
                 },
                 content = { padding ->

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/actionlist/ActionListPresenter.kt

@@ -27,6 +27,7 @@ import io.element.android.features.messages.impl.crypto.sendfailure.VerifiedUser
 import io.element.android.features.messages.impl.crypto.sendfailure.VerifiedUserSendFailureFactory
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.TimelineItemThreadInfo
+import io.element.android.features.messages.impl.timeline.model.canBeSelected
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemAttachmentsContent
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContent
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContentWithAttachment
@@ -109,6 +110,7 @@ class DefaultActionListPresenter(
         }.collectAsState(initial = persistentListOf())
 
         val isThreadsEnabled = featureFlagService.isFeatureEnabledFlow(FeatureFlags.Threads).collectAsState(false)
+        val isMultiSelectEnabled = featureFlagService.isFeatureEnabledFlow(FeatureFlags.MessageMultiSelect).collectAsState(false)
 
         fun handleEvent(event: ActionListEvent) {
             when (event) {
@@ -120,6 +122,7 @@ class DefaultActionListPresenter(
                     pinnedEventIds = pinnedEventIds,
                     target = target,
                     isThreadsEnabled = isThreadsEnabled.value,
+                    isMultiSelectEnabled = isMultiSelectEnabled.value,
                 )
             }
         }
@@ -137,6 +140,7 @@ class DefaultActionListPresenter(
         pinnedEventIds: ImmutableList<EventId>,
         target: MutableState<ActionListState.Target>,
         isThreadsEnabled: Boolean,
+        isMultiSelectEnabled: Boolean,
     ) = launch {
         target.value = ActionListState.Target.Loading(timelineItem)
 
@@ -146,6 +150,7 @@ class DefaultActionListPresenter(
             isDeveloperModeEnabled = isDeveloperModeEnabled,
             isEventPinned = pinnedEventIds.contains(timelineItem.eventId),
             isThreadsEnabled = isThreadsEnabled,
+            isMultiSelectEnabled = isMultiSelectEnabled,
         )
 
         val verifiedUserSendFailure = userSendFailureFactory.create(timelineItem.localSendState)
@@ -179,6 +184,7 @@ class DefaultActionListPresenter(
         isDeveloperModeEnabled: Boolean,
         isEventPinned: Boolean,
         isThreadsEnabled: Boolean,
+        isMultiSelectEnabled: Boolean,
     ): List<TimelineItemAction> {
         val canRedact = timelineItem.isMine && usersEventPermissions.canRedactOwn || !timelineItem.isMine && usersEventPermissions.canRedactOther
         return buildSet {
@@ -200,6 +206,9 @@ class DefaultActionListPresenter(
             if (timelineItem.isRemote && timelineItem.content.canBeForwarded()) {
                 add(TimelineItemAction.Forward)
             }
+            if (isMultiSelectEnabled && timelineItem.canBeSelected()) {
+                add(TimelineItemAction.Select)
+            }
             if (timelineItem.isEditable && usersEventPermissions.canSendMessage) {
                 if (timelineItem.content is TimelineItemEventContentWithAttachment ||
                     timelineItem.content is TimelineItemGalleryContent ||

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/actionlist/model/TimelineItemAction.kt

@@ -20,6 +20,7 @@ enum class TimelineItemAction(
 ) {
     ViewInTimeline(CommonStrings.action_view_in_timeline, CompoundDrawables.ic_compound_visibility_on),
     Forward(CommonStrings.action_forward, CompoundDrawables.ic_compound_forward),
+    Select(CommonStrings.action_select, CompoundDrawables.ic_compound_check),
     CopyText(CommonStrings.action_copy_text, CompoundDrawables.ic_compound_copy),
     CopyCaption(CommonStrings.action_copy_caption, CompoundDrawables.ic_compound_copy),
     CopyLink(CommonStrings.action_copy_link_to_message, CompoundDrawables.ic_compound_link),

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/actionlist/model/TimelineItemActionComparator.kt

@@ -19,6 +19,7 @@ class TimelineItemActionComparator : Comparator<TimelineItemAction> {
         TimelineItemAction.Reply,
         TimelineItemAction.ReplyInThread,
         TimelineItemAction.Forward,
+        TimelineItemAction.Select,
         TimelineItemAction.Edit,
         TimelineItemAction.EditPoll,
         TimelineItemAction.AddCaption,

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/pinned/list/PinnedMessagesListView.kt

@@ -33,6 +33,7 @@ import io.element.android.features.messages.impl.link.LinkEvent
 import io.element.android.features.messages.impl.link.LinkView
 import io.element.android.features.messages.impl.timeline.TimelineEvent
 import io.element.android.features.messages.impl.timeline.components.TimelineItemRow
+import io.element.android.features.messages.impl.timeline.components.TimelineItemSelectionData
 import io.element.android.features.messages.impl.timeline.components.customreaction.CustomReactionBottomSheet
 import io.element.android.features.messages.impl.timeline.components.customreaction.CustomReactionEvent
 import io.element.android.features.messages.impl.timeline.components.event.TimelineItemEventContentView
@@ -291,6 +292,7 @@ private fun PinnedMessagesListLoaded(
                         onContentLayoutChange = onContentLayoutChange
                     )
                 },
+                selectionData = TimelineItemSelectionData(),
             )
         }
     }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/SelectionState.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2026 New Vector 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.messages.impl.timeline
+
+import androidx.compose.runtime.Immutable
+import io.element.android.libraries.matrix.api.core.EventId
+import kotlinx.collections.immutable.ImmutableSet
+
+/** Maximum number of messages that can be selected at once. */
+const val MAX_SELECTION_COUNT = 30
+
+@Immutable
+sealed interface SelectionState {
+    /** Selection mode is not active. */
+    data object Disabled : SelectionState
+
+    /** Selection mode is active with the given selection. */
+    data class Active(val selectedEventIds: ImmutableSet<EventId>) : SelectionState
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineEvent.kt

@@ -29,6 +29,10 @@ sealed interface TimelineEvent {
 
     data object MarkAllAsRead : TimelineEvent
 
+    data class EnterSelectionMode(val eventId: EventId) : TimelineEvent
+    data class ToggleSelection(val eventId: EventId) : TimelineEvent
+    data object ExitSelectionMode : TimelineEvent
+
     /**
      * Events coming from a timeline item.
      */

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenter.kt

@@ -25,6 +25,7 @@ import dev.zacsweers.metro.AssistedFactory
 import dev.zacsweers.metro.AssistedInject
 import io.element.android.features.location.api.live.ActiveLiveLocationShareManager
 import io.element.android.features.messages.impl.MessagesNavigator
+import io.element.android.features.messages.impl.R
 import io.element.android.features.messages.impl.UserEventPermissions
 import io.element.android.features.messages.impl.crypto.sendfailure.resolve.ResolveVerifiedUserSendFailureEvent
 import io.element.android.features.messages.impl.crypto.sendfailure.resolve.ResolveVerifiedUserSendFailureState
@@ -33,6 +34,7 @@ import io.element.android.features.messages.impl.timeline.factories.TimelineItem
 import io.element.android.features.messages.impl.timeline.factories.TimelineItemsFactoryConfig
 import io.element.android.features.messages.impl.timeline.model.NewEventState
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.model.canBeSelected
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemReadMarkerModel
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemTypingNotificationModel
 import io.element.android.features.messages.impl.timeline.protection.TimelineProtectionEvent
@@ -46,6 +48,8 @@ import io.element.android.features.poll.api.actions.SendPollResponseAction
 import io.element.android.features.roomcall.api.RoomCallState
 import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.core.coroutine.CoroutineDispatchers
+import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
+import io.element.android.libraries.designsystem.utils.snackbar.SnackbarMessage
 import io.element.android.libraries.di.annotations.SessionCoroutineScope
 import io.element.android.libraries.featureflag.api.FeatureFlagService
 import io.element.android.libraries.featureflag.api.FeatureFlags
@@ -68,7 +72,9 @@ import io.element.android.services.analytics.api.finishLongRunningTransaction
 import io.element.android.services.analyticsproviders.api.AnalyticsUserData
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.persistentSetOf
 import kotlinx.collections.immutable.toImmutableList
+import kotlinx.collections.immutable.toPersistentSet
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.combine
@@ -100,6 +106,7 @@ class TimelinePresenter(
     private val typingNotificationPresenter: Presenter<TypingNotificationState>,
     private val roomCallStatePresenter: Presenter<RoomCallState>,
     private val featureFlagService: FeatureFlagService,
+    private val snackbarDispatcher: SnackbarDispatcher,
     private val analyticsService: AnalyticsService,
     private val liveLocationShareManager: ActiveLiveLocationShareManager,
     private val markAsFullyRead: MarkAsFullyRead,
@@ -164,6 +171,18 @@ class TimelinePresenter(
             value = featureFlagService.isFeatureEnabled(FeatureFlags.JumpToUnread)
         }
 
+        val isMultiSelectEnabled by produceState(false) {
+            featureFlagService.isFeatureEnabledFlow(FeatureFlags.MessageMultiSelect).collect { value = it }
+        }
+        var selectionState by remember { mutableStateOf<SelectionState>(SelectionState.Disabled) }
+
+        // When the feature flag is turned off, clear any active selection.
+        LaunchedEffect(isMultiSelectEnabled) {
+            if (!isMultiSelectEnabled) {
+                selectionState = SelectionState.Disabled
+            }
+        }
+
         val timelineProtectionState = timelineProtectionPresenter.present()
 
         fun handleEvent(event: TimelineEvent) {
@@ -244,6 +263,28 @@ class TimelinePresenter(
                 is TimelineEvent.JumpToLive -> {
                     timelineController.focusOnLive()
                 }
+                is TimelineEvent.EnterSelectionMode -> {
+                    if (!isMultiSelectEnabled) return
+                    selectionState = SelectionState.Active(persistentSetOf(event.eventId))
+                }
+                is TimelineEvent.ToggleSelection -> {
+                    val current = selectionState as? SelectionState.Active ?: return
+                    val selected = current.selectedEventIds
+                    selectionState = when {
+                        event.eventId in selected -> {
+                            val next = (selected - event.eventId).toPersistentSet()
+                            if (next.isEmpty()) SelectionState.Disabled else SelectionState.Active(next)
+                        }
+                        selected.size >= MAX_SELECTION_COUNT -> {
+                            snackbarDispatcher.post(SnackbarMessage(R.string.screen_room_timeline_selection_limit_reached))
+                            current
+                        }
+                        else -> SelectionState.Active((selected + event.eventId).toPersistentSet())
+                    }
+                }
+                is TimelineEvent.ExitSelectionMode -> {
+                    selectionState = SelectionState.Disabled
+                }
                 TimelineEvent.HideShieldDialog -> messageShieldDialogData.value = null
                 TimelineEvent.MarkAllAsRead -> sessionCoroutineScope.launch {
                     val latestEventId = room.liveTimeline.getLatestEventId().getOrElse {
@@ -353,6 +394,23 @@ class TimelinePresenter(
             computeNewItemState(timelineItems, prevMostRecentItemId, newEventState)
         }
 
+        // Reconcile the selection when the items change: drop any selected event that is no longer
+        // present or no longer selectable, and exit selection mode if nothing remains selected.
+        LaunchedEffect(timelineItems.map { it.identifier() }) {
+            val active = selectionState as? SelectionState.Active ?: return@LaunchedEffect
+            val stillSelectable = timelineItems
+                .filterIsInstance<TimelineItem.Event>()
+                .filter { it.canBeSelected() }
+                .mapNotNull { it.eventId }
+                .toSet()
+            val reconciled = active.selectedEventIds.filter { it in stillSelectable }.toPersistentSet()
+            selectionState = when {
+                reconciled.isEmpty() -> SelectionState.Disabled
+                reconciled.size != active.selectedEventIds.size -> SelectionState.Active(reconciled)
+                else -> active
+            }
+        }
+
         // Keyed on the full [timelineItems] reference (not just .size) so we re-scan when the
         // read marker advances in place — the SDK swaps the marker virtual item to a new position
         // without changing the list length, e.g. when [markRoomAsFullyRead] is sent while at the
@@ -463,6 +521,7 @@ class TimelinePresenter(
             displayThreadSummaries = displayThreadSummaries,
             displayJumpToUnread = displayJumpToUnread,
             jumpToUnread = jumpToUnread.value,
+            selectionState = selectionState,
             eventSink = ::handleEvent,
         )
     }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineState.kt

@@ -37,6 +37,7 @@ data class TimelineState(
     val displayThreadSummaries: Boolean,
     val displayJumpToUnread: Boolean,
     val jumpToUnread: JumpToUnreadState,
+    val selectionState: SelectionState,
     val eventSink: (TimelineEvent) -> Unit,
 ) {
     private val lastTimelineEvent = timelineItems.firstOrNull { it is TimelineItem.Event } as? TimelineItem.Event
@@ -100,3 +101,14 @@ sealed interface JumpToUnreadState {
     /** The read marker event is older than the loaded window — load it via focused-event navigation. */
     data class OutOfWindow(val eventId: EventId) : JumpToUnreadState
 }
+
+val TimelineState.isSelectionModeActive: Boolean
+    get() = selectionState is SelectionState.Active
+
+val TimelineState.selectedCount: Int
+    get() = (selectionState as? SelectionState.Active)?.selectedEventIds?.size ?: 0
+
+fun TimelineState.isSelected(eventId: EventId?): Boolean {
+    if (eventId == null) return false
+    return (selectionState as? SelectionState.Active)?.selectedEventIds?.contains(eventId) == true
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt

@@ -63,6 +63,7 @@ fun aTimelineState(
     displayJumpToUnread: Boolean = false,
     jumpToUnread: JumpToUnreadState = JumpToUnreadState.Hidden,
     newEventState: NewEventState = NewEventState.None,
+    selectionState: SelectionState = SelectionState.Disabled,
     eventSink: (TimelineEvent) -> Unit = {},
 ): TimelineState {
     val focusedEventId = timelineItems.filterIsInstance<TimelineItem.Event>().getOrNull(focusedEventIndex)?.eventId
@@ -84,6 +85,7 @@ fun aTimelineState(
         displayThreadSummaries = displayThreadSummaries,
         displayJumpToUnread = displayJumpToUnread,
         jumpToUnread = jumpToUnread,
+        selectionState = selectionState,
         eventSink = eventSink,
     )
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt

@@ -11,6 +11,7 @@ package io.element.android.features.messages.impl.timeline
 import android.view.HapticFeedbackConstants
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.core.MutableTransitionState
+import androidx.compose.animation.core.animateFloatAsState
 import androidx.compose.animation.core.tween
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
@@ -83,14 +84,17 @@ import io.element.android.compound.tokens.generated.CompoundIcons
 import io.element.android.features.messages.impl.crypto.sendfailure.resolve.ResolveVerifiedUserSendFailureView
 import io.element.android.features.messages.impl.timeline.components.FloatingDateBadgeOverlay
 import io.element.android.features.messages.impl.timeline.components.TimelineItemRow
+import io.element.android.features.messages.impl.timeline.components.TimelineItemSelectionData
 import io.element.android.features.messages.impl.timeline.components.toText
 import io.element.android.features.messages.impl.timeline.di.LocalTimelineItemPresenterFactories
 import io.element.android.features.messages.impl.timeline.di.aFakeTimelineItemPresenterFactories
 import io.element.android.features.messages.impl.timeline.focus.FocusRequestStateView
 import io.element.android.features.messages.impl.timeline.model.NewEventState
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.model.canBeSelected
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContent
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEventContentPreviewParam
+import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemTextContent
 import io.element.android.features.messages.impl.timeline.protection.TimelineProtectionState
 import io.element.android.features.messages.impl.timeline.protection.aTimelineProtectionState
 import io.element.android.libraries.androidutils.system.copyToClipboard
@@ -111,6 +115,7 @@ import io.element.android.libraries.testtags.testTag
 import io.element.android.libraries.ui.strings.CommonStrings
 import io.element.android.wysiwyg.link.Link
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.persistentSetOf
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.flow.combine
@@ -189,6 +194,18 @@ fun TimelineView(
         state.eventSink(TimelineEvent.LoadMore(Timeline.PaginationDirection.BACKWARDS))
     }
 
+    val isSelectionModeActive = state.isSelectionModeActive
+    // Animate once here (shared by every row) rather than per-row: the value is identical for all
+    // rows since it only depends on the timeline-wide selection mode.
+    val selectionProgress by animateFloatAsState(
+        targetValue = if (isSelectionModeActive) 1f else 0f,
+        label = "selectionProgress",
+    )
+    fun onToggleSelection(event: TimelineItem.Event) {
+        val eventId = event.eventId ?: return
+        state.eventSink(TimelineEvent.ToggleSelection(eventId))
+    }
+
     // Animate alpha when timeline is first displayed, to avoid flashes or glitching when viewing rooms
     AnimatedVisibility(visible = true, enter = fadeIn()) {
         Box(modifier) {
@@ -214,12 +231,21 @@ fun TimelineView(
                         isLastOutgoingMessage = state.isLastOutgoingMessage(timelineItem.identifier()),
                         focusedEventId = state.focusedEventId,
                         displayThreadSummaries = state.displayThreadSummaries,
+                        selectionData = TimelineItemSelectionData(
+                            isSelectionModeActive = isSelectionModeActive,
+                            progress = selectionProgress,
+                            isSelected = state.isSelected((timelineItem as? TimelineItem.Event)?.eventId),
+                        ),
                         onUserDataClick = onUserDataClick,
                         onLinkClick = onLinkClick,
                         onLinkLongClick = ::onLinkLongClick,
-                        onContentClick = onContentClick,
+                        onContentClick = { event ->
+                            if (isSelectionModeActive && event.canBeSelected()) onToggleSelection(event) else onContentClick(event)
+                        },
                         onGalleryItemClick = onGalleryItemClick,
-                        onLongClick = onMessageLongClick,
+                        onLongClick = { event ->
+                            if (isSelectionModeActive && event.canBeSelected()) onToggleSelection(event) else onMessageLongClick(event)
+                        },
                         inReplyToClick = ::inReplyToClick,
                         onReactionClick = onReactionClick,
                         onReactionLongClick = onReactionLongClick,
@@ -616,6 +642,36 @@ internal fun TimelineViewPreview(
     }
 }
 
+@PreviewsDayNight
+@Composable
+internal fun TimelineViewSelectionModePreview() = ElementPreview {
+    val timelineItems = aTimelineItemList(aTimelineItemTextContent())
+    val selectedEventId = timelineItems.filterIsInstance<TimelineItem.Event>().first { it.canBeSelected() }.eventId!!
+    CompositionLocalProvider(
+        LocalTimelineItemPresenterFactories provides aFakeTimelineItemPresenterFactories(),
+    ) {
+        TimelineView(
+            state = aTimelineState(
+                timelineItems = timelineItems,
+                selectionState = SelectionState.Active(persistentSetOf(selectedEventId)),
+            ),
+            timelineProtectionState = aTimelineProtectionState(),
+            onUserDataClick = {},
+            onLinkClick = {},
+            onContentClick = {},
+            onMessageLongClick = {},
+            onSwipeToReply = {},
+            onReactionClick = { _, _ -> },
+            onReactionLongClick = { _, _ -> },
+            onJoinCallClick = {},
+            onMoreReactionsClick = {},
+            onReadReceiptClick = {},
+            onGalleryItemClick = { _, _ -> },
+            forceJumpToBottomVisibility = true,
+        )
+    }
+}
+
 // The jump-to-unread FAB's indicator is always rendered when the FAB is visible — in
 // production the FAB only appears when unread content exists above. So `hasUnreadAbove`
 // here only varies the scroll-target state, not the upper indicator's visibility.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/SelectionIndicator.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2026 New Vector 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.messages.impl.timeline.components
+
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import io.element.android.compound.theme.ElementTheme
+import io.element.android.compound.tokens.generated.CompoundIcons
+import io.element.android.libraries.designsystem.preview.ElementPreview
+import io.element.android.libraries.designsystem.preview.PreviewsDayNight
+import io.element.android.libraries.designsystem.theme.components.Icon
+
+/**
+ * Compact selection indicator used in the timeline selection mode, in place of a Material
+ * [androidx.compose.material3.Checkbox] (which reserves a 48dp interactive area). It is purely
+ * visual: the tap is handled by the whole-row click target, so this only reflects [selected].
+ */
+@Composable
+internal fun SelectionIndicator(
+    selected: Boolean,
+    modifier: Modifier = Modifier,
+) {
+    Icon(
+        modifier = modifier,
+        imageVector = if (selected) CompoundIcons.CheckCircleSolid() else CompoundIcons.Circle(),
+        contentDescription = null,
+        tint = if (selected) ElementTheme.colors.iconAccentPrimary else ElementTheme.colors.iconTertiary,
+    )
+}
+
+@PreviewsDayNight
+@Composable
+internal fun SelectionIndicatorPreview() = ElementPreview {
+    Icon(
+        modifier = Modifier.size(24.dp),
+        imageVector = CompoundIcons.Circle(),
+        contentDescription = null,
+        tint = ElementTheme.colors.iconTertiary,
+    )
+}
+
+@PreviewsDayNight
+@Composable
+internal fun SelectionIndicatorSelectedPreview() = ElementPreview {
+    SelectionIndicator(selected = true)
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemEventRow.kt

@@ -24,6 +24,7 @@ import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.absoluteOffset
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
@@ -59,6 +60,7 @@ import androidx.compose.ui.semantics.traversalIndex
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextDirection
 import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.DpOffset
 import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.LayoutDirection
@@ -180,6 +182,9 @@ fun TimelineItemEventRow(
     onSwipeToReply: () -> Unit,
     eventSink: (TimelineEvent.TimelineItemEvent) -> Unit,
     modifier: Modifier = Modifier,
+    // Horizontal offset applied to this row's content by selection mode. The read receipts are
+    // anchored to the end edge and should stay pinned, so they are counter-offset by this amount.
+    selectionContentOffset: Dp = 0.dp,
     eventContentView: @Composable (Modifier, (ContentAvoidingLayoutData) -> Unit) -> Unit = { contentModifier, onContentLayoutChange ->
         // Only pass down a custom clickable lambda if the content can be clicked separately
         val onContentClick = onEventClick.takeUnless { event.isWholeContentClickable }
@@ -326,7 +331,10 @@ fun TimelineItemEventRow(
                 receipts = event.readReceiptState.receipts,
             ),
             onReadReceiptsClick = { onReadReceiptClick(event) },
-            modifier = Modifier.padding(top = 4.dp)
+            // Counter the selection-mode content slide so the end-anchored read receipts stay pinned.
+            modifier = Modifier
+                .padding(top = 4.dp)
+                .offset(x = -selectionContentOffset)
         )
     }
 }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemGroupedEventsRow.kt

@@ -190,6 +190,7 @@ private fun TimelineItemGroupedEventsRowContent(
                         onSwipeToReply = {},
                         eventSink = eventSink,
                         eventContentView = eventContentView,
+                        selectionData = TimelineItemSelectionData(),
                     )
                 }
             }

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemRow.kt

@@ -8,22 +8,30 @@
 
 package io.element.android.features.messages.impl.timeline.components
 
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.combinedClickable
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
 import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.drawWithCache
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Brush
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.platform.LocalLayoutDirection
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.semantics.contentDescription
 import androidx.compose.ui.semantics.isTraversalGroup
 import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.dp
 import io.element.android.compound.theme.ElementTheme
 import io.element.android.features.messages.impl.timeline.TimelineEvent
@@ -31,6 +39,7 @@ import io.element.android.features.messages.impl.timeline.TimelineRoomInfo
 import io.element.android.features.messages.impl.timeline.components.event.TimelineItemEventContentView
 import io.element.android.features.messages.impl.timeline.components.layout.ContentAvoidingLayoutData
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.model.canBeSelected
 import io.element.android.features.messages.impl.timeline.model.event.RtcNotificationState
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemLegacyCallInviteContent
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemPollContent
@@ -60,6 +69,7 @@ internal fun TimelineItemRow(
     timelineProtectionState: TimelineProtectionState,
     focusedEventId: EventId?,
     displayThreadSummaries: Boolean,
+    selectionData: TimelineItemSelectionData,
     onUserDataClick: (MatrixUser) -> Unit,
     onLinkClick: (Link) -> Unit,
     onLinkLongClick: (Link) -> Unit,
@@ -92,17 +102,130 @@ internal fun TimelineItemRow(
             )
         },
 ) {
-    val backgroundModifier = if (timelineItem.isEvent(focusedEventId)) {
+    val isSelectionModeActive = selectionData.isSelectionModeActive
-        val focusedEventOffset = if ((timelineItem as? TimelineItem.Event)?.showSenderInformation == true) {
+    val selectionProgress = selectionData.progress
-            14.dp
+    val isSelected = selectionData.isSelected
-        } else {
+    val backgroundModifier = when {
-            2.dp
+        isSelected -> {
+            Modifier.background(ElementTheme.colors.bgAccentSelected)
+        }
+        timelineItem.isEvent(focusedEventId) -> {
+            val focusedEventOffset =
+                if ((timelineItem as? TimelineItem.Event)?.showSenderInformation == true) {
+                    14.dp
+                } else {
+                    2.dp
+                }
+            Modifier.focusedEvent(focusedEventOffset)
+        }
+        else -> {
+            Modifier
         }
-        Modifier.focusedEvent(focusedEventOffset)
-    } else {
-        Modifier
     }
-    Box(modifier = modifier.then(backgroundModifier)) {
+    val selectableEvent = (timelineItem as? TimelineItem.Event)?.takeIf { it.canBeSelected() }
+    // Only start-aligned message bubbles slide to make room for the selection indicator:
+    //  - Outgoing (own) messages are end-aligned, opposite the indicator, so they already have room.
+    //  - Centered tiles (state events, call tiles, day dividers, grouped events) must stay put.
+    val isOutgoing = (timelineItem as? TimelineItem.Event)?.isMine == true
+    val shouldSlideContent = timelineItem.rendersAsBubble() && !isOutgoing
+    val layoutDirection = LocalLayoutDirection.current
+    val contentSlide = if (shouldSlideContent) SELECTION_COLUMN_WIDTH * selectionProgress else 0.dp
+    Box(
+        modifier = modifier.then(backgroundModifier)
+    ) {
+        TimelineItemRowContent(
+            modifier = Modifier
+                .fillMaxWidth()
+                .offset(x = contentSlide),
+            selectionContentOffset = contentSlide,
+            timelineItem = timelineItem,
+            timelineMode = timelineMode,
+            timelineRoomInfo = timelineRoomInfo,
+            timelineProtectionState = timelineProtectionState,
+            isLastOutgoingMessage = isLastOutgoingMessage,
+            focusedEventId = focusedEventId,
+            displayThreadSummaries = displayThreadSummaries,
+            onUserDataClick = onUserDataClick,
+            onLinkClick = onLinkClick,
+            onLinkLongClick = onLinkLongClick,
+            onContentClick = onContentClick,
+            onGalleryItemClick = onGalleryItemClick,
+            onLongClick = onLongClick,
+            inReplyToClick = inReplyToClick,
+            onReactionClick = onReactionClick,
+            onReactionLongClick = onReactionLongClick,
+            onMoreReactionsClick = onMoreReactionsClick,
+            onReadReceiptClick = onReadReceiptClick,
+            onJoinCallClick = onJoinCallClick,
+            onSwipeToReply = onSwipeToReply,
+            eventSink = eventSink,
+            eventContentView = eventContentView,
+        )
+        if (selectableEvent != null && selectionProgress > 0f) {
+            val slideSign = if (layoutDirection == LayoutDirection.Ltr) -1f else 1f
+            SelectionIndicator(
+                selected = isSelected,
+                modifier = Modifier
+                    .align(Alignment.CenterStart)
+                    .graphicsLayer { translationX = slideSign * SELECTION_COLUMN_WIDTH.toPx() * (1f - selectionProgress) }
+                    .padding(start = 12.dp)
+                    .size(24.dp),
+            )
+        }
+        if (isSelectionModeActive && selectableEvent != null) {
+            // In selection mode the whole row toggles selection.
+            Box(
+                modifier = Modifier
+                    .matchParentSize()
+                    .clickable { onContentClick(selectableEvent) }
+            )
+        }
+    }
+}
+
+/** Width reserved for the selection indicator; the row content slides by this amount. */
+private val SELECTION_COLUMN_WIDTH = 36.dp
+
+/**
+ * Whether this item is rendered as a start/end-aligned message bubble, as opposed to a centered
+ * tile (state event, legacy call invite, call/RTC notification, day divider, grouped events).
+ * Mirrors the dispatch in [TimelineItemRowContent]: only bubbles shift to reveal the selection
+ * indicator; centered tiles stay put.
+ */
+private fun TimelineItem.rendersAsBubble(): Boolean = this is TimelineItem.Event &&
+    content !is TimelineItemStateContent &&
+    content !is TimelineItemLegacyCallInviteContent &&
+    content !is TimelineItemRtcNotificationContent
+
+@Suppress("LongMethod")
+@Composable
+private fun TimelineItemRowContent(
+    timelineItem: TimelineItem,
+    timelineMode: Timeline.Mode,
+    timelineRoomInfo: TimelineRoomInfo,
+    isLastOutgoingMessage: Boolean,
+    timelineProtectionState: TimelineProtectionState,
+    focusedEventId: EventId?,
+    displayThreadSummaries: Boolean,
+    onUserDataClick: (MatrixUser) -> Unit,
+    onLinkClick: (Link) -> Unit,
+    onLinkLongClick: (Link) -> Unit,
+    onContentClick: (TimelineItem.Event) -> Unit,
+    onGalleryItemClick: (TimelineItem.Event, Int) -> Unit,
+    onLongClick: (TimelineItem.Event) -> Unit,
+    inReplyToClick: (EventId) -> Unit,
+    onReactionClick: (key: String, TimelineItem.Event) -> Unit,
+    onReactionLongClick: (key: String, TimelineItem.Event) -> Unit,
+    onMoreReactionsClick: (TimelineItem.Event) -> Unit,
+    onReadReceiptClick: (TimelineItem.Event) -> Unit,
+    onJoinCallClick: (isAudioCall: Boolean) -> Unit,
+    onSwipeToReply: (TimelineItem.Event) -> Unit,
+    eventSink: (TimelineEvent.TimelineItemEvent) -> Unit,
+    eventContentView: @Composable (TimelineItem.Event, Modifier, (ContentAvoidingLayoutData) -> Unit) -> Unit,
+    modifier: Modifier = Modifier,
+    selectionContentOffset: Dp = 0.dp,
+) {
+    Box(modifier) {
         when (timelineItem) {
             is TimelineItem.Virtual -> {
                 TimelineItemVirtualRow(
@@ -197,6 +320,7 @@ internal fun TimelineItemRow(
                             onSwipeToReply = { onSwipeToReply(timelineItem) },
                             onGalleryItemClick = { index -> onGalleryItemClick(timelineItem, index) },
                             eventSink = eventSink,
+                            selectionContentOffset = selectionContentOffset,
                             eventContentView = { contentModifier, onContentLayoutChange ->
                                 eventContentView(timelineItem, contentModifier, onContentLayoutChange)
                             },

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemSelectionData.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2026 New Vector 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.messages.impl.timeline.components
+
+/**
+ * Row-scoped selection state passed to [TimelineItemRow].
+ *
+ * @param isSelectionModeActive whether the timeline is currently in selection mode. Drives
+ *   behaviour (e.g. the whole-row click target) and must reflect the real mode, not [progress].
+ * @param progress animated 0f..1f value driving the visuals (content slide + indicator slide-in).
+ *   Animated once in TimelineView and shared by every row. Differs from [isSelectionModeActive]
+ *   during the enter/exit animation.
+ * @param isSelected whether this specific row's event is part of the current selection.
+ */
+data class TimelineItemSelectionData(
+    val isSelectionModeActive: Boolean = false,
+    val isSelected: Boolean = false,
+    val progress: Float = 0f,
+)

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItemSelection.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2026 New Vector 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.messages.impl.timeline.model
+
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemEncryptedContent
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemLegacyCallInviteContent
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemLocationContent
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemRedactedContent
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemRtcNotificationContent
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemStateContent
+import io.element.android.features.messages.impl.timeline.model.event.TimelineItemUnknownContent
+
+/**
+ * Whether this timeline event can be selected in multi-select ("selection") mode.
+ */
+fun TimelineItem.Event.canBeSelected(): Boolean {
+    // Local echoes (no remote eventId) and failed sends are never selectable.
+    if (!isRemote || failedToSend) return false
+    return when (content) {
+        is TimelineItemStateContent,
+        is TimelineItemRedactedContent,
+        is TimelineItemEncryptedContent,
+        is TimelineItemLegacyCallInviteContent,
+        is TimelineItemRtcNotificationContent,
+        is TimelineItemLocationContent,
+        is TimelineItemUnknownContent -> false
+        else -> true
+    }
+}

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/topbars/SelectionModeTopBar.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2026 New Vector 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.messages.impl.topbars
+
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.PreviewParameter
+import androidx.compose.ui.tooling.preview.PreviewParameterProvider
+import io.element.android.compound.tokens.generated.CompoundIcons
+import io.element.android.features.messages.impl.R
+import io.element.android.libraries.designsystem.preview.ElementPreview
+import io.element.android.libraries.designsystem.preview.PreviewsDayNight
+import io.element.android.libraries.designsystem.theme.components.Icon
+import io.element.android.libraries.designsystem.theme.components.IconButton
+import io.element.android.libraries.designsystem.theme.components.Text
+import io.element.android.libraries.designsystem.theme.components.TopAppBar
+import io.element.android.libraries.ui.strings.CommonStrings
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SelectionModeTopBar(
+    selectedCount: Int,
+    onCancelClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    TopAppBar(
+        modifier = modifier,
+        title = {
+            Text(text = pluralStringResource(R.plurals.screen_room_timeline_selection_title, selectedCount, selectedCount))
+        },
+        navigationIcon = {
+            IconButton(
+                onClick = onCancelClick,
+            ) {
+                Icon(imageVector = CompoundIcons.Close(), contentDescription = stringResource(CommonStrings.action_close))
+            }
+        },
+    )
+}
+
+@PreviewsDayNight
+@Composable
+internal fun SelectionModeTopBarPreview(
+    @PreviewParameter(SelectionCountProvider::class) count: Int,
+) = ElementPreview {
+    SelectionModeTopBar(selectedCount = count, onCancelClick = {})
+}
+
+internal class SelectionCountProvider : PreviewParameterProvider<Int> {
+    override val values = sequenceOf(0, 1, 5)
+}

features/messages/impl/src/main/res/values/temporary.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2026 New Vector Ltd.
+  ~
+  ~ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+  ~ Please see LICENSE files in the repository root for full details.
+  -->
+
+<resources>
+    <!-- %1$d is the number of selected messages -->
+    <plurals name="screen_room_timeline_selection_title">
+        <item quantity="one">%1$d selected</item>
+        <item quantity="other">%1$d selected</item>
+    </plurals>
+    <string name="screen_room_timeline_selection_limit_reached">You can select up to 30 messages</string>
+</resources>

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/actionlist/ActionListPresenterTest.kt

@@ -70,6 +70,44 @@ class ActionListPresenterTest {
         }
     }
 
+    @Test
+    fun `present - Select action is present for a remote message when multi-select is enabled`() = runTest {
+        val presenter = createActionListPresenter(
+            isDeveloperModeEnabled = false,
+            featureFlagService = FakeFeatureFlagService(initialState = mapOf(FeatureFlags.MessageMultiSelect.key to true)),
+        )
+        presenter.test {
+            val initialState = awaitItem()
+            initialState.eventSink.invoke(
+                ActionListEvent.ComputeForMessage(
+                    event = aMessageEvent(),
+                    userEventPermissions = aUserEventPermissions(canSendMessage = true),
+                )
+            )
+            val successState = awaitItem()
+            assertThat((successState.target as ActionListState.Target.Success).actions).contains(TimelineItemAction.Select)
+        }
+    }
+
+    @Test
+    fun `present - Select action is absent when multi-select is disabled`() = runTest {
+        val presenter = createActionListPresenter(
+            isDeveloperModeEnabled = false,
+            featureFlagService = FakeFeatureFlagService(initialState = mapOf(FeatureFlags.MessageMultiSelect.key to false)),
+        )
+        presenter.test {
+            val initialState = awaitItem()
+            initialState.eventSink.invoke(
+                ActionListEvent.ComputeForMessage(
+                    event = aMessageEvent(),
+                    userEventPermissions = aUserEventPermissions(canSendMessage = true),
+                )
+            )
+            val successState = awaitItem()
+            assertThat((successState.target as ActionListState.Target.Success).actions).doesNotContain(TimelineItemAction.Select)
+        }
+    }
+
     @Test
     fun `present - compute for message from me redacted`() = runTest {
         val presenter = createActionListPresenter(isDeveloperModeEnabled = true)

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/TimelinePresenterTest.kt

@@ -34,6 +34,7 @@ import io.element.android.features.poll.test.actions.FakeEndPollAction
 import io.element.android.features.poll.test.actions.FakeSendPollResponseAction
 import io.element.android.features.roomcall.api.aStandByCallState
 import io.element.android.libraries.architecture.Presenter
+import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
 import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.matrix.api.core.EventId
@@ -86,6 +87,7 @@ import io.element.android.tests.testutils.lambda.value
 import io.element.android.tests.testutils.test
 import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.persistentSetOf
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.delay
@@ -1821,6 +1823,80 @@ class TimelinePresenterTest {
         }
     }
 
+    @Test
+    fun `present - entering selection mode selects the target event`() = runTest {
+        val timelineItems = MutableStateFlow(
+            listOf(MatrixTimelineItem.Event(UniqueId("1"), anEventTimelineItem(eventId = AN_EVENT_ID, content = aMessageContent())))
+        )
+        val presenter = createTimelinePresenter(
+            timeline = FakeTimeline(timelineItems = timelineItems),
+            featureFlagService = FakeFeatureFlagService(initialState = mapOf(FeatureFlags.MessageMultiSelect.key to true)),
+        )
+        presenter.test {
+            val initialState = consumeItemsUntilPredicate { it.hasAnyEvent }.last()
+            assertThat(initialState.selectionState).isEqualTo(SelectionState.Disabled)
+            initialState.eventSink(TimelineEvent.EnterSelectionMode(AN_EVENT_ID))
+            val state = consumeItemsUntilPredicate { it.isSelectionModeActive }.last()
+            assertThat(state.selectionState).isEqualTo(SelectionState.Active(persistentSetOf(AN_EVENT_ID)))
+            assertThat(state.selectedCount).isEqualTo(1)
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `present - entering selection mode is ignored when the flag is off`() = runTest {
+        val featureFlagService = FakeFeatureFlagService(initialState = mapOf(FeatureFlags.MessageMultiSelect.key to false))
+        val presenter = createTimelinePresenter(featureFlagService = featureFlagService)
+        presenter.test {
+            val initialState = awaitFirstItem()
+            initialState.eventSink(TimelineEvent.EnterSelectionMode(AN_EVENT_ID))
+            expectNoEvents()
+            assertThat(initialState.selectionState).isEqualTo(SelectionState.Disabled)
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `present - toggling the last selected event exits selection mode`() = runTest {
+        val timelineItems = MutableStateFlow(
+            listOf(MatrixTimelineItem.Event(UniqueId("1"), anEventTimelineItem(eventId = AN_EVENT_ID, content = aMessageContent())))
+        )
+        val presenter = createTimelinePresenter(
+            timeline = FakeTimeline(timelineItems = timelineItems),
+            featureFlagService = FakeFeatureFlagService(initialState = mapOf(FeatureFlags.MessageMultiSelect.key to true)),
+        )
+        presenter.test {
+            val initialState = consumeItemsUntilPredicate { it.hasAnyEvent }.last()
+            initialState.eventSink(TimelineEvent.EnterSelectionMode(AN_EVENT_ID))
+            consumeItemsUntilPredicate { it.isSelectionModeActive }
+            initialState.eventSink(TimelineEvent.ToggleSelection(AN_EVENT_ID))
+            val state = consumeItemsUntilPredicate { !it.isSelectionModeActive }.last()
+            assertThat(state.selectionState).isEqualTo(SelectionState.Disabled)
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `present - turning the flag off clears the active selection`() = runTest {
+        val timelineItems = MutableStateFlow(
+            listOf(MatrixTimelineItem.Event(UniqueId("1"), anEventTimelineItem(eventId = AN_EVENT_ID, content = aMessageContent())))
+        )
+        val featureFlagService = FakeFeatureFlagService(initialState = mapOf(FeatureFlags.MessageMultiSelect.key to true))
+        val presenter = createTimelinePresenter(
+            timeline = FakeTimeline(timelineItems = timelineItems),
+            featureFlagService = featureFlagService,
+        )
+        presenter.test {
+            val initialState = consumeItemsUntilPredicate { it.hasAnyEvent }.last()
+            initialState.eventSink(TimelineEvent.EnterSelectionMode(AN_EVENT_ID))
+            consumeItemsUntilPredicate { it.isSelectionModeActive }
+            featureFlagService.setFeatureEnabled(FeatureFlags.MessageMultiSelect, false)
+            val state = consumeItemsUntilPredicate { !it.isSelectionModeActive }.last()
+            assertThat(state.selectionState).isEqualTo(SelectionState.Disabled)
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
     private suspend fun <T> ReceiveTurbine<T>.awaitFirstItem(): T {
         return awaitItem()
     }
@@ -1911,6 +1987,7 @@ class TimelinePresenterTest {
             typingNotificationPresenter = { aTypingNotificationState() },
             roomCallStatePresenter = { aStandByCallState() },
             featureFlagService = featureFlagService,
+            snackbarDispatcher = SnackbarDispatcher(),
             analyticsService = FakeAnalyticsService(),
             liveLocationShareManager = liveLocationShareManager,
             markAsFullyRead = markAsFullyRead,

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItemSelectionTest.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2026 New Vector 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.messages.impl.timeline.model
+
+import com.google.common.truth.Truth.assertThat
+import io.element.android.features.messages.impl.timeline.aTimelineItemEvent
+import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemRedactedContent
+import io.element.android.features.messages.impl.timeline.model.event.aTimelineItemStateEventContent
+import io.element.android.libraries.matrix.api.timeline.item.event.LocalEventSendState
+import org.junit.Test
+
+class TimelineItemSelectionTest {
+    @Test
+    fun `a remote text message can be selected`() {
+        val item = aTimelineItemEvent()
+        assertThat(item.canBeSelected()).isTrue()
+    }
+
+    @Test
+    fun `a local echo cannot be selected`() {
+        val item = aTimelineItemEvent().copy(eventId = null)
+        assertThat(item.canBeSelected()).isFalse()
+    }
+
+    @Test
+    fun `a failed to send message cannot be selected`() {
+        val item = aTimelineItemEvent(sendState = LocalEventSendState.Failed.Unknown("failed"))
+        assertThat(item.canBeSelected()).isFalse()
+    }
+
+    @Test
+    fun `a state event cannot be selected`() {
+        val item = aTimelineItemEvent(content = aTimelineItemStateEventContent())
+        assertThat(item.canBeSelected()).isFalse()
+    }
+
+    @Test
+    fun `a redacted event cannot be selected`() {
+        val item = aTimelineItemEvent(content = aTimelineItemRedactedContent())
+        assertThat(item.canBeSelected()).isFalse()
+    }
+}

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -161,4 +161,11 @@ enum class FeatureFlags(
         defaultValue = { false },
         isFinished = false,
     ),
+    MessageMultiSelect(
+        key = "feature.message_multi_select",
+        title = "Multi-select messages",
+        description = "Adds a Select action to the message menu to pick several messages at once.",
+        defaultValue = { false },
+        isFinished = false,
+    ),
 }