Add global search backfill worker (#7860)

* Add search backfill worker

This will run on background at most once an hour while the device has internet connectivity and the device is charging and start back-paginating through the user's rooms to make sure the search results are populated.

It'll run for the maximum time the default workers allow, 10 minutes.

* Create `RustMatrixClient.Factory` AssistedFactory to help with DI and add `SearchBackfillService`

* Start search backfill when entering the search screen, just once. This should help getting initial search results if none or few are found at first

features/home/impl/src/main/kotlin/io/element/android/features/home/impl/search/GlobalSearchPresenter.kt

@@ -10,12 +10,14 @@ package io.element.android.features.home.impl.search
 import androidx.compose.foundation.text.input.clearText
 import androidx.compose.foundation.text.input.rememberTextFieldState
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import dev.zacsweers.metro.Inject
 import io.element.android.features.home.impl.search.history.SearchHistoryResult
@@ -38,6 +40,7 @@ import io.element.android.libraries.matrix.api.search.MessageSearch
 import io.element.android.libraries.matrix.api.search.MessageSearchPaginationState
 import io.element.android.libraries.matrix.api.search.MessageSearchResult
 import io.element.android.libraries.matrix.api.search.MessageSearchService
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
 import io.element.android.libraries.matrix.api.timeline.item.event.AudioMessageType
 import io.element.android.libraries.matrix.api.timeline.item.event.FileMessageType
 import io.element.android.libraries.matrix.api.timeline.item.event.ImageMessageType
@@ -81,6 +84,7 @@ class GlobalSearchPresenter(
         val isEnabled by produceState(false) {
             featureFlagService.isFeatureEnabledFlow(FeatureFlags.MessageSearch).collectLatest { value = it }
         }
+
         val roomListSearchDataSource = remember { roomListSearchDataSourceFactory.create(coroutineScope = coroutineScope) }
         val queryState = rememberTextFieldState()
         var isSearchActive by remember { mutableStateOf(false) }
@@ -88,6 +92,8 @@ class GlobalSearchPresenter(
         var currentTarget: GlobalSearchTarget by remember { mutableStateOf(GlobalSearchTarget.ROOMS) }
         val currentMessageSearch: MessageSearch = remember { messageSearchService.createMessageSearch(scope = coroutineScope) }
 
+        StartSearchBackfillWhenVisible(isEnabled = isEnabled, isSearchActive = isSearchActive)
+
         val searchHistory by produceState<AsyncData<ImmutableList<SearchHistoryListItem>>>(initialValue = AsyncData.Uninitialized) {
             searchHistoryStore.history.collectLatest { history ->
                 val mappedHistoryItems = history.mapNotNull { result ->
@@ -297,6 +303,35 @@ class GlobalSearchPresenter(
         )
     }
 
+    @Composable
+    private fun StartSearchBackfillWhenVisible(
+        isEnabled: Boolean,
+        isSearchActive: Boolean,
+    ) {
+        val coroutineScope = rememberCoroutineScope()
+        var hasBackfillRun by rememberSaveable { mutableStateOf(false) }
+        if (isEnabled && isSearchActive && !hasBackfillRun) {
+            DisposableEffect(Unit) {
+                // When we open the message search, we want to backfill the search results so that we can show the user more results if they scroll down.
+                val handle = matrixClient.searchBackfillService.startSearchBackfill(SearchBackfillStrategy.FOREGROUND).getOrNull()
+                    ?: return@DisposableEffect onDispose {
+                        Timber.w("Could not start search backfill, it may already be running.")
+                    }
+
+                val job = coroutineScope.launch(coroutineDispatchers.io) {
+                    while (handle.isRunning()) {
+                        delay(100.milliseconds)
+                    }
+                    hasBackfillRun = true
+                }
+                onDispose {
+                    job.cancel()
+                    handle.close()
+                }
+            }
+        }
+    }
+
     private fun mapMediaContent(
         result: MessageSearchResult,
         roomInfo: RoomInfo,

features/home/impl/src/test/kotlin/io/element/android/features/home/impl/search/GlobalSearchPresenterTest.kt

@@ -33,13 +33,16 @@ import io.element.android.libraries.matrix.api.roomlist.RoomListService
 import io.element.android.libraries.matrix.api.search.MessageSearchService
 import io.element.android.libraries.matrix.test.A_ROOM_ID
 import io.element.android.libraries.matrix.test.FakeMatrixClient
+import io.element.android.libraries.matrix.test.FakeSdkPendingTask
 import io.element.android.libraries.matrix.test.permalink.FakePermalinkParser
 import io.element.android.libraries.matrix.test.room.aRoomSummary
 import io.element.android.libraries.matrix.test.roomlist.FakeDynamicRoomList
 import io.element.android.libraries.matrix.test.roomlist.FakeRoomListService
 import io.element.android.libraries.matrix.test.search.FakeMessageSearch
 import io.element.android.libraries.matrix.test.search.FakeMessageSearchService
+import io.element.android.libraries.matrix.test.search.FakeSearchBackfillService
 import io.element.android.tests.testutils.consumeItemsUntilPredicate
+import io.element.android.tests.testutils.lambda.lambdaRecorder
 import io.element.android.tests.testutils.test
 import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.collections.immutable.persistentListOf
@@ -205,7 +208,9 @@ class GlobalSearchPresenterTest {
     @Test
     fun `present - message search results are mapped when the message search emits`() = runTest {
         val messageSearch = FakeMessageSearch()
-        val matrixClient = FakeMatrixClient().apply {
+        val matrixClient = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(startSearchBackfillLambda = { Result.success(FakeSdkPendingTask()) }),
+        ).apply {
             getRoomInfoLambda = { Result.success(aRoomInfo()) }
         }
         val presenter = createGlobalSearchPresenter(
@@ -232,7 +237,9 @@ class GlobalSearchPresenterTest {
     @Test
     fun `present - message search displays the uninitialized state after removing the query`() = runTest {
         val messageSearch = FakeMessageSearch()
-        val matrixClient = FakeMatrixClient().apply {
+        val matrixClient = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(startSearchBackfillLambda = { Result.success(FakeSdkPendingTask()) }),
+        ).apply {
             getRoomInfoLambda = { Result.success(aRoomInfo()) }
         }
         val presenter = createGlobalSearchPresenter(
@@ -267,7 +274,9 @@ class GlobalSearchPresenterTest {
     @Test
     fun `present - UpdateVisibleRange triggers pagination for messages when near the end`() = runTest {
         val messageSearch = FakeMessageSearch()
-        val matrixClient = FakeMatrixClient().apply {
+        val matrixClient = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(startSearchBackfillLambda = { Result.success(FakeSdkPendingTask()) }),
+        ).apply {
             getRoomInfoLambda = { Result.success(aRoomInfo()) }
         }
         val presenter = createGlobalSearchPresenter(
@@ -432,6 +441,44 @@ class GlobalSearchPresenterTest {
             assertThat(awaitItem().results.isLoading()).isTrue()
         }
     }
+
+    @Test
+    fun `present - will automatically start search backfill and it will be cancelled when the presenter is closed`() = runTest {
+        var isRunning = false
+        val closeLambda = lambdaRecorder<Unit> { isRunning = false }
+        val matrixClient = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(
+                startSearchBackfillLambda = {
+                    isRunning = true
+                    Result.success(FakeSdkPendingTask(isRunningLambda = { isRunning }, closeLambda = closeLambda))
+                },
+            ),
+        )
+        val presenter = createGlobalSearchPresenter(
+            matrixClient = matrixClient,
+            featureFlagService = FakeFeatureFlagService(
+                initialState = mapOf(FeatureFlags.MessageSearch.key to true),
+            ),
+        )
+        presenter.test {
+            // Await the initial state, with the feature enabled
+            val initialState = consumeItemsUntilPredicate { it.isEnabled }.last()
+            assertThat(isRunning).isFalse()
+
+            // Opening the search starts the backfill
+            initialState.eventSink(GlobalSearchEvent.ToggleSearchVisibility)
+            consumeItemsUntilPredicate { it.isSearchActive }
+            // The backfill polling loop never ends while the task is running, so don't wait until the scheduler is idle
+            testScheduler.runCurrent()
+            assertThat(isRunning).isTrue()
+            closeLambda.assertions().isNeverCalled()
+
+            // Closing the presenter closes the task
+            cancelAndIgnoreRemainingEvents()
+            closeLambda.assertions().isCalledOnce()
+            assertThat(isRunning).isFalse()
+        }
+    }
 }
 
 private fun TestScope.createGlobalSearchPresenter(
@@ -442,7 +489,8 @@ private fun TestScope.createGlobalSearchPresenter(
     dateFormatter: DateFormatter = FakeDateFormatter(),
     fileSizeFormatter: FileSizeFormatter = FakeFileSizeFormatter(),
     permalinkParser: PermalinkParser = FakePermalinkParser(),
-    matrixClient: MatrixClient = FakeMatrixClient(),
+    matrixClient: MatrixClient =
+    FakeMatrixClient(searchBackfillService = FakeSearchBackfillService(startSearchBackfillLambda = { Result.success(FakeSdkPendingTask()) })),
     searchHistoryStore: SearchHistoryStore = FakeSearchHistoryStore(),
 ): GlobalSearchPresenter {
     return GlobalSearchPresenter(

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

@@ -40,6 +40,7 @@ import io.element.android.libraries.matrix.api.roomdirectory.RoomDirectoryServic
 import io.element.android.libraries.matrix.api.roomlist.RoomListService
 import io.element.android.libraries.matrix.api.scanner.ContentScanner
 import io.element.android.libraries.matrix.api.search.MessageSearchService
+import io.element.android.libraries.matrix.api.search.SearchBackfillService
 import io.element.android.libraries.matrix.api.spaces.SpaceService
 import io.element.android.libraries.matrix.api.sync.SlidingSyncVersion
 import io.element.android.libraries.matrix.api.sync.SyncService
@@ -133,6 +134,9 @@ interface MatrixClient : ClientUrlContentFetcher {
     /** Scans media content before it is displayed, or `null` when no content scanner is configured for this session. */
     val contentScanner: ContentScanner?
 
+    /** Backfills messages from the homeserver for searching for messages in a room. */
+    val searchBackfillService: SearchBackfillService
+
     /** Whether the session is in the process of shutting down, either because it is being logged out or its cache is being cleared. */
     val isShuttingDown: Boolean
 

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/SdkPendingTask.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.libraries.matrix.api
+
+/**
+ * Represents a pending task in the SDK that can be canceled and closed.
+ */
+interface SdkPendingTask : AutoCloseable {
+    /** Checks if the task is still running. */
+    fun isRunning(): Boolean
+}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/search/SearchBackfillService.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.api.search
+
+import io.element.android.libraries.matrix.api.SdkPendingTask
+
+/**
+ * Service interface for managing search backfill tasks in the Matrix SDK.
+ * This service allows starting, checking the status of, and canceling search backfill tasks.
+ */
+interface SearchBackfillService {
+    /**
+     * Enqueues a periodic search backfill task based on the provided strategy.
+     * The strategy parameter determines how the backfill should be performed (e.g., in the foreground or background).
+     */
+    suspend fun schedulePeriodicSearchBackfill(strategy: SearchBackfillStrategy): Result<Unit>
+
+    /**
+     * Cancels any currently scheduled periodic search backfill tasks.
+     */
+    fun cancelPeriodicSearchBackfill()
+
+    /**
+     * Starts a background task to backfill messages for rooms that have been joined but not fully backfilled yet.
+     * The strategy parameter determines how the backfill should be performed (e.g., in the foreground or background).
+     *
+     * @param strategy the strategy to use for backfilling messages.
+     * @return a [Result] indicating the success or failure of enqueuing the backfill task.
+     */
+    fun startSearchBackfill(strategy: SearchBackfillStrategy): Result<SdkPendingTask>
+
+    /**
+     * Checks if a search backfill task is currently running.
+     *
+     * @return `true` if a search backfill task is running, `false` otherwise.
+     */
+    fun isSearchBackfillRunning(): Boolean
+
+    /**
+     * Cancels the currently running search backfill task, if any.
+     *
+     * @return a [Result] indicating the success or failure of the cancellation operation.
+     */
+    fun cancelSearchBackfill(): Result<Unit>
+}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/search/SearchBackfillStrategy.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.api.search
+
+enum class SearchBackfillStrategy {
+    /**
+     * The app is in the foreground: pause between paginations so this doesn't
+     * compete with interactive traffic.
+     */
+    FOREGROUND,
+
+    /**
+     * A time-boxed background task (e.g. iOS `BGAppRefreshTask`) where there's
+     * no interactive traffic to protect.
+     */
+    BACKGROUND
+}

libraries/matrix/impl/build.gradle.kts

@@ -63,6 +63,7 @@ dependencies {
 
     implementation(projects.appconfig)
     implementation(projects.features.enterprise.api)
+    implementation(projects.features.networkmonitor.api)
     implementation(projects.libraries.androidutils)
     implementation(projects.libraries.architecture)
     implementation(projects.libraries.di)
@@ -80,6 +81,7 @@ dependencies {
 
     testCommonDependencies(libs)
     testImplementation(projects.features.enterprise.test)
+    testImplementation(projects.features.networkmonitor.test)
     testImplementation(projects.libraries.featureflag.test)
     testImplementation(projects.libraries.matrix.test)
     testImplementation(projects.libraries.previewutils)

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

@@ -8,6 +8,9 @@
 
 package io.element.android.libraries.matrix.impl
 
+import dev.zacsweers.metro.Assisted
+import dev.zacsweers.metro.AssistedFactory
+import dev.zacsweers.metro.AssistedInject
 import io.element.android.libraries.androidutils.file.getSizeOfFiles
 import io.element.android.libraries.core.bool.orFalse
 import io.element.android.libraries.core.coroutine.CoroutineDispatchers
@@ -16,7 +19,9 @@ import io.element.android.libraries.core.data.bytes
 import io.element.android.libraries.core.data.tryOrNull
 import io.element.android.libraries.core.extensions.mapFailure
 import io.element.android.libraries.core.extensions.runCatchingExceptions
+import io.element.android.libraries.di.annotations.AppCoroutineScope
 import io.element.android.libraries.featureflag.api.FeatureFlagService
+import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.matrix.api.HomeserverCapabilitiesProvider
 import io.element.android.libraries.matrix.api.MatrixClient
 import io.element.android.libraries.matrix.api.analytics.SdkStoreSizes
@@ -47,6 +52,7 @@ import io.element.android.libraries.matrix.api.room.join.JoinRule
 import io.element.android.libraries.matrix.api.roomdirectory.RoomVisibility
 import io.element.android.libraries.matrix.api.roomlist.RoomListService
 import io.element.android.libraries.matrix.api.scanner.ContentScanner
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
 import io.element.android.libraries.matrix.api.spaces.SpaceService
 import io.element.android.libraries.matrix.api.sync.SlidingSyncVersion
 import io.element.android.libraries.matrix.api.sync.SyncState
@@ -81,6 +87,8 @@ import io.element.android.libraries.matrix.impl.roomlist.RoomListFactory
 import io.element.android.libraries.matrix.impl.roomlist.RustRoomListService
 import io.element.android.libraries.matrix.impl.roomlist.roomOrNull
 import io.element.android.libraries.matrix.impl.search.RustMessageSearchService
+import io.element.android.libraries.matrix.impl.search.RustSearchBackfillService
+import io.element.android.libraries.matrix.impl.search.map
 import io.element.android.libraries.matrix.impl.spaces.RustSpaceService
 import io.element.android.libraries.matrix.impl.sync.RustSyncService
 import io.element.android.libraries.matrix.impl.sync.map
@@ -110,8 +118,10 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.buffer
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.mapNotNull
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.runBlocking
@@ -149,23 +159,37 @@ import org.matrix.rustcomponents.sdk.SyncService as ClientSyncService
 private const val AVATAR_THUMBNAIL_SIZE_IN_PIXEL = 240L
 
 @Suppress("LargeClass")
+@AssistedInject
 class RustMatrixClient(
-    override val sessionPaths: SessionPaths,
-    val innerClient: Client,
+    @Assisted override val sessionPaths: SessionPaths,
+    @Assisted val innerClient: Client,
+    @Assisted private val innerSyncService: ClientSyncService,
+    @Assisted baseCacheDirectory: File,
+    @Assisted override val contentScanner: ContentScanner?,
+    @Assisted override val isMessageSearchAvailable: Boolean,
+    @Assisted private val sessionDelegate: RustClientSessionDelegate,
     private val sessionStore: SessionStore,
-    private val sessionDelegate: RustClientSessionDelegate,
-    private val innerSyncService: ClientSyncService,
-    appCoroutineScope: CoroutineScope,
+    @AppCoroutineScope appCoroutineScope: CoroutineScope,
     dispatchers: CoroutineDispatchers,
-    baseCacheDirectory: File,
     clock: SystemClock,
     timelineEventFilterFactory: TimelineEventFilterFactory,
     private val featureFlagService: FeatureFlagService,
     private val analyticsService: AnalyticsService,
     private val workManagerScheduler: WorkManagerScheduler,
-    override val contentScanner: ContentScanner?,
-    override val isMessageSearchAvailable: Boolean,
+    private val searchBackfillServiceFactory: RustSearchBackfillService.Factory,
 ) : MatrixClient {
+    @AssistedFactory
+    interface Factory {
+        fun create(
+            sessionPaths: SessionPaths,
+            innerClient: Client,
+            innerSyncService: ClientSyncService,
+            baseCacheDirectory: File,
+            contentScanner: ContentScanner?,
+            isMessageSearchAvailable: Boolean,
+            sessionDelegate: RustClientSessionDelegate,
+        ): RustMatrixClient
+    }
     override val sessionId: UserId = UserId(innerClient.userId())
     override val deviceId: DeviceId = DeviceId(innerClient.deviceId())
     override val server: String? = innerClient.server()
@@ -280,6 +304,8 @@ class RustMatrixClient(
 
     private var clientDelegateTaskHandle: TaskHandle? = innerClient.setDelegate(sessionDelegate)
 
+    override val searchBackfillService = searchBackfillServiceFactory.create(innerClient)
+
     private val _userProfile: MutableStateFlow<MatrixUser> = MutableStateFlow(
         MatrixUser(
             userId = sessionId,
@@ -332,6 +358,9 @@ class RustMatrixClient(
 
         // Schedule regular database vacuuming to ensure DB performance remains optimal
         scheduleDatabaseVacuum()
+
+        // Schedule background search backfill if needed
+        scheduleBackgroundSearchBackfill()
     }
 
     private suspend fun setupUserProfile() {
@@ -687,6 +716,7 @@ class RustMatrixClient(
         sessionCoroutineScope.cancel()
         clientDelegateTaskHandle?.cancelAndDestroy()
         ownProfileTaskHandle?.cancelAndDestroy()
+        searchBackfillService.cancelSearchBackfill()
         sessionVerificationService.destroy()
 
         sessionDelegate.clearCurrentClient()
@@ -992,6 +1022,19 @@ class RustMatrixClient(
     override fun homeserverCapabilities(): HomeserverCapabilitiesProvider {
         return RustHomeserverCapabilitiesProvider(innerClient.homeserverCapabilities())
     }
+
+    private fun scheduleBackgroundSearchBackfill() {
+        featureFlagService.isFeatureEnabledFlow(FeatureFlags.MessageSearch)
+            .distinctUntilChanged()
+            .onEach { isEnabled ->
+                if (isEnabled) {
+                    searchBackfillService.schedulePeriodicSearchBackfill(SearchBackfillStrategy.BACKGROUND)
+                } else {
+                    searchBackfillService.cancelPeriodicSearchBackfill()
+                }
+            }
+            .launchIn(sessionCoroutineScope)
+    }
 }
 
 private fun defaultRoomCreationPowerLevels(isPublic: Boolean, isSpace: Boolean) = PowerLevels(

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

@@ -23,16 +23,13 @@ import io.element.android.libraries.matrix.api.paths.SessionPaths
 import io.element.android.libraries.matrix.impl.analytics.UtdTracker
 import io.element.android.libraries.matrix.impl.paths.getSessionPaths
 import io.element.android.libraries.matrix.impl.proxy.ProxyProvider
-import io.element.android.libraries.matrix.impl.room.TimelineEventFilterFactory
 import io.element.android.libraries.matrix.impl.scanner.RustContentScanner
 import io.element.android.libraries.matrix.impl.storage.SqliteStoreBuilderProvider
 import io.element.android.libraries.matrix.impl.util.anonymizedTokens
 import io.element.android.libraries.network.useragent.UserAgentProvider
 import io.element.android.libraries.sessionstorage.api.SessionData
 import io.element.android.libraries.sessionstorage.api.SessionStore
-import io.element.android.libraries.workmanager.api.WorkManagerScheduler
 import io.element.android.services.analytics.api.AnalyticsService
-import io.element.android.services.toolbox.api.systemclock.SystemClock
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.withContext
 import org.matrix.rustcomponents.sdk.ClientBuilder
@@ -61,14 +58,12 @@ class RustMatrixClientFactory(
     private val sessionStore: SessionStore,
     private val userAgentProvider: UserAgentProvider,
     private val proxyProvider: ProxyProvider,
-    private val clock: SystemClock,
     private val analyticsService: AnalyticsService,
     private val featureFlagService: FeatureFlagService,
-    private val timelineEventFilterFactory: TimelineEventFilterFactory,
     private val clientBuilderProvider: ClientBuilderProvider,
     private val sqliteStoreBuilderProvider: SqliteStoreBuilderProvider,
-    private val workManagerScheduler: WorkManagerScheduler,
     private val clientBuilderEnterpriseHook: ClientBuilderEnterpriseHook,
+    private val innerMatrixClientFactory: RustMatrixClient.Factory,
 ) {
     private val sessionDelegate = RustClientSessionDelegate(
         sessionStore = sessionStore,
@@ -131,22 +126,14 @@ class RustMatrixClientFactory(
             .withOfflineMode()
             .finish()
 
-        RustMatrixClient(
+        innerMatrixClientFactory.create(
             sessionPaths = sessionData.getSessionPaths(),
             innerClient = client,
-            sessionStore = sessionStore,
-            appCoroutineScope = appCoroutineScope,
-            sessionDelegate = sessionDelegate,
             innerSyncService = syncService,
-            dispatchers = coroutineDispatchers,
             baseCacheDirectory = cacheDirectory,
-            clock = clock,
-            timelineEventFilterFactory = timelineEventFilterFactory,
-            featureFlagService = featureFlagService,
-            analyticsService = analyticsService,
-            workManagerScheduler = workManagerScheduler,
             contentScanner = client.contentScanner()?.let { RustContentScanner(client, it) },
             isMessageSearchAvailable = isMessageSearchAvailable,
+            sessionDelegate = sessionDelegate,
         ).also {
             Timber.tag("RustMatrixClient").i("Creating Client with access token '$anonymizedAccessToken' and refresh token '$anonymizedRefreshToken'")
         }

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

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl
+
+import io.element.android.libraries.matrix.api.SdkPendingTask
+import io.element.android.libraries.matrix.impl.util.cancelAndDestroy
+import org.matrix.rustcomponents.sdk.TaskHandle
+import java.util.concurrent.atomic.AtomicBoolean
+
+class RustSdkPendingTask(
+    private val taskHandle: TaskHandle,
+) : SdkPendingTask {
+    private val closed = AtomicBoolean(false)
+
+    override fun isRunning(): Boolean = !closed.get() && !taskHandle.isFinished()
+
+    override fun close() {
+        if (!closed.getAndSet(true)) {
+            taskHandle.cancelAndDestroy()
+        }
+    }
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/search/RustSearchBackfillService.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search
+
+import dev.zacsweers.metro.Assisted
+import dev.zacsweers.metro.AssistedFactory
+import dev.zacsweers.metro.AssistedInject
+import io.element.android.libraries.core.extensions.runCatchingExceptions
+import io.element.android.libraries.matrix.api.SdkPendingTask
+import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.search.SearchBackfillService
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
+import io.element.android.libraries.matrix.impl.RustSdkPendingTask
+import io.element.android.libraries.matrix.impl.search.workmanager.SearchBackfillRequestBuilder
+import io.element.android.libraries.workmanager.api.WorkManagerRequestType
+import io.element.android.libraries.workmanager.api.WorkManagerScheduler
+import org.matrix.rustcomponents.sdk.Client
+import timber.log.Timber
+import java.util.concurrent.atomic.AtomicReference
+
+@AssistedInject
+class RustSearchBackfillService(
+    @Assisted private val innerClient: Client,
+    private val searchBackfillRequestBuilderFactory: SearchBackfillRequestBuilder.Factory,
+    private val workManagerScheduler: WorkManagerScheduler,
+) : SearchBackfillService {
+    @AssistedFactory
+    interface Factory {
+        fun create(innerClient: Client): RustSearchBackfillService
+    }
+
+    private val currentSearchBackfillTaskHandle: AtomicReference<SdkPendingTask?> = AtomicReference(null)
+
+    override suspend fun schedulePeriodicSearchBackfill(strategy: SearchBackfillStrategy): Result<Unit> = runCatchingExceptions {
+        val sessionId = SessionId(innerClient.userId())
+        if (workManagerScheduler.hasPendingWork(sessionId, WorkManagerRequestType.SEARCH_BACKFILL)) {
+            Timber.d("Background search backfill already scheduled for session $sessionId")
+            return@runCatchingExceptions
+        }
+        Timber.d("Scheduling background search backfill for session $sessionId")
+        val builder = searchBackfillRequestBuilderFactory.create(sessionId)
+        workManagerScheduler.submit(builder)
+    }
+
+    override fun cancelPeriodicSearchBackfill() {
+        val sessionId = SessionId(innerClient.userId())
+        Timber.d("Cancelling background search backfill for session $sessionId")
+        workManagerScheduler.cancel(sessionId, WorkManagerRequestType.SEARCH_BACKFILL)
+    }
+
+    override fun startSearchBackfill(strategy: SearchBackfillStrategy): Result<SdkPendingTask> = runCatchingExceptions {
+        if (currentSearchBackfillTaskHandle.get()?.isRunning() == true) {
+            error("Search backfill is already running")
+        }
+        RustSdkPendingTask(innerClient.runSearchBackfill(strategy.map()))
+            .also { currentSearchBackfillTaskHandle.set(it) }
+    }
+
+    override fun isSearchBackfillRunning(): Boolean {
+        return currentSearchBackfillTaskHandle.get()?.isRunning() ?: false
+    }
+
+    override fun cancelSearchBackfill(): Result<Unit> = runCatchingExceptions {
+        currentSearchBackfillTaskHandle.getAndSet(null)?.close()
+    }
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/search/SearchBackfillStrategyMapping.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search
+
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
+import uniffi.matrix_sdk.SearchBackfillStrategy as RustSearchBackfillStrategy
+
+fun RustSearchBackfillStrategy.map(): SearchBackfillStrategy = when (this) {
+    RustSearchBackfillStrategy.FOREGROUND -> SearchBackfillStrategy.FOREGROUND
+    RustSearchBackfillStrategy.BACKGROUND -> SearchBackfillStrategy.BACKGROUND
+}
+
+fun SearchBackfillStrategy.map(): RustSearchBackfillStrategy = when (this) {
+    SearchBackfillStrategy.FOREGROUND -> RustSearchBackfillStrategy.FOREGROUND
+    SearchBackfillStrategy.BACKGROUND -> RustSearchBackfillStrategy.BACKGROUND
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/search/workmanager/SearchBackfillRequestBuilder.kt

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search.workmanager
+
+import android.net.NetworkCapabilities
+import android.net.NetworkRequest
+import androidx.work.Constraints
+import androidx.work.NetworkType
+import androidx.work.PeriodicWorkRequestBuilder
+import androidx.work.workDataOf
+import dev.zacsweers.metro.AppScope
+import dev.zacsweers.metro.Assisted
+import dev.zacsweers.metro.AssistedFactory
+import dev.zacsweers.metro.AssistedInject
+import dev.zacsweers.metro.ContributesBinding
+import io.element.android.features.networkmonitor.api.NetworkMonitor
+import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.impl.search.workmanager.SearchBackfillWorker.Companion.SESSION_ID_PARAM
+import io.element.android.libraries.workmanager.api.WorkManagerRequestBuilder
+import io.element.android.libraries.workmanager.api.WorkManagerRequestType
+import io.element.android.libraries.workmanager.api.WorkManagerRequestWrapper
+import io.element.android.libraries.workmanager.api.WorkManagerWorkerType
+import io.element.android.libraries.workmanager.api.workManagerTag
+import kotlinx.coroutines.flow.first
+import timber.log.Timber
+import kotlin.time.Duration.Companion.hours
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.toJavaDuration
+
+interface SearchBackfillRequestBuilder : WorkManagerRequestBuilder {
+    fun interface Factory {
+        fun create(sessionId: SessionId): SearchBackfillRequestBuilder
+    }
+}
+
+/**
+ * Builds a work request that runs the search backfill (back paginations) only when there is network connectivity and the device is charging.
+ */
+@AssistedInject
+class DefaultSearchBackfillRequestBuilder(
+    @Assisted private val sessionId: SessionId,
+    private val networkMonitor: NetworkMonitor,
+) : SearchBackfillRequestBuilder {
+    @AssistedFactory
+    @ContributesBinding(AppScope::class)
+    interface Factory : SearchBackfillRequestBuilder.Factory {
+        override fun create(sessionId: SessionId): DefaultSearchBackfillRequestBuilder
+    }
+
+    override suspend fun build(): Result<List<WorkManagerRequestWrapper>> {
+        val tag = workManagerTag(sessionId, WorkManagerRequestType.SEARCH_BACKFILL)
+        val type = WorkManagerWorkerType.Default
+
+        val networkRequestBuilder = NetworkRequest.Builder()
+            // Only allow unmetered networks to avoid using mobile data for backfilling.
+            .addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED)
+            // Some customers use a VPN to connect to their homeserver, so VPN networks must be allowed.
+            .removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)
+
+        // In an air-gapped environment, validating internet connectivity would fail and the worker would never run.
+        if (networkMonitor.isInAirGappedEnvironment.first()) {
+            Timber.d("In an air-gapped environment, not adding NET_CAPABILITY_VALIDATED to the network request")
+            networkRequestBuilder.removeCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
+        } else {
+            networkRequestBuilder.addCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
+        }
+
+        val constraints = Constraints.Builder()
+            .setRequiredNetworkRequest(networkRequestBuilder.build(), NetworkType.UNMETERED)
+            .setRequiresCharging(true)
+            .build()
+
+        val request = PeriodicWorkRequestBuilder<SearchBackfillWorker>(1.hours.toJavaDuration())
+            // Add a delay before the first execution to avoid running the backfill immediately after the app starts
+            .setInitialDelay(5.minutes.toJavaDuration())
+            .setInputData(workDataOf(SESSION_ID_PARAM to sessionId.value))
+            .addTag(tag)
+            .setConstraints(constraints)
+            .build()
+
+        return Result.success(listOf(WorkManagerRequestWrapper(request, type)))
+    }
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/search/workmanager/SearchBackfillWorker.kt

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search.workmanager
+
+import android.content.Context
+import androidx.work.CoroutineWorker
+import androidx.work.WorkerParameters
+import dev.zacsweers.metro.AppScope
+import dev.zacsweers.metro.Assisted
+import dev.zacsweers.metro.AssistedFactory
+import dev.zacsweers.metro.AssistedInject
+import dev.zacsweers.metro.ContributesIntoMap
+import dev.zacsweers.metro.binding
+import io.element.android.libraries.di.annotations.ApplicationContext
+import io.element.android.libraries.matrix.api.MatrixClientProvider
+import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
+import io.element.android.libraries.workmanager.api.di.MetroWorkerFactory
+import io.element.android.libraries.workmanager.api.di.WorkerKey
+import kotlinx.coroutines.TimeoutCancellationException
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.withTimeout
+import timber.log.Timber
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+
+@AssistedInject
+class SearchBackfillWorker(
+    @Assisted params: WorkerParameters,
+    @ApplicationContext context: Context,
+    private val matrixClientProvider: MatrixClientProvider,
+) : CoroutineWorker(context, params) {
+    companion object {
+        const val SESSION_ID_PARAM = "session_id"
+        private val TIMEOUT = 10.minutes
+        private val POLL_INTERVAL = 5.seconds
+    }
+
+    override suspend fun doWork(): Result {
+        Timber.d("Starting search backfill. This will run up to $TIMEOUT")
+        val sessionId = inputData.getString(SESSION_ID_PARAM)?.let(::SessionId) ?: return Result.failure()
+        val client = matrixClientProvider.getOrRestore(sessionId).getOrNull() ?: return Result.failure()
+
+        if (client.searchBackfillService.isSearchBackfillRunning()) {
+            Timber.d("Search backfill is already running for session $sessionId, nothing to do")
+            return Result.success()
+        }
+
+        Timber.d("Starting search backfill for session $sessionId")
+        val task = client.searchBackfillService.startSearchBackfill(SearchBackfillStrategy.BACKGROUND).getOrElse {
+            Timber.e(it, "Failed to start search backfill")
+            return Result.failure()
+        }
+
+        return task.use {
+            try {
+                withTimeout(TIMEOUT) {
+                    while (task.isRunning()) {
+                        delay(POLL_INTERVAL)
+                    }
+                }
+                Timber.d("Search backfill finished")
+                Result.success()
+            } catch (_: TimeoutCancellationException) {
+                Timber.d("Search backfill timed out after $TIMEOUT, cancelling it")
+                // Run again later to continue backfilling.
+                Result.retry()
+            }
+        }
+    }
+
+    @ContributesIntoMap(AppScope::class, binding = binding<MetroWorkerFactory.WorkerInstanceFactory<*>>())
+    @WorkerKey(SearchBackfillWorker::class)
+    @AssistedFactory
+    interface Factory : MetroWorkerFactory.WorkerInstanceFactory<SearchBackfillWorker>
+}

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClientFactoryTest.kt

@@ -12,8 +12,12 @@ import com.google.common.truth.Truth.assertThat
 import io.element.android.features.enterprise.test.FakeClientBuilderEnterpriseHook
 import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.paths.SessionPaths
+import io.element.android.libraries.matrix.api.scanner.ContentScanner
 import io.element.android.libraries.matrix.impl.auth.FakeProxyProvider
 import io.element.android.libraries.matrix.impl.room.FakeTimelineEventFilterFactory
+import io.element.android.libraries.matrix.impl.search.RustSearchBackfillService
+import io.element.android.libraries.matrix.impl.search.workmanager.SearchBackfillRequestBuilder
 import io.element.android.libraries.matrix.impl.storage.FakeSqliteStoreBuilderProvider
 import io.element.android.libraries.matrix.impl.storage.SqliteStoreBuilderProvider
 import io.element.android.libraries.network.useragent.SimpleUserAgentProvider
@@ -21,6 +25,7 @@ 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.libraries.workmanager.api.WorkManagerRequestBuilder
+import io.element.android.libraries.workmanager.api.WorkManagerRequestWrapper
 import io.element.android.libraries.workmanager.test.FakeWorkManagerScheduler
 import io.element.android.services.analytics.test.FakeAnalyticsService
 import io.element.android.services.toolbox.test.systemclock.FakeSystemClock
@@ -29,13 +34,15 @@ import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.coroutines.test.TestScope
 import kotlinx.coroutines.test.runTest
 import org.junit.Test
+import org.matrix.rustcomponents.sdk.Client
 import java.io.File
+import org.matrix.rustcomponents.sdk.SyncService as ClientSyncService
 
 class RustMatrixClientFactoryTest {
     @Test
     fun test() = runTest {
         val scheduleVacuumLambda = lambdaRecorder<WorkManagerRequestBuilder, Unit> {}
-        val workManagerScheduler = FakeWorkManagerScheduler(submitLambda = scheduleVacuumLambda)
+        val workManagerScheduler = FakeWorkManagerScheduler(submitLambda = scheduleVacuumLambda, cancelLambda = { _, _ -> })
         val sut = createRustMatrixClientFactory(workManagerScheduler = workManagerScheduler)
 
         val result = sut.create(aSessionData())
@@ -52,7 +59,7 @@ fun TestScope.createRustMatrixClientFactory(
         updateUserProfileResult = { _, _, _, _ -> },
     ),
     clientBuilderProvider: ClientBuilderProvider = FakeClientBuilderProvider(),
-    workManagerScheduler: FakeWorkManagerScheduler = FakeWorkManagerScheduler(),
+    workManagerScheduler: FakeWorkManagerScheduler = FakeWorkManagerScheduler(cancelLambda = { _, _ -> }),
     sqliteStoreBuilderProvider: SqliteStoreBuilderProvider = FakeSqliteStoreBuilderProvider(),
 ) = RustMatrixClientFactory(
     cacheDirectory = cacheDirectory,
@@ -61,12 +68,52 @@ fun TestScope.createRustMatrixClientFactory(
     sessionStore = sessionStore,
     userAgentProvider = SimpleUserAgentProvider(),
     proxyProvider = FakeProxyProvider(),
-    clock = FakeSystemClock(),
     analyticsService = FakeAnalyticsService(),
     featureFlagService = FakeFeatureFlagService(),
-    timelineEventFilterFactory = FakeTimelineEventFilterFactory(),
     clientBuilderProvider = clientBuilderProvider,
     sqliteStoreBuilderProvider = sqliteStoreBuilderProvider,
-    workManagerScheduler = workManagerScheduler,
     clientBuilderEnterpriseHook = FakeClientBuilderEnterpriseHook(),
+    innerMatrixClientFactory = createRustMatrixClientInnerFactory(sessionStore, workManagerScheduler),
 )
+
+private fun TestScope.createRustMatrixClientInnerFactory(
+    sessionStore: SessionStore,
+    workManagerScheduler: FakeWorkManagerScheduler,
+) = object : RustMatrixClient.Factory {
+    override fun create(
+        sessionPaths: SessionPaths,
+        innerClient: Client,
+        innerSyncService: ClientSyncService,
+        baseCacheDirectory: File,
+        contentScanner: ContentScanner?,
+        isMessageSearchAvailable: Boolean,
+        sessionDelegate: RustClientSessionDelegate,
+    ) = RustMatrixClient(
+        sessionPaths = sessionPaths,
+        innerClient = innerClient,
+        innerSyncService = innerSyncService,
+        baseCacheDirectory = baseCacheDirectory,
+        contentScanner = contentScanner,
+        isMessageSearchAvailable = isMessageSearchAvailable,
+        sessionDelegate = sessionDelegate,
+        sessionStore = sessionStore,
+        appCoroutineScope = backgroundScope,
+        dispatchers = testCoroutineDispatchers(),
+        clock = FakeSystemClock(),
+        timelineEventFilterFactory = FakeTimelineEventFilterFactory(),
+        featureFlagService = FakeFeatureFlagService(),
+        analyticsService = FakeAnalyticsService(),
+        workManagerScheduler = workManagerScheduler,
+        searchBackfillServiceFactory = object : RustSearchBackfillService.Factory {
+            override fun create(innerClient: Client) = RustSearchBackfillService(
+                innerClient = innerClient,
+                searchBackfillRequestBuilderFactory = {
+                    object : SearchBackfillRequestBuilder {
+                        override suspend fun build(): Result<List<WorkManagerRequestWrapper>> = Result.success(emptyList())
+                    }
+                },
+                workManagerScheduler = workManagerScheduler,
+            )
+        },
+    )
+}

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClientTest.kt

@@ -18,6 +18,8 @@ import io.element.android.libraries.matrix.impl.fixtures.factories.aRustUserProf
 import io.element.android.libraries.matrix.impl.fixtures.fakes.FakeFfiClient
 import io.element.android.libraries.matrix.impl.fixtures.fakes.FakeFfiSyncService
 import io.element.android.libraries.matrix.impl.room.FakeTimelineEventFilterFactory
+import io.element.android.libraries.matrix.impl.search.RustSearchBackfillService
+import io.element.android.libraries.matrix.impl.search.workmanager.SearchBackfillRequestBuilder
 import io.element.android.libraries.matrix.test.AN_AVATAR_URL
 import io.element.android.libraries.matrix.test.A_DEVICE_ID
 import io.element.android.libraries.matrix.test.A_ROOM_ID
@@ -27,6 +29,7 @@ import io.element.android.libraries.matrix.test.scanner.FakeContentScanner
 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.libraries.workmanager.api.WorkManagerRequestWrapper
 import io.element.android.libraries.workmanager.test.FakeWorkManagerScheduler
 import io.element.android.services.analytics.test.FakeAnalyticsService
 import io.element.android.services.toolbox.test.systemclock.FakeSystemClock
@@ -325,8 +328,19 @@ class RustMatrixClientTest {
         timelineEventFilterFactory = FakeTimelineEventFilterFactory(),
         featureFlagService = FakeFeatureFlagService(),
         analyticsService = FakeAnalyticsService(),
-        workManagerScheduler = FakeWorkManagerScheduler(submitLambda = {}),
+        workManagerScheduler = FakeWorkManagerScheduler(submitLambda = {}, cancelLambda = { _, _ -> }),
         contentScanner = FakeContentScanner(),
         isMessageSearchAvailable = false,
+        searchBackfillServiceFactory = object : RustSearchBackfillService.Factory {
+            override fun create(innerClient: Client) = RustSearchBackfillService(
+                innerClient = innerClient,
+                searchBackfillRequestBuilderFactory = {
+                    object : SearchBackfillRequestBuilder {
+                        override suspend fun build(): Result<List<WorkManagerRequestWrapper>> = Result.success(emptyList())
+                    }
+                },
+                workManagerScheduler = FakeWorkManagerScheduler(submitLambda = {}, cancelLambda = { _, _ -> }),
+            )
+        },
     )
 }

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/RustTemporaryMatrixClientFactoryTest.kt

@@ -8,19 +8,7 @@
 package io.element.android.libraries.matrix.impl
 
 import com.google.common.truth.Truth.assertThat
-import io.element.android.features.enterprise.test.FakeClientBuilderEnterpriseHook
-import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
-import io.element.android.libraries.matrix.impl.auth.FakeProxyProvider
 import io.element.android.libraries.matrix.impl.paths.SessionPathsFactory
-import io.element.android.libraries.matrix.impl.room.FakeTimelineEventFilterFactory
-import io.element.android.libraries.matrix.impl.storage.FakeSqliteStoreBuilderProvider
-import io.element.android.libraries.network.useragent.SimpleUserAgentProvider
-import io.element.android.libraries.sessionstorage.api.SessionStore
-import io.element.android.libraries.sessionstorage.test.InMemorySessionStore
-import io.element.android.libraries.workmanager.test.FakeWorkManagerScheduler
-import io.element.android.services.analytics.test.FakeAnalyticsService
-import io.element.android.services.toolbox.test.systemclock.FakeSystemClock
-import io.element.android.tests.testutils.testCoroutineDispatchers
 import kotlinx.coroutines.test.TestScope
 import kotlinx.coroutines.test.runTest
 import org.junit.Test
@@ -56,28 +44,4 @@ class RustTemporaryMatrixClientFactoryTest {
             rustMatrixClientFactory = rustMatrixClientFactory,
         )
     }
-
-    private fun TestScope.createRustMatrixClientFactory(
-        cacheDirectory: File = File("/cache"),
-        sessionStore: SessionStore = InMemorySessionStore(
-            updateUserProfileResult = { _, _, _, _ -> },
-        ),
-        clientBuilderProvider: ClientBuilderProvider = FakeClientBuilderProvider(),
-        workManagerScheduler: FakeWorkManagerScheduler = FakeWorkManagerScheduler(),
-    ) = RustMatrixClientFactory(
-        cacheDirectory = cacheDirectory,
-        appCoroutineScope = backgroundScope,
-        coroutineDispatchers = testCoroutineDispatchers(),
-        sessionStore = sessionStore,
-        userAgentProvider = SimpleUserAgentProvider(),
-        proxyProvider = FakeProxyProvider(),
-        clock = FakeSystemClock(),
-        analyticsService = FakeAnalyticsService(),
-        featureFlagService = FakeFeatureFlagService(),
-        timelineEventFilterFactory = FakeTimelineEventFilterFactory(),
-        clientBuilderProvider = clientBuilderProvider,
-        sqliteStoreBuilderProvider = FakeSqliteStoreBuilderProvider(),
-        workManagerScheduler = workManagerScheduler,
-        clientBuilderEnterpriseHook = FakeClientBuilderEnterpriseHook(),
-    )
 }

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/auth/RustMatrixAuthenticationServiceTest.kt

@@ -265,7 +265,7 @@ class RustMatrixAuthenticationServiceTest {
             cacheDirectory = File("/cache"),
             sessionStore = sessionStore,
             clientBuilderProvider = clientBuilderProvider,
-            workManagerScheduler = FakeWorkManagerScheduler(submitLambda = {}),
+            workManagerScheduler = FakeWorkManagerScheduler(submitLambda = {}, cancelLambda = { _, _ -> }),
             sqliteStoreBuilderProvider = sqliteStoreBuilderProvider,
         )
         return RustMatrixAuthenticationService(

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/fixtures/fakes/FakeFfiClient.kt

@@ -45,6 +45,7 @@ import org.matrix.rustcomponents.sdk.SyncServiceBuilder
 import org.matrix.rustcomponents.sdk.TaskHandle
 import org.matrix.rustcomponents.sdk.UnableToDecryptDelegate
 import org.matrix.rustcomponents.sdk.UserProfile
+import uniffi.matrix_sdk.SearchBackfillStrategy
 import uniffi.matrix_sdk_base.MediaRetentionPolicy
 
 class FakeFfiClient(
@@ -73,6 +74,7 @@ class FakeFfiClient(
     private val getUrlResult: (String) -> ByteArray = { lambdaError() },
     private val getMediaThumbnailResult: (MediaSource, ULong, ULong) -> ByteArray = { _, _, _ -> byteArrayOf() },
     private val contentScannerResult: () -> ContentScanner = { FakeFfiContentScanner() },
+    private val runSearchBackfillResult: (SearchBackfillStrategy) -> TaskHandle = { lambdaError() },
     private val closeResult: () -> Unit = {},
 ) : Client(NoHandle) {
     override fun userId(): String = userId
@@ -170,5 +172,7 @@ class FakeFfiClient(
         contentScannerResult()
     }
 
+    override fun runSearchBackfill(strategy: SearchBackfillStrategy): TaskHandle = runSearchBackfillResult(strategy)
+
     override fun close() = closeResult()
 }

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/fixtures/fakes/FakeFfiTaskHandle.kt

@@ -11,7 +11,11 @@ package io.element.android.libraries.matrix.impl.fixtures.fakes
 import org.matrix.rustcomponents.sdk.NoHandle
 import org.matrix.rustcomponents.sdk.TaskHandle
 
-class FakeFfiTaskHandle : TaskHandle(NoHandle) {
-    override fun cancel() = Unit
+class FakeFfiTaskHandle(
+    private val isFinishedResult: () -> Boolean = { false },
+    private val cancelResult: () -> Unit = {},
+) : TaskHandle(NoHandle) {
+    override fun isFinished(): Boolean = isFinishedResult()
+    override fun cancel() = cancelResult()
     override fun destroy() = Unit
 }

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/search/RustSearchBackfillServiceTest.kt

@@ -0,0 +1,198 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search
+
+import com.google.common.truth.Truth.assertThat
+import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
+import io.element.android.libraries.matrix.impl.fixtures.fakes.FakeFfiClient
+import io.element.android.libraries.matrix.impl.fixtures.fakes.FakeFfiTaskHandle
+import io.element.android.libraries.matrix.impl.search.workmanager.SearchBackfillRequestBuilder
+import io.element.android.libraries.matrix.test.A_SESSION_ID
+import io.element.android.libraries.workmanager.api.WorkManagerRequestBuilder
+import io.element.android.libraries.workmanager.api.WorkManagerRequestType
+import io.element.android.libraries.workmanager.api.WorkManagerRequestWrapper
+import io.element.android.libraries.workmanager.test.FakeWorkManagerScheduler
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+import org.matrix.rustcomponents.sdk.TaskHandle
+import uniffi.matrix_sdk.SearchBackfillStrategy as RustSearchBackfillStrategy
+
+class RustSearchBackfillServiceTest {
+    @Test
+    fun `schedulePeriodicSearchBackfill submits a request when nothing is pending`() = runTest {
+        val builder = aRequestBuilder()
+        val createBuilderLambda = lambdaRecorder<SessionId, SearchBackfillRequestBuilder> { builder }
+        val submitLambda = lambdaRecorder<WorkManagerRequestBuilder, Unit> { }
+        val service = createService(
+            requestBuilderFactory = SearchBackfillRequestBuilder.Factory(createBuilderLambda),
+            workManagerScheduler = FakeWorkManagerScheduler(
+                submitLambda = submitLambda,
+                hasPendingWorkLambda = { _, _ -> false },
+            ),
+        )
+
+        val result = service.schedulePeriodicSearchBackfill(SearchBackfillStrategy.BACKGROUND)
+
+        assertThat(result.isSuccess).isTrue()
+        createBuilderLambda.assertions().isCalledOnce().with(value(A_SESSION_ID))
+        submitLambda.assertions().isCalledOnce().with(value(builder))
+    }
+
+    @Test
+    fun `schedulePeriodicSearchBackfill does nothing when work is already pending`() = runTest {
+        val hasPendingWorkLambda = lambdaRecorder<SessionId, WorkManagerRequestType, Boolean> { _, _ -> true }
+        val createBuilderLambda = lambdaRecorder<SessionId, SearchBackfillRequestBuilder> { error("Should not be called") }
+        val submitLambda = lambdaRecorder<WorkManagerRequestBuilder, Unit> { error("Should not be called") }
+        val service = createService(
+            requestBuilderFactory = SearchBackfillRequestBuilder.Factory(createBuilderLambda),
+            workManagerScheduler = FakeWorkManagerScheduler(
+                submitLambda = submitLambda,
+                hasPendingWorkLambda = hasPendingWorkLambda,
+            ),
+        )
+
+        val result = service.schedulePeriodicSearchBackfill(SearchBackfillStrategy.BACKGROUND)
+
+        assertThat(result.isSuccess).isTrue()
+        hasPendingWorkLambda.assertions().isCalledOnce().with(value(A_SESSION_ID), value(WorkManagerRequestType.SEARCH_BACKFILL))
+        createBuilderLambda.assertions().isNeverCalled()
+        submitLambda.assertions().isNeverCalled()
+    }
+
+    @Test
+    fun `schedulePeriodicSearchBackfill returns a failure when submitting fails`() = runTest {
+        val service = createService(
+            requestBuilderFactory = SearchBackfillRequestBuilder.Factory { aRequestBuilder() },
+            workManagerScheduler = FakeWorkManagerScheduler(submitLambda = { throw IllegalStateException("boom") }),
+        )
+
+        val result = service.schedulePeriodicSearchBackfill(SearchBackfillStrategy.BACKGROUND)
+
+        assertThat(result.exceptionOrNull()).isInstanceOf(IllegalStateException::class.java)
+    }
+
+    @Test
+    fun `cancelPeriodicSearchBackfill cancels the search backfill work of the session`() {
+        val cancelLambda = lambdaRecorder<SessionId, WorkManagerRequestType?, Unit> { _, _ -> }
+        val service = createService(workManagerScheduler = FakeWorkManagerScheduler(cancelLambda = cancelLambda))
+
+        service.cancelPeriodicSearchBackfill()
+
+        cancelLambda.assertions().isCalledOnce().with(value(A_SESSION_ID), value(WorkManagerRequestType.SEARCH_BACKFILL))
+    }
+
+    @Test
+    fun `startSearchBackfill maps the strategy and returns a running task`() {
+        val strategyLambda = lambdaRecorder<RustSearchBackfillStrategy, TaskHandle> { FakeFfiTaskHandle(isFinishedResult = { false }) }
+        val service = createService(client = FakeFfiClient(runSearchBackfillResult = strategyLambda))
+
+        val task = service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND).getOrThrow()
+
+        strategyLambda.assertions().isCalledOnce().with(value(RustSearchBackfillStrategy.FOREGROUND))
+        assertThat(task.isRunning()).isTrue()
+        assertThat(service.isSearchBackfillRunning()).isTrue()
+    }
+
+    @Test
+    fun `startSearchBackfill maps the background strategy`() {
+        val strategyLambda = lambdaRecorder<RustSearchBackfillStrategy, TaskHandle> { FakeFfiTaskHandle() }
+        val service = createService(client = FakeFfiClient(runSearchBackfillResult = strategyLambda))
+
+        service.startSearchBackfill(SearchBackfillStrategy.BACKGROUND)
+
+        strategyLambda.assertions().isCalledOnce().with(value(RustSearchBackfillStrategy.BACKGROUND))
+    }
+
+    @Test
+    fun `startSearchBackfill fails when a backfill is already running`() {
+        val strategyLambda = lambdaRecorder<RustSearchBackfillStrategy, TaskHandle> { FakeFfiTaskHandle(isFinishedResult = { false }) }
+        val service = createService(client = FakeFfiClient(runSearchBackfillResult = strategyLambda))
+        service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND)
+
+        val result = service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND)
+
+        assertThat(result.exceptionOrNull()).isInstanceOf(IllegalStateException::class.java)
+        strategyLambda.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `startSearchBackfill can start again once the previous task has finished`() {
+        val strategyLambda = lambdaRecorder<RustSearchBackfillStrategy, TaskHandle> { FakeFfiTaskHandle(isFinishedResult = { true }) }
+        val service = createService(client = FakeFfiClient(runSearchBackfillResult = strategyLambda))
+
+        assertThat(service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND).isSuccess).isTrue()
+        assertThat(service.isSearchBackfillRunning()).isFalse()
+        assertThat(service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND).isSuccess).isTrue()
+
+        strategyLambda.assertions().isCalledExactly(2)
+    }
+
+    @Test
+    fun `startSearchBackfill returns a failure when the SDK fails`() {
+        val service = createService(client = FakeFfiClient(runSearchBackfillResult = { error("boom") }))
+
+        val result = service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND)
+
+        assertThat(result.isFailure).isTrue()
+        assertThat(service.isSearchBackfillRunning()).isFalse()
+    }
+
+    @Test
+    fun `isSearchBackfillRunning is false when nothing was started`() {
+        assertThat(createService().isSearchBackfillRunning()).isFalse()
+    }
+
+    @Test
+    fun `cancelSearchBackfill cancels the running task`() {
+        val cancelLambda = lambdaRecorder<Unit> { }
+        val service = createService(
+            client = FakeFfiClient(runSearchBackfillResult = { FakeFfiTaskHandle(cancelResult = cancelLambda) }),
+        )
+        service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND)
+
+        val result = service.cancelSearchBackfill()
+
+        assertThat(result.isSuccess).isTrue()
+        cancelLambda.assertions().isCalledOnce()
+        assertThat(service.isSearchBackfillRunning()).isFalse()
+    }
+
+    @Test
+    fun `cancelSearchBackfill without a running task is a no-op`() {
+        assertThat(createService().cancelSearchBackfill().isSuccess).isTrue()
+    }
+
+    @Test
+    fun `startSearchBackfill works again after cancelSearchBackfill`() {
+        val strategyLambda = lambdaRecorder<RustSearchBackfillStrategy, TaskHandle> { FakeFfiTaskHandle() }
+        val service = createService(client = FakeFfiClient(runSearchBackfillResult = strategyLambda))
+        service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND)
+        service.cancelSearchBackfill()
+
+        assertThat(service.startSearchBackfill(SearchBackfillStrategy.FOREGROUND).isSuccess).isTrue()
+
+        strategyLambda.assertions().isCalledExactly(2)
+    }
+
+    private fun aRequestBuilder() = object : SearchBackfillRequestBuilder {
+        override suspend fun build(): Result<List<WorkManagerRequestWrapper>> = Result.success(emptyList())
+    }
+
+    private fun createService(
+        client: FakeFfiClient = FakeFfiClient(),
+        requestBuilderFactory: SearchBackfillRequestBuilder.Factory = SearchBackfillRequestBuilder.Factory { aRequestBuilder() },
+        workManagerScheduler: FakeWorkManagerScheduler = FakeWorkManagerScheduler(),
+    ) = RustSearchBackfillService(
+        innerClient = client,
+        searchBackfillRequestBuilderFactory = requestBuilderFactory,
+        workManagerScheduler = workManagerScheduler,
+    )
+}

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/search/workmanager/DefaultSearchBackfillRequestBuilderTest.kt

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search.workmanager
+
+import android.net.NetworkCapabilities
+import androidx.work.PeriodicWorkRequest
+import androidx.work.hasKeyWithValueOfType
+import com.google.common.truth.Truth.assertThat
+import io.element.android.features.networkmonitor.test.FakeNetworkMonitor
+import io.element.android.libraries.matrix.test.A_SESSION_ID
+import io.element.android.libraries.workmanager.api.WorkManagerRequestType
+import io.element.android.libraries.workmanager.api.WorkManagerWorkerType
+import io.element.android.libraries.workmanager.api.workManagerTag
+import io.element.android.tests.testutils.robolectric.RobolectricTest
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+import kotlin.time.Duration.Companion.hours
+import kotlin.time.Duration.Companion.minutes
+
+class DefaultSearchBackfillRequestBuilderTest : RobolectricTest() {
+    private val expectedTag = workManagerTag(A_SESSION_ID, WorkManagerRequestType.SEARCH_BACKFILL)
+
+    @Test
+    fun `build - creates a periodic request with session id and tag`() = runTest {
+        val result = createBuilder().build().getOrThrow().single()
+
+        assertThat(result.type).isEqualTo(WorkManagerWorkerType.Default)
+        result.request.run {
+            assertThat(this).isInstanceOf(PeriodicWorkRequest::class.java)
+            assertThat(workSpec.isPeriodic).isTrue()
+            assertThat(workSpec.intervalDuration).isEqualTo(1.hours.inWholeMilliseconds)
+            assertThat(workSpec.initialDelay).isEqualTo(5.minutes.inWholeMilliseconds)
+            assertThat(workSpec.input.hasKeyWithValueOfType<String>(SearchBackfillWorker.SESSION_ID_PARAM)).isTrue()
+            assertThat(workSpec.input.getString(SearchBackfillWorker.SESSION_ID_PARAM)).isEqualTo(A_SESSION_ID.value)
+            assertThat(tags).contains(expectedTag)
+            assertThat(workSpec.workerClassName).isEqualTo(SearchBackfillWorker::class.java.name)
+        }
+    }
+
+    @Test
+    fun `build - requires charging and an unmetered network`() = runTest {
+        val result = createBuilder().build().getOrThrow().single()
+
+        val constraints = result.request.workSpec.constraints
+        assertThat(constraints.requiresCharging()).isTrue()
+        val networkRequest = constraints.requiredNetworkRequest
+        assertThat(networkRequest).isNotNull()
+        assertThat(networkRequest!!.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED)).isTrue()
+    }
+
+    @Test
+    fun `build - validates the network when not in an air-gapped env`() = runTest {
+        val result = createBuilder(isInAirGapEnvironment = false).build().getOrThrow().single()
+
+        val networkRequest = result.request.workSpec.constraints.requiredNetworkRequest!!
+        assertThat(networkRequest.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)).isTrue()
+    }
+
+    @Test
+    fun `build - does not validate the network when in an air-gapped env`() = runTest {
+        val result = createBuilder(isInAirGapEnvironment = true).build().getOrThrow().single()
+
+        val networkRequest = result.request.workSpec.constraints.requiredNetworkRequest!!
+        assertThat(networkRequest.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)).isFalse()
+    }
+
+    private fun createBuilder(
+        isInAirGapEnvironment: Boolean = false,
+    ) = DefaultSearchBackfillRequestBuilder(
+        sessionId = A_SESSION_ID,
+        networkMonitor = FakeNetworkMonitor().apply { givenIsInAirGappedEnvironment(isInAirGapEnvironment) },
+    )
+}

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/search/workmanager/SearchBackfillWorkerTest.kt

@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.search.workmanager
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.work.Data
+import androidx.work.ListenableWorker
+import androidx.work.WorkerParameters
+import androidx.work.impl.utils.taskexecutor.WorkManagerTaskExecutor
+import androidx.work.workDataOf
+import com.google.common.truth.Truth.assertThat
+import com.google.common.util.concurrent.ListenableFuture
+import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.api.SdkPendingTask
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
+import io.element.android.libraries.matrix.test.A_SESSION_ID
+import io.element.android.libraries.matrix.test.FakeMatrixClient
+import io.element.android.libraries.matrix.test.FakeMatrixClientProvider
+import io.element.android.libraries.matrix.test.FakeSdkPendingTask
+import io.element.android.libraries.matrix.test.search.FakeSearchBackfillService
+import io.element.android.libraries.workmanager.api.di.MetroWorkerFactory
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
+import io.element.android.tests.testutils.robolectric.RobolectricTest
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.async
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.advanceTimeBy
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+import java.util.UUID
+import java.util.concurrent.Executor
+import java.util.concurrent.Executors
+import java.util.concurrent.TimeUnit
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class SearchBackfillWorkerTest : RobolectricTest() {
+    @Test
+    fun `missing session id - fails`() = runTest {
+        val worker = createWorker(input = null, client = FakeMatrixClient())
+
+        assertThat(worker.doWork()).isEqualTo(ListenableWorker.Result.failure())
+    }
+
+    @Test
+    fun `client cannot be restored - fails`() = runTest {
+        val worker = createWorker(client = null)
+
+        assertThat(worker.doWork()).isEqualTo(ListenableWorker.Result.failure())
+    }
+
+    @Test
+    fun `backfill already running - does not start another one`() = runTest {
+        val startLambda = lambdaRecorder<SearchBackfillStrategy, Result<SdkPendingTask>> { error("Should not be called") }
+        val client = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(
+                isSearchBackfillRunningLambda = { true },
+                startSearchBackfillLambda = startLambda,
+            ),
+        )
+
+        val result = createWorker(client = client).doWork()
+
+        assertThat(result).isEqualTo(ListenableWorker.Result.success())
+        startLambda.assertions().isNeverCalled()
+    }
+
+    @Test
+    fun `start fails - fails`() = runTest {
+        val client = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(
+                startSearchBackfillLambda = { Result.failure(IllegalStateException("boom")) },
+            ),
+        )
+
+        assertThat(createWorker(client = client).doWork()).isEqualTo(ListenableWorker.Result.failure())
+    }
+
+    @Test
+    fun `backfill finishes - succeeds and closes the task`() = runTest {
+        var running = true
+        val closeLambda = lambdaRecorder<Unit> { }
+        val startLambda = lambdaRecorder<SearchBackfillStrategy, Result<SdkPendingTask>> {
+            Result.success(FakeSdkPendingTask(isRunningLambda = { running }, closeLambda = closeLambda))
+        }
+        val client = FakeMatrixClient(searchBackfillService = FakeSearchBackfillService(startSearchBackfillLambda = startLambda))
+
+        val deferred = async { createWorker(client = client).doWork() }
+        advanceTimeBy(10.seconds)
+        running = false
+        advanceTimeBy(10.seconds)
+
+        assertThat(deferred.await()).isEqualTo(ListenableWorker.Result.success())
+        startLambda.assertions().isCalledOnce().with(value(SearchBackfillStrategy.BACKGROUND))
+        closeLambda.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `backfill times out after 10 minutes - closes the task and retries`() = runTest {
+        val closeLambda = lambdaRecorder<Unit> { }
+        val client = FakeMatrixClient(
+            searchBackfillService = FakeSearchBackfillService(
+                startSearchBackfillLambda = { Result.success(FakeSdkPendingTask(isRunningLambda = { true }, closeLambda = closeLambda)) },
+            ),
+        )
+
+        val deferred = async { createWorker(client = client).doWork() }
+        advanceTimeBy(9.minutes)
+        assertThat(deferred.isCompleted).isFalse()
+        advanceTimeBy(2.minutes)
+
+        assertThat(deferred.await()).isEqualTo(ListenableWorker.Result.retry())
+        closeLambda.assertions().isCalledOnce()
+    }
+
+    private fun TestScope.createWorker(
+        input: String? = A_SESSION_ID.value,
+        client: MatrixClient?,
+    ) = SearchBackfillWorker(
+        params = createWorkerParams(
+            inputData = input?.let { workDataOf(SearchBackfillWorker.SESSION_ID_PARAM to it) } ?: Data.EMPTY,
+        ),
+        context = InstrumentationRegistry.getInstrumentation().context,
+        matrixClientProvider = FakeMatrixClientProvider(
+            getClient = { client?.let { Result.success(it) } ?: Result.failure(IllegalStateException("No client")) }
+        ),
+    )
+
+    private fun TestScope.createWorkerParams(
+        inputData: Data = Data.EMPTY,
+    ): WorkerParameters = WorkerParameters(
+        UUID.randomUUID(),
+        inputData,
+        emptySet(),
+        WorkerParameters.RuntimeExtras(),
+        0,
+        0,
+        Executors.newSingleThreadExecutor(),
+        backgroundScope.coroutineContext,
+        WorkManagerTaskExecutor(Executors.newSingleThreadExecutor()),
+        MetroWorkerFactory(emptyMap()),
+        { _, _, _ -> FakeListenableFuture() },
+        { _, _, _ -> FakeListenableFuture() },
+    )
+}
+
+private class FakeListenableFuture<T> : ListenableFuture<T> {
+    override fun addListener(listener: Runnable, executor: Executor) = Unit
+    override fun cancel(mayInterruptIfRunning: Boolean): Boolean = true
+    override fun get(): T? = null
+    override fun get(timeout: Long, unit: TimeUnit?): T? = null
+    override fun isCancelled(): Boolean = false
+    override fun isDone(): Boolean = false
+}

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/FakeMatrixClient.kt

@@ -40,6 +40,7 @@ import io.element.android.libraries.matrix.api.roomdirectory.RoomDirectoryServic
 import io.element.android.libraries.matrix.api.roomlist.RoomListService
 import io.element.android.libraries.matrix.api.scanner.ContentScanner
 import io.element.android.libraries.matrix.api.search.MessageSearchService
+import io.element.android.libraries.matrix.api.search.SearchBackfillService
 import io.element.android.libraries.matrix.api.spaces.SpaceService
 import io.element.android.libraries.matrix.api.sync.SlidingSyncVersion
 import io.element.android.libraries.matrix.api.sync.SyncService
@@ -57,6 +58,7 @@ import io.element.android.libraries.matrix.test.pushers.FakePushersService
 import io.element.android.libraries.matrix.test.roomdirectory.FakeRoomDirectoryService
 import io.element.android.libraries.matrix.test.roomlist.FakeRoomListService
 import io.element.android.libraries.matrix.test.search.FakeMessageSearchService
+import io.element.android.libraries.matrix.test.search.FakeSearchBackfillService
 import io.element.android.libraries.matrix.test.spaces.FakeSpaceService
 import io.element.android.libraries.matrix.test.sync.FakeSyncService
 import io.element.android.libraries.matrix.test.verification.FakeSessionVerificationService
@@ -131,6 +133,7 @@ class FakeMatrixClient(
     private val markRoomAsFullyReadResult: (RoomId, EventId) -> Result<Unit> = { _, _ -> lambdaError() },
     private val markAllRoomsAsReadResult: () -> Result<Unit> = { Result.success(Unit) },
     private val performDatabaseVacuumLambda: () -> Result<Unit> = { lambdaError() },
+    override val searchBackfillService: SearchBackfillService = FakeSearchBackfillService(),
     private val getDatabaseSizesLambda: () -> Result<SdkStoreSizes> = { lambdaError() },
     private val resetWellKnownConfigLambda: () -> Result<Unit> = { lambdaError() },
     private val enableAutomaticCallStatusLambda: (Boolean) -> Unit = { },

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/FakeSdkPendingTask.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.libraries.matrix.test
+
+import io.element.android.libraries.matrix.api.SdkPendingTask
+import io.element.android.tests.testutils.lambda.lambdaError
+
+class FakeSdkPendingTask(
+    private val isRunningLambda: () -> Boolean = { lambdaError() },
+    private val closeLambda: () -> Unit = { lambdaError() },
+) : SdkPendingTask {
+    override fun isRunning(): Boolean = isRunningLambda()
+
+    override fun close() = closeLambda()
+}

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/search/FakeSearchBackfillService.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.test.search
+
+import io.element.android.libraries.matrix.api.SdkPendingTask
+import io.element.android.libraries.matrix.api.search.SearchBackfillService
+import io.element.android.libraries.matrix.api.search.SearchBackfillStrategy
+import io.element.android.tests.testutils.lambda.lambdaError
+
+class FakeSearchBackfillService(
+    private val schedulePeriodicSearchBackfillLambda: (SearchBackfillStrategy) -> Result<Unit> = { lambdaError() },
+    private val cancelPeriodicSearchBackfillLambda: () -> Unit = { lambdaError() },
+    private val startSearchBackfillLambda: (SearchBackfillStrategy) -> Result<SdkPendingTask> = { lambdaError() },
+    private val isSearchBackfillRunningLambda: () -> Boolean = { false },
+    private val cancelSearchBackfillLambda: () -> Result<Unit> = { lambdaError() },
+) : SearchBackfillService {
+    override suspend fun schedulePeriodicSearchBackfill(strategy: SearchBackfillStrategy): Result<Unit> {
+        return schedulePeriodicSearchBackfillLambda(strategy)
+    }
+
+    override fun cancelPeriodicSearchBackfill() {
+        cancelPeriodicSearchBackfillLambda()
+    }
+
+    override fun startSearchBackfill(strategy: SearchBackfillStrategy): Result<SdkPendingTask> {
+        return startSearchBackfillLambda(strategy)
+    }
+
+    override fun isSearchBackfillRunning(): Boolean {
+        return isSearchBackfillRunningLambda()
+    }
+
+    override fun cancelSearchBackfill(): Result<Unit> {
+        return cancelSearchBackfillLambda()
+    }
+}

libraries/workmanager/api/src/main/kotlin/io/element/android/libraries/workmanager/api/WorkManagerScheduler.kt

@@ -43,6 +43,7 @@ fun workManagerTag(sessionId: SessionId, requestType: WorkManagerRequestType): S
     val prefix = when (requestType) {
         WorkManagerRequestType.NOTIFICATION_SYNC -> "notifications"
         WorkManagerRequestType.DB_VACUUM -> "db_vacuum"
+        WorkManagerRequestType.SEARCH_BACKFILL -> "search_backfill"
     }
     return "$prefix-$sessionId"
 }
@@ -50,4 +51,5 @@ fun workManagerTag(sessionId: SessionId, requestType: WorkManagerRequestType): S
 enum class WorkManagerRequestType {
     NOTIFICATION_SYNC,
     DB_VACUUM,
+    SEARCH_BACKFILL,
 }