diff --git a/android/CHANGELOG.md b/android/CHANGELOG.md
index 70977dc..22c38bf 100644
--- a/android/CHANGELOG.md
+++ b/android/CHANGELOG.md
@@ -307,3 +307,9 @@
 - Added `DataStoreNotificationSettingsRepository` with persistence for global flags and per-chat override mode.
 - Added `ShouldShowMessageNotificationUseCase` and wired realtime notifications through it.
 - Added unit tests for DataStore notification settings repository and notification visibility use case.
+
+### Step 51 - Logout with full local cleanup
+- Added `LogoutUseCase` with centralized sign-out flow: disconnect realtime, clear active chat, clear auth session, and clear local cached data.
+- Added `SessionCleanupRepository` + `DefaultSessionCleanupRepository` to wipe Room tables and clear per-chat notification overrides.
+- Added logout action in chat list UI and wired it to `AuthViewModel`, with automatic navigation back to login via auth state.
+- Added unit tests for logout use case orchestration and notification override cleanup.
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/core/notifications/ActiveChatTracker.kt b/android/app/src/main/java/ru/daemonlord/messenger/core/notifications/ActiveChatTracker.kt
index 5d63ade..00160e4 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/core/notifications/ActiveChatTracker.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/core/notifications/ActiveChatTracker.kt
@@ -20,4 +20,8 @@ class ActiveChatTracker @Inject constructor() {
             _activeChatId.value = null
         }
     }
+
+    fun clear() {
+        _activeChatId.value = null
+    }
 }
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/data/auth/repository/DefaultSessionCleanupRepository.kt b/android/app/src/main/java/ru/daemonlord/messenger/data/auth/repository/DefaultSessionCleanupRepository.kt
new file mode 100644
index 0000000..9c6cebe
--- /dev/null
+++ b/android/app/src/main/java/ru/daemonlord/messenger/data/auth/repository/DefaultSessionCleanupRepository.kt
@@ -0,0 +1,24 @@
+package ru.daemonlord.messenger.data.auth.repository
+
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.withContext
+import ru.daemonlord.messenger.data.chat.local.db.MessengerDatabase
+import ru.daemonlord.messenger.di.IoDispatcher
+import ru.daemonlord.messenger.domain.auth.repository.SessionCleanupRepository
+import ru.daemonlord.messenger.domain.notifications.repository.NotificationSettingsRepository
+import javax.inject.Inject
+import javax.inject.Singleton
+
+@Singleton
+class DefaultSessionCleanupRepository @Inject constructor(
+    private val database: MessengerDatabase,
+    private val notificationSettingsRepository: NotificationSettingsRepository,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+) : SessionCleanupRepository {
+
+    override suspend fun clearLocalSessionData() = withContext(ioDispatcher) {
+        database.clearAllTables()
+        notificationSettingsRepository.clearChatOverrides()
+    }
+}
+
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepository.kt b/android/app/src/main/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepository.kt
index 1b7b1ae..24d09e0 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepository.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepository.kt
@@ -66,17 +66,25 @@ class DataStoreNotificationSettingsRepository @Inject constructor(
         }
     }
 
+    override suspend fun clearChatOverrides() {
+        dataStore.edit { preferences ->
+            val keysToRemove = preferences.asMap().keys
+                .filter { key -> key.name.startsWith(CHAT_OVERRIDE_PREFIX) }
+            keysToRemove.forEach { key -> preferences.remove(key) }
+        }
+    }
+
     private fun Preferences.chatOverride(chatId: Long): ChatNotificationOverride {
         return this[chatOverrideKey(chatId)]
             ?.let { runCatching { ChatNotificationOverride.valueOf(it) }.getOrNull() }
             ?: ChatNotificationOverride.DEFAULT
     }
 
-    private fun chatOverrideKey(chatId: Long) = stringPreferencesKey("notification_chat_override_$chatId")
+    private fun chatOverrideKey(chatId: Long) = stringPreferencesKey("$CHAT_OVERRIDE_PREFIX$chatId")
 
     private companion object {
+        const val CHAT_OVERRIDE_PREFIX = "notification_chat_override_"
         val GLOBAL_ENABLED_KEY = booleanPreferencesKey("notification_global_enabled")
         val PREVIEW_ENABLED_KEY = booleanPreferencesKey("notification_preview_enabled")
     }
 }
-
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/di/RepositoryModule.kt b/android/app/src/main/java/ru/daemonlord/messenger/di/RepositoryModule.kt
index 66dab50..bb8924b 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/di/RepositoryModule.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/di/RepositoryModule.kt
@@ -5,11 +5,13 @@ import dagger.Module
 import dagger.hilt.InstallIn
 import dagger.hilt.components.SingletonComponent
 import ru.daemonlord.messenger.data.auth.repository.NetworkAuthRepository
+import ru.daemonlord.messenger.data.auth.repository.DefaultSessionCleanupRepository
 import ru.daemonlord.messenger.data.chat.repository.NetworkChatRepository
 import ru.daemonlord.messenger.data.media.repository.NetworkMediaRepository
 import ru.daemonlord.messenger.data.message.repository.NetworkMessageRepository
 import ru.daemonlord.messenger.data.notifications.repository.DataStoreNotificationSettingsRepository
 import ru.daemonlord.messenger.domain.auth.repository.AuthRepository
+import ru.daemonlord.messenger.domain.auth.repository.SessionCleanupRepository
 import ru.daemonlord.messenger.domain.chat.repository.ChatRepository
 import ru.daemonlord.messenger.domain.media.repository.MediaRepository
 import ru.daemonlord.messenger.domain.message.repository.MessageRepository
@@ -26,6 +28,12 @@ abstract class RepositoryModule {
         repository: NetworkAuthRepository,
     ): AuthRepository
 
+    @Binds
+    @Singleton
+    abstract fun bindSessionCleanupRepository(
+        repository: DefaultSessionCleanupRepository,
+    ): SessionCleanupRepository
+
     @Binds
     @Singleton
     abstract fun bindChatRepository(
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/domain/auth/repository/SessionCleanupRepository.kt b/android/app/src/main/java/ru/daemonlord/messenger/domain/auth/repository/SessionCleanupRepository.kt
new file mode 100644
index 0000000..189d8f2
--- /dev/null
+++ b/android/app/src/main/java/ru/daemonlord/messenger/domain/auth/repository/SessionCleanupRepository.kt
@@ -0,0 +1,6 @@
+package ru.daemonlord.messenger.domain.auth.repository
+
+interface SessionCleanupRepository {
+    suspend fun clearLocalSessionData()
+}
+
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/domain/auth/usecase/LogoutUseCase.kt b/android/app/src/main/java/ru/daemonlord/messenger/domain/auth/usecase/LogoutUseCase.kt
new file mode 100644
index 0000000..c905bde
--- /dev/null
+++ b/android/app/src/main/java/ru/daemonlord/messenger/domain/auth/usecase/LogoutUseCase.kt
@@ -0,0 +1,22 @@
+package ru.daemonlord.messenger.domain.auth.usecase
+
+import ru.daemonlord.messenger.core.notifications.ActiveChatTracker
+import ru.daemonlord.messenger.domain.auth.repository.AuthRepository
+import ru.daemonlord.messenger.domain.auth.repository.SessionCleanupRepository
+import ru.daemonlord.messenger.domain.realtime.RealtimeManager
+import javax.inject.Inject
+
+class LogoutUseCase @Inject constructor(
+    private val authRepository: AuthRepository,
+    private val sessionCleanupRepository: SessionCleanupRepository,
+    private val realtimeManager: RealtimeManager,
+    private val activeChatTracker: ActiveChatTracker,
+) {
+    suspend operator fun invoke() {
+        realtimeManager.disconnect()
+        activeChatTracker.clear()
+        authRepository.logout()
+        sessionCleanupRepository.clearLocalSessionData()
+    }
+}
+
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/domain/notifications/repository/NotificationSettingsRepository.kt b/android/app/src/main/java/ru/daemonlord/messenger/domain/notifications/repository/NotificationSettingsRepository.kt
index abb7720..14b068a 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/domain/notifications/repository/NotificationSettingsRepository.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/domain/notifications/repository/NotificationSettingsRepository.kt
@@ -14,5 +14,5 @@ interface NotificationSettingsRepository {
     suspend fun getChatOverride(chatId: Long): ChatNotificationOverride
     suspend fun setChatOverride(chatId: Long, mode: ChatNotificationOverride)
     suspend fun clearChatOverride(chatId: Long)
+    suspend fun clearChatOverrides()
 }
-
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/ui/auth/AuthViewModel.kt b/android/app/src/main/java/ru/daemonlord/messenger/ui/auth/AuthViewModel.kt
index 2dc4e93..b061400 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/ui/auth/AuthViewModel.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/ui/auth/AuthViewModel.kt
@@ -9,6 +9,7 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import ru.daemonlord.messenger.domain.auth.usecase.LoginUseCase
+import ru.daemonlord.messenger.domain.auth.usecase.LogoutUseCase
 import ru.daemonlord.messenger.domain.auth.usecase.RestoreSessionUseCase
 import ru.daemonlord.messenger.domain.common.AppError
 import ru.daemonlord.messenger.domain.common.AppResult
@@ -18,6 +19,7 @@ import javax.inject.Inject
 class AuthViewModel @Inject constructor(
     private val restoreSessionUseCase: RestoreSessionUseCase,
     private val loginUseCase: LoginUseCase,
+    private val logoutUseCase: LogoutUseCase,
 ) : ViewModel() {
 
     private val _uiState = MutableStateFlow(AuthUiState())
@@ -68,6 +70,22 @@ class AuthViewModel @Inject constructor(
         }
     }
 
+    fun logout() {
+        viewModelScope.launch {
+            _uiState.update { it.copy(isLoading = true, errorMessage = null) }
+            runCatching { logoutUseCase() }
+            _uiState.update {
+                it.copy(
+                    email = "",
+                    password = "",
+                    isLoading = false,
+                    isAuthenticated = false,
+                    errorMessage = null,
+                )
+            }
+        }
+    }
+
     private fun restoreSession() {
         viewModelScope.launch {
             _uiState.update { it.copy(isCheckingSession = true) }
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/ui/chats/ChatListScreen.kt b/android/app/src/main/java/ru/daemonlord/messenger/ui/chats/ChatListScreen.kt
index d5cf038..1ff3e34 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/ui/chats/ChatListScreen.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/ui/chats/ChatListScreen.kt
@@ -29,6 +29,7 @@ import androidx.compose.material3.Surface
 import androidx.compose.material3.Tab
 import androidx.compose.material3.TabRow
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.material3.pulltorefresh.PullToRefreshBox
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
@@ -50,6 +51,7 @@ import java.time.format.DateTimeFormatter
 @Composable
 fun ChatListRoute(
     onOpenChat: (Long) -> Unit,
+    onLogout: () -> Unit,
     inviteToken: String?,
     onInviteTokenConsumed: () -> Unit,
     viewModel: ChatListViewModel = hiltViewModel(),
@@ -72,6 +74,7 @@ fun ChatListRoute(
         onFilterSelected = viewModel::onFilterSelected,
         onSearchChanged = viewModel::onSearchChanged,
         onRefresh = viewModel::onPullToRefresh,
+        onLogout = onLogout,
         onOpenChat = onOpenChat,
     )
 }
@@ -84,6 +87,7 @@ fun ChatListScreen(
     onFilterSelected: (ChatListFilter) -> Unit,
     onSearchChanged: (String) -> Unit,
     onRefresh: () -> Unit,
+    onLogout: () -> Unit,
     onOpenChat: (Long) -> Unit,
 ) {
     Column(
@@ -115,6 +119,16 @@ fun ChatListScreen(
                 .fillMaxWidth()
                 .padding(horizontal = 16.dp, vertical = 8.dp),
         )
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 16.dp),
+            horizontalArrangement = Arrangement.End,
+        ) {
+            TextButton(onClick = onLogout) {
+                Text("Logout")
+            }
+        }
         Row(
             modifier = Modifier
                 .fillMaxWidth()
diff --git a/android/app/src/main/java/ru/daemonlord/messenger/ui/navigation/AppNavGraph.kt b/android/app/src/main/java/ru/daemonlord/messenger/ui/navigation/AppNavGraph.kt
index 7faff66..5ce8c2f 100644
--- a/android/app/src/main/java/ru/daemonlord/messenger/ui/navigation/AppNavGraph.kt
+++ b/android/app/src/main/java/ru/daemonlord/messenger/ui/navigation/AppNavGraph.kt
@@ -125,6 +125,7 @@ fun MessengerNavHost(
             ChatListRoute(
                 inviteToken = inviteToken,
                 onInviteTokenConsumed = onInviteTokenConsumed,
+                onLogout = viewModel::logout,
                 onOpenChat = { chatId ->
                     navController.navigate("${Routes.Chat}/$chatId")
                 }
diff --git a/android/app/src/test/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepositoryTest.kt b/android/app/src/test/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepositoryTest.kt
index 5f1dab2..8f2156c 100644
--- a/android/app/src/test/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepositoryTest.kt
+++ b/android/app/src/test/java/ru/daemonlord/messenger/data/notifications/repository/DataStoreNotificationSettingsRepositoryTest.kt
@@ -49,6 +49,18 @@ class DataStoreNotificationSettingsRepositoryTest {
         assertTrue(mode == ChatNotificationOverride.DEFAULT)
     }
 
+    @Test
+    fun clearChatOverrides_removesAllPerChatModes() = runTest {
+        val repository = DataStoreNotificationSettingsRepository(createTestDataStore())
+        repository.setChatOverride(chatId = 1L, mode = ChatNotificationOverride.MUTED)
+        repository.setChatOverride(chatId = 2L, mode = ChatNotificationOverride.ENABLED)
+
+        repository.clearChatOverrides()
+
+        assertEquals(ChatNotificationOverride.DEFAULT, repository.getChatOverride(chatId = 1L))
+        assertEquals(ChatNotificationOverride.DEFAULT, repository.getChatOverride(chatId = 2L))
+    }
+
     private fun createTestDataStore(): DataStore<Preferences> {
         return InMemoryPreferencesDataStore()
     }
diff --git a/android/app/src/test/java/ru/daemonlord/messenger/domain/auth/usecase/LogoutUseCaseTest.kt b/android/app/src/test/java/ru/daemonlord/messenger/domain/auth/usecase/LogoutUseCaseTest.kt
new file mode 100644
index 0000000..2c9fc26
--- /dev/null
+++ b/android/app/src/test/java/ru/daemonlord/messenger/domain/auth/usecase/LogoutUseCaseTest.kt
@@ -0,0 +1,99 @@
+package ru.daemonlord.messenger.domain.auth.usecase
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import ru.daemonlord.messenger.core.notifications.ActiveChatTracker
+import ru.daemonlord.messenger.domain.auth.repository.AuthRepository
+import ru.daemonlord.messenger.domain.auth.repository.SessionCleanupRepository
+import ru.daemonlord.messenger.domain.common.AppResult
+import ru.daemonlord.messenger.domain.realtime.RealtimeManager
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import ru.daemonlord.messenger.domain.auth.model.AuthSession
+import ru.daemonlord.messenger.domain.auth.model.AuthUser
+import ru.daemonlord.messenger.domain.realtime.model.RealtimeEvent
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class LogoutUseCaseTest {
+
+    @Test
+    fun invoke_disconnectsRealtime_clearsSessionAndAuth() = runTest {
+        val authRepository = FakeAuthRepository()
+        val cleanupRepository = FakeSessionCleanupRepository()
+        val realtimeManager = FakeRealtimeManager()
+        val activeChatTracker = ActiveChatTracker().apply { setActiveChat(42L) }
+        val useCase = LogoutUseCase(
+            authRepository = authRepository,
+            sessionCleanupRepository = cleanupRepository,
+            realtimeManager = realtimeManager,
+            activeChatTracker = activeChatTracker,
+        )
+
+        useCase()
+
+        assertEquals(true, realtimeManager.disconnected)
+        assertEquals(true, authRepository.loggedOut)
+        assertEquals(true, cleanupRepository.cleaned)
+        assertEquals(null, activeChatTracker.activeChatId.value)
+    }
+
+    private class FakeAuthRepository : AuthRepository {
+        var loggedOut: Boolean = false
+
+        override suspend fun login(email: String, password: String): AppResult<AuthUser> {
+            return AppResult.Error(ru.daemonlord.messenger.domain.common.AppError.Unknown(null))
+        }
+
+        override suspend fun refreshTokens(): AppResult<Unit> {
+            return AppResult.Success(Unit)
+        }
+
+        override suspend fun getMe(): AppResult<AuthUser> {
+            return AppResult.Error(ru.daemonlord.messenger.domain.common.AppError.Unknown(null))
+        }
+
+        override suspend fun restoreSession(): AppResult<AuthUser> {
+            return AppResult.Error(ru.daemonlord.messenger.domain.common.AppError.Unauthorized)
+        }
+
+        override suspend fun listSessions(): AppResult<List<AuthSession>> {
+            return AppResult.Success(emptyList())
+        }
+
+        override suspend fun revokeSession(jti: String): AppResult<Unit> {
+            return AppResult.Success(Unit)
+        }
+
+        override suspend fun revokeAllSessions(): AppResult<Unit> {
+            return AppResult.Success(Unit)
+        }
+
+        override suspend fun logout() {
+            loggedOut = true
+        }
+    }
+
+    private class FakeSessionCleanupRepository : SessionCleanupRepository {
+        var cleaned: Boolean = false
+
+        override suspend fun clearLocalSessionData() {
+            cleaned = true
+        }
+    }
+
+    private class FakeRealtimeManager : RealtimeManager {
+        var disconnected: Boolean = false
+        private val eventsFlow = MutableStateFlow<RealtimeEvent>(RealtimeEvent.Ignored)
+
+        override val events: Flow<RealtimeEvent> = eventsFlow
+
+        override fun connect() = Unit
+
+        override fun disconnect() {
+            disconnected = true
+        }
+    }
+}
+
diff --git a/android/app/src/test/java/ru/daemonlord/messenger/domain/notifications/usecase/ShouldShowMessageNotificationUseCaseTest.kt b/android/app/src/test/java/ru/daemonlord/messenger/domain/notifications/usecase/ShouldShowMessageNotificationUseCaseTest.kt
index d02424c..6863a4e 100644
--- a/android/app/src/test/java/ru/daemonlord/messenger/domain/notifications/usecase/ShouldShowMessageNotificationUseCaseTest.kt
+++ b/android/app/src/test/java/ru/daemonlord/messenger/domain/notifications/usecase/ShouldShowMessageNotificationUseCaseTest.kt
@@ -87,6 +87,9 @@ class ShouldShowMessageNotificationUseCaseTest {
         override suspend fun clearChatOverride(chatId: Long) {
             chatOverrides.remove(chatId)
         }
+
+        override suspend fun clearChatOverrides() {
+            chatOverrides.clear()
+        }
     }
 }
-
diff --git a/docs/android-checklist.md b/docs/android-checklist.md
index 7ae3393..895da2c 100644
--- a/docs/android-checklist.md
+++ b/docs/android-checklist.md
@@ -31,7 +31,7 @@
 - [ ] Reset password flow
 - [ ] Sessions list + revoke one/all
 - [ ] 2FA TOTP + recovery codes
-- [ ] Logout с полным cleanup local state
+- [x] Logout с полным cleanup local state
 
 ## 5. Профиль и приватность
 - [ ] Просмотр/редактирование профиля