frontend update, big refactor

android/app/src/main/java/dev/zxq5/chatapp/android/ChatApplication.kt

@@ -1,11 +1,19 @@
 package dev.zxq5.chatapp.android
 
 import android.app.Application
-import dev.zxq5.chatapp.android.api.ApiClient
+import dev.zxq5.chatapp.android.core.data.TokenStore
+import dev.zxq5.chatapp.android.data.repository.AuthRepository
+import dev.zxq5.chatapp.android.data.repository.ChatRepository
+import dev.zxq5.chatapp.android.data.repository.SettingsRepository
 
 class ChatApplication : Application() {
+
+    val tokenStore by lazy { TokenStore(this) }
+    val authRepository by lazy { AuthRepository(tokenStore) }
+    val chatRepository by lazy { ChatRepository(tokenStore) }
+    val settingsRepository by lazy { SettingsRepository(tokenStore) }
+
     override fun onCreate() {
         super.onCreate()
-        ApiClient.init(this)
     }
 }

android/app/src/main/java/dev/zxq5/chatapp/android/MainActivity.kt

@@ -11,36 +11,66 @@ import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
 import androidx.lifecycle.viewmodel.compose.viewModel
-import dev.zxq5.chatapp.android.model.ChatViewModel
+import dev.zxq5.chatapp.android.core.data.TokenStore
-import dev.zxq5.chatapp.android.model.LoginState
+import dev.zxq5.chatapp.android.data.repository.AuthRepository
-import dev.zxq5.chatapp.android.model.MainScreen
+import dev.zxq5.chatapp.android.data.repository.AuthState
-import dev.zxq5.chatapp.android.ui.components.AuthScreen
+import dev.zxq5.chatapp.android.data.repository.ChatRepository
-import dev.zxq5.chatapp.android.ui.components.ChatScreen
+import dev.zxq5.chatapp.android.data.repository.SettingsRepository
-import dev.zxq5.chatapp.android.ui.components.SettingsScreen
+import dev.zxq5.chatapp.android.feature.auth.AuthViewModel
+import dev.zxq5.chatapp.android.feature.chat.ChatViewModel
+import dev.zxq5.chatapp.android.feature.chat.Screen
+import dev.zxq5.chatapp.android.feature.settings.SettingsViewModel
+import dev.zxq5.chatapp.android.feature.auth.AuthScreen
+import dev.zxq5.chatapp.android.feature.chat.ChatScreen
+import dev.zxq5.chatapp.android.feature.settings.SettingsScreen
 import dev.zxq5.chatapp.android.ui.theme.ChatappTheme
 
 class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
+        
+        val app = application as ChatApplication
+        val tokenStore = app.tokenStore
+        val authRepository = app.authRepository
+        val chatRepository = app.chatRepository
+        val settingsRepository = app.settingsRepository
+
         enableEdgeToEdge()
         setContent {
             ChatappTheme {
-                val viewModel: ChatViewModel = viewModel()
+                val authViewModel: AuthViewModel = viewModel(factory = ViewModelFactory(authRepository))
-                val loginState by viewModel.loginState.collectAsState()
+                val chatViewModel: ChatViewModel = viewModel(factory = ViewModelFactory(chatRepository))
-                val currentScreen by viewModel.currentScreen.collectAsState()
+                val settingsViewModel: SettingsViewModel = viewModel(factory = ViewModelFactory(settingsRepository))
+                
+                val authState by authViewModel.authState.collectAsState()
+                val currentScreen by chatViewModel.currentScreen.collectAsState()
 
                 Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
                     androidx.compose.foundation.layout.Box(modifier = Modifier.padding(innerPadding)) {
-                        if (loginState is LoginState.Success) {
+                        when (authState) {
-                            when (currentScreen) {
+                            AuthState.Authenticated -> {
-                                MainScreen.CHAT -> ChatScreen(viewModel = viewModel)
+                                when (currentScreen) {
-                                MainScreen.SETTINGS -> SettingsScreen(viewModel = viewModel)
+                                    Screen.CHAT -> ChatScreen(
+                                        viewModel = chatViewModel,
+                                        onNavigateToSettings = { chatViewModel.navigateTo(Screen.SETTINGS) },
+                                        onLogout = { 
+                                            authViewModel.logout()
+                                            chatViewModel.clearChat()
+                                        }
+                                    )
+                                    Screen.SETTINGS -> SettingsScreen(
+                                        viewModel = settingsViewModel,
+                                        onBack = { chatViewModel.navigateTo(Screen.CHAT) },
+                                        onLogout = {
+                                            authViewModel.logout()
+                                            chatViewModel.clearChat()
+                                        }
+                                    )
+                                }
+                            }
+                            AuthState.AwaitingTotp, AuthState.Unauthenticated -> {
+                                AuthScreen(viewModel = authViewModel)
                             }
-                        } else {
-                            AuthScreen(
-                                viewModel = viewModel,
-                                onSuccess = { }
-                            )
                         }
                     }
                 }

android/app/src/main/java/dev/zxq5/chatapp/android/ViewModelFactory.kt

@@ -0,0 +1,27 @@
+package dev.zxq5.chatapp.android
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import dev.zxq5.chatapp.android.data.repository.AuthRepository
+import dev.zxq5.chatapp.android.data.repository.ChatRepository
+import dev.zxq5.chatapp.android.data.repository.SettingsRepository
+import dev.zxq5.chatapp.android.feature.auth.AuthViewModel
+import dev.zxq5.chatapp.android.feature.chat.ChatViewModel
+import dev.zxq5.chatapp.android.feature.settings.SettingsViewModel
+
+class ViewModelFactory(private val repository: Any) : ViewModelProvider.Factory {
+    override fun <T : ViewModel> create(modelClass: Class<T>): T {
+        return when {
+            modelClass.isAssignableFrom(AuthViewModel::class.java) -> {
+                AuthViewModel(repository as AuthRepository) as T
+            }
+            modelClass.isAssignableFrom(ChatViewModel::class.java) -> {
+                ChatViewModel(repository as ChatRepository) as T
+            }
+            modelClass.isAssignableFrom(SettingsViewModel::class.java) -> {
+                SettingsViewModel(repository as SettingsRepository) as T
+            }
+            else -> throw IllegalArgumentException("Unknown ViewModel class")
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/api/ApiClient.kt

@@ -1,361 +0,0 @@
-package dev.zxq5.chatapp.android.api
-
-import android.content.Context
-import android.util.Log
-import dev.zxq5.chatapp.android.core.data.TokenStore.getScopeFromToken
-import dev.zxq5.chatapp.android.model.LoginRequest
-import dev.zxq5.chatapp.android.model.LoginResponse
-import dev.zxq5.chatapp.android.model.Message
-import dev.zxq5.chatapp.android.model.SendMessage
-import dev.zxq5.chatapp.android.model.SignupRequest
-import io.ktor.client.HttpClient
-import io.ktor.client.call.body
-import io.ktor.client.engine.android.Android
-import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
-import io.ktor.client.request.get
-import io.ktor.client.request.post
-import io.ktor.client.request.delete
-import io.ktor.client.request.prepareGet
-import io.ktor.client.request.setBody
-import io.ktor.client.statement.bodyAsChannel
-import io.ktor.http.ContentType
-import io.ktor.http.contentType
-import io.ktor.http.isSuccess
-import io.ktor.serialization.kotlinx.json.json
-import io.ktor.utils.io.readUTF8Line
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.flow
-import kotlinx.serialization.Serializable
-import kotlinx.serialization.json.Json
-
-import io.ktor.client.plugins.auth.Auth
-import io.ktor.client.plugins.auth.providers.BearerTokens
-import io.ktor.client.plugins.auth.providers.bearer
-import io.ktor.http.encodedPath
-import dev.zxq5.chatapp.android.core.BASE_URL
-import dev.zxq5.chatapp.android.core.data.TokenStore
-import dev.zxq5.chatapp.android.core.data.TokenStore.getUserIdFromToken
-import dev.zxq5.chatapp.android.core.error.ApiResult
-import kotlinx.serialization.KSerializer
-import kotlinx.serialization.descriptors.PrimitiveKind
-import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
-import kotlinx.serialization.descriptors.SerialDescriptor
-import kotlinx.serialization.encoding.Decoder
-import kotlinx.serialization.encoding.Encoder
-
-@Serializable
-data class QrResponse(val qr_code: String)
-
-@Serializable
-data class TOTPSixDigitCode(val code: String)
-
-@Serializable(with = TotpStatusSerializer::class)
-enum class TotpStatus {
-    ENABLED, DISABLED;
-    
-    val isEnabled: Boolean get() = this == ENABLED
-}
-
-object TotpStatusSerializer : KSerializer<TotpStatus> {
-    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("TotpStatus", PrimitiveKind.STRING)
-    override fun serialize(encoder: Encoder, value: TotpStatus) = encoder.encodeString(value.name.lowercase())
-    override fun deserialize(decoder: Decoder): TotpStatus = 
-        TotpStatus.valueOf(decoder.decodeString().uppercase())
-}
-
-@Serializable
-data class TotpStatusResponse(val status: TotpStatus)
-
-@Serializable
-data class PasswordChangeRequest(val old_password: String, val new_password: String)
-
-@Serializable
-data class DisplayNameRequest(val display_name: String?)
-
-object ApiClient {
-    private lateinit var appContext: Context
-
-    fun init(context: Context) {
-        appContext = context.applicationContext
-    }
-
-    fun hasToken(): Boolean {
-        return TokenStore.get(appContext) != null
-    }
-
-    fun getTokenScope(): String? {
-        val token = TokenStore.get(appContext) ?: return null
-        val scope = getScopeFromToken(token)
-        Log.d("Chat", "Current token scope: $scope")
-        return scope
-    }
-
-    fun getStoredUserId(): Int? {
-        return TokenStore.getUserId(appContext)
-    }
-
-    fun is2faEnabledLocal(): Boolean {
-        return TokenStore.is2faEnabled(appContext)
-    }
-
-    fun set2faEnabledLocal(enabled: Boolean) {
-        TokenStore.save2faEnabled(appContext, enabled)
-    }
-
-    private var _http: HttpClient? = null
-    val http: HttpClient
-        get() = synchronized(this) {
-            _http ?: createClient().also { _http = it }
-        }
-
-    private fun createClient(): HttpClient {
-        return HttpClient(Android) {
-            install(ContentNegotiation) {
-                json(Json { ignoreUnknownKeys = true })
-            }
-            install(Auth) {
-                bearer {
-                    loadTokens {
-                        val token = TokenStore.get(appContext) ?: return@loadTokens null
-                        Log.d("Chat", "Auth plugin loading token: ${getScopeFromToken(token)}")
-                        BearerTokens(token, "")
-                    }
-                    sendWithoutRequest { request ->
-                        val path = request.url.encodedPath
-                        !path.endsWith("/login") && !path.endsWith("/signup")
-                    }
-                }
-            }
-        }
-    }
-
-    private fun resetClient() {
-        Log.d("Chat", "Resetting HttpClient to refresh tokens")
-        _http?.close()
-        _http = null
-    }
-
-    suspend fun login(username: String, password: String): ApiResult<LoginResponse> {
-        return try {
-            val response = http.post("${BASE_URL}/api/login") {
-                contentType(ContentType.Application.Json)
-                setBody(LoginRequest(username, password))
-            }
-            if (response.status.isSuccess()) {
-                val body = response.body<LoginResponse>()
-                Log.d("Chat", "Login token scope: ${getScopeFromToken(body.token)}")
-                TokenStore.save(appContext, body.token)
-                resetClient()
-                ApiResult.Success(body)
-            } else {
-                ApiResult.HttpError(
-                    status = response.status.value,
-                    message = when (response.status.value) {
-                        401 -> "Invalid username or password"
-                        403 -> "Account suspended"
-                        429 -> "Too many attempts, please wait"
-                        else -> "Login failed (${response.status.value})"
-                    }
-                )
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "Login network error", e)
-            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
-        }
-    }
-
-    suspend fun signup(username: String, email: String, password: String, token: String): ApiResult<LoginResponse> {
-        return try {
-            val response = http.post("${BASE_URL}/api/signup") {
-                contentType(ContentType.Application.Json)
-                setBody(SignupRequest(username = username, email = email, password = password, access_token = token))
-            }
-            if (response.status.isSuccess()) {
-                val body = response.body<LoginResponse>()
-                TokenStore.save(appContext, body.token)
-                resetClient()
-                ApiResult.Success(body)
-            } else {
-                ApiResult.HttpError(
-                    status = response.status.value,
-                    message = when (response.status.value) {
-                        401 -> "Invalid access token"
-                        else -> "Signup failed (${response.status.value})"
-                    }
-                )
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "Signup error", e)
-            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
-        }
-    }
-
-    fun logout() {
-        TokenStore.clear(appContext)
-        resetClient()
-    }
-
-    suspend fun sendMessage(channelId: Int, text: String) {
-        val userId = TokenStore.getUserId(appContext) ?: return
-        http.post("${BASE_URL}/api/chat/$channelId") {
-            contentType(ContentType.Application.Json)
-            setBody(SendMessage(
-                user_id = userId,
-                text = text,
-                timestamp = System.currentTimeMillis()
-            ))
-        }
-    }
-
-    fun messageStream(channelId: Int): Flow<Message> = flow {
-        http.prepareGet("${BASE_URL}/api/events/$channelId").execute { response ->
-            val channel = response.bodyAsChannel()
-            while (!channel.isClosedForRead) {
-                val line = channel.readUTF8Line(256) ?: break
-                if (line.startsWith("data:")) {
-                    val json = line.removePrefix("data:").trim()
-                    runCatching { Json.decodeFromString<Message>(json) }
-                        .onSuccess { emit(it) }
-                }
-            }
-        }
-    }
-
-    suspend fun getTotpQr(): QrResponse? {
-        return try {
-            http.get("${BASE_URL}/api/totp.jpg").body<QrResponse>()
-        } catch (e: Exception) {
-            Log.e("Chat", "Error fetching TOTP QR", e)
-            null
-        }
-    }
-
-    suspend fun confirmTotp(code: String): Boolean {
-        return try {
-            val response = http.post("${BASE_URL}/api/totp") {
-                contentType(ContentType.Application.Json)
-                setBody(TOTPSixDigitCode(code))
-            }
-            if (response.status.isSuccess()) {
-                // If confirming TOTP returns a new token (e.g. from partial to full), we should save it
-                // Assuming confirm might return a LoginResponse if it upgrades the session
-                runCatching {
-                    val body = response.body<LoginResponse>()
-                    TokenStore.save(appContext, body.token)
-                    resetClient()
-                }
-                set2faEnabledLocal(true)
-                true
-            } else {
-                false
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "Error confirming TOTP", e)
-            false
-        }
-    }
-
-    suspend fun verifyTotpLogin(code: String): ApiResult<LoginResponse> {
-        return try {
-            val response = http.post("${BASE_URL}/api/totp/verify") {
-                contentType(ContentType.Application.Json)
-                setBody(TOTPSixDigitCode(code))
-            }
-            if (response.status.isSuccess()) {
-                val body = response.body<LoginResponse>()
-
-                val tok = body.token;
-                Log.d("Chat", "UID ${getUserIdFromToken(tok)}");
-                Log.d("Chat", "Token ${getScopeFromToken(tok)}");
-
-                TokenStore.save(appContext, body.token)
-                resetClient()
-                ApiResult.Success(body)
-            } else {
-                val errorText = try { response.body<String>() } catch (e: Exception) { "Unknown error" }
-                Log.e("Chat", "TOTP verify failed: ${response.status.value} - $errorText")
-                ApiResult.HttpError(
-                    status = response.status.value,
-                    message = when (response.status.value) {
-                        401 -> "Incorrect code, please try again"
-                        403 -> "Session expired, please log in again"
-                        429 -> "Too many attempts, please wait"
-                        else -> "Verification failed (${response.status.value})"
-                    }
-                )
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "TOTP verify network error", e)
-            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
-        }
-    }
-
-    suspend fun getTotpStatus(): Boolean {
-        return try {
-            val response = http.get("${BASE_URL}/api/totp/status")
-            if (response.status.isSuccess()) {
-                val status = response.body<TotpStatus>()
-                val enabled = status.isEnabled
-                set2faEnabledLocal(enabled)
-                enabled
-            } else {
-                is2faEnabledLocal()
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "Error getting TOTP status", e)
-            is2faEnabledLocal()
-        }
-    }
-
-    suspend fun disableTotp(): ApiResult<LoginResponse> {
-        return try {
-            val response = http.delete("${BASE_URL}/api/totp")
-            if (response.status.isSuccess()) {
-                val body = response.body<LoginResponse>()
-                TokenStore.save(appContext, body.token)
-                set2faEnabledLocal(false)
-                resetClient()
-                ApiResult.Success(body)
-            } else {
-                ApiResult.HttpError(response.status.value, "Failed to disable TOTP")
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "Error disabling TOTP", e)
-            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
-        }
-    }
-
-    suspend fun changePassword(old: String, new: String): ApiResult<Unit> {
-        return try {
-            val response = http.post("${BASE_URL}/api/settings/password") {
-                contentType(ContentType.Application.Json)
-                setBody(PasswordChangeRequest(old, new))
-            }
-            if (response.status.isSuccess()) {
-                ApiResult.Success(Unit)
-            } else {
-                ApiResult.HttpError(
-                    response.status.value,
-                    if (response.status.value == 401) "Old password is wrong" else "Password change failed"
-                )
-            }
-        } catch (e: Exception) {
-            Log.e("Chat", "Error changing password", e)
-            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
-        }
-    }
-
-    suspend fun updateDisplayName(name: String?): Boolean {
-        return try {
-            val response = http.post("${BASE_URL}/api/settings/display_name") {
-                contentType(ContentType.Application.Json)
-                setBody(DisplayNameRequest(name))
-            }
-            response.status.isSuccess()
-        } catch (e: Exception) {
-            Log.e("Chat", "Error updating display name", e)
-            false
-        }
-    }
-}
-

android/app/src/main/java/dev/zxq5/chatapp/android/api/AuthClient.kt

@@ -0,0 +1,116 @@
+package dev.zxq5.chatapp.android.api
+
+import android.util.Log
+import dev.zxq5.chatapp.android.api.model.LoginRequest
+import dev.zxq5.chatapp.android.api.model.LoginResponse
+import dev.zxq5.chatapp.android.api.model.TOTPSixDigitCode
+import dev.zxq5.chatapp.android.core.BASE_URL
+import dev.zxq5.chatapp.android.core.error.ApiResult
+import dev.zxq5.chatapp.android.api.model.SignupRequest
+import io.ktor.client.HttpClient
+import io.ktor.client.call.body
+import io.ktor.client.engine.android.Android
+import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
+import io.ktor.client.request.header
+import io.ktor.client.request.post
+import io.ktor.client.request.setBody
+import io.ktor.http.ContentType
+import io.ktor.http.HttpHeaders
+import io.ktor.http.contentType
+import io.ktor.http.isSuccess
+import io.ktor.serialization.kotlinx.json.json
+import kotlinx.serialization.json.Json
+
+/**
+ * Client for unauthenticated and pre-authenticated (2FA) requests.
+ */
+object AuthClient {
+    private val http = HttpClient(Android) {
+        install(ContentNegotiation) {
+            json(Json { ignoreUnknownKeys = true })
+        }
+    }
+
+    suspend fun login(username: String, password: String): ApiResult<LoginResponse> {
+        return try {
+            val response = http.post("${BASE_URL}/api/login") {
+                contentType(ContentType.Application.Json)
+                setBody(LoginRequest(username, password))
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(response.body<LoginResponse>())
+            } else {
+                ApiResult.HttpError(
+                    status = response.status.value,
+                    message = when (response.status.value) {
+                        401 -> "Invalid username or password"
+                        403 -> "Account suspended"
+                        429 -> "Too many attempts, please wait"
+                        else -> "Login failed (${response.status.value})"
+                    }
+                )
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Login network error", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun signup(username: String, email: String, password: String, token: String): ApiResult<LoginResponse> {
+        return try {
+            val response = http.post("${BASE_URL}/api/signup") {
+                contentType(ContentType.Application.Json)
+                setBody(
+                    SignupRequest(
+                        username = username,
+                        email = email,
+                        password = password,
+                        access_token = token
+                    )
+                )
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(response.body<LoginResponse>())
+            } else {
+                ApiResult.HttpError(
+                    status = response.status.value,
+                    message = when (response.status.value) {
+                        401 -> "Invalid access token"
+                        else -> "Signup failed (${response.status.value})"
+                    }
+                )
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Signup error", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun verifyTotpLogin(partialToken: String, code: String): ApiResult<LoginResponse> {
+        return try {
+            val response = http.post("${BASE_URL}/api/totp/verify") {
+                header(HttpHeaders.Authorization, "Bearer $partialToken")
+                contentType(ContentType.Application.Json)
+                setBody(TOTPSixDigitCode(code))
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(response.body<LoginResponse>())
+            } else {
+                val errorText = try { response.body<String>() } catch (e: Exception) { "Unknown error" }
+                Log.e("Chat", "TOTP verify failed: ${response.status.value} - $errorText")
+                ApiResult.HttpError(
+                    status = response.status.value,
+                    message = when (response.status.value) {
+                        401 -> "Incorrect code, please try again"
+                        403 -> "Session expired, please log in again"
+                        429 -> "Too many attempts, please wait"
+                        else -> "Verification failed (${response.status.value})"
+                    }
+                )
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "TOTP verify network error", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/api/ChatClient.kt

@@ -0,0 +1,57 @@
+package dev.zxq5.chatapp.android.api
+
+import dev.zxq5.chatapp.android.core.BASE_URL
+import dev.zxq5.chatapp.android.api.model.Message
+import dev.zxq5.chatapp.android.api.model.SendMessage
+import io.ktor.client.HttpClient
+import io.ktor.client.engine.android.Android
+import io.ktor.client.plugins.auth.Auth
+import io.ktor.client.plugins.auth.providers.BearerTokens
+import io.ktor.client.plugins.auth.providers.bearer
+import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
+import io.ktor.client.request.post
+import io.ktor.client.request.prepareGet
+import io.ktor.client.request.setBody
+import io.ktor.client.statement.bodyAsChannel
+import io.ktor.http.ContentType
+import io.ktor.http.contentType
+import io.ktor.serialization.kotlinx.json.json
+import io.ktor.utils.io.readUTF8Line
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import kotlinx.serialization.json.Json
+
+class ChatClient(private val token: String) {
+    private val http = HttpClient(Android) {
+        install(ContentNegotiation) {
+            json(Json { ignoreUnknownKeys = true })
+        }
+        install(Auth) {
+            bearer {
+                loadTokens { BearerTokens(token, "") }
+            }
+        }
+    }
+
+    suspend fun sendMessage(channelId: Int, userId: Int, text: String) {
+        http.post("${BASE_URL}/api/chat/$channelId") {
+            contentType(ContentType.Application.Json)
+            setBody(SendMessage(user_id = userId, text = text, timestamp = System.currentTimeMillis()))
+        }
+    }
+
+    fun messageStream(channelId: Int): Flow<Message> = flow {
+        http.prepareGet("${BASE_URL}/api/events/$channelId").execute { response ->
+            val channel = response.bodyAsChannel()
+            while (!channel.isClosedForRead) {
+                val line = channel.readUTF8Line(256) ?: break
+                if (line.startsWith("data:")) {
+                    val json = line.removePrefix("data:").trim()
+                    runCatching { Json.decodeFromString<Message>(json) }
+                        .onSuccess { emit(it) }
+                }
+            }
+        }
+    }
+}
+

android/app/src/main/java/dev/zxq5/chatapp/android/api/SettingsClient.kt

@@ -0,0 +1,171 @@
+package dev.zxq5.chatapp.android.api
+
+import android.util.Log
+import dev.zxq5.chatapp.android.api.model.AccountDeleteRequest
+import dev.zxq5.chatapp.android.api.model.DisplayNameRequest
+import dev.zxq5.chatapp.android.api.model.PasswordChangeRequest
+import dev.zxq5.chatapp.android.api.model.QrResponse
+import dev.zxq5.chatapp.android.api.model.TOTPSixDigitCode
+import dev.zxq5.chatapp.android.api.model.TotpStatus
+import dev.zxq5.chatapp.android.api.model.UsernameRequest
+import dev.zxq5.chatapp.android.api.model.TotpDeleteRequest
+import dev.zxq5.chatapp.android.api.model.PasswordRequest
+import dev.zxq5.chatapp.android.core.BASE_URL
+import dev.zxq5.chatapp.android.core.error.ApiResult
+import io.ktor.client.HttpClient
+import io.ktor.client.call.body
+import io.ktor.client.engine.android.Android
+import io.ktor.client.plugins.auth.Auth
+import io.ktor.client.plugins.auth.providers.BearerTokens
+import io.ktor.client.plugins.auth.providers.bearer
+import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
+import io.ktor.client.request.delete
+import io.ktor.client.request.get
+import io.ktor.client.request.patch
+import io.ktor.client.request.post
+import io.ktor.client.request.setBody
+import io.ktor.http.ContentType
+import io.ktor.http.contentType
+import io.ktor.http.isSuccess
+import io.ktor.serialization.kotlinx.json.json
+import kotlinx.serialization.json.Json
+
+/**
+ * Client for account settings and TOTP management.
+ */
+class SettingsClient(private val token: String) {
+    private val http = HttpClient(Android) {
+        install(ContentNegotiation) {
+            json(Json { ignoreUnknownKeys = true })
+        }
+        install(Auth) {
+            bearer {
+                loadTokens { BearerTokens(token, "") }
+            }
+        }
+    }
+
+    suspend fun getTotpQr(password: String): ApiResult<QrResponse> {
+        return try {
+            val response = http.post("${BASE_URL}/api/totp.jpg") {
+                contentType(ContentType.Application.Json)
+                setBody(PasswordRequest(password))
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(response.body<QrResponse>())
+            } else {
+                ApiResult.HttpError(response.status.value, "Failed to get QR code")
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Error fetching TOTP QR", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun confirmTotp(code: String): ApiResult<Unit> {
+        return try {
+            val response = http.post("${BASE_URL}/api/totp") {
+                contentType(ContentType.Application.Json)
+                setBody(TOTPSixDigitCode(code))
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(Unit)
+            } else {
+                ApiResult.HttpError(response.status.value, "Failed to confirm TOTP")
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Error confirming TOTP", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun getTotpStatus(): ApiResult<TotpStatus> {
+        return try {
+            val response = http.get("${BASE_URL}/api/totp/status")
+            if (response.status.isSuccess()) {
+                ApiResult.Success(response.body<TotpStatus>())
+            } else {
+                ApiResult.HttpError(response.status.value, "Failed to get TOTP status")
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Error getting TOTP status", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun disableTotp(password: String, totpCode: String): ApiResult<Unit> {
+        return try {
+            val response = http.delete("${BASE_URL}/api/totp") {
+                contentType(ContentType.Application.Json)
+                setBody(TotpDeleteRequest(password, totpCode))
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(Unit)
+            } else {
+                ApiResult.HttpError(response.status.value, "Failed to disable TOTP")
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Error disabling TOTP", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun changePassword(old: String, new: String): ApiResult<Unit> {
+        return try {
+            val response = http.post("${BASE_URL}/api/settings/password") {
+                contentType(ContentType.Application.Json)
+                setBody(PasswordChangeRequest(old, new))
+            }
+            if (response.status.isSuccess()) {
+                ApiResult.Success(Unit)
+            } else {
+                ApiResult.HttpError(
+                    response.status.value,
+                    if (response.status.value == 401) "Old password is wrong" else "Password change failed"
+                )
+            }
+        } catch (e: Exception) {
+            Log.e("Chat", "Error changing password", e)
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun updateDisplayName(name: String?): Boolean {
+        return try {
+            val response = http.patch("${BASE_URL}/api/settings/display_name") {
+                contentType(ContentType.Application.Json)
+                setBody(DisplayNameRequest(name))
+            }
+            response.status.isSuccess()
+        } catch (e: Exception) {
+            Log.e("Chat", "Error updating display name", e)
+            false
+        }
+    }
+
+    suspend fun updateUsername(username: String): ApiResult<Unit> {
+        return try {
+            val response = http.patch("${BASE_URL}/api/settings/username") {
+                contentType(ContentType.Application.Json)
+                setBody(UsernameRequest(username))
+            }
+            if (response.status.isSuccess()) ApiResult.Success(Unit)
+            else ApiResult.HttpError(response.status.value, "Failed to update username")
+        } catch (e: Exception) {
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+
+    suspend fun deleteAccount(password: String, totpCode: String?): ApiResult<Unit> {
+        return try {
+            val response = http.delete("${BASE_URL}/api/settings") {
+                contentType(ContentType.Application.Json)
+                setBody(AccountDeleteRequest(password, totpCode))
+            }
+            if (response.status.isSuccess()) ApiResult.Success(Unit)
+            else ApiResult.HttpError(response.status.value, "Failed to delete account")
+        } catch (e: Exception) {
+            ApiResult.NetworkError(e.localizedMessage ?: "Network error")
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/AccountDeleteRequest.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class AccountDeleteRequest(val password: String, val totp_code: String? = null)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/DisplayNameRequest.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class DisplayNameRequest(val display_name: String?)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/LoginRequest.kt

@@ -1,4 +1,4 @@
-package dev.zxq5.chatapp.android.model
+package dev.zxq5.chatapp.android.api.model
 
 import kotlinx.serialization.Serializable
 
@@ -6,6 +6,4 @@ import kotlinx.serialization.Serializable
 data class LoginRequest(
     val username: String,
     val password: String
-)
+)
-
-

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/LoginResponse.kt

@@ -1,4 +1,4 @@
-package dev.zxq5.chatapp.android.model
+package dev.zxq5.chatapp.android.api.model
 
 import kotlinx.serialization.Serializable
 

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/Message.kt

@@ -1,4 +1,4 @@
-package dev.zxq5.chatapp.android.model
+package dev.zxq5.chatapp.android.api.model
 
 import kotlinx.serialization.Serializable
 
@@ -8,4 +8,4 @@ data class Message(
     val display_name: String,
     val text: String,
     val timestamp: Long
-)
+)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/PasswordChangeRequest.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class PasswordChangeRequest(val old_password: String, val new_password: String)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/PasswordRequest.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class PasswordRequest(val password: String)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/QrResponse.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class QrResponse(val qr_code: String)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/SendMessage.kt

@@ -1,4 +1,4 @@
-package dev.zxq5.chatapp.android.model
+package dev.zxq5.chatapp.android.api.model
 
 import kotlinx.serialization.Serializable
 
@@ -7,4 +7,4 @@ data class SendMessage(
     val user_id: Int,
     val text: String,
     val timestamp: Long
-)
+)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/SignupRequest.kt

@@ -1,4 +1,4 @@
-package dev.zxq5.chatapp.android.model
+package dev.zxq5.chatapp.android.api.model
 
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
@@ -11,4 +11,4 @@ data class SignupRequest(
 
     @SerialName("access_token")
     val access_token: String
-)
+)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/TOTPSixDigitCode.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class TOTPSixDigitCode(val code: String)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/TotpDeleteRequest.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class TotpDeleteRequest(val password: String, val totp_code: String)

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/TotpStatus.kt

@@ -0,0 +1,24 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+
+@Serializable(with = TotpStatus.TotpStatusSerializer::class)
+enum class TotpStatus {
+    ENABLED, DISABLED;
+    val isEnabled: Boolean get() = this == ENABLED
+
+
+    companion object TotpStatusSerializer : KSerializer<TotpStatus> {
+        override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("TotpStatus", PrimitiveKind.STRING)
+        override fun serialize(encoder: Encoder, value: TotpStatus) = encoder.encodeString(value.name.lowercase())
+        override fun deserialize(decoder: Decoder): TotpStatus =
+            TotpStatus.valueOf(decoder.decodeString().uppercase())
+    }
+}
+

android/app/src/main/java/dev/zxq5/chatapp/android/api/model/UsernameRequest.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class UsernameRequest(val username: String)

android/app/src/main/java/dev/zxq5/chatapp/android/core/data/TokenStore.kt

@@ -8,12 +8,14 @@ import androidx.security.crypto.EncryptedSharedPreferences
 import androidx.security.crypto.MasterKey
 import org.json.JSONObject
 
-// In your ApiClient or a dedicated TokenStore
+private const val KEY = "auth_token"
-object TokenStore {
+private const val TWOFA_KEY = "twofa_enabled"
-    private const val KEY = "auth_token"
-    private const val TWOFA_KEY = "twofa_enabled"
 
-    private fun prefs(context: Context): SharedPreferences {
+// In your ChatClient.kt or a dedicated TokenStore
+class TokenStore(appContext: Context) {
+    private val context = appContext.applicationContext;
+
+    private fun prefs(): SharedPreferences {
         return EncryptedSharedPreferences.create(
             context,
             "secure_prefs",
@@ -25,54 +27,54 @@ object TokenStore {
         )
     }
 
-    fun save(context: Context, token: String) =
+    fun save(token: String) =
-        prefs(context).edit { putString(KEY, token) }
+        prefs().edit { putString(KEY, token) }
 
-    fun get(context: Context): String? =
+    fun get(): String? =
-        prefs(context).getString(KEY, null)
+        prefs().getString(KEY, null)
 
-    fun save2faEnabled(context: Context, enabled: Boolean) =
+    fun save2faEnabled( enabled: Boolean) =
-        prefs(context).edit { putBoolean(TWOFA_KEY, enabled) }
+        prefs().edit { putBoolean(TWOFA_KEY, enabled) }
 
-    fun is2faEnabled(context: Context): Boolean =
+    fun is2faEnabled(): Boolean =
-        prefs(context).getBoolean(TWOFA_KEY, false)
+        prefs().getBoolean(TWOFA_KEY, false)
 
-    fun clear(context: Context) =
+    fun clear() =
-        prefs(context).edit { remove(KEY).remove(TWOFA_KEY) }
+        prefs().edit { remove(KEY).remove(TWOFA_KEY) }
 
-    fun getUserId(context: Context): Int? {
+    fun getUserId(): Int? {
-        val token = get(context) ?: return null
+        val token = get() ?: return null
         return getUserIdFromToken(token)
     }
+}
 
-    fun getUserIdFromToken(token: String): Int? {
+fun getUserIdFromToken(token: String): Int? {
-        return try {
+    return try {
-            val payload = token.split(".")[1]
+        val payload = token.split(".")[1]
-            // base64url needs padding restored
+        // base64url needs padding restored
-            val padded = payload + "==".take((4 - payload.length % 4) % 4)
+        val padded = payload + "==".take((4 - payload.length % 4) % 4)
-            val jsonString = String(Base64.decode(padded, Base64.URL_SAFE))
+        val jsonString = String(Base64.decode(padded, Base64.URL_SAFE))
-            val json = JSONObject(jsonString)
+        val json = JSONObject(jsonString)
 
-            // Handle both standard 'sub' and custom 'user_id'
+        // Handle both standard 'sub' and custom 'user_id'
-            when {
+        when {
-                json.has("sub") -> json.getInt("sub")
+            json.has("sub") -> json.getInt("sub")
-                json.has("user_id") -> json.getInt("user_id")
+            json.has("user_id") -> json.getInt("user_id")
-                else -> null
+            else -> null
-            }
-        } catch (e: Exception) {
-            null
         }
+    } catch (e: Exception) {
+        null
     }
+}
 
-    fun getScopeFromToken(token: String): String? {
+fun getScopeFromToken(token: String): String? {
-        return try {
+    return try {
-            val payload = token.split(".")[1]
+        val payload = token.split(".")[1]
-            val padded = payload + "==".take((4 - payload.length % 4) % 4)
+        val padded = payload + "==".take((4 - payload.length % 4) % 4)
-            val jsonString = String(Base64.decode(padded, Base64.URL_SAFE))
+        val jsonString = String(Base64.decode(padded, Base64.URL_SAFE))
-            val json = JSONObject(jsonString)
+        val json = JSONObject(jsonString)
-            if (json.has("scope")) json.getString("scope") else null
+        if (json.has("scope")) json.getString("scope") else null
-        } catch (e: Exception) {
+    } catch (e: Exception) {
-            null
+        null
-        }
     }
 }

android/app/src/main/java/dev/zxq5/chatapp/android/data/repository/AuthRepository.kt

@@ -1,35 +1,83 @@
 package dev.zxq5.chatapp.android.data.repository
 
-import dev.zxq5.chatapp.android.api.ApiClient
+import dev.zxq5.chatapp.android.api.AuthClient
 import dev.zxq5.chatapp.android.core.data.TokenStore
+import dev.zxq5.chatapp.android.core.data.getScopeFromToken
 import dev.zxq5.chatapp.android.core.error.ApiResult
-//
+import dev.zxq5.chatapp.android.feature.auth.TokenScope
-//class AuthRepository(
-//    private val apiClient: ApiClient,
-//    private val tokenStore: TokenStore,
-//) {
-//
-//    suspend fun login(username: String, password: String): LoginResult {
-////        return when(val result = apiClient.login(username, password)) {
-////            is ApiResult.Success -> {
-////                tokenStore.save(context = context, result.data.token);
-////            }
-////        }
-//    }
-//}
 
+class AuthRepository(
+    private val tokenStore: TokenStore,
+) {
+    suspend fun signup(username: String, email: String, password: String, accessToken: String): SignupResult {
+        return when(val result = AuthClient.signup(username, email, password, accessToken)) {
+            is ApiResult.HttpError -> SignupResult.Error(result.message)
+            is ApiResult.NetworkError -> SignupResult.Error("Network error: ${result.message}")
+            is ApiResult.Success -> {
+                tokenStore.save(result.data.token)
+                SignupResult.Success
+            }
+        }
+    }
 
+    suspend fun verifyTotpLogin(code: String): LoginResult {
+        val partialToken = tokenStore.get() ?: return LoginResult.Error("Session expired")
+        return when(val result = AuthClient.verifyTotpLogin(partialToken, code)) {
+            is ApiResult.HttpError -> LoginResult.TotpError(result.message)
+            is ApiResult.NetworkError -> LoginResult.TotpError("Network error: ${result.message}")
+            is ApiResult.Success -> {
+                tokenStore.save(result.data.token)
+                LoginResult.Success
+            }
+        }
+    }
 
+    suspend fun login(username: String, password: String): LoginResult {
+        return when(val result = AuthClient.login(username, password)) {
+            is ApiResult.HttpError -> LoginResult.Error(result.message)
+            is ApiResult.NetworkError -> LoginResult.Error("Network error: ${result.message}")
+            is ApiResult.Success -> {
+                tokenStore.save(result.data.token)
+
+                when (val scope = getScopeFromToken(result.data.token)) {
+                    TokenScope.TOTP_PENDING -> LoginResult.TotpRequired
+                    TokenScope.FULL -> LoginResult.Success
+                    else -> LoginResult.Error("Unexpected token scope: $scope")
+                }
+            }
+       }
+    }
+
+    fun logout() {
+        tokenStore.clear()
+    }
+    
+    fun getUserId() = tokenStore.getUserId()
+
+    fun getAuthState(): AuthState {
+        val token = tokenStore.get() ?: return AuthState.Unauthenticated
+        return when (getScopeFromToken(token)) {
+            TokenScope.FULL -> AuthState.Authenticated
+            TokenScope.TOTP_PENDING -> AuthState.AwaitingTotp
+            else -> AuthState.Unauthenticated
+        }
+    }
+}
+
+sealed class SignupResult {
+    object Success : SignupResult()
+    data class Error(val message: String) : SignupResult()
+}
 
 sealed class LoginResult {
     object Success : LoginResult()
-    object TotpRequired : LoginResult()           // step 1 outcome → go to totp screen
+    object TotpRequired : LoginResult()
-    data class TotpError(val message: String) : LoginResult()  // step 2 failure → stay on totp screen, show error
+    data class TotpError(val message: String) : LoginResult()
-    data class Error(val message: String) : LoginResult()      // general failure → show on login form
+    data class Error(val message: String) : LoginResult()
 }
 
 sealed class AuthState {
     object Authenticated : AuthState()
     object AwaitingTotp : AuthState()
     object Unauthenticated : AuthState()
-}
+}

android/app/src/main/java/dev/zxq5/chatapp/android/data/repository/ChatRepository.kt

@@ -0,0 +1,38 @@
+package dev.zxq5.chatapp.android.data.repository
+
+import dev.zxq5.chatapp.android.api.ChatClient
+import dev.zxq5.chatapp.android.core.data.TokenStore
+import dev.zxq5.chatapp.android.api.model.Message
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.emptyFlow
+
+class ChatRepository(private val tokenStore: TokenStore) {
+    
+    private var _chatClient: ChatClient? = null
+    private var _lastToken: String? = null
+
+    private fun getChatClient(): ChatClient? {
+        val token = tokenStore.get() ?: return null
+        if (_chatClient == null || token != _lastToken) {
+            _chatClient = ChatClient(token)
+            _lastToken = token
+        }
+        return _chatClient
+    }
+
+    fun resetClient() {
+        _chatClient = null
+        _lastToken = null
+    }
+
+    fun getUserId() = tokenStore.getUserId()
+
+    suspend fun sendMessage(channelId: Int, text: String) {
+        val userId = tokenStore.getUserId() ?: return
+        getChatClient()?.sendMessage(channelId, userId, text)
+    }
+
+    fun messageStream(channelId: Int): Flow<Message> {
+        return getChatClient()?.messageStream(channelId) ?: emptyFlow()
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/data/repository/SettingsRepository.kt

@@ -0,0 +1,67 @@
+package dev.zxq5.chatapp.android.data.repository
+
+import dev.zxq5.chatapp.android.api.model.QrResponse
+import dev.zxq5.chatapp.android.api.SettingsClient
+import dev.zxq5.chatapp.android.api.model.TotpStatus
+import dev.zxq5.chatapp.android.core.data.TokenStore
+import dev.zxq5.chatapp.android.core.error.ApiResult
+
+class SettingsRepository(private val tokenStore: TokenStore) {
+
+    private var _settingsClient: SettingsClient? = null
+    private var _lastToken: String? = null
+
+    private fun getSettingsClient(): SettingsClient? {
+        val token = tokenStore.get() ?: return null
+        if (_settingsClient == null || token != _lastToken) {
+            _settingsClient = SettingsClient(token)
+            _lastToken = token
+        }
+        return _settingsClient
+    }
+
+    fun resetClient() {
+        _settingsClient = null
+        _lastToken = null
+    }
+
+    suspend fun getTotpQr(password: String): ApiResult<QrResponse?> {
+        val settingsClient = getSettingsClient() ?: return ApiResult.NetworkError("Not authenticated")
+        return settingsClient.getTotpQr(password)
+    }
+
+    suspend fun confirmTotp(code: String): ApiResult<Unit> {
+        val client = getSettingsClient() ?: return ApiResult.NetworkError("Not authenticated")
+        return client.confirmTotp(code)
+    }
+
+    suspend fun getTotpStatus(): ApiResult<TotpStatus> {
+        return getSettingsClient()?.getTotpStatus() ?: ApiResult.NetworkError("Not authenticated")
+    }
+
+    suspend fun disableTotp(password: String, totpCode: String): ApiResult<Unit> {
+        val client = getSettingsClient() ?: return ApiResult.NetworkError("Not authenticated")
+        return client.disableTotp(password, totpCode)
+    }
+
+    suspend fun changePassword(old: String, new: String): ApiResult<Unit> {
+        return getSettingsClient()?.changePassword(old, new) ?: ApiResult.NetworkError("Not authenticated")
+    }
+
+    suspend fun updateDisplayName(name: String?): Boolean {
+        return getSettingsClient()?.updateDisplayName(name) ?: false
+    }
+
+    suspend fun updateUsername(username: String): ApiResult<Unit> {
+        return getSettingsClient()?.updateUsername(username) ?: ApiResult.NetworkError("Not authenticated")
+    }
+
+    suspend fun deleteAccount(password: String, totpCode: String?): ApiResult<Unit> {
+        return getSettingsClient()?.deleteAccount(password, totpCode) ?: ApiResult.NetworkError("Not authenticated")
+    }
+
+    fun logout() {
+        tokenStore.clear()
+        resetClient()
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/AuthMode.kt

@@ -0,0 +1,5 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+enum class AuthMode {
+    LOGIN, SIGNUP
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/AuthScreen.kt

@@ -0,0 +1,39 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import dev.zxq5.chatapp.android.model.LoginState
+
+@Composable
+fun AuthScreen(viewModel: AuthViewModel) {
+    val loginState by viewModel.loginState.collectAsState()
+    val authMode by viewModel.authMode.collectAsState()
+    val totpError by viewModel.totpError.collectAsState()
+
+    if (loginState is LoginState.TwoFactorRequired ||
+        (loginState is LoginState.Loading && totpError != null)) {
+        TwoFactorLoginScreen(
+            onVerify = { viewModel.verifyTotpLogin(it) },
+            onBack = {
+                viewModel.clearTotpError()
+                viewModel.setAuthMode(AuthMode.LOGIN)
+            },
+            isLoading = loginState is LoginState.Loading,
+            error = totpError
+        )
+        return
+    }
+
+    if (authMode == AuthMode.SIGNUP) {
+        SignupScreen(
+            viewModel = viewModel,
+            onSwitchToLogin = { viewModel.setAuthMode(AuthMode.LOGIN) }
+        )
+    } else {
+        LoginScreen(
+            viewModel = viewModel,
+            onSwitchToSignup = { viewModel.setAuthMode(AuthMode.SIGNUP) }
+        )
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/AuthViewModel.kt

@@ -0,0 +1,107 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dev.zxq5.chatapp.android.data.repository.AuthRepository
+import dev.zxq5.chatapp.android.data.repository.LoginResult
+import dev.zxq5.chatapp.android.data.repository.SignupResult
+import dev.zxq5.chatapp.android.data.repository.AuthState
+import dev.zxq5.chatapp.android.model.LoginState
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.launch
+
+class AuthViewModel(private val authRepository: AuthRepository) : ViewModel() {
+    
+    private val _loginState = MutableStateFlow<LoginState>(LoginState.Idle)
+    val loginState: StateFlow<LoginState> = _loginState
+
+    private val _authMode = MutableStateFlow(AuthMode.LOGIN)
+    val authMode: StateFlow<AuthMode> = _authMode
+
+    private val _authState = MutableStateFlow(authRepository.getAuthState())
+    val authState: StateFlow<AuthState> = _authState
+
+    private val _totpError = MutableStateFlow<String?>(null)
+    val totpError: StateFlow<String?> = _totpError
+
+    fun setAuthMode(mode: AuthMode) {
+        _authMode.value = mode
+        if (_loginState.value is LoginState.Error) {
+            _loginState.value = LoginState.Idle
+        }
+    }
+
+    fun signup(username: String, email: String, password: String, accessToken: String) {
+        viewModelScope.launch {
+            _loginState.value = LoginState.Loading
+            when (val result = authRepository.signup(username, email, password, accessToken)) {
+                is SignupResult.Success -> {
+                    updateAuthState()
+                    _loginState.value = LoginState.Success
+                }
+                is SignupResult.Error -> {
+                    _loginState.value = LoginState.Error(result.message)
+                }
+            }
+        }
+    }
+
+    fun login(username: String, password: String) {
+        viewModelScope.launch {
+            _loginState.value = LoginState.Loading
+            when (val result = authRepository.login(username, password)) {
+                is LoginResult.Success -> {
+                    updateAuthState()
+                    _loginState.value = LoginState.Success
+                }
+                is LoginResult.TotpRequired -> {
+                    updateAuthState()
+                    _loginState.value = LoginState.TwoFactorRequired
+                }
+                is LoginResult.Error -> {
+                    _loginState.value = LoginState.Error(result.message)
+                }
+                is LoginResult.TotpError -> {
+                    _loginState.value = LoginState.Error(result.message)
+                }
+            }
+        }
+    }
+
+    fun verifyTotpLogin(code: String) {
+        viewModelScope.launch {
+            _loginState.value = LoginState.Loading
+            when (val result = authRepository.verifyTotpLogin(code)) {
+                is LoginResult.Success -> {
+                    updateAuthState()
+                    _loginState.value = LoginState.Success
+                }
+                is LoginResult.TotpError -> {
+                    _totpError.value = result.message
+                    _loginState.value = LoginState.TwoFactorRequired
+                }
+                is LoginResult.Error -> {
+                    _loginState.value = LoginState.Error(result.message)
+                }
+                is LoginResult.TotpRequired -> {
+                    _loginState.value = LoginState.TwoFactorRequired
+                }
+            }
+        }
+    }
+
+    fun logout() {
+        authRepository.logout()
+        updateAuthState()
+        _loginState.value = LoginState.Idle
+    }
+
+    private fun updateAuthState() {
+        _authState.value = authRepository.getAuthState()
+    }
+    
+    fun clearTotpError() {
+        _totpError.value = null
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/LoginScreen.kt

@@ -0,0 +1,133 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.unit.dp
+import dev.zxq5.chatapp.android.model.LoginState
+import dev.zxq5.chatapp.android.ui.components.TextField
+
+@Composable
+fun LoginScreen(
+    viewModel: AuthViewModel,
+    onSwitchToSignup: () -> Unit
+) {
+    val loginState by viewModel.loginState.collectAsState()
+    var username by remember { mutableStateOf("") }
+    var password by remember { mutableStateOf("") }
+    var localError by remember { mutableStateOf<String?>(null) }
+
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(MaterialTheme.colorScheme.background)
+            .padding(24.dp)
+            .verticalScroll(rememberScrollState()),
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+        Spacer(Modifier.height(40.dp))
+        
+        Text(
+            text = "messenger",
+            style = MaterialTheme.typography.labelSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.padding(bottom = 8.dp)
+        )
+
+        Text(
+            text = "welcome back",
+            style = MaterialTheme.typography.headlineMedium,
+            color = MaterialTheme.colorScheme.onSurface,
+            modifier = Modifier.padding(bottom = 48.dp)
+        )
+
+        Column(
+            modifier = Modifier.fillMaxWidth(),
+            verticalArrangement = Arrangement.spacedBy(12.dp)
+        ) {
+            TextField(
+                value = username,
+                onValueChange = { username = it },
+                label = "username"
+            )
+
+            TextField(
+                value = password,
+                onValueChange = { password = it },
+                label = "password",
+                isPassword = true
+            )
+        }
+
+        Spacer(Modifier.height(32.dp))
+
+        Button(
+            onClick = {
+                localError = null
+                if (username.isBlank() || password.isBlank()) {
+                    localError = "fill all fields"
+                    return@Button
+                }
+                viewModel.login(username, password)
+            },
+            enabled = loginState !is LoginState.Loading,
+            modifier = Modifier.fillMaxWidth(),
+            shape = RoundedCornerShape(8.dp),
+            colors = ButtonDefaults.buttonColors(
+                containerColor = MaterialTheme.colorScheme.primary,
+                contentColor = MaterialTheme.colorScheme.onPrimary,
+                disabledContainerColor = MaterialTheme.colorScheme.secondary
+            )
+        ) {
+            if (loginState is LoginState.Loading) {
+                CircularProgressIndicator(modifier = Modifier.size(16.dp), color = MaterialTheme.colorScheme.onPrimary, strokeWidth = 2.dp)
+            } else {
+                Text("login", style = MaterialTheme.typography.bodyLarge)
+            }
+        }
+
+        val displayError = localError ?: (loginState as? LoginState.Error)?.message
+        if (displayError != null) {
+            Text(
+                text = displayError.lowercase(),
+                style = MaterialTheme.typography.labelSmall,
+                color = Color.Red,
+                modifier = Modifier.padding(top = 16.dp)
+            )
+        }
+
+        Spacer(Modifier.height(16.dp))
+
+        TextButton(onClick = onSwitchToSignup) {
+            Text(
+                "no account? sign up",
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/SignupScreen.kt

@@ -0,0 +1,160 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.unit.dp
+import dev.zxq5.chatapp.android.model.LoginState
+import dev.zxq5.chatapp.android.ui.components.TextField
+
+@Composable
+fun SignupScreen(
+    viewModel: AuthViewModel,
+    onSwitchToLogin: () -> Unit
+) {
+    val loginState by viewModel.loginState.collectAsState()
+
+    var username by remember { mutableStateOf("") }
+    var email by remember { mutableStateOf("") }
+    var password by remember { mutableStateOf("") }
+    var confirmPassword by remember { mutableStateOf("") }
+    var accessToken by remember { mutableStateOf("") }
+    var localError by remember { mutableStateOf<String?>(null) }
+
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(MaterialTheme.colorScheme.background)
+            .padding(24.dp)
+            .verticalScroll(rememberScrollState()),
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+        Spacer(Modifier.height(40.dp))
+        
+        Text(
+            text = "messenger",
+            style = MaterialTheme.typography.labelSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.padding(bottom = 8.dp)
+        )
+
+        Text(
+            text = "create account",
+            style = MaterialTheme.typography.headlineMedium,
+            color = MaterialTheme.colorScheme.onSurface,
+            modifier = Modifier.padding(bottom = 48.dp)
+        )
+
+        Column(
+            modifier = Modifier.fillMaxWidth(),
+            verticalArrangement = Arrangement.spacedBy(12.dp)
+        ) {
+            TextField(
+                value = username,
+                onValueChange = { username = it },
+                label = "username"
+            )
+
+            TextField(
+                value = email,
+                onValueChange = { email = it },
+                label = "email"
+            )
+
+            TextField(
+                value = password,
+                onValueChange = { password = it },
+                label = "password",
+                isPassword = true
+            )
+
+            TextField(
+                value = confirmPassword,
+                onValueChange = { confirmPassword = it },
+                label = "confirm password",
+                isPassword = true
+            )
+            
+            TextField(
+                value = accessToken,
+                onValueChange = { accessToken = it },
+                label = "access token"
+            )
+        }
+
+        Spacer(Modifier.height(32.dp))
+
+        Button(
+            onClick = {
+                localError = null
+                if (username.isBlank() || email.isBlank() || password.isBlank() || accessToken.isBlank()) {
+                    localError = "fill all fields"
+                    return@Button
+                }
+                if (password != confirmPassword) {
+                    localError = "passwords mismatch"
+                    return@Button
+                }
+                viewModel.signup(username, email, password, accessToken)
+            },
+            enabled = loginState !is LoginState.Loading,
+            modifier = Modifier.fillMaxWidth(),
+            shape = RoundedCornerShape(8.dp),
+            colors = ButtonDefaults.buttonColors(
+                containerColor = MaterialTheme.colorScheme.primary,
+                contentColor = MaterialTheme.colorScheme.onPrimary,
+                disabledContainerColor = MaterialTheme.colorScheme.secondary
+            )
+        ) {
+            if (loginState is LoginState.Loading) {
+                CircularProgressIndicator(modifier = Modifier.size(16.dp), color = MaterialTheme.colorScheme.onPrimary, strokeWidth = 2.dp)
+            } else {
+                Text("sign up", style = MaterialTheme.typography.bodyLarge)
+            }
+        }
+
+        val displayError = localError ?: (loginState as? LoginState.Error)?.message
+        if (displayError != null) {
+            Text(
+                text = displayError.lowercase(),
+                style = MaterialTheme.typography.labelSmall,
+                color = Color.Red,
+                modifier = Modifier.padding(top = 16.dp)
+            )
+        }
+
+        Spacer(Modifier.height(16.dp))
+
+        TextButton(onClick = onSwitchToLogin) {
+            Text(
+                "have account? login",
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/TokenScope.kt

@@ -0,0 +1,6 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+object TokenScope {
+    const val FULL = "full"
+    const val TOTP_PENDING = "totp_pending"
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/auth/TwoFactorLoginScreen.kt

@@ -0,0 +1,138 @@
+package dev.zxq5.chatapp.android.feature.auth
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.OutlinedTextFieldDefaults
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+
+@Composable
+fun TwoFactorLoginScreen(
+    onVerify: (String) -> Unit,
+    onBack: () -> Unit,
+    isLoading: Boolean,
+    error: String?
+) {
+    var code by remember { mutableStateOf("") }
+
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(MaterialTheme.colorScheme.background)
+            .padding(24.dp),
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            verticalAlignment = Alignment.CenterVertically
+        ) {
+            IconButton(onClick = onBack) {
+                Icon(
+                    Icons.AutoMirrored.Filled.ArrowBack,
+                    contentDescription = "Back",
+                    tint = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            }
+            Text(
+                "security verification",
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+        }
+
+        Spacer(Modifier.height(80.dp))
+
+        Text(
+            "two-factor auth",
+            style = MaterialTheme.typography.headlineMedium,
+            color = MaterialTheme.colorScheme.onSurface
+        )
+
+        Text(
+            "enter the 6-digit code from your app",
+            style = MaterialTheme.typography.labelSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f),
+            modifier = Modifier.padding(top = 8.dp, bottom = 48.dp)
+        )
+
+        OutlinedTextField(
+            value = code,
+            onValueChange = { if (it.length <= 6) code = it },
+            placeholder = { Text("000000", color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.3f)) },
+            modifier = Modifier.width(200.dp),
+            textStyle = MaterialTheme.typography.headlineMedium.copy(
+                textAlign = TextAlign.Center,
+                letterSpacing = 8.sp
+            ),
+            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
+            shape = RoundedCornerShape(8.dp),
+            colors = OutlinedTextFieldDefaults.colors(
+                focusedBorderColor = MaterialTheme.colorScheme.primary,
+                unfocusedBorderColor = MaterialTheme.colorScheme.outlineVariant,
+                focusedContainerColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f),
+                unfocusedContainerColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f)
+            ),
+            singleLine = true
+        )
+
+        if (error != null) {
+            Text(
+                text = error.lowercase(),
+                style = MaterialTheme.typography.labelSmall,
+                color = Color.Red,
+                modifier = Modifier.padding(top = 12.dp)
+            )
+        } else {
+            Spacer(Modifier.height(12.dp)) 
+        }
+
+        Spacer(Modifier.height(36.dp))
+
+        Button(
+            onClick = { if (code.length == 6) onVerify(code) },
+            enabled = code.length == 6 && !isLoading,
+            modifier = Modifier.fillMaxWidth(),
+            shape = RoundedCornerShape(8.dp),
+            colors = ButtonDefaults.buttonColors(
+                containerColor = MaterialTheme.colorScheme.primary,
+                contentColor = MaterialTheme.colorScheme.onPrimary
+            )
+        ) {
+            if (isLoading) {
+                CircularProgressIndicator(modifier = Modifier.size(16.dp), color = MaterialTheme.colorScheme.onPrimary, strokeWidth = 2.dp)
+            } else {
+                Text("verify", style = MaterialTheme.typography.bodyLarge)
+            }
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/chat/ChatViewModel.kt

@@ -0,0 +1,93 @@
+package dev.zxq5.chatapp.android.feature.chat
+
+import android.util.Log
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dev.zxq5.chatapp.android.data.repository.ChatRepository
+import dev.zxq5.chatapp.android.api.model.Message
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+
+
+
+class ChatViewModel(private val chatRepository: ChatRepository) : ViewModel() {
+
+    private val _messages = MutableStateFlow<List<Message>>(emptyList())
+    val messages: StateFlow<List<Message>> = _messages
+
+    private val _channelId = MutableStateFlow<Int?>(null)
+    val channelId: StateFlow<Int?> = _channelId
+
+    private val _currentScreen = MutableStateFlow(Screen.CHAT)
+    val currentScreen: StateFlow<Screen> = _currentScreen
+
+    private val _currentUserId = MutableStateFlow<Int?>(null)
+    val currentUserId: StateFlow<Int?> = _currentUserId
+
+    private var streamJob: Job? = null
+
+    init {
+        _currentUserId.value = chatRepository.getUserId()
+        observeChannel()
+    }
+
+    private fun observeChannel() {
+        viewModelScope.launch {
+            _channelId.collect { id ->
+                streamJob?.cancel()
+                _messages.value = emptyList()
+                if (id != null) {
+                    streamJob = launch {
+                        chatRepository.messageStream(id)
+                            .catch { e -> 
+                                Log.e("Chat", "Stream error", e)
+                            }
+                            .collect { message ->
+                                _messages.update { it + message }
+                            }
+                    }
+                }
+            }
+        }
+    }
+
+    fun navigateTo(screen: Screen) {
+        _currentScreen.value = screen
+    }
+
+    fun switchChannel(id: Int?) {
+        _channelId.value = id
+        if (id != null) {
+            // Refresh user ID just in case it wasn't available at init
+            _currentUserId.value = chatRepository.getUserId()
+            chatRepository.resetClient() 
+        }
+    }
+
+    fun sendMessage(text: String) {
+        val currentId = _channelId.value ?: return
+        viewModelScope.launch {
+            runCatching {
+                chatRepository.sendMessage(
+                    channelId = currentId,
+                    text = text
+                )
+            }.onFailure { e ->
+                Log.e("Chat", "Send message error", e)
+            }
+        }
+    }
+    
+    fun clearChat() {
+        _messages.value = emptyList()
+        _channelId.value = null
+        _currentUserId.value = null
+        streamJob?.cancel()
+        chatRepository.resetClient()
+    }
+}
+

android/app/src/main/java/dev/zxq5/chatapp/android/feature/chat/Screen.kt

@@ -0,0 +1,5 @@
+package dev.zxq5.chatapp.android.feature.chat
+
+enum class Screen {
+    CHAT, SETTINGS
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/chat/chat.kt

@@ -1,5 +1,6 @@
-package dev.zxq5.chatapp.android.ui.components
+package dev.zxq5.chatapp.android.feature.chat
 
+import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
@@ -26,12 +27,7 @@ import androidx.compose.foundation.text.KeyboardActions
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
-import androidx.compose.material.icons.automirrored.filled.ExitToApp
 import androidx.compose.material.icons.filled.Add
-import androidx.compose.material.icons.filled.Send
-import androidx.compose.material.icons.filled.Settings
-import androidx.compose.material.icons.outlined.ChatBubbleOutline
-import androidx.compose.material.icons.outlined.Settings
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
@@ -45,6 +41,9 @@ import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material.icons.filled.Send
+import androidx.compose.material.icons.outlined.ChatBubbleOutline
+import androidx.compose.material.icons.outlined.Settings
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
@@ -58,21 +57,25 @@ import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.SolidColor
 import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
-import dev.zxq5.chatapp.android.model.ChatViewModel
+import dev.zxq5.chatapp.android.api.model.Message
-import dev.zxq5.chatapp.android.model.MainScreen
-import dev.zxq5.chatapp.android.model.Message
 import java.text.DateFormat
 import java.util.Date
 
 @Composable
-fun ChatScreen(viewModel: ChatViewModel) {
+fun ChatScreen(
+    viewModel: ChatViewModel,
+    onNavigateToSettings: () -> Unit,
+    onLogout: () -> Unit // Note: logout is now part of SettingsScreen in this UI, but we'll keep the param for now
+) {
     val selectedChannelId by viewModel.channelId.collectAsState()
 
     if (selectedChannelId == null) {
         ChannelListScreen(
             viewModel = viewModel,
-            onChannelSelect = { viewModel.switchChannel(it) }
+            onChannelSelect = { viewModel.switchChannel(it) },
+            onNavigateToSettings = onNavigateToSettings
         )
     } else {
         MessageScreen(
@@ -85,7 +88,11 @@ fun ChatScreen(viewModel: ChatViewModel) {
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun ChannelListScreen(viewModel: ChatViewModel, onChannelSelect: (Int) -> Unit) {
+fun ChannelListScreen(
+    viewModel: ChatViewModel, 
+    onChannelSelect: (Int) -> Unit,
+    onNavigateToSettings: () -> Unit
+) {
     Scaffold(
         containerColor = MaterialTheme.colorScheme.background,
         topBar = {
@@ -153,7 +160,7 @@ fun ChannelListScreen(viewModel: ChatViewModel, onChannelSelect: (Int) -> Unit)
                 }
             }
         },
-        bottomBar = { BottomDock(viewModel) }
+        bottomBar = { BottomDock(viewModel, onNavigateToSettings) }
     ) { padding ->
         LazyColumn(modifier = Modifier.padding(padding).fillMaxSize()) {
             items(10) { i ->
@@ -170,7 +177,7 @@ fun ChannelListScreen(viewModel: ChatViewModel, onChannelSelect: (Int) -> Unit)
 }
 
 @Composable
-fun BottomDock(viewModel: ChatViewModel) {
+fun BottomDock(viewModel: ChatViewModel, onNavigateToSettings: () -> Unit) {
     val currentScreen by viewModel.currentScreen.collectAsState()
     
     NavigationBar(
@@ -179,8 +186,8 @@ fun BottomDock(viewModel: ChatViewModel) {
         modifier = Modifier.border(0.5.dp, MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.2f), RoundedCornerShape(topStart = 0.dp, topEnd = 0.dp))
     ) {
         NavigationBarItem(
-            selected = currentScreen == MainScreen.CHAT,
+            selected = currentScreen == Screen.CHAT,
-            onClick = { viewModel.navigateTo(MainScreen.CHAT) },
+            onClick = { viewModel.navigateTo(Screen.CHAT) },
             icon = { Icon(Icons.Outlined.ChatBubbleOutline, contentDescription = "Chat") },
             label = { Text("chat", style = MaterialTheme.typography.labelSmall) },
             colors = NavigationBarItemDefaults.colors(
@@ -190,8 +197,8 @@ fun BottomDock(viewModel: ChatViewModel) {
             )
         )
         NavigationBarItem(
-            selected = currentScreen == MainScreen.SETTINGS,
+            selected = currentScreen == Screen.SETTINGS,
-            onClick = { viewModel.navigateTo(MainScreen.SETTINGS) },
+            onClick = onNavigateToSettings,
             icon = { Icon(Icons.Outlined.Settings, contentDescription = "Settings") },
             label = { Text("settings", style = MaterialTheme.typography.labelSmall) },
             colors = NavigationBarItemDefaults.colors(
@@ -409,7 +416,7 @@ fun MessageBubble(message: Message, currentUserId: Int?) {
             Column(modifier = Modifier.padding(horizontal = 11.dp, vertical = 8.dp)) {
                 if (!isMe) {
                     Text(
-                        message.display_name.lowercase(),
+                        message.display_name?.lowercase() ?: "unknown",
                         style = MaterialTheme.typography.labelSmall,
                         color = MaterialTheme.colorScheme.primary.copy(alpha = 0.7f),
                         modifier = Modifier.padding(bottom = 2.dp)
@@ -431,5 +438,5 @@ fun MessageBubble(message: Message, currentUserId: Int?) {
     }
 }
 
-private fun border(width: androidx.compose.ui.unit.Dp, color: Color) = 
+private fun border(width: Dp, color: Color) =
-    androidx.compose.foundation.BorderStroke(width, color)
+    BorderStroke(width, color)

android/app/src/main/java/dev/zxq5/chatapp/android/feature/settings/SettingsViewModel.kt

@@ -0,0 +1,157 @@
+package dev.zxq5.chatapp.android.feature.settings
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dev.zxq5.chatapp.android.api.model.QrResponse
+import dev.zxq5.chatapp.android.core.error.ApiResult
+import dev.zxq5.chatapp.android.data.repository.SettingsRepository
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.launch
+
+class SettingsViewModel(private val settingsRepository: SettingsRepository) : ViewModel() {
+
+    private val _is2faEnabled = MutableStateFlow(false)
+    val is2faEnabled: StateFlow<Boolean> = _is2faEnabled
+
+    private val _totpQr = MutableStateFlow<QrResponse?>(null)
+    val totpQr: StateFlow<QrResponse?> = _totpQr
+
+    private val _totpError = MutableStateFlow<String?>(null)
+    val totpError: StateFlow<String?> = _totpError
+
+    private val _settingsError = MutableStateFlow<String?>(null)
+    val settingsError: StateFlow<String?> = _settingsError
+
+    private val _isSuccessState = MutableStateFlow<Map<String, Boolean>>(emptyMap())
+    val isSuccessState: StateFlow<Map<String, Boolean>> = _isSuccessState
+
+    fun clearMessages() {
+        _settingsError.value = null
+        _totpError.value = null
+    }
+
+    private fun triggerSuccess(key: String) {
+        viewModelScope.launch {
+            _isSuccessState.value = _isSuccessState.value + (key to true)
+            delay(5000)
+            _isSuccessState.value = _isSuccessState.value + (key to false)
+        }
+    }
+
+    fun fetchTotpStatus() {
+        viewModelScope.launch {
+            when (val result = settingsRepository.getTotpStatus()) {
+                is ApiResult.Success -> _is2faEnabled.value = result.data.isEnabled
+                else -> {}
+            }
+        }
+    }
+
+    fun fetchTotpQr(password: String) {
+        viewModelScope.launch {
+            _totpError.value = null
+            when (val result = settingsRepository.getTotpQr(password)) {
+                is ApiResult.Success -> {
+                    _totpQr.value = result.data
+                }
+                is ApiResult.HttpError -> {
+                    _totpError.value = result.message
+                }
+                is ApiResult.NetworkError -> {
+                    _totpError.value = "Network error: ${result.message}"
+                }
+            }
+        }
+    }
+
+    fun confirmTotp(code: String) {
+        viewModelScope.launch {
+            _totpError.value = null
+            when (val result = settingsRepository.confirmTotp(code)) {
+                is ApiResult.Success -> {
+                    _is2faEnabled.value = true
+                    _totpQr.value = null
+                    triggerSuccess("2fa")
+                }
+                is ApiResult.HttpError -> {
+                    _totpError.value = result.message
+                }
+                is ApiResult.NetworkError -> {
+                    _totpError.value = "Network error: ${result.message}"
+                }
+            }
+        }
+    }
+
+    fun disableTotp(password: String, totpCode: String) {
+        viewModelScope.launch {
+            _totpError.value = null
+            when (val result = settingsRepository.disableTotp(password, totpCode)) {
+                is ApiResult.Success -> {
+                    _is2faEnabled.value = false
+                    triggerSuccess("2fa")
+                }
+                is ApiResult.HttpError -> _totpError.value = result.message
+                is ApiResult.NetworkError -> _totpError.value = "Network error: ${result.message}"
+            }
+        }
+    }
+
+    fun changePassword(old: String, new: String) {
+        viewModelScope.launch {
+            clearMessages()
+            when (val result = settingsRepository.changePassword(old, new)) {
+                is ApiResult.Success -> {
+                    triggerSuccess("password")
+                }
+                is ApiResult.HttpError -> _settingsError.value = result.message
+                is ApiResult.NetworkError -> _settingsError.value = "Network error: ${result.message}"
+            }
+        }
+    }
+
+    fun updateDisplayName(name: String?) {
+        viewModelScope.launch {
+            clearMessages()
+            if (settingsRepository.updateDisplayName(name)) {
+                triggerSuccess("display_name")
+            } else {
+                _settingsError.value = "Failed to update display name"
+            }
+        }
+    }
+
+    fun updateUsername(username: String) {
+        viewModelScope.launch {
+            clearMessages()
+            when (val result = settingsRepository.updateUsername(username)) {
+                is ApiResult.Success -> {
+                    triggerSuccess("username")
+                }
+                is ApiResult.HttpError -> _settingsError.value = result.message
+                is ApiResult.NetworkError -> _settingsError.value = "Network error: ${result.message}"
+            }
+        }
+    }
+
+    fun deleteAccount(password: String, totpCode: String?, onLogout: () -> Unit) {
+        viewModelScope.launch {
+            clearMessages()
+            when (val result = settingsRepository.deleteAccount(password, totpCode)) {
+                is ApiResult.Success -> {
+                    _isSuccessState.value = _isSuccessState.value + ("delete" to true)
+                    delay(3000)
+                    onLogout()
+                }
+                is ApiResult.HttpError -> _settingsError.value = result.message
+                is ApiResult.NetworkError -> _settingsError.value = "Network error: ${result.message}"
+            }
+        }
+    }
+
+    fun logout() {
+        settingsRepository.logout()
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/feature/settings/settings.kt

@@ -0,0 +1,534 @@
+package dev.zxq5.chatapp.android.feature.settings
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.animateColorAsState
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.filled.KeyboardArrowDown
+import androidx.compose.material.icons.filled.KeyboardArrowUp
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.OutlinedTextFieldDefaults
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.asImageBitmap
+import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.text.input.PasswordVisualTransformation
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import android.util.Base64
+import android.graphics.BitmapFactory
+import androidx.compose.ui.text.style.TextAlign
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SettingsScreen(
+    viewModel: SettingsViewModel,
+    onBack: () -> Unit,
+    onLogout: () -> Unit
+) {
+    val is2faEnabled by viewModel.is2faEnabled.collectAsState()
+    val totpQr by viewModel.totpQr.collectAsState()
+    val settingsError by viewModel.settingsError.collectAsState()
+    val isSuccessState by viewModel.isSuccessState.collectAsState()
+    val totpError by viewModel.totpError.collectAsState()
+    
+    LaunchedEffect(Unit) {
+        viewModel.clearMessages()
+        viewModel.fetchTotpStatus()
+    }
+
+    Scaffold(
+        containerColor = MaterialTheme.colorScheme.background,
+        topBar = {
+            TopAppBar(
+                title = { 
+                    Text(
+                        "settings", 
+                        style = MaterialTheme.typography.titleLarge,
+                        color = MaterialTheme.colorScheme.onSurface
+                    ) 
+                },
+                navigationIcon = {
+                    IconButton(onClick = onBack) {
+                        Icon(
+                            Icons.AutoMirrored.Filled.ArrowBack, 
+                            contentDescription = "Back",
+                            tint = MaterialTheme.colorScheme.onSurfaceVariant
+                        )
+                    }
+                },
+                colors = TopAppBarDefaults.topAppBarColors(containerColor = Color.Transparent)
+            )
+        }
+    ) { padding ->
+        Column(
+            modifier = Modifier
+                .padding(padding)
+                .fillMaxSize()
+                .verticalScroll(rememberScrollState())
+                .padding(20.dp),
+            verticalArrangement = Arrangement.spacedBy(16.dp)
+        ) {
+            SettingsSection(title = "profile") {
+                var displayName by remember { mutableStateOf("") }
+                var username by remember { mutableStateOf("") }
+
+                SettingsField(
+                    label = "display name",
+                    value = displayName,
+                    onValueChange = { displayName = it },
+                    buttonLabel = "update",
+                    isSuccess = isSuccessState["display_name"] == true,
+                    onClick = { viewModel.updateDisplayName(displayName.ifBlank { null }) }
+                )
+
+                Spacer(Modifier.height(16.dp))
+
+                SettingsField(
+                    label = "username",
+                    value = username,
+                    onValueChange = { username = it },
+                    buttonLabel = "update",
+                    isSuccess = isSuccessState["username"] == true,
+                    onClick = { if (username.isNotBlank()) viewModel.updateUsername(username) }
+                )
+            }
+
+            SettingsSection(title = "security") {
+                var oldPassword by remember { mutableStateOf("") }
+                var newPassword by remember { mutableStateOf("") }
+
+                Text("change password", style = MaterialTheme.typography.bodyMedium, modifier = Modifier.padding(bottom = 8.dp))
+                OutlinedTextField(
+                    value = oldPassword,
+                    onValueChange = { oldPassword = it },
+                    label = { Text("old password") },
+                    visualTransformation = PasswordVisualTransformation(),
+                    modifier = Modifier.fillMaxWidth(),
+                    shape = RoundedCornerShape(8.dp)
+                )
+                Spacer(Modifier.height(8.dp))
+                OutlinedTextField(
+                    value = newPassword,
+                    onValueChange = { newPassword = it },
+                    label = { Text("new password") },
+                    visualTransformation = PasswordVisualTransformation(),
+                    modifier = Modifier.fillMaxWidth(),
+                    shape = RoundedCornerShape(8.dp)
+                )
+                Spacer(Modifier.height(12.dp))
+                SuccessButton(
+                    onClick = { 
+                        viewModel.changePassword(oldPassword, newPassword)
+                        oldPassword = ""
+                        newPassword = ""
+                    },
+                    label = "update password",
+                    isSuccess = isSuccessState["password"] == true,
+                    enabled = oldPassword.isNotEmpty() && newPassword.isNotEmpty(),
+                    modifier = Modifier.fillMaxWidth()
+                )
+
+                HorizontalDivider(modifier = Modifier.padding(vertical = 16.dp), color = MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.2f))
+
+                var show2faSetup by remember { mutableStateOf(false) }
+                var setupPassword by remember { mutableStateOf("") }
+                
+                var show2faDisable by remember { mutableStateOf(false) }
+                var disablePassword by remember { mutableStateOf("") }
+                var disableCode by remember { mutableStateOf("") }
+
+                Row(
+                    modifier = Modifier.fillMaxWidth(),
+                    verticalAlignment = Alignment.CenterVertically
+                ) {
+                    Column(modifier = Modifier.weight(1f)) {
+                        Text("two-factor authentication", style = MaterialTheme.typography.bodyLarge)
+                        Text(
+                            if (is2faEnabled) "enabled" else "disabled",
+                            style = MaterialTheme.typography.labelSmall,
+                            color = if (is2faEnabled) Color.Green.copy(alpha = 0.7f) else MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f)
+                        )
+                    }
+                    
+                    if (!is2faEnabled) {
+                        Button(
+                            onClick = { 
+                                show2faSetup = !show2faSetup
+                                if (!show2faSetup) setupPassword = ""
+                            },
+                            shape = RoundedCornerShape(8.dp),
+                            colors = ButtonDefaults.buttonColors(containerColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.3f), contentColor = MaterialTheme.colorScheme.onSurface)
+                        ) {
+                            Text(if (show2faSetup) "cancel" else "setup", style = MaterialTheme.typography.labelSmall)
+                        }
+                    } else {
+                        SuccessButton(
+                            onClick = { 
+                                show2faDisable = !show2faDisable 
+                                if (!show2faDisable) {
+                                    disablePassword = ""
+                                    disableCode = ""
+                                }
+                            },
+                            label = if (show2faDisable) "cancel" else "disable",
+                            isSuccess = isSuccessState["2fa"] == true,
+                            baseColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f),
+                            contentColor = Color.Red,
+                            successColor = Color.Red
+                        )
+                    }
+                }
+
+                if (show2faSetup && !is2faEnabled) {
+                    Spacer(Modifier.height(16.dp))
+                    if (totpQr == null) {
+                        OutlinedTextField(
+                            value = setupPassword,
+                            onValueChange = { setupPassword = it },
+                            label = { Text("confirm password to setup") },
+                            visualTransformation = PasswordVisualTransformation(),
+                            modifier = Modifier.fillMaxWidth(),
+                            shape = RoundedCornerShape(8.dp)
+                        )
+                        Spacer(Modifier.height(8.dp))
+                        Button(
+                            onClick = { viewModel.fetchTotpQr(setupPassword) },
+                            enabled = setupPassword.isNotBlank(),
+                            modifier = Modifier.fillMaxWidth()
+                        ) {
+                            Text("get qr code")
+                        }
+                    } else {
+                        TwoFactorSetup(
+                            qrCodeBase64 = totpQr?.qr_code,
+                            error = totpError,
+                            onConfirm = { viewModel.confirmTotp(it) }
+                        )
+                    }
+                }
+
+                if (show2faDisable && is2faEnabled) {
+                    Spacer(Modifier.height(16.dp))
+                    OutlinedTextField(
+                        value = disablePassword,
+                        onValueChange = { disablePassword = it },
+                        label = { Text("password") },
+                        visualTransformation = PasswordVisualTransformation(),
+                        modifier = Modifier.fillMaxWidth(),
+                        shape = RoundedCornerShape(8.dp)
+                    )
+                    Spacer(Modifier.height(8.dp))
+                    OutlinedTextField(
+                        value = disableCode,
+                        onValueChange = { if (it.length <= 6) disableCode = it },
+                        label = { Text("2fa code") },
+                        modifier = Modifier.fillMaxWidth(),
+                        shape = RoundedCornerShape(8.dp),
+                        keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number)
+                    )
+                    Spacer(Modifier.height(8.dp))
+                    SuccessButton(
+                        onClick = { viewModel.disableTotp(disablePassword, disableCode) },
+                        label = "confirm disable",
+                        isSuccess = isSuccessState["2fa"] == true,
+                        baseColor = Color.Red,
+                        enabled = disablePassword.isNotBlank() && disableCode.length == 6,
+                        modifier = Modifier.fillMaxWidth()
+                    )
+                }
+                
+                if (totpError != null && !show2faSetup && !show2faDisable) {
+                     Text(totpError!!.lowercase(), color = Color.Red, style = MaterialTheme.typography.labelSmall, modifier = Modifier.padding(top = 8.dp))
+                }
+            }
+
+            SettingsSection(title = "danger zone", color = Color.Red.copy(alpha = 0.7f)) {
+                var deletePassword by remember { mutableStateOf("") }
+                var deleteTotp by remember { mutableStateOf("") }
+                var showDeleteConfirm by remember { mutableStateOf(false) }
+
+                if (!showDeleteConfirm) {
+                    Button(
+                        onClick = { showDeleteConfirm = true },
+                        modifier = Modifier.fillMaxWidth(),
+                        shape = RoundedCornerShape(8.dp),
+                        colors = ButtonDefaults.buttonColors(containerColor = Color.Red.copy(alpha = 0.1f), contentColor = Color.Red)
+                    ) {
+                        Text("delete account")
+                    }
+                } else {
+                    Text("confirm account deletion", color = Color.Red, style = MaterialTheme.typography.bodyMedium)
+                    Spacer(Modifier.height(8.dp))
+                    OutlinedTextField(
+                        value = deletePassword,
+                        onValueChange = { deletePassword = it },
+                        label = { Text("password") },
+                        visualTransformation = PasswordVisualTransformation(),
+                        modifier = Modifier.fillMaxWidth(),
+                        shape = RoundedCornerShape(8.dp)
+                    )
+                    if (is2faEnabled) {
+                        Spacer(Modifier.height(8.dp))
+                        OutlinedTextField(
+                            value = deleteTotp,
+                            onValueChange = { if (it.length <= 6) deleteTotp = it },
+                            label = { Text("2fa code") },
+                            modifier = Modifier.fillMaxWidth(),
+                            shape = RoundedCornerShape(8.dp),
+                            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number)
+                        )
+                    }
+                    Spacer(Modifier.height(12.dp))
+                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        Button(
+                            onClick = { showDeleteConfirm = false },
+                            modifier = Modifier.weight(1f),
+                            shape = RoundedCornerShape(8.dp),
+                            colors = ButtonDefaults.buttonColors(containerColor = MaterialTheme.colorScheme.surfaceVariant)
+                        ) {
+                            Text("cancel")
+                        }
+                        SuccessButton(
+                            onClick = { viewModel.deleteAccount(
+                                deletePassword, deleteTotp.ifBlank { null },
+                                onLogout
+                            ) },
+                            label = "delete forever",
+                            isSuccess = isSuccessState["delete"] == true,
+                            baseColor = Color.Red.copy(alpha = 0.1f),
+                            contentColor = Color.Red,
+                            successColor = Color.Red,
+                            modifier = Modifier.weight(1f),
+                            enabled = deletePassword.isNotEmpty() && (!is2faEnabled || deleteTotp.length == 6)
+                        )
+                    }
+                }
+            }
+
+            SettingsSection(title = "session") {
+                Spacer(Modifier.height(16.dp))
+                Button(
+                    onClick = onLogout,
+                    modifier = Modifier.fillMaxWidth(),
+                    shape = RoundedCornerShape(8.dp),
+                    colors = ButtonDefaults.buttonColors(containerColor = Color.White, contentColor = Color.Black)
+                ) {
+                    Text("logout")
+                }
+            }
+
+            if (settingsError != null) {
+                Text(settingsError!!, color = Color.Red, style = MaterialTheme.typography.bodySmall, modifier = Modifier.padding(top = 8.dp))
+            }
+        }
+    }
+}
+
+@Composable
+fun SettingsSection(
+    title: String, 
+    color: Color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f),
+    content: @Composable () -> Unit
+) {
+    var expanded by remember { mutableStateOf(true) }
+    
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .border(0.5.dp, MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.2f), RoundedCornerShape(12.dp))
+            .clip(RoundedCornerShape(12.dp))
+            .background(MaterialTheme.colorScheme.surface.copy(alpha = 0.5f))
+    ) {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .clickable { expanded = !expanded }
+                .padding(16.dp),
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.SpaceBetween
+        ) {
+            Text(title.lowercase(), style = MaterialTheme.typography.labelSmall, color = color)
+            Icon(
+                if (expanded) Icons.Default.KeyboardArrowUp else Icons.Default.KeyboardArrowDown,
+                contentDescription = null,
+                tint = color,
+                modifier = Modifier.size(16.dp)
+            )
+        }
+        
+        AnimatedVisibility(visible = expanded) {
+            Column(modifier = Modifier.padding(horizontal = 16.dp, vertical = 8.dp).padding(bottom = 8.dp)) {
+                content()
+            }
+        }
+    }
+}
+
+@Composable
+fun SettingsField(
+    label: String,
+    value: String,
+    onValueChange: (String) -> Unit,
+    buttonLabel: String,
+    isSuccess: Boolean,
+    onClick: () -> Unit
+) {
+    Column {
+        OutlinedTextField(
+            value = value,
+            onValueChange = onValueChange,
+            label = { Text(label) },
+            modifier = Modifier.fillMaxWidth(),
+            shape = RoundedCornerShape(8.dp),
+            colors = OutlinedTextFieldDefaults.colors(
+                focusedBorderColor = if (isSuccess) Color.Green else MaterialTheme.colorScheme.primary
+            )
+        )
+        Spacer(Modifier.height(8.dp))
+        SuccessButton(
+            onClick = onClick,
+            label = buttonLabel,
+            isSuccess = isSuccess,
+            enabled = value.isNotBlank(),
+            modifier = Modifier.fillMaxWidth()
+        )
+    }
+}
+
+@Composable
+fun SuccessButton(
+    onClick: () -> Unit,
+    label: String,
+    isSuccess: Boolean,
+    modifier: Modifier = Modifier,
+    enabled: Boolean = true,
+    baseColor: Color = MaterialTheme.colorScheme.primary,
+    contentColor: Color = MaterialTheme.colorScheme.onPrimary,
+    successColor: Color = Color.Green.copy(alpha = 0.8f)
+) {
+    val backgroundColor by animateColorAsState(
+        targetValue = if (isSuccess) successColor else baseColor,
+        animationSpec = tween(500)
+    )
+
+    Button(
+        onClick = onClick,
+        modifier = modifier,
+        enabled = enabled,
+        shape = RoundedCornerShape(8.dp),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = backgroundColor,
+            contentColor = if (isSuccess) Color.White else contentColor
+        )
+    ) {
+        Text(if (isSuccess) "success" else label)
+    }
+}
+
+@Composable
+fun TwoFactorSetup(
+    qrCodeBase64: String?,
+    error: String?,
+    onConfirm: (String) -> Unit
+) {
+    var code by remember { mutableStateOf("") }
+    
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .border(0.5.dp, MaterialTheme.colorScheme.outlineVariant, RoundedCornerShape(12.dp))
+            .background(MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f), RoundedCornerShape(12.dp))
+            .padding(20.dp),
+        horizontalAlignment = Alignment.CenterHorizontally
+    ) {
+        if (qrCodeBase64 != null) {
+            val bitmap = remember(qrCodeBase64) {
+                val base64Data = qrCodeBase64.substringAfter("base64,")
+                val decodedString = Base64.decode(base64Data, Base64.DEFAULT)
+                BitmapFactory.decodeByteArray(decodedString, 0, decodedString.size)
+            }
+            
+            bitmap?.let {
+                Image(
+                    bitmap = it.asImageBitmap(),
+                    contentDescription = "QR Code",
+                    modifier = Modifier
+                        .size(180.dp)
+                        .clip(RoundedCornerShape(8.dp))
+                        .background(Color.White)
+                        .padding(8.dp)
+                )
+            }
+        } else {
+            CircularProgressIndicator(modifier = Modifier.size(40.dp))
+        }
+        
+        Spacer(Modifier.height(24.dp))
+        
+        OutlinedTextField(
+            value = code,
+            onValueChange = { if (it.length <= 6) code = it },
+            placeholder = { Text("000000") },
+            modifier = Modifier.width(150.dp),
+            textStyle = MaterialTheme.typography.headlineMedium.copy(textAlign = TextAlign.Center),
+            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
+            shape = RoundedCornerShape(8.dp)
+        )
+
+        if (error != null) {
+            Text(error.lowercase(), color = Color.Red, style = MaterialTheme.typography.labelSmall, modifier = Modifier.padding(top = 8.dp))
+        }
+        
+        Spacer(Modifier.height(24.dp))
+        
+        Button(
+            onClick = { if (code.length == 6) onConfirm(code) },
+            enabled = code.length == 6,
+            modifier = Modifier.fillMaxWidth(),
+            shape = RoundedCornerShape(8.dp)
+        ) {
+            Text("confirm code")
+        }
+    }
+}

android/app/src/main/java/dev/zxq5/chatapp/android/model/ChatViewModel.kt

@@ -1,325 +0,0 @@
-package dev.zxq5.chatapp.android.model
-
-import android.util.Log
-import androidx.lifecycle.ViewModel
-import androidx.lifecycle.viewModelScope
-import dev.zxq5.chatapp.android.api.ApiClient
-import dev.zxq5.chatapp.android.core.error.ApiResult
-import dev.zxq5.chatapp.android.api.QrResponse
-import kotlinx.coroutines.Job
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.catch
-import kotlinx.coroutines.flow.filterNotNull
-import kotlinx.coroutines.flow.update
-import kotlinx.coroutines.launch
-
-enum class AuthMode {
-    LOGIN, SIGNUP
-}
-
-enum class MainScreen {
-    CHAT, SETTINGS
-}
-
-class ChatViewModel : ViewModel() {
-
-    private val _messages = MutableStateFlow<List<Message>>(emptyList())
-    val messages: StateFlow<List<Message>> = _messages
-
-    private val _channelId = MutableStateFlow<Int?>(null)
-    val channelId: StateFlow<Int?> = _channelId
-
-    private val _currentUserId = MutableStateFlow<Int?>(null)
-    val currentUserId: StateFlow<Int?> = _currentUserId
-
-    private val _currentScreen = MutableStateFlow(MainScreen.CHAT)
-    val currentScreen: StateFlow<MainScreen> = _currentScreen
-
-    val loginState = MutableStateFlow<LoginState>(LoginState.Idle)
-    
-    // Tracks whether the user is viewing the Login or Signup screen
-    val authMode = MutableStateFlow(AuthMode.LOGIN)
-
-    // 2FA state
-    private val _totpQr = MutableStateFlow<QrResponse?>(null)
-    val totpQr: StateFlow<QrResponse?> = _totpQr
-
-    private val _is2faEnabled = MutableStateFlow(false)
-    val is2faEnabled: StateFlow<Boolean> = _is2faEnabled
-
-    private val _totpError = MutableStateFlow<String?>(null)
-    val totpError: StateFlow<String?> = _totpError
-
-    // Settings state
-    private val _settingsError = MutableStateFlow<String?>(null)
-    val settingsError: StateFlow<String?> = _settingsError
-
-    private val _settingsSuccess = MutableStateFlow<String?>(null)
-    val settingsSuccess: StateFlow<String?> = _settingsSuccess
-
-    fun clearSettingsMessages() {
-        _settingsError.value = null
-        _settingsSuccess.value = null
-    }
-
-    fun clearTotpError() {
-        _totpError.value = null
-    }
-
-    private var streamJob: Job? = null
-
-    init {
-        initAuth(ApiClient.hasToken())
-    }
-    
-    fun initAuth(hasToken: Boolean) {
-        if (hasToken) {
-            val scope = ApiClient.getTokenScope()
-            if (scope == TokenScope.TOTP_PENDING) {
-                loginState.value = LoginState.TwoFactorRequired
-            } else if (scope == TokenScope.FULL) {
-                loginState.value = LoginState.Success
-                _currentUserId.value = ApiClient.getStoredUserId()
-                _is2faEnabled.value = ApiClient.is2faEnabledLocal()
-                fetchTotpStatus()
-                observeChannel()
-            } else {
-                loginState.value = LoginState.Error("Unknown token scope: $scope")
-            }
-        } else {
-            loginState.value = LoginState.Idle
-        }
-    }
-
-    private fun observeChannel() {
-        // restart stream whenever channel changes
-        viewModelScope.launch {
-            _channelId.filterNotNull().collect { id ->
-                streamJob?.cancel()
-                _messages.value = emptyList()
-                streamJob = launch {
-                    ApiClient.messageStream(id)
-                        .catch { e -> 
-                            Log.e("Chat", "Stream error", e)
-                        }
-                        .collect { message ->
-                            _messages.update { it + message }
-                        }
-                }
-            }
-        }
-    }
-
-    fun navigateTo(screen: MainScreen) {
-        _currentScreen.value = screen
-        if (screen == MainScreen.SETTINGS) {
-            fetchTotpStatus()
-        }
-    }
-
-    fun switchChannel(id: Int?) {
-        _channelId.value = id
-    }
-    
-    fun setAuthMode(mode: AuthMode) {
-        authMode.value = mode
-        // Clear errors when switching modes
-        if (loginState.value is LoginState.Error || loginState.value is LoginState.TwoFactorRequired) {
-            loginState.value = LoginState.Idle
-        }
-    }
-
-    fun sendMessage(text: String) {
-        val currentId = _channelId.value ?: return
-        viewModelScope.launch {
-            runCatching {
-                ApiClient.sendMessage(
-                    channelId = currentId,
-                    text = text
-                )
-            }.onFailure { e ->
-                Log.e("Chat", "Send message error", e)
-            }
-        }
-    }
-
-    fun login(username: String, password: String) {
-        viewModelScope.launch {
-            loginState.value = LoginState.Loading
-            when (val result = ApiClient.login(username, password)) {
-                is ApiResult.Success -> {
-                    when (val scope = ApiClient.getTokenScope()) {
-                        TokenScope.FULL -> {
-                            _currentUserId.value = ApiClient.getStoredUserId()
-                            _is2faEnabled.value = ApiClient.is2faEnabledLocal()
-                            loginState.value = LoginState.Success
-                            fetchTotpStatus()
-                            observeChannel()
-                        }
-                        TokenScope.TOTP_PENDING -> {
-                            loginState.value = LoginState.TwoFactorRequired
-                        }
-                        else -> {
-                            loginState.value = LoginState.Error("Unknown token scope: $scope")
-                        }
-                    }
-                }
-                is ApiResult.HttpError -> {
-                    loginState.value = LoginState.Error(result.message)
-                }
-                is ApiResult.NetworkError -> {
-                    loginState.value = LoginState.Error("Could not reach server: ${result.message}")
-                }
-            }
-        }
-    }
-
-    fun verifyLogin2fa(code: String) {
-        viewModelScope.launch {
-            loginState.value = LoginState.Loading
-            when (val result = ApiClient.verifyTotpLogin(code)) {
-                is ApiResult.Success -> {
-                    val scope = ApiClient.getTokenScope()
-                    if (scope == TokenScope.FULL) {
-                        _currentUserId.value = ApiClient.getStoredUserId()
-                        _is2faEnabled.value = ApiClient.is2faEnabledLocal()
-                        loginState.value = LoginState.Success
-                        fetchTotpStatus()
-                        observeChannel()
-                    } else {
-                        // token came back but scope is wrong — shouldn't happen
-                        loginState.value = LoginState.Error("Unexpected token scope after verification")
-                    }
-                }
-                is ApiResult.HttpError -> {
-                    // stay on TOTP screen but show the error
-                    loginState.value = LoginState.TwoFactorRequired
-                    // use a separate error signal so we don't lose the TOTP state
-                    _totpError.value = result.message
-                }
-                is ApiResult.NetworkError -> {
-                    loginState.value = LoginState.TwoFactorRequired
-                    _totpError.value = "Could not reach server: ${result.message}"
-                }
-            }
-        }
-    }
-    
-    fun signup(username: String, email: String, password: String, accessToken: String) {
-        viewModelScope.launch {
-            loginState.value = LoginState.Loading
-            try {
-
-                when (val result = ApiClient.signup(username, email, password, accessToken)) {
-                    is ApiResult.Success -> {
-                        _currentUserId.value = ApiClient.getStoredUserId()
-                        _is2faEnabled.value = ApiClient.is2faEnabledLocal()
-                        loginState.value = LoginState.Success
-                        observeChannel()
-                    }
-                    is ApiResult.HttpError -> {
-                        loginState.value = LoginState.Error(result.message)
-                    }
-                    is ApiResult.NetworkError -> {
-                        loginState.value = LoginState.Error("Could not reach server: ${result.message}")
-                    }
-                }
-            } catch (e: Exception) {
-                Log.e("Chat", "Signup error", e)
-                loginState.value = LoginState.Error("Signup failed: ${e.localizedMessage}")
-            }
-        }
-    }
-
-    fun logout() {
-        viewModelScope.launch {
-            ApiClient.logout()
-            _currentUserId.value = null
-            _is2faEnabled.value = false
-            loginState.value = LoginState.Idle
-            _messages.value = emptyList()
-            _channelId.value = null
-            _currentScreen.value = MainScreen.CHAT
-            streamJob?.cancel()
-        }
-    }
-
-    fun fetchTotpQr() {
-        viewModelScope.launch {
-            _totpQr.value = ApiClient.getTotpQr()
-        }
-    }
-
-    fun confirmTotp(code: String) {
-        viewModelScope.launch {
-            val success = ApiClient.confirmTotp(code)
-            if (success) {
-                _is2faEnabled.value = true
-                ApiClient.set2faEnabledLocal(true)
-                _totpQr.value = null
-            } else {
-                _totpError.value = "Invalid verification code"
-            }
-        }
-    }
-
-    fun fetchTotpStatus() {
-        viewModelScope.launch {
-            _is2faEnabled.value = ApiClient.getTotpStatus()
-        }
-    }
-
-    fun disableTotp() {
-        viewModelScope.launch {
-            when (val result = ApiClient.disableTotp()) {
-                is ApiResult.Success -> {
-                    _is2faEnabled.value = false
-                    _settingsSuccess.value = "2FA disabled successfully"
-                }
-                is ApiResult.HttpError -> {
-                    _settingsError.value = result.message
-                }
-                is ApiResult.NetworkError -> {
-                    _settingsError.value = "Network error: ${result.message}"
-                }
-            }
-        }
-    }
-
-    fun changePassword(old: String, new: String) {
-        viewModelScope.launch {
-            _settingsError.value = null
-            _settingsSuccess.value = null
-            when (val result = ApiClient.changePassword(old, new)) {
-                is ApiResult.Success -> {
-                    _settingsSuccess.value = "Password updated"
-                }
-                is ApiResult.HttpError -> {
-                    _settingsError.value = result.message
-                }
-                is ApiResult.NetworkError -> {
-                    _settingsError.value = "Network error: ${result.message}"
-                }
-            }
-        }
-    }
-
-    fun updateDisplayName(name: String?) {
-        viewModelScope.launch {
-            _settingsError.value = null
-            _settingsSuccess.value = null
-            val success = ApiClient.updateDisplayName(name)
-            if (success) {
-                _settingsSuccess.value = "Display name updated"
-            } else {
-                _settingsError.value = "Failed to update display name"
-            }
-        }
-    }
-}
-
-object TokenScope {
-    const val FULL = "full";
-    const val TOTP_PENDING = "totp_pending";
-}

android/app/src/main/java/dev/zxq5/chatapp/android/ui/components/login.kt

@@ -1,318 +0,0 @@
-package dev.zxq5.chatapp.android.ui.components
-
-import androidx.compose.foundation.background
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.size
-import androidx.compose.foundation.layout.width
-import androidx.compose.foundation.rememberScrollState
-import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.foundation.text.KeyboardOptions
-import androidx.compose.foundation.verticalScroll
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.automirrored.filled.ArrowBack
-import androidx.compose.material3.Button
-import androidx.compose.material3.ButtonDefaults
-import androidx.compose.material3.CircularProgressIndicator
-import androidx.compose.material3.Icon
-import androidx.compose.material3.IconButton
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.OutlinedTextField
-import androidx.compose.material3.OutlinedTextFieldDefaults
-import androidx.compose.material3.Text
-import androidx.compose.material3.TextButton
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.collectAsState
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.text.input.KeyboardType
-import androidx.compose.ui.text.style.TextAlign
-import androidx.compose.ui.unit.dp
-import androidx.compose.ui.unit.sp
-import dev.zxq5.chatapp.android.model.AuthMode
-import dev.zxq5.chatapp.android.model.ChatViewModel
-import dev.zxq5.chatapp.android.model.LoginState
-
-@Composable
-fun AuthScreen(viewModel: ChatViewModel, onSuccess: () -> Unit) {
-    val loginState by viewModel.loginState.collectAsState()
-    val authMode by viewModel.authMode.collectAsState()
-    val totpError by viewModel.totpError.collectAsState()
-
-    var username by remember { mutableStateOf("") }
-    var email by remember { mutableStateOf("") }
-    var password by remember { mutableStateOf("") }
-    var confirmPassword by remember { mutableStateOf("") }
-    var accessToken by remember { mutableStateOf("") }
-    var localError by remember { mutableStateOf<String?>(null) }
-
-
-
-    LaunchedEffect(loginState) {
-        if (loginState is LoginState.Success) onSuccess()
-    }
-
-    LaunchedEffect(authMode) {
-        localError = null
-    }
-
-    if (loginState is LoginState.TwoFactorRequired ||
-        (loginState is LoginState.Loading && totpError != null)) {
-        TwoFactorLoginScreen(
-            onVerify = { code -> viewModel.verifyLogin2fa(code) },
-            onBack = {
-                viewModel.clearTotpError()
-                viewModel.setAuthMode(AuthMode.LOGIN)
-            },
-            isLoading = loginState is LoginState.Loading,
-            error = totpError
-        )
-        return
-    }
-
-    Column(
-        modifier = Modifier
-            .fillMaxSize()
-            .background(MaterialTheme.colorScheme.background)
-            .padding(24.dp)
-            .verticalScroll(rememberScrollState()),
-        horizontalAlignment = Alignment.CenterHorizontally
-    ) {
-        Spacer(Modifier.height(40.dp))
-        
-        Text(
-            text = "messenger",
-            style = MaterialTheme.typography.labelSmall,
-            color = MaterialTheme.colorScheme.onSurfaceVariant,
-            modifier = Modifier.padding(bottom = 8.dp)
-        )
-
-        Text(
-            text = if (authMode == AuthMode.LOGIN) "welcome back" else "create account",
-            style = MaterialTheme.typography.headlineMedium,
-            color = MaterialTheme.colorScheme.onSurface,
-            modifier = Modifier.padding(bottom = 48.dp)
-        )
-
-        Column(
-            modifier = Modifier.fillMaxWidth(),
-            verticalArrangement = Arrangement.spacedBy(12.dp)
-        ) {
-            TextField(
-                value = username,
-                onValueChange = { username = it },
-                label = "username"
-            )
-
-            if (authMode == AuthMode.SIGNUP) {
-                TextField(
-                    value = email,
-                    onValueChange = { email = it },
-                    label = "email"
-                )
-            }
-
-            TextField(
-                value = password,
-                onValueChange = { password = it },
-                label = "password",
-                isPassword = true
-            )
-
-            if (authMode == AuthMode.SIGNUP) {
-                TextField(
-                    value = confirmPassword,
-                    onValueChange = { confirmPassword = it },
-                    label = "confirm password",
-                    isPassword = true
-                )
-                TextField(
-                    value = accessToken,
-                    onValueChange = { accessToken = it },
-                    label = "access token"
-                )
-            }
-        }
-
-        Spacer(Modifier.height(32.dp))
-
-        Button(
-            onClick = {
-                localError = null
-                if (authMode == AuthMode.LOGIN) {
-                    if (username.isBlank() || password.isBlank()) {
-                        localError = "fill all fields"
-                        return@Button
-                    }
-                    viewModel.login(username, password)
-                } else {
-                    if (username.isBlank() || email.isBlank() || password.isBlank() || accessToken.isBlank()) {
-                        localError = "fill all fields"
-                        return@Button
-                    }
-                    if (password != confirmPassword) {
-                        localError = "passwords mismatch"
-                        return@Button
-                    }
-                    viewModel.signup(username, email, password, accessToken)
-                }
-            },
-            enabled = loginState !is LoginState.Loading,
-            modifier = Modifier.fillMaxWidth(),
-            shape = RoundedCornerShape(8.dp),
-            colors = ButtonDefaults.buttonColors(
-                containerColor = MaterialTheme.colorScheme.primary,
-                contentColor = MaterialTheme.colorScheme.onPrimary,
-                disabledContainerColor = MaterialTheme.colorScheme.secondary
-            )
-        ) {
-            if (loginState is LoginState.Loading) {
-                CircularProgressIndicator(modifier = Modifier.size(16.dp), color = MaterialTheme.colorScheme.onPrimary, strokeWidth = 2.dp)
-            } else {
-                Text(
-                    if (authMode == AuthMode.LOGIN) "login" else "sign up",
-                    style = MaterialTheme.typography.bodyLarge
-                )
-            }
-        }
-
-        val displayError = localError ?: (loginState as? LoginState.Error)?.message
-        if (displayError != null) {
-            Text(
-                text = displayError.lowercase(),
-                style = MaterialTheme.typography.labelSmall,
-                color = Color.Red,
-                modifier = Modifier.padding(top = 16.dp)
-            )
-        }
-
-        Spacer(Modifier.height(16.dp))
-
-        TextButton(
-            onClick = {
-                viewModel.setAuthMode(if (authMode == AuthMode.LOGIN) AuthMode.SIGNUP else AuthMode.LOGIN)
-            }
-        ) {
-            Text(
-                if (authMode == AuthMode.LOGIN) "no account? sign up"
-                else "have account? login",
-                style = MaterialTheme.typography.labelSmall,
-                color = MaterialTheme.colorScheme.onSurfaceVariant
-            )
-        }
-    }
-}
-
-@Composable
-fun TwoFactorLoginScreen(
-    onVerify: (String) -> Unit,
-    onBack: () -> Unit,
-    isLoading: Boolean,
-    error: String?
-) {
-    var code by remember { mutableStateOf("") }
-
-    Column(
-        modifier = Modifier
-            .fillMaxSize()
-            .background(MaterialTheme.colorScheme.background)
-            .padding(24.dp),
-        horizontalAlignment = Alignment.CenterHorizontally
-    ) {
-        Row(
-            modifier = Modifier.fillMaxWidth(),
-            verticalAlignment = Alignment.CenterVertically
-        ) {
-            IconButton(onClick = onBack) {
-                Icon(
-                    Icons.AutoMirrored.Filled.ArrowBack,
-                    contentDescription = "Back",
-                    tint = MaterialTheme.colorScheme.onSurfaceVariant
-                )
-            }
-            Text(
-                "security verification",
-                style = MaterialTheme.typography.labelSmall,
-                color = MaterialTheme.colorScheme.onSurfaceVariant
-            )
-        }
-
-        Spacer(Modifier.height(80.dp))
-
-        Text(
-            "two-factor auth",
-            style = MaterialTheme.typography.headlineMedium,
-            color = MaterialTheme.colorScheme.onSurface
-        )
-
-        Text(
-            "enter the 6-digit code from your app",
-            style = MaterialTheme.typography.labelSmall,
-            color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f),
-            modifier = Modifier.padding(top = 8.dp, bottom = 48.dp)
-        )
-
-        OutlinedTextField(
-            value = code,
-            onValueChange = { if (it.length <= 6) code = it },
-            placeholder = { Text("000000", color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.3f)) },
-            modifier = Modifier.width(200.dp),
-            textStyle = MaterialTheme.typography.headlineMedium.copy(
-                textAlign = TextAlign.Center,
-                letterSpacing = 8.sp
-            ),
-            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
-            shape = RoundedCornerShape(8.dp),
-            colors = OutlinedTextFieldDefaults.colors(
-                focusedBorderColor = MaterialTheme.colorScheme.primary,
-                unfocusedBorderColor = MaterialTheme.colorScheme.outlineVariant,
-                focusedContainerColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f),
-                unfocusedContainerColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f)
-            ),
-            singleLine = true
-        )
-
-        if (error != null) {
-            Text(
-                text = error.lowercase(),
-                style = MaterialTheme.typography.labelSmall,
-                color = Color.Red,
-                modifier = Modifier.padding(top = 12.dp)
-            )
-        } else {
-            Spacer(Modifier.height(12.dp)) // keep layout stable when no error
-        }
-
-        Spacer(Modifier.height(36.dp))
-
-        Button(
-            onClick = { if (code.length == 6) onVerify(code) },
-            enabled = code.length == 6 && !isLoading,
-            modifier = Modifier.fillMaxWidth(),
-            shape = RoundedCornerShape(8.dp),
-            colors = ButtonDefaults.buttonColors(
-                containerColor = MaterialTheme.colorScheme.primary,
-                contentColor = MaterialTheme.colorScheme.onPrimary
-            )
-        ) {
-            if (isLoading) {
-                CircularProgressIndicator(modifier = Modifier.size(16.dp), color = MaterialTheme.colorScheme.onPrimary, strokeWidth = 2.dp)
-            } else {
-                Text("verify", style = MaterialTheme.typography.bodyLarge)
-            }
-        }
-    }
-}
-

android/app/src/main/java/dev/zxq5/chatapp/android/ui/components/settings.kt

@@ -1,368 +0,0 @@
-package dev.zxq5.chatapp.android.ui.components
-
-import androidx.compose.foundation.Image
-import androidx.compose.foundation.background
-import androidx.compose.foundation.border
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Box
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.size
-import androidx.compose.foundation.layout.width
-import androidx.compose.foundation.rememberScrollState
-import androidx.compose.foundation.shape.CircleShape
-import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.foundation.text.KeyboardOptions
-import androidx.compose.foundation.verticalScroll
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.automirrored.filled.ArrowBack
-import androidx.compose.material.icons.filled.Check
-import androidx.compose.material3.Button
-import androidx.compose.material3.ButtonDefaults
-import androidx.compose.material3.CircularProgressIndicator
-import androidx.compose.material3.ExperimentalMaterial3Api
-import androidx.compose.material3.HorizontalDivider
-import androidx.compose.material3.Icon
-import androidx.compose.material3.IconButton
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.OutlinedTextField
-import androidx.compose.material3.OutlinedTextFieldDefaults
-import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Switch
-import androidx.compose.material3.SwitchDefaults
-import androidx.compose.material3.Text
-import androidx.compose.material3.TopAppBar
-import androidx.compose.material3.TopAppBarDefaults
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.collectAsState
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
-import androidx.compose.ui.Alignment
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.draw.clip
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.asImageBitmap
-import androidx.compose.ui.text.font.FontWeight
-import androidx.compose.ui.text.input.KeyboardType
-import androidx.compose.ui.text.input.PasswordVisualTransformation
-import androidx.compose.ui.unit.dp
-import androidx.compose.ui.unit.sp
-import dev.zxq5.chatapp.android.model.ChatViewModel
-import dev.zxq5.chatapp.android.model.MainScreen
-import android.util.Base64
-import android.graphics.BitmapFactory
-import androidx.compose.runtime.LaunchedEffect
-
-@OptIn(ExperimentalMaterial3Api::class)
-@Composable
-fun SettingsScreen(viewModel: ChatViewModel) {
-    val is2faEnabled by viewModel.is2faEnabled.collectAsState()
-    val totpQr by viewModel.totpQr.collectAsState()
-    val settingsError by viewModel.settingsError.collectAsState()
-    val settingsSuccess by viewModel.settingsSuccess.collectAsState()
-    
-    var show2faSetup by remember { mutableStateOf(false) }
-    var displayName by remember { mutableStateOf("") }
-    var oldPassword by remember { mutableStateOf("") }
-    var newPassword by remember { mutableStateOf("") }
-
-    LaunchedEffect(Unit) {
-        viewModel.clearSettingsMessages()
-        viewModel.fetchTotpStatus()
-    }
-
-    Scaffold(
-        containerColor = MaterialTheme.colorScheme.background,
-        topBar = {
-            TopAppBar(
-                title = { 
-                    Text(
-                        "settings", 
-                        style = MaterialTheme.typography.titleLarge,
-                        color = MaterialTheme.colorScheme.onSurface
-                    ) 
-                },
-                navigationIcon = {
-                    IconButton(onClick = { viewModel.navigateTo(MainScreen.CHAT) }) {
-                        Icon(
-                            Icons.AutoMirrored.Filled.ArrowBack, 
-                            contentDescription = "Back",
-                            tint = MaterialTheme.colorScheme.onSurfaceVariant
-                        )
-                    }
-                },
-                colors = TopAppBarDefaults.topAppBarColors(
-                    containerColor = Color.Transparent
-                )
-            )
-        }
-    ) { padding ->
-        Column(
-            modifier = Modifier
-                .padding(padding)
-                .fillMaxSize()
-                .verticalScroll(rememberScrollState())
-                .padding(20.dp),
-            verticalArrangement = Arrangement.spacedBy(24.dp)
-        ) {
-            if (settingsError != null) {
-                Text(settingsError!!, color = Color.Red, style = MaterialTheme.typography.bodySmall)
-            }
-            if (settingsSuccess != null) {
-                Text(settingsSuccess!!, color = Color.Green, style = MaterialTheme.typography.bodySmall)
-            }
-
-            // Profile Section
-            Column {
-                Text(
-                    "profile",
-                    style = MaterialTheme.typography.labelSmall,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f),
-                    modifier = Modifier.padding(bottom = 12.dp)
-                )
-                
-                OutlinedTextField(
-                    value = displayName,
-                    onValueChange = { displayName = it },
-                    label = { Text("display name") },
-                    modifier = Modifier.fillMaxWidth(),
-                    shape = RoundedCornerShape(8.dp),
-                    trailingIcon = {
-                        IconButton(onClick = { viewModel.updateDisplayName(displayName.ifBlank { null }) }) {
-                            Icon(Icons.Default.Check, "Save")
-                        }
-                    }
-                )
-            }
-
-            HorizontalDivider(color = MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.2f))
-
-            // Security Section
-            Column {
-                Text(
-                    "account security",
-                    style = MaterialTheme.typography.labelSmall,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f),
-                    modifier = Modifier.padding(bottom = 12.dp)
-                )
-
-                Row(
-                    modifier = Modifier.fillMaxWidth().padding(vertical = 8.dp),
-                    verticalAlignment = Alignment.CenterVertically
-                ) {
-                    Column(modifier = Modifier.weight(1f)) {
-                        Text(
-                            "two-factor authentication",
-                            style = MaterialTheme.typography.bodyLarge,
-                            color = MaterialTheme.colorScheme.onSurface
-                        )
-                        Text(
-                            if (is2faEnabled) "enabled" else "disabled",
-                            style = MaterialTheme.typography.labelSmall,
-                            color = if (is2faEnabled) Color.Green.copy(alpha = 0.7f) else MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f)
-                        )
-                    }
-                    
-                    if (!is2faEnabled) {
-                        Button(
-                            onClick = { 
-                                show2faSetup = true
-                                viewModel.fetchTotpQr()
-                            },
-                            shape = RoundedCornerShape(8.dp),
-                            colors = ButtonDefaults.buttonColors(
-                                containerColor = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.3f),
-                                contentColor = MaterialTheme.colorScheme.onSurface
-                            ),
-                            modifier = Modifier.height(32.dp)
-                        ) {
-                            Text("setup", style = MaterialTheme.typography.labelSmall)
-                        }
-                    } else {
-                        Button(
-                            onClick = { viewModel.disableTotp() },
-                            shape = RoundedCornerShape(8.dp),
-                            colors = ButtonDefaults.buttonColors(
-                                containerColor = Color.Red.copy(alpha = 0.1f),
-                                contentColor = Color.Red
-                            ),
-                            modifier = Modifier.height(32.dp)
-                        ) {
-                            Text("disable", style = MaterialTheme.typography.labelSmall)
-                        }
-                    }
-                }
-
-                if (show2faSetup && !is2faEnabled) {
-                    Spacer(Modifier.height(16.dp))
-                    TwoFactorSetup(
-                        qrCodeBase64 = totpQr?.qr_code,
-                        onConfirm = { code ->
-                            viewModel.confirmTotp(code)
-                        },
-                        onCancel = { show2faSetup = false }
-                    )
-                }
-
-                Spacer(Modifier.height(16.dp))
-
-                Text("change password", style = MaterialTheme.typography.bodyMedium, modifier = Modifier.padding(bottom = 8.dp))
-                OutlinedTextField(
-                    value = oldPassword,
-                    onValueChange = { oldPassword = it },
-                    label = { Text("old password") },
-                    visualTransformation = PasswordVisualTransformation(),
-                    modifier = Modifier.fillMaxWidth(),
-                    shape = RoundedCornerShape(8.dp)
-                )
-                Spacer(Modifier.height(8.dp))
-                OutlinedTextField(
-                    value = newPassword,
-                    onValueChange = { newPassword = it },
-                    label = { Text("new password") },
-                    visualTransformation = PasswordVisualTransformation(),
-                    modifier = Modifier.fillMaxWidth(),
-                    shape = RoundedCornerShape(8.dp)
-                )
-                Spacer(Modifier.height(12.dp))
-                Button(
-                    onClick = { 
-                        viewModel.changePassword(oldPassword, newPassword)
-                        oldPassword = ""
-                        newPassword = ""
-                    },
-                    modifier = Modifier.fillMaxWidth(),
-                    shape = RoundedCornerShape(8.dp),
-                    enabled = oldPassword.isNotEmpty() && newPassword.isNotEmpty()
-                ) {
-                    Text("update password")
-                }
-            }
-
-            HorizontalDivider(color = MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.2f))
-
-            // Application Section
-            Column {
-                Text(
-                    "application",
-                    style = MaterialTheme.typography.labelSmall,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.5f),
-                    modifier = Modifier.padding(bottom = 12.dp)
-                )
-                
-                Button(
-                    onClick = { viewModel.logout() },
-                    modifier = Modifier.fillMaxWidth(),
-                    shape = RoundedCornerShape(8.dp),
-                    colors = ButtonDefaults.buttonColors(
-                        containerColor = Color.Red.copy(alpha = 0.1f),
-                        contentColor = Color.Red
-                    )
-                ) {
-                    Text("logout", style = MaterialTheme.typography.bodyLarge)
-                }
-            }
-        }
-    }
-}
-
-@Composable
-fun TwoFactorSetup(
-    qrCodeBase64: String?,
-    onConfirm: (String) -> Unit,
-    onCancel: () -> Unit
-) {
-    var code by remember { mutableStateOf("") }
-    
-    Column(
-        modifier = Modifier
-            .fillMaxWidth()
-            .border(0.5.dp, MaterialTheme.colorScheme.outlineVariant, RoundedCornerShape(12.dp))
-            .background(MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.1f), RoundedCornerShape(12.dp))
-            .padding(20.dp),
-        horizontalAlignment = Alignment.CenterHorizontally
-    ) {
-        Text(
-            "scan qr code",
-            style = MaterialTheme.typography.labelSmall,
-            color = MaterialTheme.colorScheme.onSurfaceVariant
-        )
-        
-        Spacer(Modifier.height(16.dp))
-        
-        if (qrCodeBase64 != null) {
-            val bitmap = remember(qrCodeBase64) {
-                val base64Data = qrCodeBase64.substringAfter("base64,")
-                val decodedString = Base64.decode(base64Data, Base64.DEFAULT)
-                BitmapFactory.decodeByteArray(decodedString, 0, decodedString.size)
-            }
-            
-            bitmap?.let {
-                Image(
-                    bitmap = it.asImageBitmap(),
-                    contentDescription = "QR Code",
-                    modifier = Modifier
-                        .size(180.dp)
-                        .clip(RoundedCornerShape(8.dp))
-                        .background(Color.White) // QR codes usually need white background
-                        .padding(8.dp)
-                )
-            }
-        } else {
-            Box(
-                modifier = Modifier.size(180.dp),
-                contentAlignment = Alignment.Center
-            ) {
-                CircularProgressIndicator(color = MaterialTheme.colorScheme.primary)
-            }
-        }
-        
-        Spacer(Modifier.height(24.dp))
-        
-        OutlinedTextField(
-            value = code,
-            onValueChange = { if (it.length <= 6) code = it },
-            placeholder = { Text("000000", color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.3f)) },
-            modifier = Modifier.width(150.dp),
-            textStyle = MaterialTheme.typography.headlineMedium.copy(
-                textAlign = androidx.compose.ui.text.style.TextAlign.Center,
-                letterSpacing = 4.sp
-            ),
-            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
-            shape = RoundedCornerShape(8.dp),
-            colors = OutlinedTextFieldDefaults.colors(
-                focusedBorderColor = MaterialTheme.colorScheme.primary,
-                unfocusedBorderColor = MaterialTheme.colorScheme.outlineVariant
-            )
-        )
-        
-        Spacer(Modifier.height(24.dp))
-        
-        Row(horizontalArrangement = Arrangement.spacedBy(12.dp)) {
-            Button(
-                onClick = onCancel,
-                modifier = Modifier.weight(1f),
-                shape = RoundedCornerShape(8.dp),
-                colors = ButtonDefaults.buttonColors(containerColor = Color.Transparent, contentColor = MaterialTheme.colorScheme.onSurfaceVariant)
-            ) {
-                Text("cancel", style = MaterialTheme.typography.labelSmall)
-            }
-            
-            Button(
-                onClick = { if (code.length == 6) onConfirm(code) },
-                enabled = code.length == 6,
-                modifier = Modifier.weight(1f),
-                shape = RoundedCornerShape(8.dp)
-            ) {
-                Text("confirm", style = MaterialTheme.typography.labelSmall)
-            }
-        }
-    }
-}