feat(android): improve settings, server switching, and local debug trust

- add notification sound preview and system notification shortcuts
- reconnect automatically when switching servers and scope chat history per server
- add clearer server switching state and related i18n updates
- trust deploy local CA for debug builds and document the setup

ReadMe.md

@@ -79,6 +79,13 @@ bash deploy/redeploy_with_lan_cert.sh
 
 适合 Android 真机、同网段设备和浏览器本地联调。
 
+Android 客户端 debug 包支持额外信任本地局域网 CA：
+
+- 把局域网 WSS 使用的 CA 证书复制到 `deploy/certs/android-local/local_ca.crt`
+- `deploy/certs/` 已在 `.gitignore` 中，只用于本地调试，不应提交到 Git
+- `assembleDebug` 会自动把它接入 debug-only 的 `networkSecurityConfig`
+- release 构建不会信任这张本地 CA
+
 ### 3. 生产准备
 
 ```bash

android-client/README.md

@@ -47,6 +47,17 @@ cd android-client
 - 真机建议地址：`ws://<你的局域网IP>:13173/`
 - 若服务端启用 WSS，需要 Android 设备信任对应证书。
 
+### Debug 本地 CA 信任
+
+如果你使用 `deploy` 目录生成的局域网自签名证书做 `wss://` 联调，debug 构建可以额外信任一张本地 CA：
+
+- 把 CA 证书放到仓库根目录的 `deploy/certs/android-local/local_ca.crt`
+- `deploy/certs/` 已在 `.gitignore` 中，这张证书只用于本地调试，不应提交到 Git
+- 执行 `./gradlew assembleDebug` 时，构建脚本会自动生成 debug-only 的 `networkSecurityConfig`
+- 如果该文件不存在，debug 仍然可以编译，只是不会额外信任本地 CA
+
+推荐把局域网部署生成的 `local_ca.crt` 放到这个位置，再连接 `wss://<你的局域网IP>:13173/`
+
 ## 协议注意事项
 
 - 鉴权签名串：

android-client/app/build.gradle.kts

@@ -5,6 +5,12 @@ plugins {
     id("com.google.devtools.ksp")
 }
 
+val localDebugCaCertSource = rootDir.resolve("../deploy/certs/android-local/local_ca.crt")
+val generatedLocalDebugTrustDir = layout.buildDirectory.dir("generated/localDebugTrust")
+val generatedLocalDebugTrustRoot = generatedLocalDebugTrustDir.get().asFile
+val generatedLocalDebugResDir = generatedLocalDebugTrustRoot.resolve("res")
+val generatedLocalDebugManifestFile = generatedLocalDebugTrustRoot.resolve("AndroidManifest.xml")
+
 android {
     namespace = "com.onlinemsg.client"
     compileSdk = 34
@@ -14,7 +20,7 @@ android {
         minSdk = 26
         targetSdk = 34
         versionCode = 1
-        versionName = "1.0.0.2"
+        versionName = "1.0.0.3"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables {
@@ -52,6 +58,13 @@ android {
             excludes += "/META-INF/{AL2.0,LGPL2.1}"
         }
     }
+
+    sourceSets {
+        getByName("debug") {
+            res.srcDir(generatedLocalDebugResDir)
+            manifest.srcFile(generatedLocalDebugManifestFile)
+        }
+    }
 }
 
 dependencies {
@@ -93,6 +106,56 @@ val debugApkExportDir: String = providers.gradleProperty("debugApkExportDir")
     .get()
 val debugApkExportName = "onlinemsgclient-debug.apk"
 
+val prepareLocalDebugTrust by tasks.registering {
+    val sourceFile = localDebugCaCertSource
+
+    inputs.file(sourceFile).optional()
+    outputs.dir(generatedLocalDebugTrustDir)
+
+    doLast {
+        generatedLocalDebugTrustRoot.deleteRecursively()
+        generatedLocalDebugTrustRoot.mkdirs()
+
+        if (sourceFile.exists()) {
+            val rawDir = generatedLocalDebugResDir.resolve("raw")
+            val xmlDir = generatedLocalDebugResDir.resolve("xml")
+            rawDir.mkdirs()
+            xmlDir.mkdirs()
+
+            sourceFile.copyTo(rawDir.resolve("local_ca.crt"), overwrite = true)
+            xmlDir.resolve("network_security_config.xml").writeText(
+                """
+                <?xml version="1.0" encoding="utf-8"?>
+                <network-security-config>
+                    <base-config>
+                        <trust-anchors>
+                            <certificates src="system" />
+                            <certificates src="@raw/local_ca" />
+                        </trust-anchors>
+                    </base-config>
+                </network-security-config>
+                """.trimIndent() + "\n"
+            )
+
+            generatedLocalDebugManifestFile.writeText(
+                """
+                <?xml version="1.0" encoding="utf-8"?>
+                <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+                    <application android:networkSecurityConfig="@xml/network_security_config" />
+                </manifest>
+                """.trimIndent() + "\n"
+            )
+        } else {
+            generatedLocalDebugManifestFile.writeText(
+                """
+                <?xml version="1.0" encoding="utf-8"?>
+                <manifest xmlns:android="http://schemas.android.com/apk/res/android" />
+                """.trimIndent() + "\n"
+            )
+        }
+    }
+}
+
 val exportDebugApk by tasks.registering(Copy::class) {
     from(layout.buildDirectory.file("outputs/apk/debug/app-debug.apk"))
     into(debugApkExportDir)
@@ -102,6 +165,11 @@ val exportDebugApk by tasks.registering(Copy::class) {
     }
 }
 
+tasks.matching { it.name == "preDebugBuild" }.configureEach {
+    dependsOn(prepareLocalDebugTrust)
+}
+
 tasks.matching { it.name == "assembleDebug" }.configureEach {
+    dependsOn(prepareLocalDebugTrust)
     finalizedBy(exportDebugApk)
 }

android-client/app/src/main/java/com/onlinemsg/client/data/local/ChatDatabase.kt

@@ -9,7 +9,7 @@ import androidx.sqlite.db.SupportSQLiteDatabase
 
 @Database(
     entities = [ChatMessageEntity::class],
-    version = 2,
+    version = 3,
     exportSchema = false
 )
 abstract class ChatDatabase : RoomDatabase() {
@@ -29,6 +29,12 @@ abstract class ChatDatabase : RoomDatabase() {
             }
         }
 
+        private val MIGRATION_2_3 = object : Migration(2, 3) {
+            override fun migrate(db: SupportSQLiteDatabase) {
+                db.execSQL("ALTER TABLE chat_messages ADD COLUMN serverKey TEXT NOT NULL DEFAULT ''")
+            }
+        }
+
         fun getInstance(context: Context): ChatDatabase {
             return instance ?: synchronized(this) {
                 instance ?: Room.databaseBuilder(
@@ -36,7 +42,7 @@ abstract class ChatDatabase : RoomDatabase() {
                     ChatDatabase::class.java,
                     DB_NAME
                 )
-                    .addMigrations(MIGRATION_1_2)
+                    .addMigrations(MIGRATION_1_2, MIGRATION_2_3)
                     .build().also { db ->
                     instance = db
                 }

android-client/app/src/main/java/com/onlinemsg/client/data/local/ChatHistoryRepository.kt

@@ -6,27 +6,38 @@ import com.onlinemsg.client.ui.MessageRole
 import com.onlinemsg.client.ui.UiMessage
 
 class ChatHistoryRepository(private val messageDao: ChatMessageDao) {
-    suspend fun loadMessages(limit: Int): List<UiMessage> {
+    suspend fun loadMessages(serverKey: String, limit: Int): List<UiMessage> {
-        return messageDao.listAll()
+        migrateLegacyMessagesIfNeeded(serverKey)
+        return messageDao.listByServer(serverKey)
             .asSequence()
             .mapNotNull { entity -> entity.toUiMessageOrNull() }
             .toList()
             .takeLast(limit)
     }
 
-    suspend fun appendMessage(message: UiMessage, limit: Int) {
+    suspend fun appendMessage(serverKey: String, message: UiMessage, limit: Int) {
-        messageDao.upsert(message.toEntity())
+        messageDao.upsert(message.toEntity(serverKey))
-        messageDao.trimToLatest(limit)
+        messageDao.trimToLatest(serverKey, limit)
     }
 
-    suspend fun clearAll() {
+    suspend fun clearAll(serverKey: String) {
-        messageDao.clearAll()
+        messageDao.clearAll(serverKey)
+    }
+
+    private suspend fun migrateLegacyMessagesIfNeeded(serverKey: String) {
+        if (messageDao.countByServer(serverKey) > 0) return
+        if (messageDao.countLegacyMessages() == 0) return
+        messageDao.migrateLegacyMessagesToServer(
+            serverKey = serverKey,
+            idPrefix = storageIdPrefix(serverKey)
+        )
     }
 }
 
-private fun UiMessage.toEntity(): ChatMessageEntity {
+private fun UiMessage.toEntity(serverKey: String): ChatMessageEntity {
     return ChatMessageEntity(
-        id = id,
+        id = toStorageId(serverKey, id),
+        serverKey = serverKey,
         role = role.name,
         sender = sender,
         subtitle = subtitle,
@@ -57,3 +68,13 @@ private fun ChatMessageEntity.toUiMessageOrNull(): UiMessage? {
         audioDurationMillis = audioDurationMillis
     )
 }
+
+private fun toStorageId(serverKey: String, messageId: String): String {
+    return if (messageId.startsWith(storageIdPrefix(serverKey))) {
+        messageId
+    } else {
+        storageIdPrefix(serverKey) + messageId
+    }
+}
+
+private fun storageIdPrefix(serverKey: String): String = "$serverKey::"

android-client/app/src/main/java/com/onlinemsg/client/data/local/ChatMessageDao.kt

@@ -7,8 +7,8 @@ import androidx.room.Query
 
 @Dao
 interface ChatMessageDao {
-    @Query("SELECT * FROM chat_messages ORDER BY timestampMillis ASC")
+    @Query("SELECT * FROM chat_messages WHERE serverKey = :serverKey ORDER BY timestampMillis ASC")
-    suspend fun listAll(): List<ChatMessageEntity>
+    suspend fun listByServer(serverKey: String): List<ChatMessageEntity>
 
     @Insert(onConflict = OnConflictStrategy.REPLACE)
     suspend fun upsert(message: ChatMessageEntity)
@@ -16,16 +16,27 @@ interface ChatMessageDao {
     @Query(
         """
         DELETE FROM chat_messages
-        WHERE id NOT IN (
+        WHERE serverKey = :serverKey
+          AND id NOT IN (
             SELECT id
             FROM chat_messages
+            WHERE serverKey = :serverKey
             ORDER BY timestampMillis DESC
             LIMIT :limit
         )
         """
     )
-    suspend fun trimToLatest(limit: Int)
+    suspend fun trimToLatest(serverKey: String, limit: Int)
 
-    @Query("DELETE FROM chat_messages")
+    @Query("DELETE FROM chat_messages WHERE serverKey = :serverKey")
-    suspend fun clearAll()
+    suspend fun clearAll(serverKey: String)
+
+    @Query("SELECT COUNT(*) FROM chat_messages WHERE serverKey = :serverKey")
+    suspend fun countByServer(serverKey: String): Int
+
+    @Query("SELECT COUNT(*) FROM chat_messages WHERE serverKey = ''")
+    suspend fun countLegacyMessages(): Int
+
+    @Query("UPDATE chat_messages SET serverKey = :serverKey, id = :idPrefix || id WHERE serverKey = ''")
+    suspend fun migrateLegacyMessagesToServer(serverKey: String, idPrefix: String)
 }

android-client/app/src/main/java/com/onlinemsg/client/data/local/ChatMessageEntity.kt

@@ -6,6 +6,7 @@ import androidx.room.PrimaryKey
 @Entity(tableName = "chat_messages")
 data class ChatMessageEntity(
     @PrimaryKey val id: String,
+    val serverKey: String,
     val role: String,
     val sender: String,
     val subtitle: String,

android-client/app/src/main/java/com/onlinemsg/client/ui/ChatScreen.kt

@@ -1,12 +1,21 @@
 package com.onlinemsg.client.ui
 
 import android.Manifest
+import android.app.NotificationManager
 import android.content.Context
+import android.content.Intent
 import android.content.pm.PackageManager
+import android.media.AudioAttributes
 import android.media.MediaPlayer
 import android.os.Build
+import android.provider.Settings
 import android.util.Base64
 import android.view.MotionEvent
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.slideInVertically
+import androidx.compose.animation.slideOutVertically
 import androidx.compose.animation.core.RepeatMode
 import androidx.compose.animation.core.animateFloat
 import androidx.compose.animation.core.infiniteRepeatable
@@ -54,6 +63,7 @@ import androidx.compose.material3.AssistChip
 import androidx.compose.material3.Button
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.FilterChip
 import androidx.compose.material3.HorizontalDivider
@@ -92,8 +102,12 @@ import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
+import androidx.core.app.NotificationManagerCompat
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.compose.LocalLifecycleOwner
 import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
 import androidx.compose.foundation.isSystemInDarkTheme
 import com.onlinemsg.client.ui.theme.OnlineMsgTheme
 import java.time.Instant
@@ -103,6 +117,7 @@ import java.io.File
 import com.onlinemsg.client.ui.theme.themeOptions
 import com.onlinemsg.client.util.AudioRecorder
 import com.onlinemsg.client.util.LanguageManager
+import com.onlinemsg.client.util.NotificationSoundCatalog
 import kotlinx.coroutines.delay
 
 
@@ -230,7 +245,7 @@ fun OnlineMsgApp(viewModel: ChatViewModel = viewModel()) {
                         onServerUrlChange = viewModel::updateServerUrl,
                         onSaveServer = viewModel::saveCurrentServerUrl,
                         onRemoveServer = viewModel::removeCurrentServerUrl,
-                        onSelectServer = viewModel::updateServerUrl,
+                        onSelectServer = viewModel::selectServerUrl,
                         onToggleShowSystem = viewModel::toggleShowSystemMessages,
                         onRevealPublicKey = viewModel::revealMyPublicKey,
                         onCopyPublicKey = {
@@ -472,6 +487,57 @@ private fun ChatTab(
         }
 
         Spacer(modifier = Modifier.height(8.dp))
+        AnimatedVisibility(
+            visible = state.isSwitchingServer,
+            enter = fadeIn(animationSpec = tween(180)) + slideInVertically(
+                animationSpec = tween(220),
+                initialOffsetY = { -it / 2 }
+            ),
+            exit = fadeOut(animationSpec = tween(140)) + slideOutVertically(
+                animationSpec = tween(180),
+                targetOffsetY = { -it / 3 }
+            )
+        ) {
+            Card(
+                colors = CardDefaults.cardColors(
+                    containerColor = MaterialTheme.colorScheme.secondaryContainer
+                ),
+                shape = RoundedCornerShape(14.dp),
+                modifier = Modifier.fillMaxWidth()
+            ) {
+                Row(
+                    modifier = Modifier.padding(horizontal = 12.dp, vertical = 10.dp),
+                    verticalAlignment = Alignment.CenterVertically,
+                    horizontalArrangement = Arrangement.spacedBy(10.dp)
+                ) {
+                    CircularProgressIndicator(
+                        modifier = Modifier.size(18.dp),
+                        strokeWidth = 2.dp,
+                        color = MaterialTheme.colorScheme.primary
+                    )
+                    Column(
+                        modifier = Modifier.weight(1f),
+                        verticalArrangement = Arrangement.spacedBy(2.dp)
+                    ) {
+                        Text(
+                            text = t("session.hint.switching_server"),
+                            style = MaterialTheme.typography.labelLarge,
+                            color = MaterialTheme.colorScheme.onSecondaryContainer
+                        )
+                        Text(
+                            text = state.switchingServerLabel,
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSecondaryContainer.copy(alpha = 0.8f),
+                            maxLines = 1,
+                            overflow = TextOverflow.Ellipsis
+                        )
+                    }
+                }
+            }
+        }
+        if (state.isSwitchingServer) {
+            Spacer(modifier = Modifier.height(8.dp))
+        }
         val statusHintText = if (audioHint.isNotBlank()) {
             audioHint
         } else {
@@ -1043,6 +1109,14 @@ private fun SettingsTab(
     onLanguageChange: (String) -> Unit,
     onNotificationSoundChange: (String) -> Unit
 ) {
+    val context = LocalContext.current
+    val previewPlayer = remember(context) { NotificationSoundPreviewPlayer(context) }
+    val notificationStatus = rememberNotificationSoundStatus(state.notificationSound)
+
+    DisposableEffect(Unit) {
+        onDispose { previewPlayer.release() }
+    }
+
     fun t(key: String) = LanguageManager.getString(key, state.language)
 
     val settingsCardModifier = Modifier.fillMaxWidth()
@@ -1083,11 +1157,27 @@ private fun SettingsTab(
                     verticalArrangement = settingsCardContentSpacing
                 ) {
                     Text(t("settings.notification_sound"), style = MaterialTheme.typography.titleMedium)
+                    Text(
+                        text = when {
+                            !notificationStatus.notificationsEnabled -> t("settings.notification_disabled")
+                            !notificationStatus.channelSoundEnabled -> t("settings.notification_sound_disabled")
+                            else -> t("settings.notification_enabled")
+                        },
+                        style = MaterialTheme.typography.bodySmall,
+                        color = if (notificationStatus.notificationsEnabled && notificationStatus.channelSoundEnabled) {
+                            MaterialTheme.colorScheme.onSurfaceVariant
+                        } else {
+                            MaterialTheme.colorScheme.error
+                        }
+                    )
                     LazyRow(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
-                        items(listOf("default", "ding", "nameit5", "wind_chime")) { sound ->
+                        items(NotificationSoundCatalog.soundCodes) { sound ->
                             FilterChip(
                                 selected = state.notificationSound == sound,
-                                onClick = { onNotificationSoundChange(sound) },
+                                onClick = {
+                                    previewPlayer.play(sound)
+                                    onNotificationSoundChange(sound)
+                                },
                                 label = { Text(t("sound.$sound")) },
                                 leadingIcon = {
                                     Icon(
@@ -1099,6 +1189,23 @@ private fun SettingsTab(
                             )
                         }
                     }
+                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        OutlinedButton(onClick = { openAppNotificationSettings(context) }) {
+                            Text(t("settings.notification_system_settings"))
+                        }
+                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                            OutlinedButton(
+                                onClick = {
+                                    openNotificationChannelSettings(
+                                        context = context,
+                                        soundCode = state.notificationSound
+                                    )
+                                }
+                            ) {
+                                Text(t("settings.notification_channel_settings"))
+                            }
+                        }
+                    }
                 }
             }
         }
@@ -1352,6 +1459,124 @@ private class AudioMessagePlayer(private val context: Context) {
     }
 }
 
+private data class NotificationSoundStatus(
+    val notificationsEnabled: Boolean,
+    val channelSoundEnabled: Boolean
+)
+
+@Composable
+private fun rememberNotificationSoundStatus(soundCode: String): NotificationSoundStatus {
+    val context = LocalContext.current
+    val lifecycleOwner = LocalLifecycleOwner.current
+    var status by remember(soundCode, context) {
+        mutableStateOf(queryNotificationSoundStatus(context, soundCode))
+    }
+
+    LaunchedEffect(soundCode, context) {
+        status = queryNotificationSoundStatus(context, soundCode)
+    }
+
+    DisposableEffect(soundCode, context, lifecycleOwner) {
+        val observer = LifecycleEventObserver { _, event ->
+            if (event == Lifecycle.Event.ON_RESUME) {
+                status = queryNotificationSoundStatus(context, soundCode)
+            }
+        }
+        lifecycleOwner.lifecycle.addObserver(observer)
+        onDispose {
+            lifecycleOwner.lifecycle.removeObserver(observer)
+        }
+    }
+    return status
+}
+
+private fun queryNotificationSoundStatus(context: Context, soundCode: String): NotificationSoundStatus {
+    val notificationsEnabled = NotificationManagerCompat.from(context).areNotificationsEnabled()
+    if (!notificationsEnabled) {
+        return NotificationSoundStatus(
+            notificationsEnabled = false,
+            channelSoundEnabled = false
+        )
+    }
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+        return NotificationSoundStatus(
+            notificationsEnabled = true,
+            channelSoundEnabled = true
+        )
+    }
+
+    val manager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+    val channel = manager.getNotificationChannel(NotificationSoundCatalog.channelId(soundCode))
+    val channelSoundEnabled = channel?.importance != NotificationManager.IMPORTANCE_NONE &&
+        (channel?.sound != null || channel == null)
+    return NotificationSoundStatus(
+        notificationsEnabled = true,
+        channelSoundEnabled = channelSoundEnabled
+    )
+}
+
+private fun openAppNotificationSettings(context: Context) {
+    val intent = Intent(Settings.ACTION_APP_NOTIFICATION_SETTINGS).apply {
+        putExtra(Settings.EXTRA_APP_PACKAGE, context.packageName)
+        addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+    }
+    context.startActivity(intent)
+}
+
+private fun openNotificationChannelSettings(context: Context, soundCode: String) {
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+        openAppNotificationSettings(context)
+        return
+    }
+    val intent = Intent(Settings.ACTION_CHANNEL_NOTIFICATION_SETTINGS).apply {
+        putExtra(Settings.EXTRA_APP_PACKAGE, context.packageName)
+        putExtra(Settings.EXTRA_CHANNEL_ID, NotificationSoundCatalog.channelId(soundCode))
+        addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+    }
+    context.startActivity(intent)
+}
+
+private class NotificationSoundPreviewPlayer(private val context: Context) {
+    private var mediaPlayer: MediaPlayer? = null
+
+    fun play(soundCode: String) {
+        val resId = NotificationSoundCatalog.resId(soundCode) ?: return
+        release()
+        val afd = context.resources.openRawResourceFd(resId) ?: return
+        val player = MediaPlayer()
+        val started = runCatching {
+            player.setAudioAttributes(
+                AudioAttributes.Builder()
+                    .setUsage(AudioAttributes.USAGE_NOTIFICATION_EVENT)
+                    .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
+                    .build()
+            )
+            player.setDataSource(afd.fileDescriptor, afd.startOffset, afd.length)
+            afd.close()
+            player.setOnCompletionListener { release() }
+            player.setOnErrorListener { _, _, _ ->
+                release()
+                true
+            }
+            player.prepare()
+            player.start()
+            true
+        }.getOrElse {
+            runCatching { afd.close() }
+            runCatching { player.release() }
+            false
+        }
+        if (!started) return
+        mediaPlayer = player
+    }
+
+    fun release() {
+        runCatching { mediaPlayer?.stop() }
+        runCatching { mediaPlayer?.release() }
+        mediaPlayer = null
+    }
+}
+
 private fun formatAudioDuration(durationMillis: Long): String {
     val totalSeconds = (durationMillis / 1000L).coerceAtLeast(0L)
     val minutes = totalSeconds / 60L

android-client/app/src/main/java/com/onlinemsg/client/ui/ChatSessionManager.kt

@@ -16,7 +16,6 @@ import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationManagerCompat
 import androidx.core.content.ContextCompat
 import com.onlinemsg.client.MainActivity
-import com.onlinemsg.client.R
 import com.onlinemsg.client.data.crypto.RsaCryptoManager
 import com.onlinemsg.client.data.local.ChatDatabase
 import com.onlinemsg.client.data.local.ChatHistoryRepository
@@ -32,6 +31,7 @@ import com.onlinemsg.client.data.protocol.SignedPayloadDto
 import com.onlinemsg.client.data.protocol.asPayloadText
 import com.onlinemsg.client.service.ChatForegroundService
 import com.onlinemsg.client.util.LanguageManager
+import com.onlinemsg.client.util.NotificationSoundCatalog
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
@@ -184,7 +184,9 @@ object ChatSessionManager {
                 _uiState.update {
                     it.copy(
                         status = ConnectionStatus.ERROR,
-                        statusHint = t("session.hint.connection_error_retrying")
+                        statusHint = t("session.hint.connection_error_retrying"),
+                        isSwitchingServer = false,
+                        switchingServerLabel = ""
                     )
                 }
                 scheduleReconnect(t("session.reason.connection_error"))
@@ -207,7 +209,7 @@ object ChatSessionManager {
         scope.launch {
             val pref = preferencesRepository.preferencesFlow.first()
             val historyMessages = withContext(Dispatchers.IO) {
-                historyRepository.loadMessages(MAX_MESSAGES)
+                historyRepository.loadMessages(serverKeyFor(pref.currentServerUrl), MAX_MESSAGES)
             }
             keepAliveRequested = pref.shouldAutoReconnect
             ensureMessageNotificationChannel(pref.notificationSound)
@@ -299,6 +301,20 @@ object ChatSessionManager {
         _uiState.update { it.copy(serverUrl = value) }
     }
 
+    /**
+     * 选择历史服务器并切换会话。
+     */
+    fun selectServerUrl(value: String) {
+        val normalized = ServerUrlFormatter.normalize(value)
+        if (normalized.isBlank()) return
+        switchServer(
+            normalized = normalized,
+            nextUrls = _uiState.value.serverUrls,
+            statusHint = null,
+            persist = { preferencesRepository.setCurrentServerUrl(normalized) }
+        )
+    }
+
     /**
      * 更新私聊目标公钥。
      * @param value 公钥字符串
@@ -345,7 +361,7 @@ object ChatSessionManager {
         _uiState.update { it.copy(messages = emptyList()) }
         scope.launch(Dispatchers.IO) {
             runCatching {
-                historyRepository.clearAll()
+                historyRepository.clearAll(currentServerKey())
             }
         }
     }
@@ -363,18 +379,13 @@ object ChatSessionManager {
         }
 
         val nextUrls = ServerUrlFormatter.append(_uiState.value.serverUrls, normalized)
-        _uiState.update {
+        switchServer(
-            it.copy(
+            normalized = normalized,
-                serverUrl = normalized,
+            nextUrls = nextUrls,
-                serverUrls = nextUrls,
+            statusHint = t("session.hint.server_saved"),
-                statusHint = t("session.hint.server_saved")
+            persist = { preferencesRepository.saveCurrentServerUrl(normalized) },
-            )
+            snackbarMessage = t("session.snackbar.server_saved")
-        }
+        )
-
-        scope.launch {
-            preferencesRepository.saveCurrentServerUrl(normalized)
-            _events.emit(UiEvent.ShowSnackbar(t("session.snackbar.server_saved")))
-        }
     }
 
     /**
@@ -392,22 +403,17 @@ object ChatSessionManager {
             filtered
         }
 
-        _uiState.update {
+        switchServer(
-            it.copy(
+            normalized = nextUrls.first(),
-                serverUrls = nextUrls,
+            nextUrls = nextUrls,
-                serverUrl = nextUrls.first(),
+            statusHint = if (filtered.isEmpty()) {
-                statusHint = if (filtered.isEmpty()) {
+                t("session.hint.server_restored_default")
-                    t("session.hint.server_restored_default")
+            } else {
-                } else {
+                t("session.hint.server_removed")
-                    t("session.hint.server_removed")
+            },
-                }
+            persist = { preferencesRepository.removeCurrentServerUrl(normalized) },
-            )
+            snackbarMessage = t("session.snackbar.server_list_updated")
-        }
+        )
-
-        scope.launch {
-            preferencesRepository.removeCurrentServerUrl(normalized)
-            _events.emit(UiEvent.ShowSnackbar(t("session.snackbar.server_list_updated")))
-        }
     }
 
     /**
@@ -450,17 +456,23 @@ object ChatSessionManager {
      * 内部连接逻辑，区分自动恢复和手动连接。
      * @param isAutoRestore 是否为应用启动时的自动恢复连接
      */
-    private fun connectInternal(isAutoRestore: Boolean) {
+    private fun connectInternal(
+        isAutoRestore: Boolean,
+        overrideUrl: String? = null,
+        forceReconnect: Boolean = false
+    ) {
         if (!initialized) return
         val state = _uiState.value
-        if (!state.canConnect) return
+        if (!forceReconnect && !state.canConnect) return
 
-        val normalized = ServerUrlFormatter.normalize(state.serverUrl)
+        val normalized = ServerUrlFormatter.normalize(overrideUrl ?: state.serverUrl)
         if (normalized.isBlank()) {
             _uiState.update {
                 it.copy(
                     status = ConnectionStatus.ERROR,
-                    statusHint = t("session.hint.fill_valid_server")
+                    statusHint = t("session.hint.fill_valid_server"),
+                    isSwitchingServer = false,
+                    switchingServerLabel = ""
                 )
             }
             return
@@ -511,7 +523,9 @@ object ChatSessionManager {
         _uiState.update {
             it.copy(
                 status = ConnectionStatus.IDLE,
-                statusHint = t("session.hint.connection_closed")
+                statusHint = t("session.hint.connection_closed"),
+                isSwitchingServer = false,
+                switchingServerLabel = ""
             )
         }
         autoReconnectTriggered = false
@@ -690,7 +704,9 @@ object ChatSessionManager {
                 _uiState.update {
                     it.copy(
                         status = ConnectionStatus.ERROR,
-                        statusHint = t("session.hint.handshake_incomplete_response")
+                        statusHint = t("session.hint.handshake_incomplete_response"),
+                        isSwitchingServer = false,
+                        switchingServerLabel = ""
                     )
                 }
                 return
@@ -752,7 +768,9 @@ object ChatSessionManager {
                 _uiState.update {
                     it.copy(
                         status = ConnectionStatus.ERROR,
-                        statusHint = t("session.hint.connection_timeout_retry")
+                        statusHint = t("session.hint.connection_timeout_retry"),
+                        isSwitchingServer = false,
+                        switchingServerLabel = ""
                     )
                 }
                 addSystemMessage(t("session.msg.auth_timeout"))
@@ -769,7 +787,9 @@ object ChatSessionManager {
             _uiState.update {
                 it.copy(
                     status = ConnectionStatus.ERROR,
-                    statusHint = t("session.hint.auth_failed")
+                    statusHint = t("session.hint.auth_failed"),
+                    isSwitchingServer = false,
+                    switchingServerLabel = ""
                 )
             }
             addSystemMessage(
@@ -846,7 +866,9 @@ object ChatSessionManager {
                 _uiState.update {
                     it.copy(
                         status = ConnectionStatus.READY,
-                        statusHint = t("session.hint.ready_to_chat")
+                        statusHint = t("session.hint.ready_to_chat"),
+                        isSwitchingServer = false,
+                        switchingServerLabel = ""
                     )
                 }
                 addSystemMessage(t("session.msg.ready"))
@@ -955,7 +977,9 @@ object ChatSessionManager {
                     statusHint = tf(
                         "session.hint.server_rejected",
                         reason.ifBlank { t("session.text.policy_restriction") }
-                    )
+                    ),
+                    isSwitchingServer = false,
+                    switchingServerLabel = ""
                 )
             }
             addSystemMessage(
@@ -998,7 +1022,9 @@ object ChatSessionManager {
         _uiState.update {
             it.copy(
                 status = ConnectionStatus.ERROR,
-                statusHint = t("session.hint.connection_interrupted_retry")
+                statusHint = t("session.hint.connection_interrupted_retry"),
+                isSwitchingServer = false,
+                switchingServerLabel = ""
             )
         }
         addSystemMessage(
@@ -1284,11 +1310,78 @@ object ChatSessionManager {
         if (message.role == MessageRole.SYSTEM) return
         scope.launch(Dispatchers.IO) {
             runCatching {
-                historyRepository.appendMessage(message, MAX_MESSAGES)
+                historyRepository.appendMessage(currentServerKey(), message, MAX_MESSAGES)
+            }
+        }
+    }
+
+    private fun switchServer(
+        normalized: String,
+        nextUrls: List<String>,
+        statusHint: String?,
+        persist: suspend () -> Unit,
+        snackbarMessage: String? = null
+    ) {
+        val targetServerKey = serverKeyFor(normalized)
+        val previousServerKey = currentServerKey()
+        val shouldReconnect = previousServerKey != targetServerKey || _uiState.value.status != ConnectionStatus.READY
+        val switchingLabel = summarizeServerLabel(normalized)
+
+        scope.launch {
+            _uiState.update {
+                it.copy(
+                    serverUrl = normalized,
+                    serverUrls = nextUrls,
+                    isSwitchingServer = shouldReconnect,
+                    switchingServerLabel = if (shouldReconnect) switchingLabel else "",
+                    statusHint = statusHint ?: it.statusHint
+                )
+            }
+            persist()
+            val historyMessages = withContext(Dispatchers.IO) {
+                historyRepository.loadMessages(targetServerKey, MAX_MESSAGES)
+            }
+            _uiState.update {
+                it.copy(
+                    serverUrl = normalized,
+                    serverUrls = nextUrls,
+                    messages = historyMessages,
+                    certFingerprint = if (previousServerKey == targetServerKey) it.certFingerprint else "",
+                    statusHint = statusHint ?: it.statusHint
+                )
+            }
+            if (shouldReconnect) {
+                connectInternal(
+                    isAutoRestore = false,
+                    overrideUrl = normalized,
+                    forceReconnect = !_uiState.value.canConnect
+                )
+            }
+            if (!snackbarMessage.isNullOrBlank()) {
+                _events.emit(UiEvent.ShowSnackbar(snackbarMessage))
             }
         }
     }
 
+    private fun currentServerKey(): String = serverKeyFor(_uiState.value.serverUrl)
+
+    private fun serverKeyFor(rawUrl: String): String {
+        return ServerUrlFormatter.normalize(rawUrl).ifBlank { ServerUrlFormatter.defaultServerUrl }
+    }
+
+    private fun summarizeServerLabel(rawUrl: String): String {
+        val normalized = serverKeyFor(rawUrl)
+        val parsed = runCatching { Uri.parse(normalized) }.getOrNull()
+        val host = parsed?.host
+        val port = parsed?.port?.takeIf { it > 0 }
+        val path = parsed?.encodedPath?.takeIf { !it.isNullOrBlank() && it != "/" }
+        return buildString {
+            append(host ?: normalized)
+            if (port != null) append(":$port")
+            if (path != null) append(path)
+        }.ifBlank { normalized }
+    }
+
     /**
      * 取消认证超时任务。
      */
@@ -1392,7 +1485,9 @@ object ChatSessionManager {
                 _uiState.update {
                     it.copy(
                         status = ConnectionStatus.ERROR,
-                        statusHint = t("session.hint.handshake_timeout")
+                        statusHint = t("session.hint.handshake_timeout"),
+                        isSwitchingServer = false,
+                        switchingServerLabel = ""
                     )
                 }
                 addSystemMessage(tf("session.msg.handshake_timeout_with_url", currentUrl))
@@ -1485,7 +1580,7 @@ object ChatSessionManager {
     private fun ensureMessageNotificationChannel(soundCode: String = "default") {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return
         val manager = app.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
-        val channelId = "${MESSAGE_CHANNEL_ID}_$soundCode"
+        val channelId = NotificationSoundCatalog.channelId(soundCode)
         if (manager.getNotificationChannel(channelId) != null) return
 
         val channel = NotificationChannel(
@@ -1508,13 +1603,7 @@ object ChatSessionManager {
     }
 
     private fun getSoundUri(code: String): Uri? {
-        val resId = when (code) {
+        val resId = NotificationSoundCatalog.resId(code) ?: return null
-            "ding" -> R.raw.load
-            "nameit5" -> R.raw.nameit5
-            "wind_chime" -> R.raw.notification_sound_effects
-            "default" -> R.raw.default_sound
-            else -> return null
-        }
         return Uri.parse("${ContentResolver.SCHEME_ANDROID_RESOURCE}://${app.packageName}/$resId")
     }
 
@@ -1540,7 +1629,7 @@ object ChatSessionManager {
             launchIntent,
             PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
         )
-        val channelId = "${MESSAGE_CHANNEL_ID}_${_uiState.value.notificationSound}"
+        val channelId = NotificationSoundCatalog.channelId(_uiState.value.notificationSound)
         ensureMessageNotificationChannel(_uiState.value.notificationSound)
 
         val notification = NotificationCompat.Builder(app, channelId)
@@ -1589,7 +1678,6 @@ object ChatSessionManager {
     private const val MAX_MESSAGES = 500
     private const val MAX_RECONNECT_DELAY_SECONDS = 30
     private const val SYSTEM_MESSAGE_TTL_MS = 1_000L
-    private const val MESSAGE_CHANNEL_ID = "onlinemsg_messages"
     private const val AUDIO_MESSAGE_PREFIX = "[[OMS_AUDIO_V1]]"
     private const val AUDIO_CHUNK_MESSAGE_PREFIX = "[[OMS_AUDIO_CHUNK_V1]]"
     private const val AUDIO_CHUNK_BASE64_SIZE = 20_000

android-client/app/src/main/java/com/onlinemsg/client/ui/ChatUiState.kt

@@ -98,7 +98,9 @@ data class ChatUiState(
     val themeId: String = "blue",
     val useDynamicColor: Boolean = true,
     val language: String = "zh",
-    val notificationSound: String = "default"
+    val notificationSound: String = "default",
+    val isSwitchingServer: Boolean = false,
+    val switchingServerLabel: String = ""
 ) {
     /**
      * 是否允许连接。

android-client/app/src/main/java/com/onlinemsg/client/ui/ChatViewModel.kt

@@ -19,6 +19,7 @@ class ChatViewModel(application: Application) : AndroidViewModel(application) {
 
     fun updateDisplayName(value: String) = ChatSessionManager.updateDisplayName(value)
     fun updateServerUrl(value: String) = ChatSessionManager.updateServerUrl(value)
+    fun selectServerUrl(value: String) = ChatSessionManager.selectServerUrl(value)
     fun updateTargetKey(value: String) = ChatSessionManager.updateTargetKey(value)
     fun updateDraft(value: String) = ChatSessionManager.updateDraft(value)
     fun toggleDirectMode(enabled: Boolean) = ChatSessionManager.toggleDirectMode(enabled)

android-client/app/src/main/java/com/onlinemsg/client/util/LanguageManager.kt

@@ -31,6 +31,11 @@ object LanguageManager {
         "settings.chat_data" to "聊天資料",
         "settings.dynamic_color" to "使用動態顏色",
         "settings.notification_sound" to "通知音效",
+        "settings.notification_enabled" to "系統通知與音效已啟用",
+        "settings.notification_disabled" to "系統通知目前已關閉",
+        "settings.notification_sound_disabled" to "目前音效渠道已被靜音",
+        "settings.notification_system_settings" to "系統通知設定",
+        "settings.notification_channel_settings" to "當前音效設定",
         "status.idle" to "未連線",
         "status.connecting" to "連線中",
         "status.ready" to "已連線",
@@ -40,6 +45,7 @@ object LanguageManager {
         "hint.ready_chat" to "已連線，可以開始聊天",
         "hint.closed" to "連線已關閉",
         "hint.reconnecting" to "連線已中斷，正在重試",
+        "session.hint.switching_server" to "正在切換伺服器",
         "hint.reconnect_invalid_server" to "重連失敗：伺服器位址無效",
         "hint.fill_target_key" to "請先填寫目標公鑰，再傳送私訊",
         "hint.server_rejected_prefix" to "伺服器拒絕連線：",
@@ -105,6 +111,11 @@ object LanguageManager {
             "settings.chat_data" to "聊天数据",
             "settings.dynamic_color" to "使用动态颜色",
             "settings.notification_sound" to "通知音效",
+            "settings.notification_enabled" to "系统通知与音效已启用",
+            "settings.notification_disabled" to "系统通知当前已关闭",
+            "settings.notification_sound_disabled" to "当前音效渠道已被静音",
+            "settings.notification_system_settings" to "系统通知设置",
+            "settings.notification_channel_settings" to "当前音效设置",
             "sound.default" to "默认",
             "sound.ding" to "叮",
             "sound.nameit5" to "音效 5",
@@ -118,6 +129,7 @@ object LanguageManager {
             "hint.ready_chat" to "已连接，可以开始聊天",
             "hint.closed" to "连接已关闭",
             "hint.reconnecting" to "连接已中断，正在重试",
+            "session.hint.switching_server" to "正在切换服务器",
             "hint.reconnect_invalid_server" to "重连失败：服务器地址无效",
             "hint.fill_target_key" to "请先填写目标公钥，再发送私聊消息",
             "hint.server_rejected_prefix" to "服务器拒绝连接：",
@@ -259,6 +271,11 @@ object LanguageManager {
             "settings.chat_data" to "Chat Data",
             "settings.dynamic_color" to "Use dynamic color",
             "settings.notification_sound" to "Notification Sound",
+            "settings.notification_enabled" to "Notifications and sound are enabled",
+            "settings.notification_disabled" to "Notifications are currently disabled",
+            "settings.notification_sound_disabled" to "The selected sound channel is muted",
+            "settings.notification_system_settings" to "System Notification Settings",
+            "settings.notification_channel_settings" to "Current Sound Channel",
             "sound.default" to "Default",
             "sound.ding" to "Ding",
             "sound.nameit5" to "Sound 5",
@@ -272,6 +289,7 @@ object LanguageManager {
             "hint.ready_chat" to "Connected, ready to chat",
             "hint.closed" to "Connection closed",
             "hint.reconnecting" to "Connection interrupted, reconnecting",
+            "session.hint.switching_server" to "Switching server",
             "hint.reconnect_invalid_server" to "Reconnect failed: invalid server address",
             "hint.fill_target_key" to "Please fill target public key before private message",
             "hint.server_rejected_prefix" to "Server rejected connection: ",
@@ -413,6 +431,11 @@ object LanguageManager {
             "settings.chat_data" to "チャットデータ",
             "settings.dynamic_color" to "動的カラーを使用",
             "settings.notification_sound" to "通知音",
+            "settings.notification_enabled" to "通知と音が有効です",
+            "settings.notification_disabled" to "通知が現在オフです",
+            "settings.notification_sound_disabled" to "現在の音声チャンネルはミュートされています",
+            "settings.notification_system_settings" to "システム通知設定",
+            "settings.notification_channel_settings" to "現在の音設定",
             "sound.default" to "デフォルト",
             "sound.ding" to "ディン",
             "sound.nameit5" to "効果音 5",
@@ -426,6 +449,7 @@ object LanguageManager {
             "hint.ready_chat" to "接続完了、チャット可能",
             "hint.closed" to "接続を閉じました",
             "hint.reconnecting" to "接続が中断され、再接続中",
+            "session.hint.switching_server" to "サーバーを切り替え中",
             "hint.reconnect_invalid_server" to "再接続失敗：サーバーアドレス無効",
             "hint.fill_target_key" to "個人チャット前に相手の公開鍵を入力してください",
             "hint.server_rejected_prefix" to "サーバーが接続を拒否しました：",
@@ -567,6 +591,11 @@ object LanguageManager {
             "settings.chat_data" to "채팅 데이터",
             "settings.dynamic_color" to "동적 색상 사용",
             "settings.notification_sound" to "알림 효과음",
+            "settings.notification_enabled" to "시스템 알림과 효과음이 켜져 있습니다",
+            "settings.notification_disabled" to "시스템 알림이 현재 꺼져 있습니다",
+            "settings.notification_sound_disabled" to "현재 효과음 채널이 음소거되어 있습니다",
+            "settings.notification_system_settings" to "시스템 알림 설정",
+            "settings.notification_channel_settings" to "현재 효과음 설정",
             "sound.default" to "기본값",
             "sound.ding" to "딩",
             "sound.nameit5" to "효과음 5",
@@ -580,6 +609,7 @@ object LanguageManager {
             "hint.ready_chat" to "연결 완료, 채팅 가능",
             "hint.closed" to "연결이 종료되었습니다",
             "hint.reconnecting" to "연결이 끊겨 재연결 중입니다",
+            "session.hint.switching_server" to "서버 전환 중",
             "hint.reconnect_invalid_server" to "재연결 실패: 서버 주소가 올바르지 않습니다",
             "hint.fill_target_key" to "비공개 채팅 전 대상 공개키를 입력하세요",
             "hint.server_rejected_prefix" to "서버가 연결을 거부했습니다: ",

android-client/app/src/main/java/com/onlinemsg/client/util/NotificationSoundCatalog.kt

@@ -0,0 +1,19 @@
+package com.onlinemsg.client.util
+
+import com.onlinemsg.client.R
+
+object NotificationSoundCatalog {
+    val soundCodes: List<String> = listOf("default", "ding", "nameit5", "wind_chime")
+
+    fun resId(code: String): Int? {
+        return when (code) {
+            "default" -> R.raw.default_sound
+            "ding" -> R.raw.load
+            "nameit5" -> R.raw.nameit5
+            "wind_chime" -> R.raw.notification_sound_effects
+            else -> null
+        }
+    }
+
+    fun channelId(code: String): String = "onlinemsg_messages_$code"
+}