diff --git a/app/src/main/java/com/example/login_v3/data/di/DatabaseModule.kt b/app/src/main/java/com/example/login_v3/data/di/DatabaseModule.kt
index e54ba23..0173217 100644
--- a/app/src/main/java/com/example/login_v3/data/di/DatabaseModule.kt
+++ b/app/src/main/java/com/example/login_v3/data/di/DatabaseModule.kt
@@ -2,7 +2,10 @@ package com.example.login_v3.data.di
 
 import android.content.Context
 import androidx.room.Room
+import com.example.login_v3.data.local.dao.BlockedUserDao
+import com.example.login_v3.data.local.dao.FriendDao
 import com.example.login_v3.data.local.dao.MessageDao
+import com.example.login_v3.data.local.dao.RoomLocalDao
 import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
@@ -31,7 +34,24 @@ object DatabaseModule {
     @Provides
     @Singleton
     fun provideMessageDao(database: AppDatabase): MessageDao {
-        // 💡 告訴 Hilt：當有人要 MessageDao 時，就從 database 裡面把 messageDao() 拿出來提供給他！
         return database.messageDao()
     }
-}
\ No newline at end of file
+
+    @Provides
+    @Singleton
+    fun provideFriendDao(database: AppDatabase): FriendDao {
+        return database.friendDao()
+    }
+
+    @Provides
+    @Singleton
+    fun provideRoomLocalDao(database: AppDatabase): RoomLocalDao {
+        return database.roomLocalDao()
+    }
+
+    @Provides
+    @Singleton
+    fun provideBlockedUserDao(database: AppDatabase): BlockedUserDao {
+        return database.blockedUserDao()
+    }
+}
diff --git a/app/src/main/java/com/example/login_v3/data/repository/basic/Friends_Repository.kt b/app/src/main/java/com/example/login_v3/data/repository/basic/Friends_Repository.kt
index 9252d1e..d66445a 100644
--- a/app/src/main/java/com/example/login_v3/data/repository/basic/Friends_Repository.kt
+++ b/app/src/main/java/com/example/login_v3/data/repository/basic/Friends_Repository.kt
@@ -7,13 +7,31 @@ import com.example.login_v3.data.api.api_class.Friend
 import com.example.login_v3.data.api.api_class.PendingFriendApiModel
 import com.example.login_v3.data.api.api_class.UserDetail
 import com.example.login_v3.data.api.api_class.UserSearchResponse
+import com.example.login_v3.data.local.dao.FriendDao
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
 import retrofit2.Response
 import javax.inject.Inject
 
 class FriendsRepository @Inject constructor(
-    private val apiService: TecnologiaApi
+    private val apiService: TecnologiaApi,
+    private val friendDao: FriendDao
 ) {
 
+    // 🌟 核心：監聽本地資料庫的好友列表 Flow
+    val friendsFlow: Flow<List<Friend>> = friendDao.getAllFriendsFlow().map { entities ->
+        entities.map { entity ->
+            Friend(
+                friendId = entity.userId,
+                username = entity.username,
+                displayName = entity.displayName,
+                avatarUrl = entity.avatarUrl,
+                status = entity.status,
+                acceptedAt = null // Sync API 目前沒給這個，先設為 null
+            )
+        }
+    }
+
     suspend fun getFriendList(): Result<List<Friend>> {
         return try {
             val response = apiService.getFriends()
diff --git a/app/src/main/java/com/example/login_v3/data/repository/basic/SyncRepository.kt b/app/src/main/java/com/example/login_v3/data/repository/basic/SyncRepository.kt
index cb83022..26645d7 100644
--- a/app/src/main/java/com/example/login_v3/data/repository/basic/SyncRepository.kt
+++ b/app/src/main/java/com/example/login_v3/data/repository/basic/SyncRepository.kt
@@ -1,5 +1,6 @@
 package com.example.login_v3.data.repository.basic
 
+import android.util.Log
 import androidx.room.withTransaction
 import com.example.login_v3.data.api.TecnologiaApi
 import com.example.login_v3.data.di.AppDatabase
@@ -8,6 +9,8 @@ import com.example.login_v3.data.local.entities.BlockedUserLocalEntity
 import com.example.login_v3.data.local.entities.FriendLocalEntity
 import com.example.login_v3.data.local.entities.RoomLocalEntity
 import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -20,86 +23,121 @@ class SyncRepository @Inject constructor(
     private val friendDao = db.friendDao()
     private val roomDao = db.roomLocalDao()
     private val blockDao = db.blockedUserDao()
+    
+    // 🔒 使用 Mutex 確保同一時間只有一個同步任務在執行，避免重複請求
+    private val syncMutex = Mutex()
 
     suspend fun performSync(): Result<Unit> {
-        return try {
-            val since = userPrefs.syncSinceFlow.first()
-            val response = api.sync(since)
+        // 如果已經有同步在跑，直接回傳成功（避免重複排隊）
+        if (syncMutex.isLocked) {
+            Log.d("SyncDebug", "⏳ [Sync] 偵測到已有同步任務正在進行，跳過本次請求")
+            return Result.success(Unit)
+        }
 
-            if (response.isSuccessful) {
-                val body = response.body() ?: return Result.failure(Exception("Sync body is null"))
+        return syncMutex.withLock {
+            try {
+                val since = userPrefs.syncSinceFlow.first()
+                Log.d("SyncDebug", "🚀 [Sync] 開始同步 | since: $since")
 
-                db.withTransaction {
-                    if (body.fullSnapshot) {
-                        friendDao.deleteAll()
-                        roomDao.deleteAll()
-                        blockDao.deleteAll()
-                    }
+                val response = api.sync(since)
 
-                    // Process Blocks
-                    body.blocks.forEach { block ->
-                        if (block.removed) {
-                            blockDao.deleteById(block.userId)
-                        } else {
-                            blockDao.insertOrUpdate(listOf(
-                                BlockedUserLocalEntity(
-                                    userId = block.userId,
-                                    username = block.username,
-                                    displayName = block.displayName,
-                                    avatarUrl = block.avatarUrl,
-                                    blockedAt = block.blockedAt
-                                )
-                            ))
+                if (response.isSuccessful) {
+                    val body = response.body() ?: return Result.failure(Exception("Sync body is null"))
+
+                    Log.d("SyncDebug", "✅ [Sync] API 成功 | FullSnapshot: ${body.fullSnapshot} | nextSince: ${body.nextSince}")
+                    Log.d("SyncDebug", "📦 [Sync] 收到: Blocks(${body.blocks.size}), Friends(${body.friends.size}), Rooms(${body.rooms.size})")
+
+                    db.withTransaction {
+                        if (body.fullSnapshot) {
+                            Log.w("SyncDebug", "⚠️ [Sync] 收到 FullSnapshot，正在清空本地舊資料...")
+                            friendDao.deleteAll()
+                            roomDao.deleteAll()
+                            blockDao.deleteAll()
                         }
-                    }
 
-                    // Process Friends
-                    body.friends.forEach { friend ->
-                        if (friend.removed) {
-                            friendDao.deleteById(friend.userId)
-                        } else {
-                            friendDao.insertOrUpdate(listOf(
-                                FriendLocalEntity(
-                                    userId = friend.userId,
-                                    username = friend.username,
-                                    displayName = friend.displayName,
-                                    avatarUrl = friend.avatarUrl,
-                                    status = friend.status,
-                                    presenceStatus = friend.presenceStatus
-                                )
-                            ))
+                        // 1. 處理黑名單
+                        body.blocks.forEach { block ->
+                            if (block.removed) {
+                                blockDao.deleteById(block.userId)
+                            } else {
+                                blockDao.insertOrUpdate(listOf(
+                                    BlockedUserLocalEntity(
+                                        userId = block.userId,
+                                        username = block.username,
+                                        displayName = block.displayName,
+                                        avatarUrl = block.avatarUrl,
+                                        blockedAt = block.blockedAt
+                                    )
+                                ))
+                            }
                         }
-                    }
 
-                    // Process Rooms
-                    body.rooms.forEach { room ->
-                        if (room.removed) {
-                            roomDao.deleteById(room.roomId)
-                        } else {
-                            roomDao.insertOrUpdate(listOf(
-                                RoomLocalEntity(
-                                    roomId = room.roomId,
-                                    nickname = room.nickname,
-                                    isHidden = room.isHidden,
-                                    isMuted = room.isMuted,
-                                    isPinned = room.isPinned,
-                                    unreadCount = room.unreadCount,
-                                    mentionCount = room.mentionCount,
-                                    partner = room.partner,
-                                    lastMessage = room.lastMessage
-                                )
-                            ))
+                        // 2. 處理好友
+                        body.friends.forEach { friend ->
+                            if (friend.removed) {
+                                friendDao.deleteById(friend.userId)
+                            } else {
+                                friendDao.insertOrUpdate(listOf(
+                                    FriendLocalEntity(
+                                        userId = friend.userId,
+                                        username = friend.username,
+                                        displayName = friend.displayName,
+                                        avatarUrl = friend.avatarUrl,
+                                        status = friend.status,
+                                        presenceStatus = friend.presenceStatus
+                                    )
+                                ))
+                            }
                         }
-                    }
 
-                    userPrefs.saveSyncSince(body.nextSince)
+                        // 3. 處理聊天室
+                        body.rooms.forEach { room ->
+                            if (room.removed) {
+                                roomDao.deleteById(room.roomId)
+                            } else {
+                                roomDao.insertOrUpdate(listOf(
+                                    RoomLocalEntity(
+                                        roomId = room.roomId,
+                                        nickname = room.nickname,
+                                        isHidden = room.isHidden,
+                                        isMuted = room.isMuted,
+                                        isPinned = room.isPinned,
+                                        unreadCount = room.unreadCount,
+                                        mentionCount = room.mentionCount,
+                                        partner = room.partner,
+                                        lastMessage = room.lastMessage
+                                    )
+                                ))
+                            }
+                        }
+
+                        userPrefs.saveSyncSince(body.nextSince)
+                        Log.d("SyncDebug", "💾 [Sync] 同步完成，已更新 nextSince 為 ${body.nextSince}")
+                    }
+                    Result.success(Unit)
+                } else {
+                    Log.e("SyncDebug", "❌ [Sync] API 失敗 | Code: ${response.code()}")
+                    Result.failure(Exception("Sync API failed: ${response.code()}"))
                 }
-                Result.success(Unit)
-            } else {
-                Result.failure(Exception("Sync API failed: ${response.code()}"))
+            } catch (e: Exception) {
+                Log.e("SyncDebug", "❌ [Sync] 發生異常", e)
+                Result.failure(e)
             }
-        } catch (e: Exception) {
-            Result.failure(e)
         }
     }
+
+    /**
+     * 🛠️ 調試專用：重置同步狀態並清空本地資料
+     * 呼叫此方法後，下一次同步將會從 since=0 開始抓取完整資料
+     */
+    suspend fun resetSyncAndClearData() {
+        Log.w("SyncDebug", "🧨 [Debug] 正在重置同步狀態並清空資料庫...")
+        db.withTransaction {
+            friendDao.deleteAll()
+            roomDao.deleteAll()
+            blockDao.deleteAll()
+            userPrefs.saveSyncSince(0L)
+        }
+        Log.d("SyncDebug", "✅ [Debug] 重置完成")
+    }
 }
diff --git a/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt b/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt
index 9ceefb1..af670a4 100644
--- a/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt
+++ b/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt
@@ -18,8 +18,10 @@ import com.example.login_v3.data.api.api_class.WebSocketEventResponse
 import com.example.login_v3.data.di.ChatWebSocketManager
 import com.example.login_v3.data.repository.basic.TokenManager
 import com.example.login_v3.data.local.dao.MessageDao
+import com.example.login_v3.data.local.dao.RoomLocalDao
 import com.example.login_v3.data.local.entities.MessageEntity
 import com.example.login_v3.data.local.entities.MessageStatus
+import com.example.login_v3.data.local.entities.RoomLocalEntity
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
 import com.squareup.moshi.Moshi
@@ -52,12 +54,31 @@ import kotlin.jvm.java
 class ChatRoomsRepository @Inject constructor(
     private val api: TecnologiaApi,
     private val messageDao: MessageDao,
+    private val roomLocalDao: RoomLocalDao, // 👈 新增：注入房間 DAO
     private val webSocketManager: ChatWebSocketManager, // 👈 1. 注入 Socket 管理器
     private val moshi: Moshi, // 👈 用於解析 Socket 傳來的 JSON
     private val tokenManager: TokenManager,
     @ApplicationContext private val context: Context // 注入 ApplicationContext 用於處理 Uri 檔案
 ) {
 
+    // 🌟 核心：監聽本地資料庫的聊天室列表 Flow
+    val chatRoomsFlow: Flow<List<ChatRoom>> = roomLocalDao.getAllRoomsFlow().map { entities ->
+        entities.map { entity ->
+            ChatRoom(
+                roomId = entity.roomId,
+                roomName = entity.nickname, // 或者 entity.partner?.displayName ? 根據 DTO 結構映射
+                roomType = null, // Entity 暫時沒存，可視需求補上
+                roomIconUrl = null, // Entity 暫時沒存，可視需求補上
+                isMuted = entity.isMuted,
+                isPinned = entity.isPinned,
+                unreadCount = entity.unreadCount,
+                mentionCount = entity.mentionCount,
+                partner = entity.partner,
+                lastMessage = entity.lastMessage
+            )
+        }
+    }
+
     // 建立一個跟著 Repository 生命週期走的 Scope
     private val repositoryScope = CoroutineScope(SupervisorJob() + Dispatchers.IO)
 
diff --git a/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Detail/Contact_list_ViewModel.kt b/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Detail/Contact_list_ViewModel.kt
index 3b18327..98c3996 100644
--- a/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Detail/Contact_list_ViewModel.kt
+++ b/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Detail/Contact_list_ViewModel.kt
@@ -7,6 +7,7 @@ import com.example.login_v3.data.api.api_class.Friend
 import com.example.login_v3.data.api.api_class.PendingFriendApiModel
 import com.example.login_v3.data.api.api_class.UserDetail
 import com.example.login_v3.data.repository.basic.FriendsRepository
+import com.example.login_v3.data.repository.basic.SyncRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
@@ -31,32 +32,42 @@ data class ContactUiState(
 )
 @HiltViewModel
 class ContactListViewModel @Inject constructor(
-    private val repository: FriendsRepository
+    private val repository: FriendsRepository,
+    private val syncRepository: SyncRepository
 ) : ViewModel() {
 
     private val _uiState = MutableStateFlow(ContactUiState())
     val uiState: StateFlow<ContactUiState> = _uiState.asStateFlow()
 
     init {
+        // 1. 監聽本地好友 Flow，一旦資料庫變動，UI 自動刷新
+        observeFriends()
+        // 2. 啟動時跑一次同步
         refreshAll()
     }
 
+    private fun observeFriends() {
+        viewModelScope.launch {
+            repository.friendsFlow.collect { friends ->
+                _uiState.update { it.copy(friends = friends) }
+            }
+        }
+    }
+
     fun refreshAll() {
         viewModelScope.launch {
-            // 1. 開始 Loading 並清除舊錯誤
             _uiState.update { it.copy(isLoading = true, error = null) }
 
-            // 2. 使用 zip 或單獨 fetch，這裡示範簡單的循序或並行處理
-            val friendsResult = repository.getFriendList()
+            // 🎯 同步核心：跑 Delta-Sync
+            val syncResult = syncRepository.performSync()
+            // 同時還是要抓一下 Pending Request (目前 Sync API 沒給這塊)
             val pendingResult = repository.getPendingRequests()
 
-            // 3. 統一處理結果
             _uiState.update { state ->
                 state.copy(
                     isLoading = false,
-                    friends = friendsResult.getOrDefault(state.friends),
                     pendingRequests = pendingResult.getOrDefault(state.pendingRequests),
-                    error = (friendsResult.exceptionOrNull() ?: pendingResult.exceptionOrNull())?.message
+                    error = (syncResult.exceptionOrNull() ?: pendingResult.exceptionOrNull())?.message
                 )
             }
         }
diff --git a/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Message_ViewModel.kt b/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Message_ViewModel.kt
index 3b3fb97..43286e2 100644
--- a/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Message_ViewModel.kt
+++ b/app/src/main/java/com/example/login_v3/home/Message/ViewModel/Message_ViewModel.kt
@@ -9,49 +9,42 @@ import com.example.login_v3.R
 import com.example.login_v3.data.api.api_class.ChatRoom
 import com.example.login_v3.data.api.api_class.Message
 import com.example.login_v3.data.repository.dm.ChatRoomsRepository
+import com.example.login_v3.data.repository.basic.SyncRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
-
-
-
-
-
 @HiltViewModel
 class ChatRoomsViewModel @Inject constructor(
-    private val repository: ChatRoomsRepository
+    private val repository: ChatRoomsRepository,
+    private val syncRepository: SyncRepository
 ) : ViewModel() {
 
     private val _roomsState = MutableStateFlow<List<ChatRoom>>(emptyList())
     val roomsState: StateFlow<List<ChatRoom>> = _roomsState
 
+    init {
+        observeRooms()
+        loadRooms()
+    }
+
+    private fun observeRooms() {
+        viewModelScope.launch {
+            repository.chatRoomsFlow.collectLatest { rooms ->
+                _roomsState.value = rooms
+            }
+        }
+    }
+
     fun loadRooms() {
         viewModelScope.launch {
-            Log.d("ChatRoomsDebug", "1. 開始呼叫 loadRooms()...")
-            val result = repository.fetchRooms()
-
-            result.onSuccess { response ->
-                val roomsList = response.rooms
-                Log.d("ChatRoomsDebug", "2. API 請求成功！拿到 ${roomsList?.size ?: 0} 個聊天室")
-
-                if (roomsList.isNullOrEmpty()) {
-                    Log.w("ChatRoomsDebug", "⚠️ 注意：後端回傳的 rooms 列表是空的(或為 null)！")
-                } else {
-                    roomsList.forEach { room ->
-                        Log.d("ChatRoomsDebug", "-> 房間 ID: ${room.roomId}, 名稱: ${room.roomName}, Partner: ${room.partner?.displayName}, 狀態: ${room.partner?.status}")
-                    }
-                }
-
-                // 更新狀態
-                _roomsState.value = roomsList ?: emptyList()
-                Log.d("ChatRoomsDebug", "3. _roomsState 已更新，當前長度: ${_roomsState.value.size}")
-
-            }.onFailure { error ->
-                // ⭐ 這裡非常重要，一定要印出 stackTrace 才知道為什麼失敗（例如：JSON 解析失敗、404、網路斷線）
-                Log.e("ChatRoomsDebug", "❌ API 請求失敗 (onFailure)!!", error)
+            Log.d("ChatRoomsDebug", "📡 [ChatRoomsViewModel] 觸發同步...")
+            val result = syncRepository.performSync()
+            result.onFailure { error ->
+                Log.e("ChatRoomsDebug", "❌ 同步失敗", error)
             }
         }
     }