diff --git a/app/src/main/java/com/example/login_v3/data/repository/basic/Token_Manager.kt b/app/src/main/java/com/example/login_v3/data/repository/basic/Token_Manager.kt
index 448d6f8..90c681d 100644
--- a/app/src/main/java/com/example/login_v3/data/repository/basic/Token_Manager.kt
+++ b/app/src/main/java/com/example/login_v3/data/repository/basic/Token_Manager.kt
@@ -6,6 +6,7 @@ import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.core.booleanPreferencesKey
 import androidx.datastore.preferences.core.edit
 import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.core.stringSetPreferencesKey
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 import javax.inject.Inject
@@ -13,32 +14,73 @@ import javax.inject.Inject
 class TokenManager @Inject constructor(
     private val dataStore: DataStore<Preferences>
 ) {
-    companion object {
-        // 建議 Key 名稱與變數名稱一致
-        private val ACCESS_TOKEN = stringPreferencesKey("access_token")
-        private val IS_LOGIN = booleanPreferencesKey("is_login")
+    private val USER_ID_LIST = stringSetPreferencesKey("user_id_list")
+    // 獲取所有已登入的使用者 ID 清單
+    val allUserIds: Flow<Set<String>> = dataStore.data.map { preferences ->
+        preferences[USER_ID_LIST] ?: emptySet()
     }
 
-    // 1.2.1 版本依然使用 suspend edit
-    suspend fun saveAuthData(token: String) {
+    companion object {
+        // 1. 記錄目前正在使用的 UserId
+        private val CURRENT_USER_ID = stringPreferencesKey("current_user_id")
+
+        // 2. 輔助函式：根據 userId 動態產生 Token 的 Key
+        private fun accessTokenKey(userId: String) = stringPreferencesKey("access_token_$userId")
+    }
+
+    // 儲存特定使用者的 Token
+    suspend fun saveAuthData(userId: String, token: String) {
         dataStore.edit { preferences ->
-            preferences[ACCESS_TOKEN] = token
-            preferences[IS_LOGIN] = true
+            preferences[accessTokenKey(userId)] = token
+            preferences[CURRENT_USER_ID] = userId
+
+            // 更新 ID 清單：把新的 userId 加進去
+            val currentList = preferences[USER_ID_LIST] ?: emptySet()
+            preferences[USER_ID_LIST] = currentList + userId
         }
     }
 
-    // 使用 Flow 讀取資料
-    val accessToken: Flow<String?> = dataStore.data.map { preferences ->
-        preferences[ACCESS_TOKEN]
+    // 獲取「當前活躍使用者」的 ID
+    val currentUserId: Flow<String?> = dataStore.data.map { it[CURRENT_USER_ID] }
+
+    // 自動讀取「當前帳號」的 Token
+    val currentAccessToken: Flow<String?> = dataStore.data.map { preferences ->
+        val userId = preferences[CURRENT_USER_ID]
+        if (userId != null) {
+            preferences[accessTokenKey(userId)]
+        } else {
+            null
+        }
     }
 
-    val isLogin: Flow<Boolean> = dataStore.data.map { preferences ->
-        preferences[IS_LOGIN] ?: false
-    }
-
-    suspend fun clearAuthData() {
+    // 切換帳號：只需更改 CURRENT_USER_ID
+    suspend fun switchAccount(userId: String) {
         dataStore.edit { preferences ->
-            preferences.clear()
+            // 先檢查該 userId 的 token 是否存在
+            if (preferences.contains(accessTokenKey(userId))) {
+                preferences[CURRENT_USER_ID] = userId
+            }
+        }
+    }
+
+    // 登出特定帳號
+    suspend fun logout(userId: String) {
+        dataStore.edit { preferences ->
+            preferences.remove(accessTokenKey(userId))
+
+            // 從 ID 清單中移除
+            val currentList = preferences[USER_ID_LIST] ?: emptySet()
+            preferences[USER_ID_LIST] = currentList - userId
+
+            // 如果登出的是當前帳號，自動選另一個帳號或清空
+            if (preferences[CURRENT_USER_ID] == userId) {
+                val remainingUser = (currentList - userId).firstOrNull()
+                if (remainingUser != null) {
+                    preferences[CURRENT_USER_ID] = remainingUser
+                } else {
+                    preferences.remove(CURRENT_USER_ID)
+                }
+            }
         }
     }
 }
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