diff --git a/app/src/main/java/com/example/login_v3/auth/login/Login_Page_ViewModel.kt b/app/src/main/java/com/example/login_v3/auth/login/Login_Page_ViewModel.kt
index fcb8e9e..b4220c5 100644
--- a/app/src/main/java/com/example/login_v3/auth/login/Login_Page_ViewModel.kt
+++ b/app/src/main/java/com/example/login_v3/auth/login/Login_Page_ViewModel.kt
@@ -5,6 +5,7 @@ import androidx.lifecycle.viewModelScope
 import com.example.login_v3.data.api.api_class.LoginRequest
 import com.example.login_v3.data.api.api_class.UserInfo
 import com.example.login_v3.data.repository.basic.AuthRepository
+import com.example.login_v3.data.repository.basic.TokenManager
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -21,27 +22,28 @@ sealed class LoginUiState {
 
 @HiltViewModel
 class AuthViewModel @Inject constructor(
-    private val repository: AuthRepository
+    private val repository: AuthRepository,
+    private val tokenManager: TokenManager // 注入 TokenManager
 ) : ViewModel() {
 
-    // 用於內部修改的私有狀態
     private val _loginState = MutableStateFlow<LoginUiState>(LoginUiState.Idle)
-    // 暴露給 Compose 觀察的公開狀態
     val loginState: StateFlow<LoginUiState> = _loginState.asStateFlow()
 
     fun login(username: String, password: String) {
         viewModelScope.launch {
             _loginState.value = LoginUiState.Loading
-
             try {
                 val request = LoginRequest(username = username, password = password)
                 val response = repository.login(request)
 
                 if (response.isSuccessful && response.body() != null) {
-                    // 登入成功，儲存 User 資訊
-                    _loginState.value = LoginUiState.Success(response.body()!!.user)
+                    val loginResponse = response.body()!!
 
-                    // 提示：通常這裡還會處理 Token 持久化（儲存在 DataStore 或 EncryptedSharedPreferences）
+                    // 1. 先把 Token 存入 DataStore
+                    tokenManager.saveAuthData(loginResponse.access_token)
+
+                    // 2. 更新 UI 狀態
+                    _loginState.value = LoginUiState.Success(loginResponse.user)
                 } else {
                     _loginState.value = LoginUiState.Error("登入失敗：${response.code()}")
                 }
diff --git a/app/src/main/java/com/example/login_v3/data/di/DataStoreModule.kt b/app/src/main/java/com/example/login_v3/data/di/DataStoreModule.kt
index ba09bea..ffaeacc 100644
--- a/app/src/main/java/com/example/login_v3/data/di/DataStoreModule.kt
+++ b/app/src/main/java/com/example/login_v3/data/di/DataStoreModule.kt
@@ -6,6 +6,7 @@ import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.preferencesDataStore
 import com.example.login_v3.data.local.UserPreferences.UserPreferencesRepository
+import com.example.login_v3.data.repository.basic.TokenManager
 import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
@@ -21,12 +22,24 @@ private val Context.dataStore: DataStore<Preferences> by preferencesDataStore(na
 // 修正 2: 移除 private，讓 Hilt 可以訪問這個模組
 object DataStoreModule {
 
+
+    //data store instance
+    @Provides
+    @Singleton
+    fun provideDataStore(@ApplicationContext context: Context): DataStore<Preferences> {
+        return context.dataStore
+    }
+
     //UserPreferencesRepository
     @Provides
     @Singleton
-    fun provideUserPreferencesRepository(
-        @ApplicationContext context: Context
-    ): UserPreferencesRepository {
-        return UserPreferencesRepository(context.dataStore)
+    fun provideUserPreferencesRepository(dataStore: DataStore<Preferences>): UserPreferencesRepository {
+        return UserPreferencesRepository(dataStore)
+    }
+
+    @Provides
+    @Singleton
+    fun provideTokenManager(dataStore: DataStore<Preferences>): TokenManager {
+        return TokenManager(dataStore)
     }
 }
\ No newline at end of file
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
new file mode 100644
index 0000000..448d6f8
--- /dev/null
+++ b/app/src/main/java/com/example/login_v3/data/repository/basic/Token_Manager.kt
@@ -0,0 +1,44 @@
+package com.example.login_v3.data.repository.basic
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+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 kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+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")
+    }
+
+    // 1.2.1 版本依然使用 suspend edit
+    suspend fun saveAuthData(token: String) {
+        dataStore.edit { preferences ->
+            preferences[ACCESS_TOKEN] = token
+            preferences[IS_LOGIN] = true
+        }
+    }
+
+    // 使用 Flow 讀取資料
+    val accessToken: Flow<String?> = dataStore.data.map { preferences ->
+        preferences[ACCESS_TOKEN]
+    }
+
+    val isLogin: Flow<Boolean> = dataStore.data.map { preferences ->
+        preferences[IS_LOGIN] ?: false
+    }
+
+    suspend fun clearAuthData() {
+        dataStore.edit { preferences ->
+            preferences.clear()
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/example/login_v3/navigation/nav_controller.kt b/app/src/main/java/com/example/login_v3/navigation/nav_controller.kt
index 0a2c234..9e98da8 100644
--- a/app/src/main/java/com/example/login_v3/navigation/nav_controller.kt
+++ b/app/src/main/java/com/example/login_v3/navigation/nav_controller.kt
@@ -28,7 +28,7 @@ fun AppNavGraph(
 
         AppScreen.Login -> LoginScreen(
             paddingValues = paddingValues,
-            onLoginSuccess = { appViewModel.onLoginSuccess() }
+            onLoginSuccess = { appViewModel.goTo(AppScreen.ScreensTab) }
         )
 
         AppScreen.Register -> {