diff --git a/app/src/main/java/com/umc/edison/data/datasources/BubbleLocalDataSource.kt b/app/src/main/java/com/umc/edison/data/datasources/BubbleLocalDataSource.kt
index be229578f..91af3c011 100644
--- a/app/src/main/java/com/umc/edison/data/datasources/BubbleLocalDataSource.kt
+++ b/app/src/main/java/com/umc/edison/data/datasources/BubbleLocalDataSource.kt
@@ -5,7 +5,7 @@ import com.umc.edison.data.model.bubble.BubbleEntity
 interface BubbleLocalDataSource {
     // CREATE
     suspend fun addBubbles(bubbles: List<BubbleEntity>)
-    suspend fun addBubble(bubble: BubbleEntity) : BubbleEntity
+    suspend fun addBubble(bubble: BubbleEntity, userEmail: String? = null) : BubbleEntity
 
     // READ
     suspend fun getAllActiveBubbles(): List<BubbleEntity>
@@ -24,6 +24,7 @@ interface BubbleLocalDataSource {
     suspend fun trashBubbles(bubbles: List<BubbleEntity>)
     suspend fun markAsSynced(bubble: BubbleEntity)
     suspend fun syncBubbles(bubbles: List<BubbleEntity>)
+    suspend fun linkGuestBubblesToUser(userEmail: String)
 
     // DELETE
     suspend fun deleteBubbles(bubbles: List<BubbleEntity>)
diff --git a/app/src/main/java/com/umc/edison/data/repository/BubbleRepositoryImpl.kt b/app/src/main/java/com/umc/edison/data/repository/BubbleRepositoryImpl.kt
index f2ff3203b..8909d0be5 100644
--- a/app/src/main/java/com/umc/edison/data/repository/BubbleRepositoryImpl.kt
+++ b/app/src/main/java/com/umc/edison/data/repository/BubbleRepositoryImpl.kt
@@ -1,5 +1,6 @@
 package com.umc.edison.data.repository
 
+import android.util.Log
 import com.umc.edison.data.bound.FlowBoundResourceFactory
 import com.umc.edison.data.datasources.BubbleLocalDataSource
 import com.umc.edison.data.datasources.BubbleRemoteDataSource
@@ -7,6 +8,7 @@ import com.umc.edison.data.model.bubble.ClusteredBubbleEntity
 import com.umc.edison.data.model.bubble.KeywordBubbleEntity
 import com.umc.edison.data.model.bubble.toData
 import com.umc.edison.common.logging.AppLogger
+import com.umc.edison.data.token.TokenManager
 import com.umc.edison.domain.DataResource
 import com.umc.edison.domain.model.bubble.Bubble
 import com.umc.edison.domain.model.bubble.ClusteredBubble
@@ -19,7 +21,7 @@ import javax.inject.Inject
 class BubbleRepositoryImpl @Inject constructor(
     private val bubbleLocalDataSource: BubbleLocalDataSource,
     private val bubbleRemoteDataSource: BubbleRemoteDataSource,
-    private val resourceFactory: FlowBoundResourceFactory
+    private val resourceFactory: FlowBoundResourceFactory,
 ) : BubbleRepository {
     // CREATE
     override fun addBubbles(bubbles: List<Bubble>): Flow<DataResource<Unit>> =
@@ -41,7 +43,9 @@ class BubbleRepositoryImpl @Inject constructor(
 
     override fun addBubble(bubble: Bubble): Flow<DataResource<Bubble>> =
         resourceFactory.sync(
-            localAction = { bubbleLocalDataSource.addBubble(bubble.toData()) },
+            localAction = {
+                bubbleLocalDataSource.addBubble(bubble.toData())
+            },
             remoteSync = {
                 val newBubble = bubbleLocalDataSource.getActiveBubble(bubble.id)
                 bubbleRemoteDataSource.syncBubble(newBubble)
@@ -193,6 +197,10 @@ class BubbleRepositoryImpl @Inject constructor(
             }
         )
 
+    override suspend fun linkGuestBubblesToUser(userEmail: String) {
+        bubbleLocalDataSource.linkGuestBubblesToUser(userEmail)
+    }
+
     // DELETE
     override fun deleteBubbles(bubbles: List<Bubble>): Flow<DataResource<Unit>> =
         resourceFactory.sync(
@@ -212,7 +220,8 @@ class BubbleRepositoryImpl @Inject constructor(
                 }
             },
             onRemoteSuccess = { deletedBubbles ->
-               val localBubbles = deletedBubbles.map { remote -> bubbleLocalDataSource.getRawBubble(remote.id) }
+                val localBubbles =
+                    deletedBubbles.map { remote -> bubbleLocalDataSource.getRawBubble(remote.id) }
                 bubbleLocalDataSource.deleteBubbles(localBubbles)
             }
         )
diff --git a/app/src/main/java/com/umc/edison/data/repository/UserRepositoryImpl.kt b/app/src/main/java/com/umc/edison/data/repository/UserRepositoryImpl.kt
index b988be850..7153f56da 100644
--- a/app/src/main/java/com/umc/edison/data/repository/UserRepositoryImpl.kt
+++ b/app/src/main/java/com/umc/edison/data/repository/UserRepositoryImpl.kt
@@ -9,6 +9,7 @@ import com.umc.edison.data.token.TokenManager
 import com.umc.edison.domain.DataResource
 import com.umc.edison.domain.model.identity.Identity
 import com.umc.edison.domain.model.user.User
+import com.umc.edison.domain.repository.BubbleRepository
 import com.umc.edison.domain.repository.UserRepository
 import kotlinx.coroutines.flow.Flow
 import javax.inject.Inject
@@ -18,11 +19,12 @@ class UserRepositoryImpl @Inject constructor(
     private val resourceFactory: FlowBoundResourceFactory,
     private val tokenManager: TokenManager,
 ) : UserRepository {
-    // CREATE
+
     override fun googleLogin(idToken: String): Flow<DataResource<User>> = resourceFactory.remote(
         dataAction = {
             val userWithToken: UserWithTokenEntity = userRemoteDataSource.googleLogin(idToken)
             tokenManager.setToken(userWithToken.accessToken, userWithToken.refreshToken)
+            tokenManager.saveUserEmail(userWithToken.user.email)
             userWithToken
         }
     )
@@ -33,23 +35,21 @@ class UserRepositoryImpl @Inject constructor(
         identity: List<Identity>
     ): Flow<DataResource<User>> = resourceFactory.remote(
         dataAction = {
-            val userWithToken: UserWithTokenEntity =
-                userRemoteDataSource.googleSignup(
-                    idToken = idToken,
-                    nickname = nickname,
-                    identity = identity.map { it.toData() }
-                )
+            val userWithToken: UserWithTokenEntity = userRemoteDataSource.googleSignup(
+                idToken = idToken,
+                nickname = nickname,
+                identity = identity.map { it.toData() }
+            )
             tokenManager.setToken(userWithToken.accessToken, userWithToken.refreshToken)
+            tokenManager.saveUserEmail(userWithToken.user.email)
             userWithToken
         }
     )
 
-
-
     // READ
     override fun getLogInState(): Flow<DataResource<Boolean>> = resourceFactory.local(
         dataAction = {
-            tokenManager.loadAccessToken()?.isNotEmpty()
+            tokenManager.loadAccessToken()?.isNotEmpty() == true
         }
     )
 
diff --git a/app/src/main/java/com/umc/edison/data/token/TokenManager.kt b/app/src/main/java/com/umc/edison/data/token/TokenManager.kt
index 2f5f0a186..4c5a1bfba 100644
--- a/app/src/main/java/com/umc/edison/data/token/TokenManager.kt
+++ b/app/src/main/java/com/umc/edison/data/token/TokenManager.kt
@@ -1,9 +1,9 @@
 package com.umc.edison.data.token
 
-import com.umc.edison.data.datasources.PrefDataSource
-import com.umc.edison.data.di.ApplicationScope
 import javax.inject.Inject
 import javax.inject.Singleton
+import com.umc.edison.data.datasources.PrefDataSource
+import com.umc.edison.data.di.ApplicationScope
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.Mutex
@@ -17,19 +17,27 @@ class TokenManager @Inject constructor(
 
     private val mutex = Mutex()
 
-    private var cachedAccessToken: String? = null
-    private var cachedRefreshToken: String? = null
-
     init {
         applicationScope.launch {
             preloadTokens()
+            loadUserEmail()
         }
     }
 
+    private var cachedAccessToken: String? = null
+    private var cachedRefreshToken: String? = null
+    private var cachedUserEmail: String? = null
+
+
     override fun getAccessToken(): String? = cachedAccessToken
 
     override fun getRefreshToken(): String? = cachedRefreshToken
 
+    suspend fun getUserEmail(): String? {
+        if (cachedUserEmail != null) return cachedUserEmail
+        return loadUserEmail()
+    }
+
     override suspend fun clearCachedTokens() {
         mutex.withLock {
             cachedAccessToken = null
@@ -60,6 +68,17 @@ class TokenManager @Inject constructor(
         }
     }
 
+    suspend fun loadUserEmail(): String? {
+        val email = prefDataSource.get(USER_EMAIL_KEY, "")
+        cachedUserEmail = email.ifEmpty { null }
+        return cachedUserEmail
+    }
+
+    suspend fun saveUserEmail(userEmail: String) {
+        cachedUserEmail = userEmail
+        prefDataSource.set(USER_EMAIL_KEY, userEmail)
+    }
+
     suspend fun setToken(accessToken: String, refreshToken: String? = null) {
         mutex.withLock {
             cachedAccessToken = accessToken
@@ -75,8 +94,10 @@ class TokenManager @Inject constructor(
         mutex.withLock {
             cachedAccessToken = null
             cachedRefreshToken = null
+            cachedUserEmail = null
             prefDataSource.remove(ACCESS_TOKEN_KEY)
             prefDataSource.remove(REFRESH_TOKEN_KEY)
+            prefDataSource.remove(USER_EMAIL_KEY)
         }
     }
 
@@ -90,5 +111,6 @@ class TokenManager @Inject constructor(
     companion object {
         private const val ACCESS_TOKEN_KEY = "access_token"
         private const val REFRESH_TOKEN_KEY = "refresh_token"
+        private const val USER_EMAIL_KEY = "user_email"
     }
 }
diff --git a/app/src/main/java/com/umc/edison/domain/repository/BubbleRepository.kt b/app/src/main/java/com/umc/edison/domain/repository/BubbleRepository.kt
index 0efd09170..93f6ea6ec 100644
--- a/app/src/main/java/com/umc/edison/domain/repository/BubbleRepository.kt
+++ b/app/src/main/java/com/umc/edison/domain/repository/BubbleRepository.kt
@@ -26,6 +26,7 @@ interface BubbleRepository {
     fun recoverBubbles(bubbles: List<Bubble>): Flow<DataResource<Unit>>
     fun updateBubbles(bubbles: List<Bubble>): Flow<DataResource<Unit>>
     fun updateBubble(bubble: Bubble): Flow<DataResource<Bubble>>
+    suspend fun linkGuestBubblesToUser(userEmail: String)
 
     // DELETE
     fun deleteBubbles(bubbles: List<Bubble>): Flow<DataResource<Unit>>
diff --git a/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleLoginUseCase.kt b/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleLoginUseCase.kt
index c690eb655..2942098ad 100644
--- a/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleLoginUseCase.kt
+++ b/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleLoginUseCase.kt
@@ -2,13 +2,21 @@ package com.umc.edison.domain.usecase.user
 
 import com.umc.edison.domain.DataResource
 import com.umc.edison.domain.model.user.User
+import com.umc.edison.domain.repository.BubbleRepository
 import com.umc.edison.domain.repository.UserRepository
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.onEach
 import javax.inject.Inject
 
 class GoogleLoginUseCase @Inject constructor(
-    private val userRepository: UserRepository
+    private val userRepository: UserRepository,
+    private val bubbleRepository: BubbleRepository
 ) {
     operator fun invoke(idToken: String): Flow<DataResource<User>> =
-        userRepository.googleLogin(idToken)
-}
+        userRepository.googleLogin(idToken).onEach { resource ->
+            if (resource is DataResource.Success) {
+                val userEmail = resource.data.email
+                bubbleRepository.linkGuestBubblesToUser(userEmail)
+            }
+        }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleSignUpUseCase.kt b/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleSignUpUseCase.kt
index 98ccdc4c6..2b42e0ef3 100644
--- a/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleSignUpUseCase.kt
+++ b/app/src/main/java/com/umc/edison/domain/usecase/user/GoogleSignUpUseCase.kt
@@ -3,17 +3,25 @@ package com.umc.edison.domain.usecase.user
 import com.umc.edison.domain.DataResource
 import com.umc.edison.domain.model.identity.Identity
 import com.umc.edison.domain.model.user.User
+import com.umc.edison.domain.repository.BubbleRepository
 import com.umc.edison.domain.repository.UserRepository
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.onEach
 import javax.inject.Inject
 
 class GoogleSignUpUseCase @Inject constructor(
-    private val userRepository: UserRepository
+    private val userRepository: UserRepository,
+    private val bubbleRepository: BubbleRepository
 ) {
     operator fun invoke(
         idToken: String,
         nickname: String,
         identities: List<Identity>
     ): Flow<DataResource<User>> =
-        userRepository.googleSignUp(idToken, nickname, identities)
+        userRepository.googleSignUp(idToken, nickname, identities).onEach { resource ->
+            if (resource is DataResource.Success) {
+                val userEmail = resource.data.email
+                bubbleRepository.linkGuestBubblesToUser(userEmail)
+            }
+        }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/umc/edison/local/datasources/BaseLocalDataSourceImpl.kt b/app/src/main/java/com/umc/edison/local/datasources/BaseLocalDataSourceImpl.kt
index 1dff639a9..6d425f2d3 100644
--- a/app/src/main/java/com/umc/edison/local/datasources/BaseLocalDataSourceImpl.kt
+++ b/app/src/main/java/com/umc/edison/local/datasources/BaseLocalDataSourceImpl.kt
@@ -25,7 +25,10 @@ open class BaseLocalDataSourceImpl<T : BaseSyncLocal>(
 
     // UPDATE
     suspend fun update(entity: T, tableName: String, isSynced: Boolean = false) {
-        val query = SimpleSQLiteQuery("SELECT * FROM $tableName WHERE id = '${entity.uuid}'")
+        val query = SimpleSQLiteQuery(
+            "SELECT * FROM $tableName WHERE id = ?",
+            arrayOf(entity.uuid)
+        )
         baseDao.getById(query)?.let {
             entity.createdAt = it.createdAt
             entity.updatedAt = Date()
@@ -36,7 +39,10 @@ open class BaseLocalDataSourceImpl<T : BaseSyncLocal>(
 
     suspend fun markAsSynced(tableName: String, id: String) {
         val date = Date()
-        val query = SimpleSQLiteQuery("UPDATE $tableName SET is_synced = 1, updated_at = '$date' WHERE id = '$id'")
+        val query = SimpleSQLiteQuery(
+            "UPDATE $tableName SET is_synced = 1, updated_at = ? WHERE id = ?",
+            arrayOf(date.time, id)
+        )
         baseDao.markAsSynced(query)
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/umc/edison/local/datasources/BubbleLocalDataSourceImpl.kt b/app/src/main/java/com/umc/edison/local/datasources/BubbleLocalDataSourceImpl.kt
index c808ac237..1b631c65e 100644
--- a/app/src/main/java/com/umc/edison/local/datasources/BubbleLocalDataSourceImpl.kt
+++ b/app/src/main/java/com/umc/edison/local/datasources/BubbleLocalDataSourceImpl.kt
@@ -3,6 +3,7 @@ package com.umc.edison.local.datasources
 import android.icu.util.Calendar
 import com.umc.edison.data.datasources.BubbleLocalDataSource
 import com.umc.edison.data.model.bubble.BubbleEntity
+import com.umc.edison.data.token.TokenManager
 import com.umc.edison.local.model.BubbleLocal
 import com.umc.edison.local.model.toLocal
 import com.umc.edison.local.room.RoomConstant
@@ -17,53 +18,75 @@ class BubbleLocalDataSourceImpl @Inject constructor(
     private val bubbleDao: BubbleDao,
     private val labelDao: LabelDao,
     private val bubbleLabelDao: BubbleLabelDao,
-    private val linkedBubbleDao: LinkedBubbleDao
+    private val linkedBubbleDao: LinkedBubbleDao,
+    private val tokenManager: TokenManager
 ) : BubbleLocalDataSource, BaseLocalDataSourceImpl<BubbleLocal>(bubbleDao) {
 
     private val tableName = RoomConstant.getTableNameByClass(BubbleLocal::class.java)
 
-    // CREATE
+    override suspend fun linkGuestBubblesToUser(userEmail: String) {
+        bubbleDao.linkGuestBubblesToUser(userEmail)
+    }
+
+    // --- CREATE ---
     override suspend fun addBubbles(bubbles: List<BubbleEntity>) {
+        val userEmail = tokenManager.getUserEmail()
         bubbles.forEach { bubble ->
-            addBubble(bubble)
+            addBubble(bubble, userEmail)
         }
     }
 
-    override suspend fun addBubble(bubble: BubbleEntity): BubbleEntity {
-        val id = insert(bubble.toLocal())
-        val insertedBubble = bubble.copy(id = id)
+    override suspend fun addBubble(bubble: BubbleEntity, userEmail: String?): BubbleEntity {
+        val targetUserEmail = userEmail ?: tokenManager.getUserEmail()
+        val localBubble = BubbleLocal(
+            uuid = bubble.id,
+            userEmail = targetUserEmail,
+            title = bubble.title,
+            content = bubble.content,
+            mainImage = bubble.mainImage,
+            isSynced = bubble.isSynced,
+            isTrashed = bubble.isTrashed,
+            isDeleted = bubble.isDeleted,
+            createdAt = bubble.createdAt,
+            updatedAt = bubble.updatedAt,
+            deletedAt = bubble.deletedAt
+        )
 
-        addBubbleLabel(insertedBubble)
-        addLinkedBubble(insertedBubble)
+        val id = insert(localBubble)
 
+        val insertedBubble = bubble.copy(id = id)
+        addBubbleLabel(insertedBubble)
         return getActiveBubble(insertedBubble.id)
     }
 
-    // READ
+    // --- READ ---
     override suspend fun getAllActiveBubbles(): List<BubbleEntity> {
-        val localBubbles: List<BubbleLocal> = bubbleDao.getAllActiveBubbles()
-
+        val userEmail = tokenManager.getUserEmail()
+        val localBubbles: List<BubbleLocal> = bubbleDao.getAllActiveBubbles(userEmail)
         return convertLocalBubblesToBubbleEntities(localBubbles)
     }
 
     override suspend fun getAllRecentBubbles(dayBefore: Int): List<BubbleEntity> {
+        val userEmail = tokenManager.getUserEmail()
         val timestampLimit = Calendar.getInstance().apply {
             add(Calendar.DAY_OF_YEAR, -dayBefore)
         }.time.time
-        val localBubbles: List<BubbleLocal> = bubbleDao.getAllRecentBubbles(timestampLimit)
+        val localBubbles: List<BubbleLocal> = bubbleDao.getAllRecentBubbles(timestampLimit, userEmail)
 
         return convertLocalBubblesToBubbleEntities(localBubbles)
     }
 
     override suspend fun getAllTrashedBubbles(): List<BubbleEntity> {
-        val deletedBubbles: List<BubbleLocal> = bubbleDao.getAllTrashedBubbles()
+        val userEmail = tokenManager.getUserEmail()
+        val deletedBubbles: List<BubbleLocal> = bubbleDao.getAllTrashedBubbles(userEmail)
 
         return convertLocalBubblesToBubbleEntities(deletedBubbles)
     }
 
     override suspend fun getActiveBubble(id: String): BubbleEntity {
-        val bubble = bubbleDao.getActiveBubbleById(id)?.toData()
-            ?: throw IllegalArgumentException("Bubble with id $id not found")
+        val userEmail = tokenManager.getUserEmail()
+        val bubble = bubbleDao.getActiveBubbleById(id, userEmail)?.toData()
+            ?: throw IllegalArgumentException("Bubble with id $id not found for current user")
 
         val result = bubble.copy(
             labels = labelDao.getAllActiveLabelsByBubbleId(id).map { it.toData() },
@@ -75,7 +98,8 @@ class BubbleLocalDataSourceImpl @Inject constructor(
     }
 
     override suspend fun getRawBubble(id: String): BubbleEntity {
-        val bubble = bubbleDao.getRawBubbleById(id)?.toData()
+        val userEmail = tokenManager.getUserEmail()
+        val bubble = bubbleDao.getRawBubbleById(id, userEmail)?.toData()
             ?: throw IllegalArgumentException("Bubble with id $id not found")
 
         val result = bubble.copy(
@@ -88,27 +112,29 @@ class BubbleLocalDataSourceImpl @Inject constructor(
     }
 
     override suspend fun getBubblesByLabelId(labelId: String): List<BubbleEntity> {
-        val localBubbles: List<BubbleLocal> = bubbleDao.getBubblesByLabelId(labelId)
+        val userEmail = tokenManager.getUserEmail()
+        val localBubbles: List<BubbleLocal> = bubbleDao.getBubblesByLabelId(labelId, userEmail)
         return convertLocalBubblesToBubbleEntities(localBubbles)
     }
 
     override suspend fun getBubblesWithoutLabel(): List<BubbleEntity> {
-        val localBubbles: List<BubbleLocal> = bubbleDao.getBubblesWithoutLabel()
+        val userEmail = tokenManager.getUserEmail()
+        val localBubbles: List<BubbleLocal> = bubbleDao.getBubblesWithoutLabel(userEmail)
         return convertLocalBubblesToBubbleEntities(localBubbles)
     }
 
     override suspend fun getSearchBubbleResults(query: String): List<BubbleEntity> {
-        val localBubbles: List<BubbleLocal> = bubbleDao.getSearchBubbles(query)
+        val userEmail = tokenManager.getUserEmail()
+        val localBubbles: List<BubbleLocal> = bubbleDao.getSearchBubbles(query, userEmail)
         return convertLocalBubblesToBubbleEntities(localBubbles)
     }
 
     override suspend fun getUnSyncedBubbles(): List<BubbleEntity> {
         val localBubbles: List<BubbleLocal> = getAllUnSyncedRows(tableName)
-
         return convertLocalBubblesToBubbleEntities(localBubbles)
     }
 
-    // UPDATE
+    // --- UPDATE ---
     override suspend fun updateBubbles(bubbles: List<BubbleEntity>) {
         bubbles.forEach { bubble ->
             updateBubble(bubble)
@@ -125,6 +151,10 @@ class BubbleLocalDataSourceImpl @Inject constructor(
         addBubbleLabel(bubble)
         addLinkedBubble(bubble)
 
+        if (isSynced) {
+            markAsSynced(bubble)
+        }
+
         return getActiveBubble(bubble.id)
     }
 
@@ -136,8 +166,7 @@ class BubbleLocalDataSourceImpl @Inject constructor(
                 deletedAt = Date()
             )
         }
-
-        trashedBubbles.map {
+        trashedBubbles.forEach {
             update(it.toLocal(), tableName)
         }
     }
@@ -148,68 +177,63 @@ class BubbleLocalDataSourceImpl @Inject constructor(
 
     override suspend fun syncBubbles(bubbles: List<BubbleEntity>) {
         if (bubbles.isEmpty()) return
-        
-        // 배치로 처리하기 위해 모든 관련 버블 ID 수집
+
         val allBubbleIds = mutableSetOf<String>()
         bubbles.forEach { bubble ->
             allBubbleIds.add(bubble.id)
             bubble.backLinks.forEach { allBubbleIds.add(it.id) }
             bubble.linkedBubble?.let { allBubbleIds.add(it.id) }
         }
-        
-        // 기존 버블들을 배치로 조회
+
+        val userEmail = tokenManager.getUserEmail()
         val existingBubbles = convertLocalBubblesToBubbleEntities(
-            bubbleDao.getActiveBubblesByIds(allBubbleIds.toList())
+            bubbleDao.getActiveBubblesByIds(allBubbleIds.toList(), userEmail)
         ).associateBy { it.id }
-        
-        // 각 버블 동기화
+
         bubbles.forEach { bubble ->
             syncBubbleWithExistingData(bubble, existingBubbles)
         }
     }
-    
+
     private suspend fun syncBubbleWithExistingData(
-        bubble: BubbleEntity, 
+        bubble: BubbleEntity,
         existingBubbles: Map<String, BubbleEntity>
     ) {
-        // backLinks 처리
         for(backLink in bubble.backLinks) {
             val existingBackLink = existingBubbles[backLink.id]
             if (existingBackLink != null) {
                 if (existingBackLink.same(backLink) && existingBackLink.updatedAt > backLink.updatedAt) continue
                 updateBubble(backLink, true)
             } else {
-                addBubble(backLink)
+                addBubble(backLink, null)
             }
             markAsSynced(backLink)
         }
 
-        // linkedBubble 처리
         bubble.linkedBubble?.let { linkedBubble ->
             val existingLinkedBubble = existingBubbles[linkedBubble.id]
             if (existingLinkedBubble != null) {
                 if (!existingLinkedBubble.same(linkedBubble)) {
-                    updateBubble(linkedBubble)
+                    updateBubble(linkedBubble, true)
                 }
             } else {
-                addBubble(linkedBubble)
+                addBubble(linkedBubble, null)
             }
             markAsSynced(linkedBubble)
         }
 
-        // 현재 버블 처리
         val existingBubble = existingBubbles[bubble.id]
         if (existingBubble != null) {
             if (!existingBubble.same(bubble)) {
-                updateBubble(bubble)
+                updateBubble(bubble, true)
             }
         } else {
-            addBubble(bubble)
+            addBubble(bubble, null)
         }
         markAsSynced(bubble)
     }
 
-    // DELETE
+    // --- DELETE ---
     override suspend fun deleteBubbles(bubbles: List<BubbleEntity>) {
         bubbleDao.deleteBubbles(bubbles.map { it.id })
     }
@@ -217,21 +241,19 @@ class BubbleLocalDataSourceImpl @Inject constructor(
     // Helper function
     private suspend fun addBubbleLabel(bubble: BubbleEntity) {
         if (bubble.labels.isEmpty()) return
-        
+
         val labelIds = bubble.labels.map { it.id }
         val existingLabels = labelDao.getLabelsByIds(labelIds)
         val existingLabelIds = existingLabels.map { it.uuid }.toSet()
-        
-        // 존재하지 않는 라벨들을 배치로 삽입
+
         val newLabels = bubble.labels.filter { it.id !in existingLabelIds }
         newLabels.forEach { label ->
             labelDao.insert(label.toLocal())
         }
-        
-        // 버블-라벨 관계 확인 및 삽입
+
         val existingRelations = bubbleLabelDao.getBubbleLabelsByIds(listOf(bubble.id), labelIds)
         val existingRelationPairs = existingRelations.map { "${it.bubbleId}-${it.labelId}" }.toSet()
-        
+
         bubble.labels.forEach { label ->
             val relationKey = "${bubble.id}-${label.id}"
             if (relationKey !in existingRelationPairs) {
@@ -241,18 +263,17 @@ class BubbleLocalDataSourceImpl @Inject constructor(
     }
 
     private suspend fun addLinkedBubble(bubble: BubbleEntity) {
-        // LinkedBubble 처리
         bubble.linkedBubble?.let { linkedBubble ->
             val id = linkedBubbleDao.getLinkedBubbleId(bubble.id, linkedBubble.id, false)
             if (id == null) linkedBubbleDao.insert(bubble.id, linkedBubble.id, false)
         }
 
-        // BackLinks 배치 처리
         if (bubble.backLinks.isNotEmpty()) {
             val backLinkIds = bubble.backLinks.map { it.id }
-            val existingBubbles = bubbleDao.getActiveBubblesByIds(backLinkIds)
+            val userEmail = tokenManager.getUserEmail()
+            val existingBubbles = bubbleDao.getActiveBubblesByIds(backLinkIds, userEmail)
             val existingBubbleIds = existingBubbles.map { it.uuid }.toSet()
-            
+
             bubble.backLinks.forEach { backLink ->
                 if (backLink.id in existingBubbleIds) {
                     val id = linkedBubbleDao.getLinkedBubbleId(bubble.id, backLink.id, true)
@@ -264,24 +285,21 @@ class BubbleLocalDataSourceImpl @Inject constructor(
 
     private suspend fun convertLocalBubblesToBubbleEntities(localBubbles: List<BubbleLocal>): List<BubbleEntity> {
         if (localBubbles.isEmpty()) return emptyList()
-        
+
         val bubbleIds = localBubbles.map { it.uuid }
-        
-        // 배치로 모든 관련 데이터를 한 번에 조회
+
         val labelsWithBubbleId = labelDao.getAllActiveLabelsByBubbleIds(bubbleIds)
         val linkedBubblesWithParentId = linkedBubbleDao.getActiveLinkedBubblesByBubbleIds(bubbleIds)
         val backLinksWithParentId = linkedBubbleDao.getActiveBackLinksByBubbleIds(bubbleIds)
-        
-        // 버블 ID별로 그룹화
+
         val labelsByBubbleId = labelsWithBubbleId.groupBy { it.bubbleId }
         val linkedBubblesByBubbleId = linkedBubblesWithParentId.groupBy { it.parentBubbleId }
         val backLinksByBubbleId = backLinksWithParentId.groupBy { it.parentBubbleId }
-        
-        // 각 버블에 대해 관련 데이터를 조합하여 BubbleEntity 생성
+
         return localBubbles.map { localBubble ->
             val bubbleId = localBubble.uuid
             val baseEntity = localBubble.toData()
-            
+
             baseEntity.copy(
                 labels = labelsByBubbleId[bubbleId]?.map { it.toLabelEntity() } ?: emptyList(),
                 linkedBubble = linkedBubblesByBubbleId[bubbleId]?.firstOrNull()?.toBubbleEntity(),
@@ -289,4 +307,4 @@ class BubbleLocalDataSourceImpl @Inject constructor(
             )
         }
     }
-}
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/umc/edison/local/model/BubbleLocal.kt b/app/src/main/java/com/umc/edison/local/model/BubbleLocal.kt
index 74eba36ba..67443c1d8 100644
--- a/app/src/main/java/com/umc/edison/local/model/BubbleLocal.kt
+++ b/app/src/main/java/com/umc/edison/local/model/BubbleLocal.kt
@@ -11,6 +11,7 @@ import java.util.UUID
 data class BubbleLocal(
     @PrimaryKey
     @ColumnInfo(name = "id") override val uuid: String = UUID.randomUUID().toString(),
+    @ColumnInfo(name = "user_email") val userEmail: String? = null, // 컬럼명 변경
     val title: String?,
     val content: String?,
     @ColumnInfo(name = "main_image") val mainImage: String?,
diff --git a/app/src/main/java/com/umc/edison/local/room/dao/BubbleDao.kt b/app/src/main/java/com/umc/edison/local/room/dao/BubbleDao.kt
index 5fcccb8c7..7f70fe874 100644
--- a/app/src/main/java/com/umc/edison/local/room/dao/BubbleDao.kt
+++ b/app/src/main/java/com/umc/edison/local/room/dao/BubbleDao.kt
@@ -7,27 +7,55 @@ import com.umc.edison.local.room.RoomConstant
 
 @Dao
 interface BubbleDao : BaseSyncDao<BubbleLocal> {
-    // READ
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE is_deleted = 0 AND is_trashed = 0")
-    suspend fun getAllActiveBubbles(): List<BubbleLocal>
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE is_deleted = 0 AND is_trashed = 0 AND created_at >= :dayBefore")
-    suspend fun getAllRecentBubbles(dayBefore: Long): List<BubbleLocal>
+    @Query("UPDATE ${RoomConstant.Table.BUBBLE} SET user_email = :newUserEmail WHERE user_email IS NULL")
+    suspend fun linkGuestBubblesToUser(newUserEmail: String)
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE is_trashed = 1 AND is_deleted = 0")
-    suspend fun getAllTrashedBubbles(): List<BubbleLocal>
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE is_deleted = 0 AND is_trashed = 0
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getAllActiveBubbles(userEmail: String?): List<BubbleLocal>
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE id = :bubbleId AND is_deleted = 0 AND is_trashed = 0")
-    suspend fun getActiveBubbleById(bubbleId: String): BubbleLocal?
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE is_deleted = 0 AND is_trashed = 0 
+        AND created_at >= :dayBefore
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getAllRecentBubbles(dayBefore: Long, userEmail: String?): List<BubbleLocal>
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE id = :bubbleId")
-    suspend fun getRawBubbleById(bubbleId: String): BubbleLocal?
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE is_trashed = 1 AND is_deleted = 0
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getAllTrashedBubbles(userEmail: String?): List<BubbleLocal>
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE id IN (SELECT bubble_id FROM ${RoomConstant.Table.BUBBLE_LABEL} WHERE label_id = :labelId) AND is_deleted = 0 AND is_trashed = 0")
-    suspend fun getBubblesByLabelId(labelId: String): List<BubbleLocal>
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE id = :bubbleId AND is_deleted = 0 AND is_trashed = 0
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getActiveBubbleById(bubbleId: String, userEmail: String?): BubbleLocal?
 
-    @Query(
-        """
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE id = :bubbleId
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getRawBubbleById(bubbleId: String, userEmail: String?): BubbleLocal?
+
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE id IN (SELECT bubble_id FROM ${RoomConstant.Table.BUBBLE_LABEL} WHERE label_id = :labelId) 
+        AND is_deleted = 0 AND is_trashed = 0
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getBubblesByLabelId(labelId: String, userEmail: String?): List<BubbleLocal>
+
+    @Query("""
         SELECT DISTINCT b.* FROM ${RoomConstant.Table.BUBBLE} b
         LEFT JOIN ${RoomConstant.Table.BUBBLE_LABEL} bl ON b.id = bl.bubble_id
         LEFT JOIN ${RoomConstant.Table.LABEL} l ON bl.label_id = l.id
@@ -37,17 +65,25 @@ interface BubbleDao : BaseSyncDao<BubbleLocal> {
             OR l.name LIKE '%' || :query || '%')
             AND b.is_deleted = 0 
             AND b.is_trashed = 0
-        """
-    )
-    suspend fun getSearchBubbles(query: String): List<BubbleLocal>
+            AND ((:userEmail IS NULL AND b.user_email IS NULL) OR (b.user_email = :userEmail))
+    """)
+    suspend fun getSearchBubbles(query: String, userEmail: String?): List<BubbleLocal>
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE id NOT IN (SELECT bubble_id FROM ${RoomConstant.Table.BUBBLE_LABEL}) AND is_deleted = 0 AND is_trashed = 0")
-    suspend fun getBubblesWithoutLabel(): List<BubbleLocal>
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE id NOT IN (SELECT bubble_id FROM ${RoomConstant.Table.BUBBLE_LABEL}) 
+        AND is_deleted = 0 AND is_trashed = 0
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getBubblesWithoutLabel(userEmail: String?): List<BubbleLocal>
 
-    @Query("SELECT * FROM ${RoomConstant.Table.BUBBLE} WHERE id IN (:bubbleIds) AND is_deleted = 0 AND is_trashed = 0")
-    suspend fun getActiveBubblesByIds(bubbleIds: List<String>): List<BubbleLocal>
+    @Query("""
+        SELECT * FROM ${RoomConstant.Table.BUBBLE} 
+        WHERE id IN (:bubbleIds) AND is_deleted = 0 AND is_trashed = 0
+        AND ((:userEmail IS NULL AND user_email IS NULL) OR (user_email = :userEmail))
+    """)
+    suspend fun getActiveBubblesByIds(bubbleIds: List<String>, userEmail: String?): List<BubbleLocal>
 
-    // DELETE
     @Query("DELETE FROM ${RoomConstant.Table.BUBBLE} WHERE id IN (:ids)")
     suspend fun deleteBubbles(ids: List<String>)