diff --git a/.github/workflows/ci-cd-main.yaml b/.github/workflows/ci-cd-main.yaml
index 3a069f8d..84f07cc6 100644
--- a/.github/workflows/ci-cd-main.yaml
+++ b/.github/workflows/ci-cd-main.yaml
@@ -90,6 +90,7 @@ jobs:
           envs: APP, COMPOSE
           script_stop: true
           script: |
+            ssh api1 "aws ecr get-login-password --region ${{ env.AWS_REGION }} | docker login --username AWS --password-stdin ${{ secrets.AWS_ECR_REGISTRY }}"
             ssh api1 docker-compose -f $COMPOSE down
             ssh api1 docker pull ${{secrets.IMAGE_API}}
             ssh api1 docker-compose -p api -f $COMPOSE up -d
@@ -178,6 +179,7 @@ jobs:
           envs: APP, COMPOSE
           script_stop: true
           script: |
+            ssh notification1 "aws ecr get-login-password --region ${{ env.AWS_REGION }} | docker login --username AWS --password-stdin ${{ secrets.AWS_ECR_REGISTRY }}"
             ssh notification1 docker-compose -f $COMPOSE down
             ssh notification1 docker pull ${{secrets.IMAGE_NOTIFICATION}}
             ssh notification1 docker-compose -p notification -f $COMPOSE up -d
@@ -264,6 +266,7 @@ jobs:
           envs: APP, COMPOSE
           script_stop: true
           script: |
+            ssh batch1 "aws ecr get-login-password --region ${{ env.AWS_REGION }} | docker login --username AWS --password-stdin ${{ secrets.AWS_ECR_REGISTRY }}"
             ssh batch1 docker-compose -f $COMPOSE down
             ssh batch1 docker pull ${{secrets.IMAGE_BATCH}}
             ssh batch1 docker-compose -p batch -f $COMPOSE up -d
@@ -350,6 +353,7 @@ jobs:
           envs: APP, COMPOSE
           script_stop: true
           script: |
+            ssh realtime1 "aws ecr get-login-password --region ${{ env.AWS_REGION }} | docker login --username AWS --password-stdin ${{ secrets.AWS_ECR_REGISTRY }}"
             ssh realtime1 docker-compose -f $COMPOSE down
             ssh realtime1 docker pull ${{secrets.IMAGE_REALTIME}}
             ssh realtime1 docker-compose -p realtime -f $COMPOSE up -d
diff --git a/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/ChatWithUserDto.kt b/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/ChatWithUserDto.kt
index 2449be83..c89a9812 100644
--- a/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/ChatWithUserDto.kt
+++ b/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/ChatWithUserDto.kt
@@ -5,7 +5,7 @@ import com.backgu.amaker.api.user.dto.UserDto
 import com.backgu.amaker.domain.chat.ChatType
 import com.backgu.amaker.domain.chat.ChatWithUser
 import com.backgu.amaker.domain.chat.DefaultChatWithUser
-import com.backgu.amaker.domain.event.EventWithUser
+import com.backgu.amaker.domain.chat.EventChatWithUser
 import java.time.LocalDateTime
 
 sealed interface ChatWithUserDto<T> {
@@ -31,11 +31,11 @@ sealed interface ChatWithUserDto<T> {
                         user = UserDto.of(chatWithUser.user),
                     )
 
-                else ->
+                is EventChatWithUser ->
                     EventChatWithUserDto(
                         id = chatWithUser.id,
                         chatRoomId = chatWithUser.chatRoomId,
-                        content = EventWithUserDto.of(chatWithUser.content as EventWithUser),
+                        content = EventWithUserDto.of(chatWithUser.content),
                         chatType = chatWithUser.chatType,
                         createdAt = chatWithUser.createdAt,
                         updatedAt = chatWithUser.updatedAt,
diff --git a/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/response/ChatWithUserResponse.kt b/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/response/ChatWithUserResponse.kt
index be4db264..8b411c03 100644
--- a/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/response/ChatWithUserResponse.kt
+++ b/api/src/main/kotlin/com/backgu/amaker/api/chat/dto/response/ChatWithUserResponse.kt
@@ -1,6 +1,7 @@
 package com.backgu.amaker.api.chat.dto.response
 
 import com.backgu.amaker.api.chat.dto.ChatWithUserDto
+import com.backgu.amaker.api.chat.dto.DefaultChatWithUserDto
 import com.backgu.amaker.api.chat.dto.EventChatWithUserDto
 import com.backgu.amaker.api.user.dto.response.UserResponse
 import com.backgu.amaker.domain.chat.ChatType
@@ -32,7 +33,7 @@ interface ChatWithUserResponse<T> {
         fun of(chatWithUserDto: ChatWithUserDto<*>): ChatWithUserResponse<*> =
             when (chatWithUserDto) {
                 is EventChatWithUserDto -> EventChatWithUserResponse.of(chatWithUserDto)
-                else -> DefaultChatWithUserResponse.of(chatWithUserDto)
+                is DefaultChatWithUserDto -> DefaultChatWithUserResponse.of(chatWithUserDto)
             }
     }
 }
diff --git a/api/src/main/kotlin/com/backgu/amaker/api/chat/service/ChatFacadeService.kt b/api/src/main/kotlin/com/backgu/amaker/api/chat/service/ChatFacadeService.kt
index b1be3e3c..55f27c52 100644
--- a/api/src/main/kotlin/com/backgu/amaker/api/chat/service/ChatFacadeService.kt
+++ b/api/src/main/kotlin/com/backgu/amaker/api/chat/service/ChatFacadeService.kt
@@ -139,9 +139,15 @@ class ChatFacadeService(
                 chatUserCacheFacadeService.findChat(chatRoomId, it)
             }
 
-        if (cachedChat != null) return ChatWithUserDto.of(cachedChat)
+        if (cachedChat != null) {
+            markMostRecentChatAsRead(chatRoomId, userId)
+            return ChatWithUserDto.of(cachedChat)
+        }
 
-        val chat = chatQueryService.getOneWithUser(chatRoomUser.lastReadChatId)
+        val chat =
+            chatQueryService.getOneWithUser(
+                chatRoomUser.lastReadChatId ?: chatRoomService.getById(chatRoomId).lastChatId,
+            )
 
         if (!ChatType.isEventChat(chat.chatType)) return DefaultChatWithUserDto.of(chat)
 
diff --git a/domain/src/main/kotlin/com/backgu/amaker/domain/chat/ChatWithUser.kt b/domain/src/main/kotlin/com/backgu/amaker/domain/chat/ChatWithUser.kt
index ec4d7558..fc30976e 100644
--- a/domain/src/main/kotlin/com/backgu/amaker/domain/chat/ChatWithUser.kt
+++ b/domain/src/main/kotlin/com/backgu/amaker/domain/chat/ChatWithUser.kt
@@ -3,7 +3,7 @@ package com.backgu.amaker.domain.chat
 import com.backgu.amaker.domain.user.User
 import java.time.LocalDateTime
 
-interface ChatWithUser<T> {
+sealed interface ChatWithUser<T> {
     val id: Long
     val chatRoomId: Long
     val content: T
diff --git a/domain/src/main/kotlin/com/backgu/amaker/domain/workspace/Workspace.kt b/domain/src/main/kotlin/com/backgu/amaker/domain/workspace/Workspace.kt
index 1ac5d2bb..8fb4de53 100644
--- a/domain/src/main/kotlin/com/backgu/amaker/domain/workspace/Workspace.kt
+++ b/domain/src/main/kotlin/com/backgu/amaker/domain/workspace/Workspace.kt
@@ -35,7 +35,6 @@ class Workspace(
 
     fun createDefaultChatRoom(): ChatRoom = ChatRoom(workspaceId = id, name = "일반 채팅", chatRoomType = ChatRoomType.DEFAULT)
 
-    override fun toString(): String {
-        return "Workspace(id=$id, name='$name', thumbnail='$thumbnail', belongingNumber=$belongingNumber, workspacePlan=$workspacePlan)"
-    }
+    override fun toString(): String =
+        "Workspace(id=$id, name='$name', thumbnail='$thumbnail', belongingNumber=$belongingNumber, workspacePlan=$workspacePlan)"
 }
diff --git a/infra/src/main/kotlin/com/backgu/amaker/application/chat/service/ChatUserCacheFacadeService.kt b/infra/src/main/kotlin/com/backgu/amaker/application/chat/service/ChatUserCacheFacadeService.kt
index fbcc60b2..871e1e36 100644
--- a/infra/src/main/kotlin/com/backgu/amaker/application/chat/service/ChatUserCacheFacadeService.kt
+++ b/infra/src/main/kotlin/com/backgu/amaker/application/chat/service/ChatUserCacheFacadeService.kt
@@ -58,8 +58,8 @@ class ChatUserCacheFacadeService(
                 userCacheService.save(fetchedUser)
             }
 
-        when (chat) {
-            is DefaultChatWithUserCache -> return chat.toDomain(user)
+        return when (chat) {
+            is DefaultChatWithUserCache -> chat.toDomain(user)
             is EventChatWithUserCache -> {
                 val userIds = chat.content.users
                 val cachedUsers = userCacheService.findAllByUserIds(userIds)
@@ -68,7 +68,7 @@ class ChatUserCacheFacadeService(
                     userService.getAllByUserIds(missingUserIds).onEach { userCacheService.save(it) }
                 val allUsers = cachedUsers + fetchedUsers
 
-                return chat.toDomain(user, chat.content.toDomain(allUsers))
+                chat.toDomain(user, chat.content.toDomain(allUsers))
             }
         }
     }
@@ -150,10 +150,6 @@ class ChatUserCacheFacadeService(
 
                 return chat.toDomain(user, chat.content.toDomain(allUsers))
             }
-
-            else -> {
-                throw IllegalArgumentException("Invalid chat type")
-            }
         }
     }
 }
diff --git a/infra/src/main/kotlin/com/backgu/amaker/application/workspace/WorkspaceService.kt b/infra/src/main/kotlin/com/backgu/amaker/application/workspace/WorkspaceService.kt
index 444cf6fd..d616eb4c 100644
--- a/infra/src/main/kotlin/com/backgu/amaker/application/workspace/WorkspaceService.kt
+++ b/infra/src/main/kotlin/com/backgu/amaker/application/workspace/WorkspaceService.kt
@@ -23,7 +23,10 @@ class WorkspaceService(
 
     @Transactional
     fun updateBelonging(workspace: Workspace) {
-        workspaceRepository.updateBelongingWithLimit(workspace.id, workspace.workspacePlan.belongingLimit) != 1 &&
+        workspaceRepository.updateBelongingWithLimit(
+            workspace.id,
+            workspace.workspacePlan.belongingLimit,
+        ) != 1 &&
             throw BusinessException(StatusCode.INVALID_WORKSPACE_JOIN)
     }