feat(user-creator-chat): DM 생성 수신자 필드를 일반화한다

src/main/kotlin/kr/co/vividnext/sodalive/v2/usercreatorchat/controller/UserCreatorChatController.kt

@@ -28,7 +28,7 @@ class UserCreatorChatController(
         @RequestBody request: CreateUserCreatorChatRoomRequest
     ) = run {
         if (member == null) throw SodaException(messageKey = "common.error.bad_credentials")
-        ApiResponse.ok(service.createOrGetRoom(member, request.creatorId))
+        ApiResponse.ok(service.createOrGetRoom(member, request.recipientMemberId()))
     }
 
     @GetMapping("/{roomId}/open")

src/main/kotlin/kr/co/vividnext/sodalive/v2/usercreatorchat/dto/UserCreatorChatDtos.kt

@@ -1,8 +1,18 @@
 package kr.co.vividnext.sodalive.v2.usercreatorchat.dto
 
+import kr.co.vividnext.sodalive.common.SodaException
+
 data class CreateUserCreatorChatRoomRequest(
-    val creatorId: Long
+    val recipientId: Long? = null,
-)
+    val creatorId: Long? = null
+) {
+    fun recipientMemberId(): Long {
+        if (recipientId != null && creatorId != null && recipientId != creatorId) {
+            throw SodaException(messageKey = "common.error.invalid_request")
+        }
+        return recipientId ?: creatorId ?: throw SodaException(messageKey = "common.error.invalid_request")
+    }
+}
 
 data class CreateUserCreatorChatRoomResponse(
     val roomId: Long

src/test/kotlin/kr/co/vividnext/sodalive/v2/usercreatorchat/UserCreatorChatControllerMappingTest.kt

@@ -1,7 +1,13 @@
 package kr.co.vividnext.sodalive.v2.usercreatorchat
 
+import kr.co.vividnext.sodalive.common.SodaException
+import kr.co.vividnext.sodalive.member.Member
 import kr.co.vividnext.sodalive.v2.usercreatorchat.controller.UserCreatorChatController
+import kr.co.vividnext.sodalive.v2.usercreatorchat.dto.CreateUserCreatorChatRoomRequest
+import kr.co.vividnext.sodalive.v2.usercreatorchat.dto.CreateUserCreatorChatRoomResponse
 import kr.co.vividnext.sodalive.v2.usercreatorchat.service.UserCreatorChatService
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertThrows
 import org.junit.jupiter.api.Test
 import org.mockito.Mockito
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get
@@ -23,4 +29,41 @@ class UserCreatorChatControllerMappingTest {
         mockMvc.perform(post("/api/v2/user-creator-chat/rooms/10/messages/text"))
             .andExpect(status().isNotFound)
     }
+
+    @Test
+    fun shouldCreateRoomWithRecipientId() {
+        val service = Mockito.mock(UserCreatorChatService::class.java)
+        val controller = UserCreatorChatController(service)
+        val member = Member(email = "creator@test.com", password = "pw", nickname = "creator").apply { id = 10L }
+        Mockito.`when`(service.createOrGetRoom(member, 20L))
+            .thenReturn(CreateUserCreatorChatRoomResponse(roomId = 30L))
+
+        val response = controller.createOrGetRoom(
+            member,
+            CreateUserCreatorChatRoomRequest(recipientId = 20L, creatorId = null)
+        )
+
+        Mockito.verify(service).createOrGetRoom(member, 20L)
+        assertEquals(30L, response.data!!.roomId)
+    }
+
+    @Test
+    fun shouldCreateRoomWithLegacyCreatorId() {
+        val request = CreateUserCreatorChatRoomRequest(recipientId = null, creatorId = 20L)
+
+        assertEquals(20L, request.recipientMemberId())
+    }
+
+    @Test
+    fun shouldRejectMissingOrConflictingRecipientIds() {
+        val missing = assertThrows(SodaException::class.java) {
+            CreateUserCreatorChatRoomRequest(recipientId = null, creatorId = null).recipientMemberId()
+        }
+        assertEquals("common.error.invalid_request", missing.messageKey)
+
+        val conflict = assertThrows(SodaException::class.java) {
+            CreateUserCreatorChatRoomRequest(recipientId = 20L, creatorId = 21L).recipientMemberId()
+        }
+        assertEquals("common.error.invalid_request", conflict.messageKey)
+    }
 }