feat(quota)!: AI 채팅 쿼터(무료/유료) 도입 및 입장/전송 응답에 상태 포함

- ChatQuota 엔티티/레포/서비스/컨트롤러 추가
- 입장 시 Lazy refill 적용, 전송 시 무료 우선 차감 및 잔여/리필 시간 응답 포함
- ChatRoomEnterResponse에 totalRemaining/nextRechargeAtEpoch 추가
- SendChatMessageResponse 신설 및 send API 응답 스키마 변경
- CanUsage에 CHAT_QUOTA_PURCHASE 추가, CanPaymentService/CanService에 결제 흐름 반영

src/main/kotlin/kr/co/vividnext/sodalive/can/CanService.kt

@@ -74,6 +74,7 @@ class CanService(private val repository: CanRepository) {
                     CanUsage.AUDITION_VOTE -> "[오디션 투표] ${it.auditionApplicant?.role?.audition?.title ?: ""}"
                     CanUsage.CHAT_MESSAGE_PURCHASE -> "[메시지 구매] ${it.characterImage?.chatCharacter?.name ?: ""}"
                     CanUsage.CHARACTER_IMAGE_PURCHASE -> "[캐릭터 이미지 구매] ${it.characterImage?.chatCharacter?.name ?: ""}"
+                    CanUsage.CHAT_QUOTA_PURCHASE -> "AI 채팅 개수 구매"
                 }
 
                 val createdAt = it.createdAt!!

src/main/kotlin/kr/co/vividnext/sodalive/can/payment/CanPaymentService.kt

@@ -110,6 +110,9 @@ class CanPaymentService(
             recipientId = liveRoom.member!!.id!!
             useCan.room = liveRoom
             useCan.member = member
+        } else if (canUsage == CanUsage.CHAT_QUOTA_PURCHASE) {
+            // 채팅 쿼터 구매는 수신자 개념 없이 본인에게 귀속
+            useCan.member = member
         } else {
             throw SodaException("잘못된 요청입니다.")
         }

src/main/kotlin/kr/co/vividnext/sodalive/can/use/CanUsage.kt

@@ -11,5 +11,6 @@ enum class CanUsage {
     ALARM_SLOT,
     AUDITION_VOTE,
     CHAT_MESSAGE_PURCHASE, // 메시지를 통한 구매(이미지 등 다양한 리소스에 공통 적용)
-    CHARACTER_IMAGE_PURCHASE // 캐릭터 이미지 단독 구매
+    CHARACTER_IMAGE_PURCHASE, // 캐릭터 이미지 단독 구매
+    CHAT_QUOTA_PURCHASE // 채팅 횟수(쿼터) 충전
 }

src/main/kotlin/kr/co/vividnext/sodalive/chat/quota/ChatQuota.kt

@@ -0,0 +1,21 @@
+package kr.co.vividnext.sodalive.chat.quota
+
+import java.time.LocalDateTime
+import javax.persistence.Entity
+import javax.persistence.Id
+import javax.persistence.Table
+import javax.persistence.Version
+
+@Entity
+@Table(name = "chat_quota")
+class ChatQuota(
+    @Id
+    val memberId: Long,
+    var remainingFree: Int = 10,
+    var remainingPaid: Int = 0,
+    var nextRechargeAt: LocalDateTime? = null,
+    @Version
+    var version: Long? = null
+) {
+    fun total(): Int = remainingFree + remainingPaid
+}

src/main/kotlin/kr/co/vividnext/sodalive/chat/quota/ChatQuotaController.kt

@@ -0,0 +1,65 @@
+package kr.co.vividnext.sodalive.chat.quota
+
+import kr.co.vividnext.sodalive.can.use.CanUsage
+import kr.co.vividnext.sodalive.common.ApiResponse
+import kr.co.vividnext.sodalive.common.SodaException
+import kr.co.vividnext.sodalive.member.Member
+import org.springframework.security.core.annotation.AuthenticationPrincipal
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+@RequestMapping("/api/chat/quota")
+class ChatQuotaController(
+    private val chatQuotaService: ChatQuotaService,
+    private val canPaymentService: kr.co.vividnext.sodalive.can.payment.CanPaymentService
+) {
+
+    data class ChatQuotaStatusResponse(
+        val totalRemaining: Int,
+        val nextRechargeAtEpoch: Long?
+    )
+
+    data class ChatQuotaPurchaseRequest(
+        val container: String,
+        val addPaid: Int = 50,
+        val needCan: Int = 30
+    )
+
+    @GetMapping("/me")
+    fun getMyQuota(
+        @AuthenticationPrincipal(expression = "#this == 'anonymousUser' ? null : member") member: Member?
+    ): ApiResponse<ChatQuotaStatusResponse> = run {
+        if (member == null) throw SodaException("로그인 정보를 확인해주세요.")
+        if (member.auth == null) throw SodaException("본인인증을 하셔야 합니다.")
+
+        val s = chatQuotaService.getStatus(member.id!!)
+        ApiResponse.ok(ChatQuotaStatusResponse(s.totalRemaining, s.nextRechargeAtEpochMillis))
+    }
+
+    @PostMapping("/purchase")
+    fun purchaseQuota(
+        @AuthenticationPrincipal(expression = "#this == 'anonymousUser' ? null : member") member: Member?,
+        @RequestBody request: ChatQuotaPurchaseRequest
+    ): ApiResponse<Boolean> = run {
+        if (member == null) throw SodaException("로그인 정보를 확인해주세요.")
+        if (member.auth == null) throw SodaException("본인인증을 하셔야 합니다.")
+        if (request.container.isBlank()) throw SodaException("container를 확인해주세요.")
+
+        // 30캔 차감 처리 (결제 기록 남김)
+        canPaymentService.spendCan(
+            memberId = member.id!!,
+            needCan = if (request.needCan > 0) request.needCan else 30,
+            canUsage = CanUsage.CHAT_QUOTA_PURCHASE,
+            container = request.container
+        )
+
+        // 유료 횟수 적립 (기본 50)
+        val add = if (request.addPaid > 0) request.addPaid else 50
+        chatQuotaService.purchase(member.id!!, add)
+        ApiResponse.ok(true)
+    }
+}

src/main/kotlin/kr/co/vividnext/sodalive/chat/quota/ChatQuotaRepository.kt

@@ -0,0 +1,15 @@
+package kr.co.vividnext.sodalive.chat.quota
+
+import org.springframework.data.jpa.repository.JpaRepository
+import org.springframework.data.jpa.repository.Lock
+import org.springframework.data.jpa.repository.Query
+import org.springframework.data.repository.query.Param
+import javax.persistence.LockModeType
+
+interface ChatQuotaRepository : JpaRepository<ChatQuota, Long> {
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    @Query("select q from ChatQuota q where q.memberId = :memberId")
+    fun findForUpdate(@Param("memberId") memberId: Long): ChatQuota?
+
+    fun findByMemberId(memberId: Long): ChatQuota?
+}

src/main/kotlin/kr/co/vividnext/sodalive/chat/quota/ChatQuotaService.kt

@@ -0,0 +1,80 @@
+package kr.co.vividnext.sodalive.chat.quota
+
+import kr.co.vividnext.sodalive.common.SodaException
+import org.springframework.stereotype.Service
+import org.springframework.transaction.annotation.Transactional
+import java.time.LocalDateTime
+import java.time.ZoneId
+
+@Service
+class ChatQuotaService(
+    private val repo: ChatQuotaRepository
+) {
+    companion object {
+        private const val FREE_BUCKET = 10
+        private const val RECHARGE_HOURS = 6L
+    }
+
+    data class QuotaStatus(
+        val totalRemaining: Int,
+        val nextRechargeAtEpochMillis: Long?
+    )
+
+    @Transactional
+    fun applyRefillOnEnterAndGetStatus(memberId: Long): QuotaStatus {
+        val now = LocalDateTime.now()
+        val quota = repo.findForUpdate(memberId) ?: repo.save(ChatQuota(memberId = memberId))
+        if (quota.remainingFree == 0 && quota.nextRechargeAt != null && !now.isBefore(quota.nextRechargeAt)) {
+            quota.remainingFree = FREE_BUCKET
+            quota.nextRechargeAt = null
+        }
+        val epoch = quota.nextRechargeAt?.atZone(ZoneId.systemDefault())?.toInstant()?.toEpochMilli()
+        return QuotaStatus(totalRemaining = quota.total(), nextRechargeAtEpochMillis = epoch)
+    }
+
+    @Transactional
+    fun consumeOne(memberId: Long) {
+        val now = LocalDateTime.now()
+        val quota = repo.findForUpdate(memberId) ?: repo.save(ChatQuota(memberId = memberId))
+
+        when {
+            quota.remainingFree > 0 -> {
+                quota.remainingFree -= 1
+                if (quota.remainingFree + quota.remainingPaid == 0 && quota.nextRechargeAt == null) {
+                    quota.nextRechargeAt = now.plusHours(RECHARGE_HOURS)
+                }
+            }
+
+            quota.remainingPaid > 0 -> {
+                quota.remainingPaid -= 1
+                if (quota.remainingFree + quota.remainingPaid == 0 && quota.nextRechargeAt == null) {
+                    quota.nextRechargeAt = now.plusHours(RECHARGE_HOURS)
+                }
+            }
+
+            else -> {
+                if (quota.nextRechargeAt == null) {
+                    quota.nextRechargeAt = now.plusHours(RECHARGE_HOURS)
+                }
+                throw SodaException("채팅 가능 횟수가 모두 소진되었습니다. 다음 무료 충전 이후 이용해주세요.")
+            }
+        }
+    }
+
+    @Transactional(readOnly = true)
+    fun getStatus(memberId: Long): QuotaStatus {
+        val q = repo.findByMemberId(memberId) ?: return QuotaStatus(
+            totalRemaining = FREE_BUCKET,
+            nextRechargeAtEpochMillis = null
+        )
+        val total = q.remainingFree + q.remainingPaid
+        val epoch = q.nextRechargeAt?.atZone(ZoneId.systemDefault())?.toInstant()?.toEpochMilli()
+        return QuotaStatus(totalRemaining = total, nextRechargeAtEpochMillis = epoch)
+    }
+
+    @Transactional
+    fun purchase(memberId: Long, addPaid: Int) {
+        val quota = repo.findForUpdate(memberId) ?: repo.save(ChatQuota(memberId = memberId))
+        quota.remainingPaid += addPaid
+    }
+}

src/main/kotlin/kr/co/vividnext/sodalive/chat/room/dto/ChatRoomDto.kt

@@ -180,5 +180,16 @@ data class ChatRoomEnterResponse(
     val roomId: Long,
     val character: ChatRoomEnterCharacterDto,
     val messages: List<ChatMessageItemDto>,
-    val hasMoreMessages: Boolean
+    val hasMoreMessages: Boolean,
+    val totalRemaining: Int,
+    val nextRechargeAtEpoch: Long?
+)
+
+/**
+ * 채팅 메시지 전송 응답 DTO (메시지 + 쿼터 상태)
+ */
+data class SendChatMessageResponse(
+    val messages: List<ChatMessageItemDto>,
+    val totalRemaining: Int,
+    val nextRechargeAtEpoch: Long?
 )

src/main/kotlin/kr/co/vividnext/sodalive/chat/room/service/ChatRoomService.kt

@@ -19,6 +19,7 @@ import kr.co.vividnext.sodalive.chat.room.dto.CreateChatRoomResponse
 import kr.co.vividnext.sodalive.chat.room.dto.ExternalChatSendResponse
 import kr.co.vividnext.sodalive.chat.room.dto.ExternalChatSessionCreateResponse
 import kr.co.vividnext.sodalive.chat.room.dto.ExternalChatSessionGetResponse
+import kr.co.vividnext.sodalive.chat.room.dto.SendChatMessageResponse
 import kr.co.vividnext.sodalive.chat.room.repository.ChatMessageRepository
 import kr.co.vividnext.sodalive.chat.room.repository.ChatParticipantRepository
 import kr.co.vividnext.sodalive.chat.room.repository.ChatRoomRepository
@@ -49,6 +50,7 @@ class ChatRoomService(
     private val characterImageService: CharacterImageService,
     private val canPaymentService: kr.co.vividnext.sodalive.can.payment.CanPaymentService,
     private val imageCloudFront: kr.co.vividnext.sodalive.aws.cloudfront.ImageContentCloudFront,
+    private val chatQuotaService: kr.co.vividnext.sodalive.chat.quota.ChatQuotaService,
 
     @Value("\${weraser.api-key}")
     private val apiKey: String,
@@ -335,11 +337,16 @@ class ChatRoomService(
         val messagesAsc = fetched.sortedBy { it.createdAt }
         val items = messagesAsc.map { toChatMessageItemDto(it, member) }
 
+        // 입장 시 Lazy refill 적용 후 상태 반환
+        val quotaStatus = chatQuotaService.applyRefillOnEnterAndGetStatus(member.id!!)
+
         return ChatRoomEnterResponse(
             roomId = room.id!!,
             character = characterDto,
             messages = items,
-            hasMoreMessages = hasMore
+            hasMoreMessages = hasMore,
+            totalRemaining = quotaStatus.totalRemaining,
+            nextRechargeAtEpoch = quotaStatus.nextRechargeAtEpochMillis
         )
     }
 
@@ -490,7 +497,7 @@ class ChatRoomService(
     }
 
     @Transactional
-    fun sendMessage(member: Member, chatRoomId: Long, message: String): List<ChatMessageItemDto> {
+    fun sendMessage(member: Member, chatRoomId: Long, message: String): SendChatMessageResponse {
         // 1) 방 존재 확인
         val room = chatRoomRepository.findById(chatRoomId).orElseThrow {
             SodaException("채팅방을 찾을 수 없습니다.")
@@ -512,7 +519,10 @@ class ChatRoomService(
         val sessionId = room.sessionId
         val characterUUID = character.characterUUID
 
-        // 5) 외부 API 호출 (최대 3회 재시도)
+        // 5) 쿼터 확인 및 차감
+        chatQuotaService.consumeOne(member.id!!)
+
+        // 6) 외부 API 호출 (최대 3회 재시도)
         val characterReply = callExternalApiForChatSendWithRetry(userId, characterUUID, message, sessionId)
 
         // 6) 내 메시지 저장
@@ -553,6 +563,8 @@ class ChatRoomService(
             hasAccess = true
         )
 
+        val status = chatQuotaService.getStatus(member.id!!)
+
         // 8) 트리거 매칭 → 이미지 메시지 추가 저장(있을 경우)
         val matchedImage = findTriggeredCharacterImage(character.id!!, characterReply)
         if (matchedImage != null) {
@@ -579,10 +591,18 @@ class ChatRoomService(
             )
 
             val imageDto = toChatMessageItemDto(imageMsg, member)
-            return listOf(textDto, imageDto)
+            return SendChatMessageResponse(
+                messages = listOf(textDto, imageDto),
+                totalRemaining = status.totalRemaining,
+                nextRechargeAtEpoch = status.nextRechargeAtEpochMillis
+            )
         }
 
-        return listOf(textDto)
+        return SendChatMessageResponse(
+            messages = listOf(textDto),
+            totalRemaining = status.totalRemaining,
+            nextRechargeAtEpoch = status.nextRechargeAtEpochMillis
+        )
     }
 
     private fun toChatMessageItemDto(