diff --git a/build.gradle.kts b/build.gradle.kts
index 6a91807..93b18cc 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,6 +1,7 @@
 plugins {
     kotlin("jvm") version "2.2.21"
     kotlin("plugin.spring") version "2.2.21"
+    kotlin("plugin.jpa") version "2.2.21"
     id("org.springframework.boot") version "4.0.2"
     id("io.spring.dependency-management") version "1.1.7"
     id("com.google.devtools.ksp") version "2.3.4" apply false
diff --git a/src/main/kotlin/org/example/ticket/TicketApplication.kt b/src/main/kotlin/org/example/SecondChanceApplication.kt
similarity index 63%
rename from src/main/kotlin/org/example/ticket/TicketApplication.kt
rename to src/main/kotlin/org/example/SecondChanceApplication.kt
index 36c0af1..66be87e 100644
--- a/src/main/kotlin/org/example/ticket/TicketApplication.kt
+++ b/src/main/kotlin/org/example/SecondChanceApplication.kt
@@ -1,11 +1,11 @@
-package org.example.ticket
+package org.example
 
 import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.runApplication
 
 @SpringBootApplication
-class TicketApplication
+class SecondChanceApplication
 
 fun main(args: Array<String>) {
-    runApplication<TicketApplication>(*args)
+    runApplication<SecondChanceApplication>(*args)
 }
diff --git a/src/main/kotlin/org/example/deal/application/dto/DealEndDto.kt b/src/main/kotlin/org/example/deal/application/dto/DealEndDto.kt
new file mode 100644
index 0000000..da02873
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/application/dto/DealEndDto.kt
@@ -0,0 +1,7 @@
+package org.example.deal.application.dto
+
+import org.example.deal.domain.enum.PaymentType
+
+data class DealEndDto(
+    val paymentType: PaymentType
+)
diff --git a/src/main/kotlin/org/example/deal/application/dto/DealResponseDto.kt b/src/main/kotlin/org/example/deal/application/dto/DealResponseDto.kt
new file mode 100644
index 0000000..6e7d294
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/application/dto/DealResponseDto.kt
@@ -0,0 +1,14 @@
+package org.example.deal.application.dto
+
+import org.example.deal.domain.enum.DealStatus
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+data class DealResponseDto(
+    val barcode: String,
+    val sellerName: String,
+    val buyerName: String,
+    val sellingPrice: BigDecimal,
+    val reservedDateTime: LocalDateTime,
+    val dealStatus: DealStatus
+)
diff --git a/src/main/kotlin/org/example/deal/application/dto/DealStartDto.kt b/src/main/kotlin/org/example/deal/application/dto/DealStartDto.kt
new file mode 100644
index 0000000..77dae54
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/application/dto/DealStartDto.kt
@@ -0,0 +1,7 @@
+package org.example.deal.application.dto
+
+data class DealStartDto(
+    val barcode: String,
+    val buyerName: String,
+)
+
diff --git a/src/main/kotlin/org/example/deal/application/service/DealService.kt b/src/main/kotlin/org/example/deal/application/service/DealService.kt
new file mode 100644
index 0000000..d1eaa7b
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/application/service/DealService.kt
@@ -0,0 +1,73 @@
+package org.example.deal.application.service
+
+import jakarta.transaction.Transactional
+import org.example.deal.application.dto.DealEndDto
+import org.example.deal.application.dto.DealResponseDto
+import org.example.deal.application.dto.DealStartDto
+import org.example.deal.domain.model.Deal
+import org.example.deal.infrastructure.api.PaymentGatewayResolver
+import org.example.deal.infrastructure.repository.DealJpaRepository
+import org.example.ticket.infrastructure.repository.TicketJpaRepository
+import org.springframework.stereotype.Service
+
+@Service
+class DealService(
+    private val dealRepository: DealJpaRepository,
+    private val ticketRepository: TicketJpaRepository,
+    private val paymentGatewayResolver: PaymentGatewayResolver
+) {
+    @Transactional
+    fun dealStart(dealStartDto: DealStartDto): DealResponseDto {
+        val ticket = requireNotNull(ticketRepository.findByBarcode(dealStartDto.barcode)) { "존재하지 않는 티켓입니다." }
+        val sellingPrice = requireNotNull(ticket.sellingPrice) { "판매가가 설정되지 않았습니다." }
+
+        val deal = Deal(
+            barcode = ticket.barcode,
+            sellerName = ticket.sellerName,
+            buyerName = dealStartDto.buyerName,
+            sellingPrice = sellingPrice
+        )
+
+        ticket.ticketReserve()
+        val savedDeal = dealRepository.save(deal)
+        return DealResponseDto(
+            barcode = savedDeal.barcode,
+            sellerName = savedDeal.sellerName,
+            buyerName = savedDeal.buyerName,
+            sellingPrice = savedDeal.sellingPrice,
+            reservedDateTime = savedDeal.reservedDateTime,
+            dealStatus = savedDeal.dealStatus
+        )
+    }
+    @Transactional
+    fun dealEnd(barcode:String, dealEndDto: DealEndDto): DealResponseDto {
+        val deal = requireNotNull(dealRepository.findByBarcode(barcode)) { "존재하지 않는 거래입니다." }
+        val ticket = requireNotNull(ticketRepository.findByBarcode(barcode)) { "존재하지 않는 티켓입니다." }
+        val dealExpiredCheck = deal.reservedTimeExpiredCheck()
+        if (dealExpiredCheck) {
+            deal.dealCancel()
+            ticket.ticketOnSale()
+            return DealResponseDto(
+                barcode = deal.barcode,
+                sellerName = deal.sellerName,
+                buyerName = deal.buyerName,
+                sellingPrice = deal.sellingPrice,
+                reservedDateTime = deal.reservedDateTime,
+                dealStatus = deal.dealStatus
+            )
+        }
+        val paymentGateway = paymentGatewayResolver.resolve(dealEndDto.paymentType)
+        paymentGateway.pay(deal.buyerName, deal.sellerName, deal.sellingPrice)
+        deal.dealComplete()
+        ticket.ticketSold()
+        return DealResponseDto(
+            barcode = deal.barcode,
+            sellerName = deal.sellerName,
+            buyerName = deal.buyerName,
+            sellingPrice = deal.sellingPrice,
+            reservedDateTime = deal.reservedDateTime,
+            dealStatus = deal.dealStatus
+        )
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/domain/enum/DealStatus.kt b/src/main/kotlin/org/example/deal/domain/enum/DealStatus.kt
new file mode 100644
index 0000000..3094b42
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/domain/enum/DealStatus.kt
@@ -0,0 +1,7 @@
+package org.example.deal.domain.enum
+
+enum class DealStatus {
+    RESERVED,
+    COMPLETED,
+    CANCELLED,
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/domain/enum/PaymentType.kt b/src/main/kotlin/org/example/deal/domain/enum/PaymentType.kt
new file mode 100644
index 0000000..b9b7c78
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/domain/enum/PaymentType.kt
@@ -0,0 +1,6 @@
+package org.example.deal.domain.enum
+
+enum class PaymentType {
+    KAKAO,
+    TOSS
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/domain/model/Deal.kt b/src/main/kotlin/org/example/deal/domain/model/Deal.kt
new file mode 100644
index 0000000..a1d997d
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/domain/model/Deal.kt
@@ -0,0 +1,46 @@
+package org.example.deal.domain.model
+
+import jakarta.persistence.Entity
+import jakarta.persistence.GeneratedValue
+import jakarta.persistence.GenerationType
+import jakarta.persistence.Id
+import org.example.deal.domain.enum.DealStatus
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+@Entity
+class Deal(
+    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
+    val id: Long? = null,
+    val barcode: String,
+    val sellerName: String,
+    val buyerName: String,
+    val reservedDateTime: LocalDateTime = LocalDateTime.now(),
+    val sellingPrice: BigDecimal,
+) {
+    var dealStatus: DealStatus = DealStatus.RESERVED
+        private set
+
+
+    companion object {}
+
+    init {
+        require(sellerName != buyerName) { "본인이 등록한 티켓은 구매할 수 없습니다." }
+    }
+
+    fun dealComplete() {
+        require(dealStatus == DealStatus.RESERVED) { "예약 상태인 거래만 완료할 수 있습니다." }
+        dealStatus = DealStatus.COMPLETED
+
+    }
+
+    fun dealCancel() {
+        require(dealStatus == DealStatus.RESERVED) { "예약 상태인 거래만 취소 할 수 있습니다." }
+        dealStatus = DealStatus.CANCELLED
+    }
+
+    fun reservedTimeExpiredCheck(): Boolean {
+        return dealStatus == DealStatus.RESERVED && reservedDateTime.plusMinutes(10).isBefore(LocalDateTime.now())
+    }
+
+}
diff --git a/src/main/kotlin/org/example/deal/infrastructure/api/KakaoPaymentGateway.kt b/src/main/kotlin/org/example/deal/infrastructure/api/KakaoPaymentGateway.kt
new file mode 100644
index 0000000..16dd447
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/infrastructure/api/KakaoPaymentGateway.kt
@@ -0,0 +1,23 @@
+package org.example.deal.infrastructure.api
+
+import org.example.deal.domain.enum.PaymentType
+import org.springframework.stereotype.Component
+import org.example.user.infrastructure.repository.UserJpaRepository
+import java.math.BigDecimal
+
+
+@Component
+class KakaoPaymentGateway(
+    private val userJpaRepository: UserJpaRepository
+) : PaymentGateway {
+    override fun pay(buyerName: String, sellerName: String, price: BigDecimal) {
+        val buyer = requireNotNull(userJpaRepository.findByName(buyerName)) { "구매자 정보를 찾을 수 없습니다." }
+        val seller = requireNotNull(userJpaRepository.findByName(sellerName)) { "판매자 정보를 찾을 수 없습니다." }
+        buyer.withdraw(price)
+        seller.deposit(price)
+    }
+
+    override fun type(): PaymentType {
+        return PaymentType.KAKAO
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/infrastructure/api/PaymentGateway.kt b/src/main/kotlin/org/example/deal/infrastructure/api/PaymentGateway.kt
new file mode 100644
index 0000000..1ba2416
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/infrastructure/api/PaymentGateway.kt
@@ -0,0 +1,9 @@
+package org.example.deal.infrastructure.api
+
+import org.example.deal.domain.enum.PaymentType
+import java.math.BigDecimal
+
+interface PaymentGateway {
+    fun pay(buyerName: String, sellerName: String, price: BigDecimal)
+    fun type(): PaymentType
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/infrastructure/api/PaymentGatewayResolver.kt b/src/main/kotlin/org/example/deal/infrastructure/api/PaymentGatewayResolver.kt
new file mode 100644
index 0000000..27488e1
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/infrastructure/api/PaymentGatewayResolver.kt
@@ -0,0 +1,14 @@
+package org.example.deal.infrastructure.api
+
+import org.example.deal.domain.enum.PaymentType
+import org.springframework.stereotype.Component
+
+@Component
+class PaymentGatewayResolver(
+    private val gateways: List<PaymentGateway>
+) {
+    fun resolve(offerPaymentType: PaymentType): PaymentGateway {
+        val paymentType = gateways.find { it.type() == offerPaymentType }
+        return paymentType ?: throw IllegalArgumentException("지원하지 않는 결제 수단입니다.")
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/infrastructure/api/TossPaymentGateway.kt b/src/main/kotlin/org/example/deal/infrastructure/api/TossPaymentGateway.kt
new file mode 100644
index 0000000..2037425
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/infrastructure/api/TossPaymentGateway.kt
@@ -0,0 +1,22 @@
+package org.example.deal.infrastructure.api
+
+import org.example.deal.domain.enum.PaymentType
+import org.example.user.infrastructure.repository.UserJpaRepository
+import org.springframework.stereotype.Component
+import java.math.BigDecimal
+
+@Component
+class TossPaymentGateway(
+    private val userJpaRepository: UserJpaRepository
+) : PaymentGateway {
+    override fun pay(buyerName: String, sellerName: String, price: BigDecimal) {
+        val buyer = requireNotNull(userJpaRepository.findByName(buyerName)) { "구매자 정보를 찾을 수 없습니다." }
+        val seller = requireNotNull(userJpaRepository.findByName(sellerName)) { "판매자 정보를 찾을 수 없습니다." }
+        buyer.withdraw(price)
+        seller.deposit(price)
+    }
+
+    override fun type(): PaymentType {
+        return PaymentType.TOSS
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/deal/infrastructure/repository/DealJpaRepository.kt b/src/main/kotlin/org/example/deal/infrastructure/repository/DealJpaRepository.kt
new file mode 100644
index 0000000..427d6e0
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/infrastructure/repository/DealJpaRepository.kt
@@ -0,0 +1,9 @@
+package org.example.deal.infrastructure.repository
+
+import org.example.deal.domain.model.Deal
+import org.springframework.data.jpa.repository.JpaRepository
+
+interface DealJpaRepository : JpaRepository<Deal, Long> {
+    fun findByBarcode(barcode: String): Deal?
+    fun findBySellerName(sellerName: String): Deal?
+}
diff --git a/src/main/kotlin/org/example/deal/presentation/controller/DealController.kt b/src/main/kotlin/org/example/deal/presentation/controller/DealController.kt
new file mode 100644
index 0000000..2f35686
--- /dev/null
+++ b/src/main/kotlin/org/example/deal/presentation/controller/DealController.kt
@@ -0,0 +1,31 @@
+package org.example.deal.presentation.controller
+
+import org.example.deal.application.dto.DealEndDto
+import org.example.deal.application.dto.DealResponseDto
+import org.example.deal.application.dto.DealStartDto
+import org.example.deal.application.service.DealService
+import org.springframework.web.bind.annotation.PatchMapping
+import org.springframework.web.bind.annotation.PathVariable
+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(value = ["/deals"])
+class DealController(
+    private val dealService: DealService
+) {
+    @PostMapping("")
+    fun dealStart(@RequestBody dealStartDto: DealStartDto): DealResponseDto {
+        return dealService.dealStart(dealStartDto)
+    }
+
+    @PatchMapping("/{barcode}")
+    fun dealEnd(
+        @PathVariable("barcode") barcode: String,
+        @RequestBody dealEndDto: DealEndDto
+    ): DealResponseDto {
+        return dealService.dealEnd(barcode, dealEndDto)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/error/controller/ErrorResponse.kt b/src/main/kotlin/org/example/error/controller/ErrorResponse.kt
new file mode 100644
index 0000000..6da70fe
--- /dev/null
+++ b/src/main/kotlin/org/example/error/controller/ErrorResponse.kt
@@ -0,0 +1,6 @@
+package org.example.error.controller
+
+data class ErrorResponse(
+    val message: String,
+    val status: Int
+)
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/error/controller/GlobalExceptionHandler.kt b/src/main/kotlin/org/example/error/controller/GlobalExceptionHandler.kt
new file mode 100644
index 0000000..d0a23b9
--- /dev/null
+++ b/src/main/kotlin/org/example/error/controller/GlobalExceptionHandler.kt
@@ -0,0 +1,19 @@
+package org.example.error.controller
+
+import org.springframework.http.HttpStatus
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.ExceptionHandler
+import org.springframework.web.bind.annotation.RestControllerAdvice
+
+@RestControllerAdvice
+class GlobalExceptionHandler {
+
+    @ExceptionHandler(IllegalArgumentException::class)
+    fun handleIllegalArgument(e: IllegalArgumentException): ResponseEntity<ErrorResponse> {
+        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(
+                ErrorResponse(
+                    message = e.message ?: "잘못된 요청입니다.", status = 400
+                )
+            )
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/application/dto/TicketCreationDto.kt b/src/main/kotlin/org/example/ticket/application/dto/TicketCreationDto.kt
index 29339a3..34114ba 100644
--- a/src/main/kotlin/org/example/ticket/application/dto/TicketCreationDto.kt
+++ b/src/main/kotlin/org/example/ticket/application/dto/TicketCreationDto.kt
@@ -1,5 +1,6 @@
 package org.example.ticket.application.dto
 
 data class TicketCreationDto(
-    val varCode: String
+    val sellerName: String,
+    val barcode: String
 )
diff --git a/src/main/kotlin/org/example/ticket/application/dto/TicketResponseDto.kt b/src/main/kotlin/org/example/ticket/application/dto/TicketResponseDto.kt
new file mode 100644
index 0000000..c6b4aa3
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/application/dto/TicketResponseDto.kt
@@ -0,0 +1,14 @@
+package org.example.ticket.application.dto
+
+import org.example.ticket.domain.enum.TicketStatus
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+data class TicketResponseDto(
+    val barcode: String,
+    val seller: String,
+    val originalPrice: BigDecimal,
+    val sellingPrice: BigDecimal?,
+    val expirationDate: LocalDateTime,
+    val ticketStatus: TicketStatus
+)
diff --git a/src/main/kotlin/org/example/ticket/application/dto/TicketSellingPriceOfferDto.kt b/src/main/kotlin/org/example/ticket/application/dto/TicketSellingPriceOfferDto.kt
new file mode 100644
index 0000000..e8e83a8
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/application/dto/TicketSellingPriceOfferDto.kt
@@ -0,0 +1,8 @@
+package org.example.ticket.application.dto
+
+import java.math.BigDecimal
+
+data class TicketSellingPriceOfferDto(
+    val sellerName: String,
+    val sellingPrice: BigDecimal,
+)
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/application/service/TicketService.kt b/src/main/kotlin/org/example/ticket/application/service/TicketService.kt
index 1e731a3..413ada1 100644
--- a/src/main/kotlin/org/example/ticket/application/service/TicketService.kt
+++ b/src/main/kotlin/org/example/ticket/application/service/TicketService.kt
@@ -1,27 +1,55 @@
 package org.example.ticket.application.service
 
+import jakarta.transaction.Transactional
 import org.example.ticket.application.dto.TicketCreationDto
-import org.example.ticket.domain.model.Ticket
-import org.example.ticket.infra.api.TicketApiClient
-import org.example.ticket.infra.repository.TicketJpaRepository
+import org.example.ticket.application.dto.TicketResponseDto
+import org.example.ticket.application.dto.TicketSellingPriceOfferDto
+import org.example.ticket.infrastructure.repository.TicketJpaRepository
+import org.example.ticket.infrastructure.api.TicketApiClientResolver
 import org.springframework.stereotype.Service
 
 @Service
 class TicketService(
-    private val ticketApiClient: List<TicketApiClient>,
+    private val ticketApiClientResolver: TicketApiClientResolver,
     private val ticketRepository: TicketJpaRepository
 ) {
-    fun createTicket(ticketCreationDto: TicketCreationDto) {
-        val ticketType = Ticket.ticketType(ticketCreationDto.varCode)
-        val apiClient = ticketApiClient.first { it.type(ticketCreationDto.varCode) == ticketType }
-
-        val ticketResponseDto = apiClient.getTicket(ticketCreationDto.varCode)
-        val ticket = ticketResponseDto.toTicket()
-
-        ticketRepository.save(ticket)
+    @Transactional
+    fun createTicket(ticketCreationDto: TicketCreationDto): TicketResponseDto {
+        val apiClient = ticketApiClientResolver.resolve(ticketCreationDto.barcode)
+        val ticketResponseDto = apiClient.getTicket(ticketCreationDto.barcode)
+        val ticket = ticketRepository.save(
+            ticketResponseDto.toTicket(
+                ticketCreationDto.barcode,
+                ticketCreationDto.sellerName,
+                apiClient.type(),
+            )
+        )
+        return TicketResponseDto(
+            barcode = ticket.barcode,
+            seller = ticket.sellerName,
+            originalPrice = ticket.originalPrice,
+            sellingPrice = ticket.sellingPrice,
+            expirationDate = ticket.expirationDateTime,
+            ticketStatus = ticket.ticketStatus,
+        )
     }
-
-    fun applySellerOfferPrice() {
-        // TODO : 구현
+    @Transactional
+    fun applySellerOfferPrice(barcode: String, ticketSellingPriceOfferDto: TicketSellingPriceOfferDto): TicketResponseDto {
+        val ticket = requireNotNull(ticketRepository.findByBarcode(barcode)){
+            "해당 티켓 정보가 존재하지 않습니다."
+        }
+        ticket.applySellerOfferPrice(
+            ticketSellingPriceOfferDto.sellerName,
+            ticketSellingPriceOfferDto.sellingPrice
+        )
+        return TicketResponseDto(
+            barcode = ticket.barcode,
+            seller = ticket.sellerName,
+            originalPrice = ticket.originalPrice,
+            sellingPrice = ticket.sellingPrice,
+            expirationDate = ticket.expirationDateTime,
+            ticketStatus = ticket.ticketStatus,
+        )
     }
-}
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/domain/enumeration/TicketStatus.kt b/src/main/kotlin/org/example/ticket/domain/enum/TicketStatus.kt
similarity index 62%
rename from src/main/kotlin/org/example/ticket/domain/enumeration/TicketStatus.kt
rename to src/main/kotlin/org/example/ticket/domain/enum/TicketStatus.kt
index 2e6260c..715cb8f 100644
--- a/src/main/kotlin/org/example/ticket/domain/enumeration/TicketStatus.kt
+++ b/src/main/kotlin/org/example/ticket/domain/enum/TicketStatus.kt
@@ -1,4 +1,4 @@
-package org.example.ticket.domain.enumeration
+package org.example.ticket.domain.enum
 
 enum class TicketStatus {
     ON_SALE,
diff --git a/src/main/kotlin/org/example/ticket/domain/enum/TicketType.kt b/src/main/kotlin/org/example/ticket/domain/enum/TicketType.kt
new file mode 100644
index 0000000..a44ee3a
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/domain/enum/TicketType.kt
@@ -0,0 +1,7 @@
+package org.example.ticket.domain.enum
+
+enum class TicketType {
+    MELON,
+    NOL,
+    MOL
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/domain/enumeration/TicketType.kt b/src/main/kotlin/org/example/ticket/domain/enumeration/TicketType.kt
deleted file mode 100644
index ad89680..0000000
--- a/src/main/kotlin/org/example/ticket/domain/enumeration/TicketType.kt
+++ /dev/null
@@ -1,6 +0,0 @@
-package org.example.ticket.domain.enumeration
-
-enum class TicketType {
-    NOL,
-    MELON
-}
diff --git a/src/main/kotlin/org/example/ticket/domain/model/Ticket.kt b/src/main/kotlin/org/example/ticket/domain/model/Ticket.kt
index de898a3..230fe6d 100644
--- a/src/main/kotlin/org/example/ticket/domain/model/Ticket.kt
+++ b/src/main/kotlin/org/example/ticket/domain/model/Ticket.kt
@@ -1,43 +1,92 @@
 package org.example.ticket.domain.model
 
-import org.example.ticket.domain.enumeration.TicketStatus
-import org.example.ticket.domain.enumeration.TicketType
+import jakarta.persistence.Entity
+import jakarta.persistence.GeneratedValue
+import jakarta.persistence.GenerationType
+import jakarta.persistence.Id
+import org.example.ticket.domain.enum.TicketStatus
+import org.example.ticket.domain.enum.TicketType
 import java.math.BigDecimal
 import java.time.LocalDateTime
 
+@Entity
 class Ticket(
-    val id: Long? = null,
-    val expirationAt: LocalDateTime,
-    val originalPrice: BigDecimal,
-    private var sellingPrice: BigDecimal? = null,
-    val ticketStatus: TicketStatus = TicketStatus.ON_SALE,
+    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
+    val id: Long? = null, // ? => DB에 넘기기전에 id를 안넣으려고 (자동생성)
+    val barcode: String,
+    val expirationDateTime: LocalDateTime,
+    val originalPrice: BigDecimal, // BigDecimal => 10진수로 저장(소수점 계산을 위해)
+    val sellerName: String,
+    val ticketType: TicketType
 ) {
+    var sellingPrice: BigDecimal? = null
+        private set
+    var ticketStatus: TicketStatus = TicketStatus.ON_SALE
+        private set
+
     companion object {
-        val ACTIVATION_DEAD_LINE: LocalDateTime = LocalDateTime.now().plusHours(3L)
-        private val HALF = BigDecimal("0.5")
-
-        fun ticketType(varCode: String): TicketType {
-            return if (varCode.contains("MELON")) {
-                TicketType.MELON
-            } else {
-                TicketType.NOL
-            }
-        }
+        private val BARCODE_LENGTH = 8;
+        private val PERFORMANCE_DAY_SALE_POLICY = BigDecimal("0.5")
+
     }
 
     init {
-        require(expirationAt.isAfter(ACTIVATION_DEAD_LINE)) { "ticket cannot be registered after expiration" }
+        require(barcode.length == BARCODE_LENGTH) { "바코드는 8자리여야 합니다." }
+        ticketTimeCheck()
+    }
+
+    private fun getTicketDeadLine(): LocalDateTime {
+        return expirationDateTime.minusHours(1)
     }
 
-    fun applySellerOfferPrice(offerPrice: BigDecimal) {
-        val isPerformanceDay = LocalDateTime.now().toLocalDate() == expirationAt.toLocalDate()
-        if (isPerformanceDay) {
-            val maxAllowedPrice = originalPrice.multiply(HALF)
-            require(offerPrice <= maxAllowedPrice) {
-                "on performance day, selling price must be <= 50% of regular price"
-            }
+    private fun ticketTimeCheck() {
+        val now = LocalDateTime.now()
+        val deadLine = getTicketDeadLine()
+        require(now.isBefore(deadLine)) {
+            "공연 시작 1시간 전까지만 등록할 수 있습니다."
         }
+    }
+
+    fun applySellerOfferPrice(offerSellerName: String, offerPrice: BigDecimal) {
+        require(sellerName == offerSellerName) { "티켓에 등록된 판매자가 아닙니다." }
+        require(offerPrice >= BigDecimal.ZERO) { "판매가격에 음수는 입력할 수 없습니다." }
+        require(offerPrice <= originalPrice) { "티켓의 가격은 정가를 초과할 수 없습니다." }
+        if (ticketStatus != TicketStatus.SOLD && LocalDateTime.now().isAfter(getTicketDeadLine())) {
+            ticketExpired()
+        }
+        require(ticketStatus == TicketStatus.ON_SALE) { "판매중인 제품만 가격을 수정할 수 있습니다." }
+        val isPerformanceDateTime = LocalDateTime.now().toLocalDate() == expirationDateTime.toLocalDate()
+        if (isPerformanceDateTime) {
+            val maxAllowedPrice = originalPrice.multiply(PERFORMANCE_DAY_SALE_POLICY)
+            require(offerPrice <= maxAllowedPrice) { "공연 당일에는 가격을 정가의 50% 이하로만 설정할 수 있습니다." }
+        }
+        sellingPrice = offerPrice
+    }
 
-        this.sellingPrice = offerPrice
+
+    fun ticketOnSale() {
+        require(ticketStatus == TicketStatus.RESERVED) { "예약중인 티켓만 판매중으로 되돌릴 수 있습니다." }
+        ticketStatus = TicketStatus.ON_SALE
+    }
+
+    fun ticketReserve() {
+        require(ticketStatus == TicketStatus.ON_SALE) { "판매중인 티켓만 예약할 수 있습니다" }
+        ticketStatus = TicketStatus.RESERVED
+    }
+
+    fun ticketSold() {
+        require(ticketStatus == TicketStatus.RESERVED) { "예약중인 티켓만 판매완료할 수 있습니다." }
+        ticketStatus = TicketStatus.SOLD
+    }
+
+    fun ticketExpired() {
+        require(ticketStatus != TicketStatus.SOLD) { "판매완료된 티켓은 만료할 수 없습니다." }
+        val now = LocalDateTime.now()
+        val deadLine = getTicketDeadLine()
+        require(now.isAfter(deadLine)) { "만료되지 않은 티켓입니다." }
+        ticketStatus = TicketStatus.EXPIRED
     }
 }
+
+
+
diff --git a/src/main/kotlin/org/example/ticket/infra/api/MelonTicketApiClient.kt b/src/main/kotlin/org/example/ticket/infra/api/MelonTicketApiClient.kt
deleted file mode 100644
index 6737a08..0000000
--- a/src/main/kotlin/org/example/ticket/infra/api/MelonTicketApiClient.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-package org.example.ticket.infra.api
-
-import org.example.ticket.domain.enumeration.TicketType
-import org.example.ticket.infra.dto.TicketApiResponseDto
-import org.springframework.stereotype.Component
-import java.math.BigDecimal
-import java.time.LocalDateTime
-
-@Component
-class MelonTicketApiClient : TicketApiClient {
-    override fun getTicket(varCode: String): TicketApiResponseDto {
-        return TicketApiResponseDto(
-            LocalDateTime.now().plusDays(20), BigDecimal.valueOf(10000)
-        )
-    }
-
-    override fun type(varCode: String): TicketType {
-        return TicketType.MELON
-    }
-}
diff --git a/src/main/kotlin/org/example/ticket/infra/api/NolTicketClient.kt b/src/main/kotlin/org/example/ticket/infra/api/NolTicketClient.kt
deleted file mode 100644
index 0b289cc..0000000
--- a/src/main/kotlin/org/example/ticket/infra/api/NolTicketClient.kt
+++ /dev/null
@@ -1,18 +0,0 @@
-package org.example.ticket.infra.api
-
-import org.example.ticket.domain.enumeration.TicketType
-import org.example.ticket.infra.dto.TicketApiResponseDto
-import org.springframework.stereotype.Component
-import java.math.BigDecimal
-import java.time.LocalDateTime
-
-@Component
-class NolTicketClient : TicketApiClient {
-    override fun getTicket(varCode: String): TicketApiResponseDto {
-        return TicketApiResponseDto(LocalDateTime.now().plusDays(10), BigDecimal.valueOf(20000))
-    }
-
-    override fun type(varCode: String): TicketType {
-        return TicketType.NOL
-    }
-}
diff --git a/src/main/kotlin/org/example/ticket/infra/api/TicketApiClient.kt b/src/main/kotlin/org/example/ticket/infra/api/TicketApiClient.kt
deleted file mode 100644
index 3e8e3c4..0000000
--- a/src/main/kotlin/org/example/ticket/infra/api/TicketApiClient.kt
+++ /dev/null
@@ -1,9 +0,0 @@
-package org.example.ticket.infra.api
-
-import org.example.ticket.domain.enumeration.TicketType
-import org.example.ticket.infra.dto.TicketApiResponseDto
-
-interface TicketApiClient {
-    fun getTicket(varCode: String) : TicketApiResponseDto
-    fun type(varCode: String) : TicketType
-}
diff --git a/src/main/kotlin/org/example/ticket/infra/dto/TicketApiResponseDto.kt b/src/main/kotlin/org/example/ticket/infra/dto/TicketApiResponseDto.kt
deleted file mode 100644
index 855c1af..0000000
--- a/src/main/kotlin/org/example/ticket/infra/dto/TicketApiResponseDto.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-package org.example.ticket.infra.dto
-
-import org.example.ticket.domain.model.Ticket
-import java.math.BigDecimal
-import java.time.LocalDateTime
-
-data class TicketApiResponseDto(
-    val performanceDate: LocalDateTime,
-    val price: BigDecimal
-) {
-    fun toTicket(): Ticket {
-        return Ticket(
-            expirationAt = performanceDate,
-            originalPrice = price,
-        )
-    }
-}
diff --git a/src/main/kotlin/org/example/ticket/infra/repository/TicketJpaRepository.kt b/src/main/kotlin/org/example/ticket/infra/repository/TicketJpaRepository.kt
deleted file mode 100644
index 235c684..0000000
--- a/src/main/kotlin/org/example/ticket/infra/repository/TicketJpaRepository.kt
+++ /dev/null
@@ -1,7 +0,0 @@
-package org.example.ticket.infra.repository
-
-import org.example.ticket.domain.model.Ticket
-import org.springframework.data.jpa.repository.JpaRepository
-
-interface TicketJpaRepository: JpaRepository<Ticket, Long> {
-}
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/api/MelonTicketApiClient.kt b/src/main/kotlin/org/example/ticket/infrastructure/api/MelonTicketApiClient.kt
new file mode 100644
index 0000000..b857f42
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/api/MelonTicketApiClient.kt
@@ -0,0 +1,22 @@
+package org.example.ticket.infrastructure.api
+
+import org.example.ticket.domain.enum.TicketType
+import org.example.ticket.infrastructure.dto.TicketApiResponseDto
+import org.springframework.stereotype.Component
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+@Component
+class MelonTicketApiClient : TicketApiClient {
+    override fun getTicket(barcode: String): TicketApiResponseDto {
+        return TicketApiResponseDto(
+
+            performanceDateTime = LocalDateTime.now().plusDays(3),
+            price = BigDecimal.valueOf(10000)
+        )
+    }
+
+    override fun type(): TicketType {
+        return TicketType.MELON
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/api/MolTicketApiClient.kt b/src/main/kotlin/org/example/ticket/infrastructure/api/MolTicketApiClient.kt
new file mode 100644
index 0000000..57b0238
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/api/MolTicketApiClient.kt
@@ -0,0 +1,21 @@
+package org.example.ticket.infrastructure.api
+
+import org.example.ticket.domain.enum.TicketType
+import org.example.ticket.infrastructure.dto.TicketApiResponseDto
+import org.springframework.stereotype.Component
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+@Component
+class MolTicketApiClient : TicketApiClient {
+    override fun getTicket(barcode: String): TicketApiResponseDto {
+        return TicketApiResponseDto(
+            performanceDateTime = LocalDateTime.now().plusDays(5),
+            price = BigDecimal.valueOf(30000)
+        )
+    }
+
+    override fun type(): TicketType {
+        return TicketType.MOL
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/api/NolTicketApiClient.kt b/src/main/kotlin/org/example/ticket/infrastructure/api/NolTicketApiClient.kt
new file mode 100644
index 0000000..050f582
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/api/NolTicketApiClient.kt
@@ -0,0 +1,21 @@
+package org.example.ticket.infrastructure.api
+
+import org.example.ticket.domain.enum.TicketType
+import org.example.ticket.infrastructure.dto.TicketApiResponseDto
+import org.springframework.stereotype.Component
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+@Component
+class NolTicketApiClient : TicketApiClient {
+    override fun getTicket(barcode: String): TicketApiResponseDto {
+        return TicketApiResponseDto(
+            performanceDateTime = LocalDateTime.now().plusDays(5),
+            price = BigDecimal.valueOf(20000)
+        )
+    }
+
+    override fun type(): TicketType {
+        return TicketType.NOL
+    }
+}
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/api/TicketApiClient.kt b/src/main/kotlin/org/example/ticket/infrastructure/api/TicketApiClient.kt
new file mode 100644
index 0000000..0992793
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/api/TicketApiClient.kt
@@ -0,0 +1,10 @@
+package org.example.ticket.infrastructure.api
+
+import org.example.ticket.domain.enum.TicketType
+import org.example.ticket.infrastructure.dto.TicketApiResponseDto
+
+interface TicketApiClient {
+    fun getTicket(barcode: String): TicketApiResponseDto
+    fun type(): TicketType
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/api/TicketApiClientResolver.kt b/src/main/kotlin/org/example/ticket/infrastructure/api/TicketApiClientResolver.kt
new file mode 100644
index 0000000..86c116c
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/api/TicketApiClientResolver.kt
@@ -0,0 +1,22 @@
+package org.example.ticket.infrastructure.api
+
+import org.example.ticket.domain.enum.TicketType
+import org.springframework.stereotype.Component
+
+@Component
+class TicketApiClientResolver(
+    private val ticketApiClients: List<TicketApiClient>
+) {
+    fun resolve(barcode: String): TicketApiClient {
+        val ticketType = resolveTicketType(barcode)
+        return ticketApiClients.first { it.type() == ticketType }
+    }
+
+    private fun resolveTicketType(barcode: String): TicketType {
+        return when {
+            barcode.all { it.isLetter() } -> TicketType.MELON
+            barcode.all { it.isDigit() } -> TicketType.NOL
+            else -> TicketType.MOL
+        }
+    }
+}
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/dto/TicketApiResponseDto.kt b/src/main/kotlin/org/example/ticket/infrastructure/dto/TicketApiResponseDto.kt
new file mode 100644
index 0000000..b2a1b61
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/dto/TicketApiResponseDto.kt
@@ -0,0 +1,22 @@
+package org.example.ticket.infrastructure.dto
+
+import org.example.ticket.domain.enum.TicketType
+import org.example.ticket.domain.model.Ticket
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+data class TicketApiResponseDto(
+    val performanceDateTime: LocalDateTime,
+    val price: BigDecimal
+) {
+    fun toTicket(barcode: String, sellerId: String, ticketType: TicketType): Ticket {
+        return Ticket(
+            barcode = barcode,
+            ticketType = ticketType,
+            sellerName = sellerId,
+            expirationDateTime = performanceDateTime,
+            originalPrice = price
+        )
+    }
+}
+
diff --git a/src/main/kotlin/org/example/ticket/infrastructure/repository/TicketJpaRepository.kt b/src/main/kotlin/org/example/ticket/infrastructure/repository/TicketJpaRepository.kt
new file mode 100644
index 0000000..77a14d8
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/infrastructure/repository/TicketJpaRepository.kt
@@ -0,0 +1,123 @@
+package org.example.ticket.infrastructure.repository
+
+import org.example.ticket.domain.model.Ticket
+import org.springframework.data.jpa.repository.JpaRepository
+
+interface TicketJpaRepository : JpaRepository<Ticket, Long> {
+    fun findByBarcode(barcode: String): Ticket? // ? 넣어야 null 처리되서 조회 안될때 에러가 안남
+}
+
+/* JPA 동작 방식
+     스프링이 JPA 의존성을 보고 어떻게 이 라이브러리코드가 동작하도록 끌어오는가?
+     1. 의존성에 JPA가 존재하는걸 확인
+     2. JpaRepository 상속한 인터페이스를 찾음
+     3. 런타임 메모리에 CRUD 메서드가 선언된 클래스 자동 생성
+     4. 생성된 클래스 자바빈 등록
+     5. JpaRepository를 상속받은 클래스(작성한 클래스)를 통해 CRUD가능
+*/
+
+/* 이해 안가던 점
+    1. Repository를 CrudRepository가 확장
+    2. CrudRepository를 ListCrudRepository가 확장
+    3. JpaRepository가 ListCrudRepository를 확장
+
+    A : JpaRepository -> TicketJpaRepository
+    B : JpaRepository -> JpaRepositoryImplementation -> SimpleJpaRepository
+
+    SimpleRepository(라이브러리)/TicketJpaRepository(내구현)
+
+    1. TicketJpaRepository.save를 타고올라가면 CrudRepository.save가 나옴
+    2. CrudRepository.save를 구현한건 SimpleJpaRepository임
+    3. ? 그런데 우리가 쓰는건 TicketJpaRepository인데 SimpleJpaRepository.save가 어떻게 연결되지?
+       (TicketJpaRepository.save는 선언안했는데?)
+
+    => 스프링이 프록시를 자동 생성해주기 때문
+        최상위 부터 동작을 추적하면
+
+        1. Spring Boot Auto Configuration
+        => "JPA 의존성 있네? @EnableJpaRepositories 자동 활성화"
+
+        2. JpaRepositoriesRegistrar
+        => "JpaRepository 상속한 인터페이스 스캔해" → TicketJpaRepository 발견
+
+        3. JpaRepositoryFactoryBean (인터페이스당 하나 생성)
+        => "TicketJpaRepository를 처리할 팩토리 만들자"
+
+        4. JpaRepositoryFactory
+        => SimpleJpaRepository 생성
+        => 프록시로 감싸기
+        => Bean 등록
+
+      => 결론 : TicketJpaRepository.save가 SimpleJpaRepository.save로 호출되는건 단순하게 스프링 내부 동작임
+        SimpleJpaRepository에 보면 라고 선언되어 있는데
+        * Default implementation of the {@link org.springframework.data.repository.CrudRepository} interface. This will offer
+        * you a more sophisticated interface than the plain {@link EntityManager} .
+        이렇게 SimpleJpaRepository에가 CrudRepository의 기본 구현체라고 기입되어 있는데,
+        => 프록시가 자동으로 연결해준단 말임
+        => extends(확장/상속)가 아니라 delegation(위임)하는 형태
+        => 이해하기 어려운 부분은 작성하는 코드에 보이는게 아니라 런타임 구현체를 스프링이 생성한다고 보는것
+        => 본인 코드만 보면 이 동작을 절대 알 수 없음 => Spring Doc를 읽읍시다
+
+*/
+
+
+/*
+JPA 내부동작
+JPA의 핵심은 "객체와 DB 테이블을 매핑해서, SQL을 직접 안 짜고 객체로 DB를 다루게 해주는 것"
+TicketJpaRepository → JpaRepository → ListCrudRepository → CrudRepository
+전부 인터페이스 → 껍데기만 있음 → save()의 실제 코드가 없음
+Spring이 해주는 건 이 껍데기에 SimpleJpaRepository라는 구현체를 연결해주는 것입니다.
+  1. 매핑 (앱 시작 시)
+  Ticket 클래스를 분석 (리플렉션)
+    → @Entity 확인 → "이건 DB 테이블이구나"
+    → 클래스명 Ticket → 테이블명 ticket
+    → 필드 barcode: String → 컬럼 barcode VARCHAR
+    → 필드 originalPrice: BigDecimal → 컬럼 original_price DECIMAL
+    → 필드 id: Long + @Id → Primary Key
+
+  결과: 객체 ↔ 테이블 매핑 정보를 메모리에 보관
+
+  2. 영속성 컨텍스트 (핵심)
+
+  JPA는 객체와 DB 사이에 중간 저장소를 둡니다:
+
+  우리 코드 ↔ 영속성 컨텍스트(메모리) ↔ DB
+
+  모든 동작이 이 영속성 컨텍스트를 거칩니다:
+
+  save(ticket)    → 영속성 컨텍스트에 등록 → 커밋 시 INSERT
+  findById(1L)    → 영속성 컨텍스트에 있으면 그거 반환 (DB 안 감)
+                  → 없으면 DB 조회 → 영속성 컨텍스트에 저장 → 반환
+  delete(ticket)  → 영속성 컨텍스트에서 삭제 표시 → 커밋 시 DELETE
+
+  3. 변경 감지 (Dirty Checking)
+
+  이게 JPA의 가장 강력한 기능입니다:
+
+  val ticket = ticketRepository.findById(1L)  // DB에서 조회
+  ticket.ticketStatus = TicketStatus.SOLD     // 필드만 바꿈
+  // save() 안 해도 됨!
+  // 트랜잭션 커밋 시 JPA가 "어? 값이 바뀌었네" → UPDATE 자동 실행
+
+  조회 시: 원본 스냅샷을 저장해둠      {status: ON_SALE}
+  커밋 시: 현재 상태와 스냅샷 비교     {status: SOLD} vs {status: ON_SALE}
+           → "status 바뀌었네" → UPDATE ticket SET status = 'SOLD' WHERE id = 1
+
+  4. 전체 흐름 정리
+
+  트랜잭션 시작
+    ↓
+  조회/저장/수정/삭제 → 전부 영속성 컨텍스트에서 처리
+    ↓
+  트랜잭션 커밋
+    ↓
+  영속성 컨텍스트와 DB의 차이를 비교
+    ↓
+  필요한 SQL만 생성해서 DB에 실행 (INSERT, UPDATE, DELETE)
+    ↓
+  영속성 컨텍스트 초기화
+
+  결국 JPA는 **"DB를 직접 건드리지 말고, 객체만 다뤄. 나머지는 내가 알아서 SQL로 바꿔줄게"**가 전부입니다.
+  영속성 컨텍스트가 그 중간다리 역할을 하는 거고요.
+
+ */
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/ticket/presentation/TicketController.kt b/src/main/kotlin/org/example/ticket/presentation/TicketController.kt
deleted file mode 100644
index 4dff4a0..0000000
--- a/src/main/kotlin/org/example/ticket/presentation/TicketController.kt
+++ /dev/null
@@ -1,19 +0,0 @@
-package org.example.ticket.presentation
-
-import org.example.ticket.application.dto.TicketCreationDto
-import org.example.ticket.application.service.TicketService
-import org.springframework.web.bind.annotation.PostMapping
-import org.springframework.web.bind.annotation.RequestBody
-import org.springframework.web.bind.annotation.RestController
-
-@RestController
-class TicketController(
-    private val ticketService: TicketService
-) {
-    @PostMapping("/tickets")
-    fun registerTicket(
-        @RequestBody ticketCreationDto: TicketCreationDto
-    ) {
-        ticketService.createTicket(ticketCreationDto)
-    }
-}
diff --git a/src/main/kotlin/org/example/ticket/presentation/controller/TicketController.kt b/src/main/kotlin/org/example/ticket/presentation/controller/TicketController.kt
new file mode 100644
index 0000000..c1d3104
--- /dev/null
+++ b/src/main/kotlin/org/example/ticket/presentation/controller/TicketController.kt
@@ -0,0 +1,31 @@
+package org.example.ticket.presentation.controller
+
+import org.example.ticket.application.dto.TicketCreationDto
+import org.example.ticket.application.dto.TicketResponseDto
+import org.example.ticket.application.dto.TicketSellingPriceOfferDto
+import org.example.ticket.application.service.TicketService
+import org.springframework.web.bind.annotation.PatchMapping
+import org.springframework.web.bind.annotation.PathVariable
+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("/tickets")
+class TicketController(
+    private val ticketService: TicketService
+) {
+    @PostMapping("")
+    fun createTicket(@RequestBody requestDto: TicketCreationDto): TicketResponseDto {
+        return ticketService.createTicket(requestDto)
+    }
+
+    @PatchMapping("/{barcode}/price")
+    fun applySellerOfferPrice(
+        @PathVariable("barcode") barcode: String,
+        @RequestBody dto: TicketSellingPriceOfferDto
+    ): TicketResponseDto {
+        return ticketService.applySellerOfferPrice(barcode, dto)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/user/domain/enum/UserRole.kt b/src/main/kotlin/org/example/user/domain/enum/UserRole.kt
new file mode 100644
index 0000000..e97da0e
--- /dev/null
+++ b/src/main/kotlin/org/example/user/domain/enum/UserRole.kt
@@ -0,0 +1,6 @@
+package org.example.user.domain.enum
+
+enum class UserRole {
+    SELLER,
+    BUYER,
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/user/domain/model/User.kt b/src/main/kotlin/org/example/user/domain/model/User.kt
new file mode 100644
index 0000000..13604b2
--- /dev/null
+++ b/src/main/kotlin/org/example/user/domain/model/User.kt
@@ -0,0 +1,26 @@
+package org.example.user.domain.model
+
+
+import org.example.user.domain.enum.UserRole
+import java.math.BigDecimal
+
+class User(
+    val id: Long? = null,
+    val name: String,
+    val role: UserRole,
+    var money: BigDecimal = BigDecimal.ZERO
+) {
+    fun deposit(amount: BigDecimal) {
+        require(amount > BigDecimal.ZERO) { "입금액은 0보다 커야 합니다." }
+        require(amount >= money) { "잔액이 부족합니다." }
+        money = money.add(amount)
+    }
+
+    fun withdraw(amount: BigDecimal) {
+        require(amount > BigDecimal.ZERO) { "출금액은 0보다 커야 합니다." }
+        require(money >= amount) { "잔액이 부족합니다." }
+        money = money.subtract(amount)
+    }
+
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/org/example/user/infrastructure/repository/UserJpaRepository.kt b/src/main/kotlin/org/example/user/infrastructure/repository/UserJpaRepository.kt
new file mode 100644
index 0000000..5c2d381
--- /dev/null
+++ b/src/main/kotlin/org/example/user/infrastructure/repository/UserJpaRepository.kt
@@ -0,0 +1,18 @@
+package org.example.user.infrastructure.repository
+
+import org.example.user.domain.enum.UserRole
+import org.example.user.domain.model.User
+import org.springframework.stereotype.Repository
+import java.math.BigDecimal
+
+@Repository
+class UserJpaRepository {
+    private val users = mutableListOf(
+        User(id = 1, name = "판매자1", role = UserRole.SELLER),
+        User(id = 2, name = "판매자2", role = UserRole.SELLER),
+        User(id = 3, name = "구매자1", role = UserRole.BUYER).apply { deposit(BigDecimal(10000)) },
+        User(id = 4, name = "구매자2", role = UserRole.BUYER).apply { deposit(BigDecimal(50000)) },
+    )
+
+    fun findByName(name: String): User? = users.find { it.name == name }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/org/example/ticket/TicketApplicationTests.kt b/src/test/kotlin/org/example/SecondChanceApplicationTests.kt
similarity index 73%
rename from src/test/kotlin/org/example/ticket/TicketApplicationTests.kt
rename to src/test/kotlin/org/example/SecondChanceApplicationTests.kt
index aca8487..62faf02 100644
--- a/src/test/kotlin/org/example/ticket/TicketApplicationTests.kt
+++ b/src/test/kotlin/org/example/SecondChanceApplicationTests.kt
@@ -1,10 +1,10 @@
-package org.example.ticket
+package org.example
 
 import org.junit.jupiter.api.Test
 import org.springframework.boot.test.context.SpringBootTest
 
 @SpringBootTest
-class TicketApplicationTests {
+class SecondChanceApplicationTests {
 
     @Test
     fun contextLoads() {
diff --git a/src/test/kotlin/org/example/deal/domain/DealTest.kt b/src/test/kotlin/org/example/deal/domain/DealTest.kt
new file mode 100644
index 0000000..15cc70f
--- /dev/null
+++ b/src/test/kotlin/org/example/deal/domain/DealTest.kt
@@ -0,0 +1,63 @@
+package org.example.deal.domain
+
+import org.example.deal.domain.model.Deal
+import org.example.deal.domain.enum.DealStatus
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import org.assertj.core.api.Assertions.assertThat
+import java.math.BigDecimal
+import java.time.LocalDateTime
+
+class DealTest {
+
+    @Test
+    fun `판매자는 자신의 티켓을 구매할 수 없다`() {
+        assertThrows<IllegalArgumentException> {
+            Deal(
+                barcode = "ABCDEFGH",
+                sellerName = "판매자1",
+                buyerName = "판매자1",
+                sellingPrice = BigDecimal(10000)
+            )
+        }
+    }
+
+    @Test
+    fun `거래 생성 시 상태는 RESERVED이다`() {
+        val deal = Deal(
+            barcode = "ABCDEFGH",
+            sellerName = "판매자1",
+            buyerName = "구매자1",
+            sellingPrice = BigDecimal(10000)
+        )
+        assertThat(deal.dealStatus).isEqualTo(DealStatus.RESERVED)
+    }
+
+
+    @Test
+    fun `예약 상태인 거래만 완료할 수 있다`() {
+        val deal = Deal(
+            barcode = "ABCDEFGH",
+            sellerName = "판매자1",
+            buyerName = "구매자1",
+            sellingPrice = BigDecimal(10000),
+        )
+        deal.dealComplete() // RESERVED → COMPLETED
+        assertThrows<IllegalArgumentException> {
+            deal.dealComplete() // COMPLETED → 💥 예외
+        }
+    }
+
+    @Test
+    fun `10분이 지나면 예약이 만료된다`() {
+        val deal = Deal(
+            barcode = "ABCDEFGH",
+            sellerName = "판매자1",
+            buyerName = "구매자1",
+            sellingPrice = BigDecimal(10000),
+            reservedDateTime = LocalDateTime.now().minusMinutes(11) // 11분 전
+        )
+        assertThat(deal.reservedTimeExpiredCheck()).isTrue()
+    }
+}
+
diff --git a/src/test/kotlin/org/example/deal/infrastructure/api/KakaoPaymentGatewayTest.kt b/src/test/kotlin/org/example/deal/infrastructure/api/KakaoPaymentGatewayTest.kt
new file mode 100644
index 0000000..b577d94
--- /dev/null
+++ b/src/test/kotlin/org/example/deal/infrastructure/api/KakaoPaymentGatewayTest.kt
@@ -0,0 +1,48 @@
+
+package org.example.deal.infrastructure.api
+
+import org.assertj.core.api.Assertions.assertThat
+import org.example.user.domain.enum.UserRole
+import org.example.user.domain.model.User
+import org.example.user.infrastructure.repository.UserJpaRepository
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import org.junit.jupiter.api.extension.ExtendWith
+import org.mockito.InjectMocks
+import org.mockito.Mock
+import org.mockito.Mockito.`when`
+import org.mockito.junit.jupiter.MockitoExtension
+import java.math.BigDecimal
+
+@ExtendWith(MockitoExtension::class)
+class KakaoPaymentGatewayTest {
+
+    @Mock
+    private lateinit var userJpaRepository: UserJpaRepository
+
+    @InjectMocks
+    private lateinit var kakaoPaymentGateway: KakaoPaymentGateway
+
+    @Test
+    fun `결제에 성공한다`() {
+        val buyer = User(name = "구매자1", role = UserRole.BUYER).apply {
+            deposit(BigDecimal(50000)) }
+        val seller = User(name = "판매자1", role = UserRole.SELLER)
+
+        `when`(userJpaRepository.findByName("구매자1")).thenReturn(buyer)
+        `when`(userJpaRepository.findByName("판매자1")).thenReturn(seller)
+
+        kakaoPaymentGateway.pay("구매자1", "판매자1", BigDecimal(10000))
+        assertThat(buyer.money).isEqualTo(BigDecimal(40000))
+        assert(seller.money == BigDecimal(10000))
+    }
+
+    @Test
+    fun `존재하지 않는 구매자일경우 구매할 수 없다`() {
+        // Mock은 기본적으로 null을 반환하므로
+        // findByName("없는유저") → null → requireNotNull에서 예외 발생
+        assertThrows<IllegalArgumentException> {
+            kakaoPaymentGateway.pay("없는유저", "판매자1", BigDecimal(10000))
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/org/example/ticket/domain/TicketTest.kt b/src/test/kotlin/org/example/ticket/domain/TicketTest.kt
index 55dee9c..6e17926 100644
--- a/src/test/kotlin/org/example/ticket/domain/TicketTest.kt
+++ b/src/test/kotlin/org/example/ticket/domain/TicketTest.kt
@@ -2,46 +2,144 @@ package org.example.ticket.domain
 
 import org.assertj.core.api.Assertions.assertThat
 import org.assertj.core.api.SoftAssertions.assertSoftly
+import org.example.ticket.domain.enum.TicketStatus
+import org.example.ticket.domain.enum.TicketType
 import org.example.ticket.domain.model.Ticket
+import org.example.user.domain.enum.UserRole
+import org.example.user.domain.model.User
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import java.math.BigDecimal
 import java.time.LocalDateTime
 
 class TicketTest {
+    private fun createUser(
+        name: String = "테스트유저",
+        role: UserRole = UserRole.BUYER,
+    ): User = User(name = name, role = role)
+
+    private fun createTicket(
+        barcode: String = "ABCDEFGH",
+        sellerName: String = "Seller A",
+        expirationDateTime: LocalDateTime = LocalDateTime.now().plusHours(2),
+        originalPrice: BigDecimal = BigDecimal.TEN,
+        ticketType: TicketType = TicketType.MELON
+    ): Ticket {
+        return Ticket(
+            barcode = barcode,
+            sellerName = sellerName,
+            expirationDateTime = expirationDateTime,
+            originalPrice = originalPrice,
+            ticketType = ticketType
+        )
+    }
+
     @Test
     fun `티켓_만들기`() {
-        val ticket = Ticket(1L, LocalDateTime.now(), BigDecimal.TEN)
-
+        val ticket = createTicket();
         assertSoftly {
             assertThat(ticket.id).isEqualTo(1L)
-            assertThat(ticket.expirationAt).isNotNull
+            assertThat(ticket.ticketStatus).isEqualTo(TicketStatus.ON_SALE)
+            assertThat(ticket.expirationDateTime).isNotNull
             assertThat(ticket.originalPrice).isEqualTo(BigDecimal.TEN)
         }
     }
+    @Test
+    fun `바코드가 8자리가 아니면 에러`() {
+        assertThrows<IllegalArgumentException> {
+            val ticket = createTicket(barcode= "ABC")
+        }
+    }
+
+
 
     @Test
     fun `티켓 유효기간이 등록 기준 시간보다 늦으면 예외이다`() {
         assertThrows<IllegalArgumentException> {
-            Ticket(expirationAt = Ticket.ACTIVATION_DEAD_LINE.minusSeconds(1), originalPrice = BigDecimal.TEN)
+            createTicket(expirationDateTime = LocalDateTime.now().plusHours(1).minusSeconds(1),)
         }
     }
 
     @Test
     fun `공연 당일에는 가격을 정가의 50% 이하로만 설정 할 수 있다`() {
-        val ticketPrice = BigDecimal.TEN
-        val ticket = Ticket(1L, Ticket.ACTIVATION_DEAD_LINE.plusSeconds(1), ticketPrice)
-
+        val ticket = createTicket(originalPrice = BigDecimal(10000))
         assertThrows<IllegalArgumentException> {
-            ticket.applySellerOfferPrice(BigDecimal.valueOf(100.0))
+            ticket.applySellerOfferPrice("Seller A", BigDecimal(6000))
         }
     }
 
     @Test
     fun `양도 가격은 정가를 초과 할 수 없다`() {
-        // API
+        val ticket = Ticket(
+            id = 1L,
+            barcode = "ABCDEFGH",
+            sellerName = "Seller A",
+            expirationDateTime = LocalDateTime.now().plusDays(1),
+            originalPrice = BigDecimal.TEN,
+            ticketType = TicketType.MELON
+        )
+
+        assertThrows<IllegalArgumentException> {
+            ticket.applySellerOfferPrice("Seller A", BigDecimal(20))
+        }
+    }
+    @Test
+    fun `판매중인 티켓을 예약할 수 있다`() {
+        val ticket = Ticket(
+            id = 1L,
+            barcode = "ABCDEFGH",
+            sellerName = "Seller A",
+            expirationDateTime = LocalDateTime.now().plusHours(2),
+            originalPrice = BigDecimal.TEN,
+            ticketType = TicketType.MELON
+        )
+        ticket.ticketReserve()
+        assertThat(ticket.ticketStatus).isEqualTo(TicketStatus.RESERVED)
+    }
+    @Test
+    fun `예약중인 티켓을 판매중으로 되돌릴 수 있다`() {
+        val ticket = Ticket(
+            id = 1L,
+            barcode = "ABCDEFGH",
+            sellerName = "Seller A",
+            expirationDateTime = LocalDateTime.now().plusHours(2),
+            originalPrice = BigDecimal.TEN,
+            ticketType = TicketType.MELON
+        )
+        ticket.ticketReserve()
+        ticket.ticketOnSale()
+        assertThat(ticket.ticketStatus).isEqualTo(TicketStatus.ON_SALE)
+    }
+    @Test
+    fun `예약중인 티켓만 판매완료할 수 있다`() {
+        val ticket = Ticket(
+            id = 1L,
+            barcode = "ABCDEFGH",
+            sellerName = "Seller A",
+            expirationDateTime = LocalDateTime.now().plusHours(2),
+            originalPrice = BigDecimal.TEN,
+            ticketType = TicketType.MELON,
+        )
+        ticket.ticketReserve()
+        ticket.ticketSold()
+        assertThat(ticket.ticketStatus).isEqualTo(TicketStatus.SOLD)
+    }
+
+    @Test
+    fun `판매중 상태에서 바로 판매완료할 수 없다`() {
+        val ticket = Ticket(
+            id = 1L,
+            barcode = "ABCDEFGH",
+            sellerName = "Seller A",
+            expirationDateTime = LocalDateTime.now().plusHours(2),
+            originalPrice = BigDecimal.TEN,
+            ticketType = TicketType.MELON,
+        )
         assertThrows<IllegalArgumentException> {
-            Ticket(1L, LocalDateTime.now(), BigDecimal.TEN)
+            ticket.ticketSold()
         }
     }
+
+
+
 }
diff --git a/src/test/kotlin/org/example/user/domain/UserTest.kt b/src/test/kotlin/org/example/user/domain/UserTest.kt
new file mode 100644
index 0000000..44fd784
--- /dev/null
+++ b/src/test/kotlin/org/example/user/domain/UserTest.kt
@@ -0,0 +1,62 @@
+package org.example.user.domain
+
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.SoftAssertions.assertSoftly
+import org.example.user.domain.enum.UserRole
+import org.example.user.domain.model.User
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import java.math.BigDecimal
+
+class UserTest {
+    private fun createUser(
+        name: String = "테스트유저",
+        role: UserRole = UserRole.BUYER,
+        money: BigDecimal = BigDecimal(0),
+    ): User = User(name = name, role = role)
+
+    @Test
+    fun `입금에 성공한다`() {
+        val user = createUser()
+        user.deposit(BigDecimal(10000))
+        assertThat(user.money).isEqualTo(BigDecimal(10000))
+    }
+
+    @Test
+    fun `출금에 성공한다`() {
+        val user = createUser(money = BigDecimal(10000))
+        user.withdraw(BigDecimal(3000))
+        assertThat(user.money).isEqualTo(BigDecimal(7000))
+    }
+    @Test
+    fun `0원을 입금할 수 없다`(){
+        val user = createUser(money = BigDecimal(10000))
+        assertThrows<IllegalArgumentException> {
+            user.deposit(BigDecimal.ZERO)
+        }
+    }
+    @Test
+    fun `0원을 출금할 수 없다`(){
+        val user = createUser()
+        assertThrows<IllegalArgumentException> {
+            user.withdraw(BigDecimal.ZERO)
+        }
+    }
+    @Test
+    fun `잔액이 부족하면 입금할 수 없다`() {
+        val user = createUser()
+        assertThrows<IllegalArgumentException> {
+            user.deposit(BigDecimal(5000))
+        }
+    }
+    @Test
+    fun `출금액이 부족하면 출금할 수 없다`() {
+        val user = createUser()
+        assertSoftly {
+            assertThrows<IllegalArgumentException> {
+                user.withdraw(BigDecimal(1000))
+            }
+        }
+    }
+
+}
\ No newline at end of file