feat(recommend): 콘텐츠 조회 이력 서비스를 추가한다

src/main/kotlin/kr/co/vividnext/sodalive/v2/recommend/application/CreatorContentViewHistoryService.kt

@@ -0,0 +1,28 @@
+package kr.co.vividnext.sodalive.v2.recommend.application
+
+import kr.co.vividnext.sodalive.v2.recommend.port.out.CreatorContentViewHistoryPort
+import kr.co.vividnext.sodalive.v2.recommend.port.out.CreatorContentViewHistoryRecord
+import org.springframework.stereotype.Service
+import org.springframework.transaction.annotation.Propagation
+import org.springframework.transaction.annotation.Transactional
+import java.time.LocalDateTime
+
+@Service
+class CreatorContentViewHistoryService(
+    private val port: CreatorContentViewHistoryPort
+) {
+    @Transactional(propagation = Propagation.REQUIRES_NEW)
+    fun recordView(memberId: Long?, contentId: Long, viewedAt: LocalDateTime = LocalDateTime.now()) {
+        if (memberId == null) return
+
+        val genreId = port.findGenreIdByContentId(contentId) ?: return
+        port.save(
+            CreatorContentViewHistoryRecord(
+                memberId = memberId,
+                contentId = contentId,
+                genreId = genreId,
+                viewedAt = viewedAt
+            )
+        )
+    }
+}

src/test/kotlin/kr/co/vividnext/sodalive/v2/recommend/application/CreatorContentViewHistoryServiceTest.kt

@@ -0,0 +1,64 @@
+package kr.co.vividnext.sodalive.v2.recommend.application
+
+import kr.co.vividnext.sodalive.v2.recommend.port.out.CreatorContentViewHistoryPort
+import kr.co.vividnext.sodalive.v2.recommend.port.out.CreatorContentViewHistoryRecord
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import java.time.LocalDateTime
+
+class CreatorContentViewHistoryServiceTest {
+    private val port = FakeCreatorContentViewHistoryPort()
+    private val service = CreatorContentViewHistoryService(port)
+
+    @Test
+    @DisplayName("인증 회원의 콘텐츠 상세 진입 시 memberId/contentId/genreId/viewedAt을 저장한다")
+    fun shouldRecordAuthenticatedMemberContentViewWithGenreAndViewedAt() {
+        val viewedAt = LocalDateTime.of(2026, 5, 31, 10, 0)
+        port.genreIdByContentId[20L] = 30L
+
+        service.recordView(memberId = 10L, contentId = 20L, viewedAt = viewedAt)
+
+        assertEquals(
+            listOf(
+                CreatorContentViewHistoryRecord(
+                    memberId = 10L,
+                    contentId = 20L,
+                    genreId = 30L,
+                    viewedAt = viewedAt
+                )
+            ),
+            port.savedRecords
+        )
+    }
+
+    @Test
+    @DisplayName("비회원 콘텐츠 상세 진입은 조회 이력을 저장하지 않는다")
+    fun shouldNotRecordAnonymousContentView() {
+        service.recordView(memberId = null, contentId = 20L)
+
+        assertTrue(port.savedRecords.isEmpty())
+    }
+
+    @Test
+    @DisplayName("콘텐츠의 활성 장르를 찾지 못하면 조회 이력을 저장하지 않는다")
+    fun shouldNotRecordWhenContentGenreDoesNotExist() {
+        service.recordView(memberId = 10L, contentId = 20L)
+
+        assertTrue(port.savedRecords.isEmpty())
+    }
+
+    private class FakeCreatorContentViewHistoryPort : CreatorContentViewHistoryPort {
+        val genreIdByContentId = mutableMapOf<Long, Long>()
+        val savedRecords = mutableListOf<CreatorContentViewHistoryRecord>()
+
+        override fun findGenreIdByContentId(contentId: Long): Long? {
+            return genreIdByContentId[contentId]
+        }
+
+        override fun save(record: CreatorContentViewHistoryRecord) {
+            savedRecords.add(record)
+        }
+    }
+}