feat(recommend): 홈 장르 추천 후보 조회를 보강한다

src/test/kotlin/kr/co/vividnext/sodalive/v2/recommend/adapter/out/persistence/DefaultHomeRecommendationQueryRepositoryTest.kt

@@ -1504,8 +1504,95 @@ class DefaultHomeRecommendationQueryRepositoryTest @Autowired constructor(
     }
 
     @Test
-    @DisplayName("장르 기반 크리에이터 추천은 서비스 중복 제거용 후보 그룹을 genreLimit보다 많이 반환한다")
-    fun shouldReturnMoreCandidateGroupsThanFinalGenreLimitForServiceDeduplicationBackfill() {
+    @DisplayName("조회 이력이 없으면 크리에이터 8명을 채울 수 있는 콘텐츠 테마 후보를 먼저 반환한다")
+    fun shouldRecommendFullRandomThemeCandidatesFirstWhenViewHistoryDoesNotExist() {
+        repeat(5) { themeIndex ->
+            val theme = saveTheme("no-history-underfilled-theme-$themeIndex")
+            saveAudioContent(
+                saveMember("no-history-underfilled-creator-$themeIndex", MemberRole.CREATOR),
+                LocalDateTime.of(2026, 5, 30, 10, 0).plusMinutes(themeIndex.toLong()),
+                isActive = true,
+                theme = theme
+            )
+        }
+        repeat(5) { themeIndex ->
+            val theme = saveTheme("no-history-full-theme-$themeIndex")
+            repeat(8) { creatorIndex ->
+                saveAudioContent(
+                    saveMember("no-history-full-$themeIndex-creator-$creatorIndex", MemberRole.CREATOR),
+                    LocalDateTime.of(2026, 5, 30, 11, 0).plusMinutes((themeIndex * 10 + creatorIndex).toLong()),
+                    isActive = true,
+                    theme = theme
+                )
+            }
+        }
+        flushAndClear()
+
+        val recommendations = repository.findGenreCreatorRecommendations(
+            memberId = null,
+            includeAdultGenres = false,
+            genreLimit = 5,
+            creatorLimit = 8
+        )
+
+        assertEquals(true, recommendations.size >= 5)
+        assertEquals(true, recommendations.take(5).all { it.genreName.startsWith("no-history-full-theme-") })
+        assertEquals(true, recommendations.take(5).all { it.creators.size == 8 })
+    }
+
+    @Test
+    @DisplayName("조회 이력 콘텐츠 테마는 8명이 되지 않아도 후보에 포함하고 부족한 장르는 8명 보유 테마 후보로 채운다")
+    fun shouldKeepViewedThemeCandidateEvenWhenUnderfilledAndReturnFullRandomThemeCandidates() {
+        val viewer = saveMember("viewed-partial-viewer", MemberRole.USER)
+        val viewedTheme = saveTheme("viewed-partial-theme")
+        val viewedContent = saveAudioContent(
+            saveMember("viewed-partial-creator", MemberRole.CREATOR),
+            LocalDateTime.of(2026, 5, 30, 10, 0),
+            isActive = true,
+            theme = viewedTheme
+        )
+        repeat(5) { themeIndex ->
+            val theme = saveTheme("viewed-fill-full-theme-$themeIndex")
+            repeat(8) { creatorIndex ->
+                saveAudioContent(
+                    saveMember("viewed-fill-full-$themeIndex-creator-$creatorIndex", MemberRole.CREATOR),
+                    LocalDateTime.of(2026, 5, 30, 11, 0).plusMinutes((themeIndex * 10 + creatorIndex).toLong()),
+                    isActive = true,
+                    theme = theme
+                )
+            }
+        }
+        entityManager.persist(
+            CreatorContentViewHistory(
+                memberId = viewer.id!!,
+                contentId = viewedContent.id!!,
+                genreId = 999L,
+                viewedAt = LocalDateTime.of(2026, 5, 31, 10, 0)
+            )
+        )
+        flushAndClear()
+
+        val recommendations = repository.findGenreCreatorRecommendations(
+            memberId = viewer.id!!,
+            includeAdultGenres = false,
+            genreLimit = 5,
+            creatorLimit = 8
+        )
+
+        assertEquals(true, recommendations.size >= 5)
+        assertEquals(true, recommendations.any { it.genreId == viewedTheme.id && it.creators.size == 1 })
+        assertEquals(
+            true,
+            recommendations
+                .filter { it.genreId != viewedTheme.id }
+                .take(4)
+                .all { it.genreName.startsWith("viewed-fill-full-theme-") && it.creators.size == 8 }
+        )
+    }
+
+    @Test
+    @DisplayName("장르 기반 크리에이터 추천 repository는 service 보충용 후보 그룹을 genreLimit보다 많이 반환한다")
+    fun shouldReturnMoreCandidateGroupsThanFinalGenreLimitForServiceBackfill() {
         val sharedCreator = saveMember("candidate-shared", MemberRole.CREATOR)
         val backfillCreator = saveMember("candidate-backfill", MemberRole.CREATOR)
         val firstTheme = saveTheme("candidate-first-theme")