From eb4df66ece8f8d6bf1438b17908c60c4fa08cc36 Mon Sep 17 00:00:00 2001
From: Klaus <klaus@vividnext.co.kr>
Date: Fri, 10 Jul 2026 03:20:20 +0900
Subject: [PATCH] =?UTF-8?q?feat(home):=20AI=20=EC=BA=90=EB=A6=AD=ED=84=B0?=
 =?UTF-8?q?=20=EC=8A=A4=EB=83=85=EC=83=B7=20=EC=A7=91=EA=B3=84=20=EA=B8=B0?=
 =?UTF-8?q?=EA=B0=84=EC=9D=84=20=EC=A0=95=EC=9D=98=ED=95=9C=EB=8B=A4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../RecommendationSnapshotWindowPolicy.kt     | 41 +++++++++++++++++++
 .../RecommendationSnapshotWindowPolicyTest.kt | 20 +++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 src/main/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicy.kt
 create mode 100644 src/test/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicyTest.kt

diff --git a/src/main/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicy.kt b/src/main/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicy.kt
new file mode 100644
index 00000000..bdd9dd13
--- /dev/null
+++ b/src/main/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicy.kt
@@ -0,0 +1,41 @@
+package kr.co.vividnext.sodalive.v2.recommendation.domain
+
+import java.time.LocalDateTime
+import java.time.ZoneId
+
+class RecommendationSnapshotWindowPolicy {
+    fun previousKstDayUtcWindow(nowUtc: LocalDateTime): RecommendationSnapshotWindow {
+        val previousKstDate = nowUtc
+            .atZone(UTC_ZONE)
+            .withZoneSameInstant(KST_ZONE)
+            .toLocalDate()
+            .minusDays(1)
+        val startUtc = previousKstDate
+            .atStartOfDay(KST_ZONE)
+            .withZoneSameInstant(UTC_ZONE)
+            .toLocalDateTime()
+        val endExclusiveUtc = previousKstDate
+            .plusDays(1)
+            .atStartOfDay(KST_ZONE)
+            .withZoneSameInstant(UTC_ZONE)
+            .toLocalDateTime()
+        val snapshotAt = endExclusiveUtc.minusSeconds(1)
+
+        return RecommendationSnapshotWindow(
+            startUtc = startUtc,
+            endExclusiveUtc = endExclusiveUtc,
+            snapshotAt = snapshotAt
+        )
+    }
+
+    companion object {
+        private val UTC_ZONE: ZoneId = ZoneId.of("UTC")
+        private val KST_ZONE: ZoneId = ZoneId.of("Asia/Seoul")
+    }
+}
+
+data class RecommendationSnapshotWindow(
+    val startUtc: LocalDateTime,
+    val endExclusiveUtc: LocalDateTime,
+    val snapshotAt: LocalDateTime
+)
diff --git a/src/test/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicyTest.kt b/src/test/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicyTest.kt
new file mode 100644
index 00000000..a2cefa11
--- /dev/null
+++ b/src/test/kotlin/kr/co/vividnext/sodalive/v2/recommendation/domain/RecommendationSnapshotWindowPolicyTest.kt
@@ -0,0 +1,20 @@
+package kr.co.vividnext.sodalive.v2.recommendation.domain
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import java.time.LocalDateTime
+
+class RecommendationSnapshotWindowPolicyTest {
+    private val policy = RecommendationSnapshotWindowPolicy()
+
+    @Test
+    @DisplayName("KST 전날 하루를 UTC 조회 범위로 변환한다")
+    fun shouldConvertPreviousKstDayToUtcWindow() {
+        val window = policy.previousKstDayUtcWindow(LocalDateTime.of(2026, 7, 9, 21, 0, 0))
+
+        assertEquals(LocalDateTime.of(2026, 7, 8, 15, 0, 0), window.startUtc)
+        assertEquals(LocalDateTime.of(2026, 7, 9, 15, 0, 0), window.endExclusiveUtc)
+        assertEquals(LocalDateTime.of(2026, 7, 9, 14, 59, 59), window.snapshotAt)
+    }
+}