diff --git a/lotto/app/db.py b/lotto/app/db.py
index 0093ed5..eacd8d1 100644
--- a/lotto/app/db.py
+++ b/lotto/app/db.py
@@ -279,6 +279,25 @@ def init_db() -> None:
         """)
         conn.execute("CREATE INDEX IF NOT EXISTS idx_review_draw ON weekly_review(draw_no DESC)")
 
+        # ── lotto_briefings.picks 4계층 마이그레이션 (1회 변환) ───────────────
+        # 기존: picks가 JSON 리스트 [{numbers,risk_tag,reason}]
+        # 신규: picks가 JSON 객체 {core:[...], bonus:[], extended:[], pool:[]}
+        rows = conn.execute("SELECT id, picks FROM lotto_briefings").fetchall()
+        for r in rows:
+            try:
+                p = json.loads(r["picks"])
+                if isinstance(p, list):
+                    new_picks = {"core": p, "bonus": [], "extended": [], "pool": []}
+                    conn.execute(
+                        "UPDATE lotto_briefings SET picks=? WHERE id=?",
+                        (json.dumps(new_picks, ensure_ascii=False), r["id"]),
+                    )
+            except (json.JSONDecodeError, TypeError):
+                continue
+
+        _ensure_column(conn, "lotto_briefings", "tier_rationale",
+                       "ALTER TABLE lotto_briefings ADD COLUMN tier_rationale TEXT NOT NULL DEFAULT '{}'")
+