diff --git a/stock/app/db.py b/stock/app/db.py
index 95a9986..1fca446 100644
--- a/stock/app/db.py
+++ b/stock/app/db.py
@@ -509,7 +509,7 @@ def add_alert_history(ticker: str, name: str, kind: str, condition: str, price,
 def get_alert_history(days: int = 7) -> list:
     with _conn() as conn:
         rows = conn.execute(
-            "SELECT * FROM trade_alert_history WHERE fired_at >= datetime('now', ?) ORDER BY fired_at DESC",
+            "SELECT * FROM trade_alert_history WHERE fired_at >= strftime('%Y-%m-%dT%H:%M:%fZ','now', ?) ORDER BY fired_at DESC",
             (f"-{int(days)} days",),
         ).fetchall()
     return [
diff --git a/stock/tests/test_trade_alerts_db.py b/stock/tests/test_trade_alerts_db.py
index 5e68820..b8c551f 100644
--- a/stock/tests/test_trade_alerts_db.py
+++ b/stock/tests/test_trade_alerts_db.py
@@ -31,3 +31,18 @@ def test_alert_history_records_and_reads(db):
     assert len(rows) == 1
     assert rows[0]["ticker"] == "005930" and rows[0]["kind"] == "buy"
     assert rows[0]["detail"]["vol"] == 2.1
+
+def test_alert_history_days_filter_format_consistency(db):
+    """fired_at은 ISO(T/Z)로 저장 — 필터도 ISO여야 경계일 비교가 정확.
+    7일 경계 밖(정확히 7일 전 자정) 레코드는 제외되어야 한다. 포맷 불일치면 잘못 포함됨."""
+    db.add_alert_history("005930", "삼성", "buy", "buy_breakout", 71500, {})  # now
+    conn = sqlite3.connect(db.DB_PATH)
+    conn.execute(
+        "INSERT INTO trade_alert_history(ticker,name,kind,condition,price,detail_json,fired_at) "
+        "VALUES('000660','SK','sell','sell_stop_loss',60000,'{}', "
+        "strftime('%Y-%m-%dT%H:%M:%fZ','now','-7 days','start of day'))"
+    )
+    conn.commit(); conn.close()
+    tickers = [r["ticker"] for r in db.get_alert_history(days=7)]
+    assert "005930" in tickers
+    assert "000660" not in tickers