refactor(stock): Phase 1 리뷰 반영 (public get_krx_tickers·타입·limit명명·테스트)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

stock/app/test_holdings_db.py

@@ -1,4 +1,4 @@
-import os, tempfile, importlib
+import os, tempfile
 
 def _fresh_db(monkeypatch):
     tmp = tempfile.mkdtemp()
@@ -20,5 +20,18 @@ def test_holdings_signals_table_and_upsert(monkeypatch):
     assert len(rows) == 1                       # upsert 멱등
     assert rows[0]["action"] == "trim"
     assert rows[0]["exit_flags"]["ma50_break"] is True   # JSON 역직렬화
-    hist = db.get_holdings_signal_history("005930", days=30)
+    hist = db.get_holdings_signal_history("005930", limit=30)
     assert len(hist) == 1
+
+
+def test_get_latest_holdings_date(monkeypatch):
+    db = _fresh_db(monkeypatch)
+    # empty table → None
+    assert db.get_latest_holdings_date() is None
+    # after an upsert → returns that date
+    db.upsert_holdings_signal(
+        date="2026-05-30", ticker="005930", name="삼성전자",
+        action="hold", tech_score=70.0, exit_flags={}, issues=[],
+        close=80000, pnl_rate=4.0, reasons="테스트",
+    )
+    assert db.get_latest_holdings_date() == "2026-05-30"