feat: universe discover에 SEC EDGAR fallback 추가

yf.screen() 401 에러 시 SEC EDGAR company_tickers_exchange.json으로 자동 전환.
- 5,848개 NYSE/NASDAQ/AMEX/ARCA 종목 등록 가능
- response에 source 필드 추가 (yfinance / sec_edgar)
- market_cap_min 필터는 yfinance 사용 시에만 적용 (SEC Edgar fallback 시 미적용, 스크리닝 시점에 필터링)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/services/universe_service.py

@@ -52,13 +52,8 @@ class UniverseService:
             sortField="intradaymarketcap", sortAsc=False,
         )
 
-    async def discover_tickers(self, db: AsyncSession, market_cap_min: float = 1e8) -> Dict:
-        """
-        Discover US-listed stocks via yfinance screener and store in registry.
-        Filters out ETFs, mutual funds, and foreign-listed stocks.
-
-        Returns: { tickers_found, tickers_registered }
-        """
+    async def _discover_via_yfinance(self, market_cap_min: float) -> List[dict]:
+        """Try yfinance screener. Returns list of quote dicts or raises on 401/error."""
         from yfinance import EquityQuery
 
         query = EquityQuery("and", [
@@ -84,7 +79,83 @@ class UniverseService:
                 break
             await asyncio.sleep(0.3)
 
-        logger.info(f"Universe: screener returned {len(all_quotes)} quotes")
+        return all_quotes
+
+    async def _discover_via_sec_edgar(self) -> List[dict]:
+        """
+        Fallback: use SEC EDGAR company_tickers_exchange.json.
+        Returns list of dicts with ticker/name/cik/exchange.
+        No sector/industry (those remain NULL in registry).
+        No market_cap filter (filter happens at screening time).
+        """
+        _US_EXCHANGES = {"NYSE", "NASDAQ", "AMEX", "ARCA", "BATS", "NYSEArca", "OTC"}
+        try:
+            data = await self._http.fetch_json(
+                "https://www.sec.gov/files/company_tickers_exchange.json"
+            )
+        except Exception as e:
+            raise RuntimeError(f"SEC EDGAR company_tickers_exchange.json fetch failed: {e}")
+
+        fields = data.get("fields", [])
+        rows_raw = data.get("data", [])
+        try:
+            cik_idx = fields.index("cik")
+            name_idx = fields.index("name")
+            ticker_idx = fields.index("ticker")
+            exchange_idx = fields.index("exchange")
+        except ValueError as e:
+            raise RuntimeError(f"Unexpected company_tickers_exchange.json schema: {e}")
+
+        quotes = []
+        for row in rows_raw:
+            try:
+                ticker = str(row[ticker_idx]).upper().strip()
+                exchange = str(row[exchange_idx]).strip()
+                if not ticker or len(ticker) > 10:
+                    continue
+                # Keep only major US exchanges
+                if exchange not in _US_EXCHANGES:
+                    continue
+                quotes.append({
+                    "symbol": ticker,
+                    "shortName": str(row[name_idx]) if row[name_idx] else None,
+                    "cik_override": str(row[cik_idx]).zfill(10),
+                    "exchange": exchange,
+                    "sector": None,
+                    "industry": None,
+                    "quoteType": "EQUITY",
+                })
+            except (IndexError, TypeError):
+                continue
+
+        logger.info(f"Universe: SEC EDGAR fallback returned {len(quotes)} tickers")
+        return quotes
+
+    async def discover_tickers(self, db: AsyncSession, market_cap_min: float = 1e8) -> Dict:
+        """
+        Discover US-listed stocks and store in registry.
+
+        Primary:  yfinance screener (includes market_cap filter + sector/industry)
+        Fallback: SEC EDGAR company_tickers_exchange.json (no market_cap filter,
+                  no sector/industry — those remain NULL)
+
+        Returns: { tickers_found, tickers_registered, source }
+        """
+        source = "yfinance"
+        all_quotes: List[dict] = []
+
+        try:
+            all_quotes = await self._discover_via_yfinance(market_cap_min)
+            if not all_quotes:
+                raise RuntimeError("yfinance screener returned 0 results")
+            logger.info(f"Universe: yfinance screener returned {len(all_quotes)} quotes")
+        except Exception as e:
+            logger.warning(
+                f"Universe: yfinance screener failed ({e}), "
+                "falling back to SEC EDGAR company_tickers_exchange.json"
+            )
+            source = "sec_edgar"
+            all_quotes = await self._discover_via_sec_edgar()
 
         # Fetch CIK map from SEC once (disk-cached after first call)
         cik_map = await self._fetch_cik_map()
@@ -106,7 +177,7 @@ class UniverseService:
             rows.append({
                 "ticker": ticker,
                 "name": q.get("shortName") or q.get("longName"),
-                "cik": cik_map.get(ticker),
+                "cik": q.get("cik_override") or cik_map.get(ticker),
                 "sector": q.get("sector"),
                 "industry": q.get("industry"),
                 "exchange": _REVERSE_EXCHANGE.get(exchange_code, exchange_code) or None,
@@ -114,7 +185,7 @@ class UniverseService:
             })
 
         if not rows:
-            return {"tickers_found": len(all_quotes), "tickers_registered": 0}
+            return {"tickers_found": len(all_quotes), "tickers_registered": 0, "source": source}
 
         for i in range(0, len(rows), _CHUNK):
             chunk = rows[i:i + _CHUNK]
@@ -134,8 +205,8 @@ class UniverseService:
             await db.execute(stmt)
         await db.commit()
 
-        logger.info(f"Universe: upserted {len(rows)} tickers into registry")
-        return {"tickers_found": len(all_quotes), "tickers_registered": len(rows)}
+        logger.info(f"Universe: upserted {len(rows)} tickers into registry (source={source})")
+        return {"tickers_found": len(all_quotes), "tickers_registered": len(rows), "source": source}
 
     async def _fetch_cik_map(self) -> Dict[str, str]:
         """Fetch SEC company_tickers.json once → {TICKER: padded_cik}."""