feat: wavelets simulation

backend/services/data_fetcher.py

@@ -160,12 +160,17 @@ def get_all_quotes() -> Dict[str, List[Dict[str, Any]]]:
     return result
 
 
-def get_historical(symbol: str, period: str = "1y", interval: str = "1d") -> List[Dict[str, Any]]:
+def get_historical(
+    symbol: str, period: str = "1y", interval: str = "1d",
+    start: Optional[str] = None, end: Optional[str] = None,
+) -> List[Dict[str, Any]]:
+    """`start`/`end` (ISO date strings) take priority over `period` when given — yfinance
+    only accepts one or the other, never both."""
     try:
         from urllib.parse import unquote
         symbol = unquote(symbol)
         ticker = yf.Ticker(symbol)
-        hist = ticker.history(period=period, interval=interval)
+        hist = ticker.history(start=start, end=end, interval=interval) if start else ticker.history(period=period, interval=interval)
         if hist.empty:
             return []
         hist = hist.reset_index()