fix(dataflows): let the next vendor serve what Alpha Vantage cannot

- an indicator it does not carry raises instead of returning prose the router counts as an answer
- ticker news asks for the configured article limit

tests/test_alpha_vantage_hardening.py

@@ -183,3 +183,31 @@ def test_the_news_window_includes_the_analysis_day(monkeypatch):
 
     assert seen["time_from"] == "20260310T0000"
     assert seen["time_to"] == "20260314T2359"
+
+
+@pytest.mark.unit
+@pytest.mark.parametrize("indicator", ["vwma", "mfi"])
+def test_an_indicator_this_vendor_lacks_lets_the_next_one_serve_it(indicator):
+    """Returning prose counts as success to the router, so the chain stops at a
+    vendor that cannot compute the indicator while the next one can."""
+    from tradingagents.dataflows import alpha_vantage_indicator
+    from tradingagents.dataflows.errors import VendorError
+
+    with pytest.raises(VendorError):
+        alpha_vantage_indicator.get_indicator("AAPL", indicator, "2026-05-08", 30)
+
+
+@pytest.mark.unit
+def test_ticker_news_asks_for_only_as_many_articles_as_configured(monkeypatch):
+    """The endpoint returns 50 articles with per-article sentiment arrays by
+    default, and the whole payload went into the prompt."""
+    from tradingagents.dataflows import alpha_vantage_news
+
+    monkeypatch.setattr(alpha_vantage_news, "get_config", lambda: {"news_article_limit": 8})
+    seen = {}
+    monkeypatch.setattr(alpha_vantage_news, "_make_api_request",
+                        lambda fn, params: seen.update(params) or "{}")
+
+    alpha_vantage_news.get_news("AAPL", "2026-03-10", "2026-03-14")
+
+    assert seen["limit"] == "8"

tradingagents/dataflows/alpha_vantage_indicator.py

@@ -1,6 +1,7 @@
 import logging
 
-from .alpha_vantage_common import AlphaVantageNotConfiguredError, _make_api_request
+from .alpha_vantage_common import _make_api_request
+from .errors import NoMarketDataError, VendorError
 
 logger = logging.getLogger(__name__)
 
@@ -64,8 +65,11 @@ def get_indicator(
     }
 
     if indicator not in supported_indicators:
-        raise ValueError(
+        # A vendor error, not a caller error: another vendor may compute it, and
-            f"Indicator {indicator} is not supported. Please choose from: {list(supported_indicators.keys())}"
+        # the router decides. yfinance rejects a name nobody serves.
+        raise NoMarketDataError(
+            symbol, symbol,
+            f"Alpha Vantage does not serve {indicator}; it serves {list(supported_indicators)}"
         )
 
     curr_date_dt = datetime.strptime(curr_date, "%Y-%m-%d")
@@ -134,12 +138,13 @@ def get_indicator(
                 "time_period": str(time_period),
                 "datatype": "csv"
             })
-        elif indicator == "vwma":
-            # Alpha Vantage doesn't have direct VWMA, so we'll return an informative message
-            # In a real implementation, this would need to be calculated from OHLCV data
-            return f"## VWMA (Volume Weighted Moving Average) for {symbol}:\n\nVWMA calculation requires OHLCV data and is not directly available from Alpha Vantage API.\nThis indicator would need to be calculated from the raw stock data using volume-weighted price averaging.\n\n{indicator_descriptions.get('vwma', 'No description available.')}"
         else:
-            return f"Error: Indicator {indicator} not implemented yet."
+            # This vendor has no endpoint for the indicator. Raising lets the
+            # router try the next vendor, which computes it; returning prose
+            # counted as a successful answer and ended the chain here.
+            raise NoMarketDataError(
+                symbol, symbol, f"Alpha Vantage does not serve the {indicator} indicator"
+            )
 
         # Parse CSV data and extract values for the date range
         lines = data.strip().split('\n')
@@ -209,11 +214,11 @@ def get_indicator(
 
         return result_str
 
-    except AlphaVantageNotConfiguredError:
+    except VendorError:
-        # Vendor unavailable (no API key). Let it propagate so the router can
+        # Unavailable vendor, throttle, or an indicator this vendor does not
-        # fall back / emit the no-data sentinel instead of returning this as a
+        # serve. Let it propagate so the router falls back to a vendor that can,
-        # successful-looking error string.
+        # instead of returning the failure as a successful-looking string.
         raise
     except Exception as e:
         logger.warning("Alpha Vantage indicator %s failed: %s", indicator, e)
-        return f"Error retrieving {indicator} data: {str(e)}"
+        raise NoMarketDataError(symbol, symbol, f"{indicator} unavailable: {e}") from e

tradingagents/dataflows/alpha_vantage_news.py

@@ -18,10 +18,13 @@ def get_news(ticker, start_date, end_date) -> dict[str, str] | str:
         Dictionary containing news sentiment data or JSON string.
     """
 
+    # Without a limit the endpoint returns 50 articles, each with per-ticker
+    # sentiment arrays, and all of it reaches the prompt.
     params = {
         "tickers": ticker,
         "time_from": format_datetime_for_api(start_date),
         "time_to": format_datetime_for_api(end_date, end_of_day=True),
+        "limit": str(get_config()["news_article_limit"]),
     }
 
     return _make_api_request("NEWS_SENTIMENT", params)