fix(yahoo): read a news article whose fields are null (#1458)

- each article field falls back to its default on a null as well as on a missing key, so one malformed article no longer loses a ticker's news

tests/test_news_lookahead.py

@@ -255,3 +255,33 @@ def test_the_article_limit_still_caps_what_is_returned(monkeypatch):
     out = ynews.get_global_news_yfinance("2025-05-09", look_back_days=7, limit=3)
 
     assert out.count("### ") == 3
+
+
+@pytest.mark.unit
+@pytest.mark.parametrize("field", ["title", "summary", "provider", "canonicalUrl", "pubDate"])
+def test_an_article_with_a_null_field_is_read_with_its_default(field):
+    """Yahoo sends some fields as null rather than leaving them out (#1458)."""
+    content = {"title": "T", "summary": "S", "provider": {"displayName": "P"},
+               "canonicalUrl": {"url": "https://x"}, "pubDate": "2026-09-22T10:00:00Z", field: None}
+    data = ynews._extract_article_data({"content": content})
+    assert isinstance(data["title"], str) and isinstance(data["summary"], str)
+    assert isinstance(data["publisher"], str) and isinstance(data["link"], str)
+
+
+@pytest.mark.unit
+@pytest.mark.parametrize("field", ["title", "summary", "publisher", "link"])
+def test_a_flat_article_with_a_null_field_is_read_with_its_default(field):
+    data = ynews._extract_article_data({"title": "T", "summary": "S", "publisher": "P", "link": "L",
+                                        "providerPublishTime": _epoch("2026-09-22"), field: None})
+    assert all(isinstance(data[k], str) for k in ("title", "summary", "publisher", "link"))
+
+
+@pytest.mark.unit
+def test_one_malformed_article_does_not_lose_the_feed(monkeypatch):
+    good = {"content": {"title": "Kept", "summary": "", "provider": {"displayName": "Wire"},
+                        "pubDate": "2026-09-22T10:00:00Z"}}
+    bad = {"content": {"title": "Also kept", "summary": None, "provider": None,
+                       "pubDate": "2026-09-22T11:00:00Z"}}
+    _ticker_with([good, bad], monkeypatch)
+    out = ynews.get_news_yfinance("ZS", "2026-09-20", "2026-09-23")
+    assert "Kept" in out and "Also kept" in out

tradingagents/dataflows/vendors/yahoo/news.py

@@ -13,48 +13,44 @@ from tradingagents.dataflows.vendors.yahoo.common import yf_retry
 
 
 def _extract_article_data(article: dict) -> dict:
-    """Extract article data from yfinance news format (handles nested 'content' structure)."""
-    if "content" in article:
-        content = article["content"]
-        title = content.get("title", "No title")
-        summary = content.get("summary", "")
-        provider = content.get("provider", {})
-        publisher = provider.get("displayName", "Unknown")
+    """Extract article data from yfinance news format (handles nested 'content' structure).
 
+    Yahoo sends some fields as null rather than leaving them out, so each falls
+    back to its default on a null as well as on a missing key (#1458).
+    """
+    content = article.get("content")
+    if isinstance(content, dict):
         url_obj = content.get("canonicalUrl") or content.get("clickThroughUrl") or {}
-        link = url_obj.get("url", "")
-
-        pub_date_str = content.get("pubDate", "")
+        pub_date_str = content.get("pubDate") or ""
         pub_date = None
         if pub_date_str:
             with contextlib.suppress(ValueError, AttributeError):
                 pub_date = datetime.fromisoformat(pub_date_str.replace("Z", "+00:00"))
 
         return {
-            "title": title,
-            "summary": summary,
-            "publisher": publisher,
-            "link": link,
-            "pub_date": pub_date,
-        }
-    else:
-        # Fallback for flat structure. Parse the epoch publish time so flat
-        # articles are date-filterable too (otherwise they bypass the
-        # historical window and leak future news, #992/#1007).
-        pub_date = None
-        ts = article.get("providerPublishTime")
-        if ts:
-            # Epoch seconds are UTC; parse them as UTC-aware so filtering does
-            # not shift with the host timezone (#1126).
-            with contextlib.suppress(ValueError, OSError, TypeError):
-                pub_date = datetime.fromtimestamp(ts, tz=UTC)
-        return {
-            "title": article.get("title", "No title"),
-            "summary": article.get("summary", ""),
-            "publisher": article.get("publisher", "Unknown"),
-            "link": article.get("link", ""),
+            "title": content.get("title") or "No title",
+            "summary": content.get("summary") or "",
+            "publisher": (content.get("provider") or {}).get("displayName") or "Unknown",
+            "link": url_obj.get("url") or "",
             "pub_date": pub_date,
         }
+    # Fallback for flat structure. Parse the epoch publish time so flat
+    # articles are date-filterable too (otherwise they bypass the
+    # historical window and leak future news, #992/#1007).
+    pub_date = None
+    ts = article.get("providerPublishTime")
+    if ts:
+        # Epoch seconds are UTC; parse them as UTC-aware so filtering does
+        # not shift with the host timezone (#1126).
+        with contextlib.suppress(ValueError, OSError, TypeError):
+            pub_date = datetime.fromtimestamp(ts, tz=UTC)
+    return {
+        "title": article.get("title") or "No title",
+        "summary": article.get("summary") or "",
+        "publisher": article.get("publisher") or "Unknown",
+        "link": article.get("link") or "",
+        "pub_date": pub_date,
+    }
 
 
 def get_news_yfinance(