fix(broker): get_latest_price uses market-data API (was always 0)

get_latest_price queried TradingClient.get_asset (asset metadata — no price fields) so it ALWAYS returned Decimal('0'). Every Kevin signal was priced 0, so the executor skipped them ("No current price") even after the Phase 1 sizing fix; the market-closed deferral masked it until the market-open drain.

Use StockHistoricalDataClient.get_stock_latest_trade with a daily-bar close fallback — both return the last session's data, so they work when the market is closed (Kevin posts at all hours). Validated live: MRVL 263.16, AVGO 385.10 with the market closed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_broker.py

@@ -164,13 +164,71 @@ def mock_client() -> MagicMock:
 
 
 @pytest.fixture
-def broker(mock_client: MagicMock) -> AlpacaBroker:
-    """Return an ``AlpacaBroker`` whose internal client is mocked."""
-    with patch("shared.broker.alpaca_broker.TradingClient", return_value=mock_client):
+def mock_data_client() -> MagicMock:
+    """Return a mocked ``StockHistoricalDataClient`` (market-data API)."""
+    return MagicMock()
+
+
+@pytest.fixture
+def broker(mock_client: MagicMock, mock_data_client: MagicMock) -> AlpacaBroker:
+    """Return an ``AlpacaBroker`` whose internal clients are mocked."""
+    with (
+        patch("shared.broker.alpaca_broker.TradingClient", return_value=mock_client),
+        patch(
+            "shared.broker.alpaca_broker.StockHistoricalDataClient",
+            return_value=mock_data_client,
+        ),
+    ):
         b = AlpacaBroker(api_key="test-key", secret_key="test-secret", paper=True)
     return b
 
 
+# ---------------------------------------------------------------------------
+# get_latest_price — market-data API (works when market closed)
+# ---------------------------------------------------------------------------
+
+
+class TestGetLatestPrice:
+    @pytest.mark.asyncio
+    async def test_returns_latest_trade_price(
+        self, broker: AlpacaBroker, mock_data_client: MagicMock
+    ) -> None:
+        from decimal import Decimal
+
+        trade = MagicMock()
+        trade.price = 263.16
+        mock_data_client.get_stock_latest_trade.return_value = {"MRVL": trade}
+
+        price = await broker.get_latest_price("MRVL")
+        assert price == Decimal("263.16")
+
+    @pytest.mark.asyncio
+    async def test_falls_back_to_daily_bar_close(
+        self, broker: AlpacaBroker, mock_data_client: MagicMock
+    ) -> None:
+        from decimal import Decimal
+
+        mock_data_client.get_stock_latest_trade.side_effect = Exception("no quote")
+        bar = MagicMock()
+        bar.close = 263.47
+        mock_data_client.get_stock_bars.return_value = MagicMock(data={"MRVL": [bar]})
+
+        price = await broker.get_latest_price("MRVL")
+        assert price == Decimal("263.47")
+
+    @pytest.mark.asyncio
+    async def test_returns_zero_when_all_lookups_fail(
+        self, broker: AlpacaBroker, mock_data_client: MagicMock
+    ) -> None:
+        from decimal import Decimal
+
+        mock_data_client.get_stock_latest_trade.side_effect = Exception("x")
+        mock_data_client.get_stock_bars.side_effect = Exception("y")
+
+        price = await broker.get_latest_price("MRVL")
+        assert price == Decimal("0")
+
+
 # ---------------------------------------------------------------------------
 # Order submission
 # ---------------------------------------------------------------------------