feat(reflection): configurable alpha benchmark for non-US tickers

SPY was hardcoded as the alpha benchmark in both the return-fetch
path and the reflection label, which produced meaningless alpha for
.NS / .T / .HK / .L / .TO / .AX / .BO listings — FX drift between a
local-currency stock and a USD index dominates the spread.

DEFAULT_CONFIG now exposes benchmark_ticker (explicit override) and
benchmark_map (suffix → regional index, with SPY as the empty-suffix
default). TRADINGAGENTS_BENCHMARK_TICKER joins the env-overlay table.
Trading graph resolves the benchmark once per ticker and threads it
through to both _fetch_returns and reflect_on_final_decision, so the
alpha label reads "Alpha vs ^N225" for Tokyo listings, "Alpha vs ^HSI"
for Hong Kong, etc., instead of the misleading "Alpha vs SPY".

tests/test_memory_log.py

@@ -535,6 +535,93 @@ class TestDeferredReflection:
         assert raw is not None and alpha is not None and days is not None
         assert days == 2
 
+    # TradingAgentsGraph._resolve_benchmark — picks index for alpha calc
+
+    def test_resolve_benchmark_explicit_override(self):
+        """config['benchmark_ticker'] wins for every ticker."""
+        mock_graph = MagicMock(spec=TradingAgentsGraph)
+        mock_graph.config = {
+            "benchmark_ticker": "QQQ",
+            "benchmark_map": {"": "SPY", ".T": "^N225"},
+        }
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "7203.T") == "QQQ"
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "NVDA") == "QQQ"
+
+    def test_resolve_benchmark_suffix_map(self):
+        """Known suffixes route to their regional index."""
+        mock_graph = MagicMock(spec=TradingAgentsGraph)
+        mock_graph.config = {
+            "benchmark_ticker": None,
+            "benchmark_map": {
+                ".T": "^N225", ".HK": "^HSI", ".NS": "^NSEI",
+                ".L": "^FTSE", ".TO": "^GSPTSE", ".AX": "^AXJO",
+                ".BO": "^BSESN", "": "SPY",
+            },
+        }
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "7203.T") == "^N225"
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "0700.HK") == "^HSI"
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "RELIANCE.NS") == "^NSEI"
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "AZN.L") == "^FTSE"
+
+    def test_resolve_benchmark_us_ticker_defaults_to_spy(self):
+        """US tickers (no dotted suffix) take the empty-suffix entry."""
+        mock_graph = MagicMock(spec=TradingAgentsGraph)
+        mock_graph.config = {
+            "benchmark_ticker": None,
+            "benchmark_map": {"": "SPY", ".T": "^N225"},
+        }
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "NVDA") == "SPY"
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "AAPL") == "SPY"
+
+    def test_resolve_benchmark_unknown_suffix_falls_back(self):
+        """Unrecognised suffix (BRK.B, FAKE.XX) falls back to SPY."""
+        mock_graph = MagicMock(spec=TradingAgentsGraph)
+        mock_graph.config = {
+            "benchmark_ticker": None,
+            "benchmark_map": {"": "SPY", ".T": "^N225"},
+        }
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "FAKE.XX") == "SPY"
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "BRK.B") == "SPY"
+
+    def test_resolve_benchmark_case_insensitive(self):
+        """Suffix matching is case-insensitive so 7203.t resolves like 7203.T."""
+        mock_graph = MagicMock(spec=TradingAgentsGraph)
+        mock_graph.config = {
+            "benchmark_ticker": None,
+            "benchmark_map": {".T": "^N225", "": "SPY"},
+        }
+        assert TradingAgentsGraph._resolve_benchmark(mock_graph, "7203.t") == "^N225"
+
+    def test_reflector_includes_benchmark_in_label(self):
+        """benchmark_name appears in the prompt label, not 'SPY' hardcoded."""
+        mock_llm = MagicMock()
+        mock_llm.invoke.return_value.content = "Directionally correct."
+        reflector = Reflector(mock_llm)
+        reflector.reflect_on_final_decision(
+            final_decision=DECISION_BUY,
+            raw_return=0.05,
+            alpha_return=0.02,
+            benchmark_name="^N225",
+        )
+        messages = mock_llm.invoke.call_args[0][0]
+        human_content = next(content for role, content in messages if role == "human")
+        assert "Alpha vs ^N225:" in human_content
+        assert "Alpha vs SPY:" not in human_content
+
+    def test_reflector_defaults_to_spy_for_unupdated_callers(self):
+        """Default benchmark_name keeps the SPY label for legacy callers."""
+        mock_llm = MagicMock()
+        mock_llm.invoke.return_value.content = "ok"
+        reflector = Reflector(mock_llm)
+        reflector.reflect_on_final_decision(
+            final_decision=DECISION_BUY,
+            raw_return=0.05,
+            alpha_return=0.02,
+        )
+        messages = mock_llm.invoke.call_args[0][0]
+        human_content = next(content for role, content in messages if role == "human")
+        assert "Alpha vs SPY:" in human_content
+
     # TradingAgentsGraph._resolve_pending_entries
 
     def test_resolve_skips_other_tickers(self, tmp_path):