fix(graph): stop keeping every run's full state in the graph

- a graph reused across a backtest grid held each run's complete state for its whole life
- the state log is written from the run's own state; the ticker attribute it read is removed

tests/test_cli_display.py

@@ -35,21 +35,12 @@ def test_the_other_shapes_are_unchanged(value, expected):
     assert extract_content_string(value) == expected
 
 
-@pytest.mark.unit
-def test_the_state_log_keeps_non_ascii_readable(tmp_path):
-    """Reports can be in any language; the log is read by a person."""
-    from tradingagents.graph.trading_graph import TradingAgentsGraph
-
-    graph = object.__new__(TradingAgentsGraph)
-    graph.config = {"results_dir": str(tmp_path)}
-    graph.ticker = "600519.SS"
-    graph.log_states_dict = {}
-
-    graph._log_state("2026-09-01", {
-        "company_of_interest": "600519.SS", "trade_date": "2026-09-01",
+def _state(ticker, final="评级: 买入"):
+    return {
+        "company_of_interest": ticker, "trade_date": "2026-09-01",
         "market_report": "市场", "sentiment_report": "情绪", "news_report": "新闻",
         "fundamentals_report": "基本面", "investment_plan": "计划",
-        "trader_investment_plan": "交易计划", "final_trade_decision": "评级: 买入",
+        "trader_investment_plan": "交易计划", "final_trade_decision": final,
         "investment_debate_state": {"bull_history": "", "bear_history": "", "history": "",
                                     "current_response": "", "judge_decision": "", "count": 0},
         "risk_debate_state": {"aggressive_history": "", "conservative_history": "",
@@ -57,7 +48,21 @@ def test_the_state_log_keeps_non_ascii_readable(tmp_path):
                               "latest_speaker": "", "current_aggressive_response": "",
                               "current_conservative_response": "", "current_neutral_response": "",
                               "count": 0},
-    })
+    }
+
+
+def _bare_graph(tmp_path):
+    from tradingagents.graph.trading_graph import TradingAgentsGraph
+
+    graph = object.__new__(TradingAgentsGraph)
+    graph.config = {"results_dir": str(tmp_path)}
+    return graph
+
+
+@pytest.mark.unit
+def test_the_state_log_keeps_non_ascii_readable(tmp_path):
+    """Reports can be in any language; the log is read by a person."""
+    _bare_graph(tmp_path)._log_state("2026-09-01", _state("600519.SS"))
 
     written = next(tmp_path.rglob("full_states_log*.json")).read_text(encoding="utf-8")
     assert "买入" in written

tests/test_graph_end_to_end.py

@@ -153,3 +153,16 @@ def test_an_interrupted_run_resumes_from_its_checkpoint(tmp_path, monkeypatch, o
     _graph(tmp_path / "fresh", monkeypatch, full_run).propagate("NVDA", TRADE_DATE)
     # The resumed run makes only the calls the interrupted one had not completed.
     assert resumed_calls == len(full_run.calls) - (model.fail_at - 1)
+
+
+@pytest.mark.unit
+def test_a_graph_reused_across_runs_keeps_no_run_state(tmp_path, monkeypatch, offline):
+    """A backtest reuses one graph over its whole grid; holding every run's full
+    state would grow without bound."""
+    graph = _graph(tmp_path, monkeypatch, ScriptedModel())
+    for trade_date in ("2026-01-08", TRADE_DATE):
+        graph.propagate("NVDA", trade_date)
+
+    held = [v for v in vars(graph).values() if isinstance(v, dict) and TRADE_DATE in v]
+    assert held == []
+    assert len(list(tmp_path.glob("results/NVDA/TradingAgentsStrategy_logs/*.json"))) == 2

tests/test_memory_log.py

@@ -932,7 +932,6 @@ class TestLegacyRemoval:
         }
         mock_graph = MagicMock()
         mock_graph.memory_log = TradingMemoryLog({"memory_log_path": str(tmp_path / "mem.md")})
-        mock_graph.log_states_dict = {}
         mock_graph.debug = False
         mock_graph.config = {"results_dir": str(tmp_path)}
         mock_graph.graph.invoke.return_value = fake_state