fix(strategy): apply saved parameters during execution

backend/app/strategy/engine.py

@@ -284,16 +284,16 @@ class StrategyEngine:
             strategy_id:        策略 ID
             as_of:              选股日期
             pool:               限定股票池
-            params:             策略参数 (用户在设置面板调的值)
-            overrides:          用户覆盖配置 (basic_filter/scoring/stop_loss 等)
+            params:             本次执行显式传入的策略参数
+            overrides:          用户覆盖配置 (params/basic_filter/scoring/stop_loss 等)
             precomputed:        已加载的 enriched 数据 (run_all 场景复用)
             precomputed_history: 已加载的历史窗口数据 (run_all 场景复用)
         """
         t0 = time.perf_counter()
 
         s = self.get(strategy_id)
-        params = params or {}
         overrides = overrides or {}
+        params = {**(overrides.get("params") or {}), **(params or {})}
 
         # 加载数据。普通策略只读目标日期；声明 filter_history 的策略读取历史窗口。
         if s.filter_history_fn:

backend/tests/test_strategy_saved_params.py

@@ -0,0 +1,48 @@
+from datetime import date
+
+import polars as pl
+
+from app.strategy.engine import StrategyDef, StrategyEngine
+
+
+def _make_engine() -> StrategyEngine:
+    df = pl.DataFrame({"symbol": ["A", "B", "C"], "value": [1, 2, 3]})
+    engine = StrategyEngine(enriched_loader=lambda _as_of: df)
+    engine._strategies["saved_params"] = StrategyDef(
+        meta={"id": "saved_params", "scoring": {}, "limit": 100},
+        basic_filter={"enabled": False},
+        entry_signals=[],
+        exit_signals=[],
+        stop_loss=None,
+        trailing_stop=None,
+        trailing_take_profit_activate=None,
+        trailing_take_profit_drawdown=None,
+        max_hold_days=None,
+        alerts=[],
+        filter_fn=lambda _df, params: pl.col("value") >= params.get("min_value", 1),
+        filter_history_fn=None,
+        lookback_days=1,
+        source="custom",
+    )
+    return engine
+
+
+def test_run_applies_saved_strategy_params():
+    result = _make_engine().run(
+        "saved_params",
+        date(2026, 7, 15),
+        overrides={"params": {"min_value": 2}},
+    )
+
+    assert [row["symbol"] for row in result.rows] == ["B", "C"]
+
+
+def test_explicit_params_override_saved_strategy_params():
+    result = _make_engine().run(
+        "saved_params",
+        date(2026, 7, 15),
+        params={"min_value": 3},
+        overrides={"params": {"min_value": 2}},
+    )
+
+    assert [row["symbol"] for row in result.rows] == ["C"]