diff --git a/src/quant_platform_kit/common/runtime_config.py b/src/quant_platform_kit/common/runtime_config.py
index 907bd271..ad93034f 100644
--- a/src/quant_platform_kit/common/runtime_config.py
+++ b/src/quant_platform_kit/common/runtime_config.py
@@ -39,6 +39,38 @@ def resolve_bool_value(raw_value: str | None) -> bool:
     return str(raw_value or "").strip().lower() in {"1", "true", "yes", "y", "on"}
 
 
+def resolve_optional_bool_env(
+    env: Mapping[str, str | None],
+    name: str,
+) -> bool | None:
+    raw_value = env.get(name)
+    if raw_value is None or str(raw_value).strip() == "":
+        return None
+    return resolve_bool_value(raw_value)
+
+
+def resolve_cash_only_execution_env(
+    env: Mapping[str, str | None],
+    *,
+    platform_env_prefix: str | None = None,
+    legacy_name: str = "CASH_ONLY_EXECUTION",
+    default: bool = True,
+) -> bool:
+    """Resolve cash-only execution with platform-specific override precedence."""
+    candidates: list[str] = []
+    prefix = str(platform_env_prefix or "").strip().upper()
+    if prefix:
+        candidates.append(f"{prefix}_CASH_ONLY_EXECUTION")
+    legacy = str(legacy_name or "").strip()
+    if legacy:
+        candidates.append(legacy)
+    for name in candidates:
+        value = resolve_optional_bool_env(env, name)
+        if value is not None:
+            return value
+    return default
+
+
 def resolve_dry_run_env(
     env: Mapping[str, str | None],
     name: str,
diff --git a/tests/test_runtime_config.py b/tests/test_runtime_config.py
index 234f4325..4acdaaf6 100644
--- a/tests/test_runtime_config.py
+++ b/tests/test_runtime_config.py
@@ -7,8 +7,10 @@
 from quant_platform_kit.common.runtime_config import (
     first_non_empty,
     resolve_bool_value,
+    resolve_cash_only_execution_env,
     resolve_dry_run_env,
     resolve_float_env,
+    resolve_optional_bool_env,
     resolve_optional_float_env,
     resolve_quantity_step_env,
     resolve_strategy_config_path,
@@ -200,6 +202,28 @@ def test_resolve_strategy_runtime_path_settings_prefers_env_over_derived_paths(s
             self.assertEqual(settings.strategy_config_source, "env")
             self.assertIsNone(settings.reconciliation_output_path)
 
+    def test_resolve_cash_only_execution_env_prefers_platform_override(self) -> None:
+        env = {
+            "CASH_ONLY_EXECUTION": "false",
+            "IBKR_CASH_ONLY_EXECUTION": "true",
+            "SCHWAB_CASH_ONLY_EXECUTION": "false",
+        }
+        self.assertTrue(
+            resolve_cash_only_execution_env(env, platform_env_prefix="IBKR")
+        )
+        self.assertFalse(
+            resolve_cash_only_execution_env(env, platform_env_prefix="SCHWAB")
+        )
+        self.assertFalse(resolve_cash_only_execution_env(env))
+        self.assertTrue(
+            resolve_cash_only_execution_env({}, platform_env_prefix="IBKR")
+        )
+
+    def test_resolve_optional_bool_env_treats_blank_as_unset(self) -> None:
+        self.assertIsNone(resolve_optional_bool_env({"FLAG": ""}, "FLAG"))
+        self.assertIsNone(resolve_optional_bool_env({}, "FLAG"))
+        self.assertFalse(resolve_optional_bool_env({"FLAG": "false"}, "FLAG"))
+
 
 if __name__ == "__main__":
     unittest.main()