diff --git a/tests/conftest.py b/tests/conftest.py
index 504ffb12d..5983446f5 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -19,6 +19,8 @@ _API_KEY_ENV_VARS = (
     "DEEPSEEK_API_KEY",
     "DASHSCOPE_API_KEY",
     "ZHIPU_API_KEY",
+    "MINIMAX_API_KEY",
+    "MINIMAX_CN_API_KEY",
     "OPENROUTER_API_KEY",
     "AZURE_OPENAI_API_KEY",
     "ALPHA_VANTAGE_API_KEY",
diff --git a/tests/test_dataflows_config.py b/tests/test_dataflows_config.py
new file mode 100644
index 000000000..ab0800eee
--- /dev/null
+++ b/tests/test_dataflows_config.py
@@ -0,0 +1,61 @@
+"""Config isolation: get/set must not leak nested-dict references."""
+
+import copy
+import unittest
+
+import pytest
+
+import tradingagents.default_config as default_config
+from tradingagents.dataflows.config import get_config, set_config
+
+
+@pytest.mark.unit
+class DataflowsConfigIsolationTests(unittest.TestCase):
+    def setUp(self):
+        set_config(copy.deepcopy(default_config.DEFAULT_CONFIG))
+
+    def test_get_config_returns_deep_copy(self):
+        cfg = get_config()
+        cfg["data_vendors"]["core_stock_apis"] = "alpha_vantage"
+        cfg["tool_vendors"]["get_stock_data"] = "alpha_vantage"
+
+        fresh = get_config()
+        self.assertEqual(fresh["data_vendors"]["core_stock_apis"], "yfinance")
+        self.assertNotIn("get_stock_data", fresh["tool_vendors"])
+
+    def test_set_config_does_not_alias_caller_nested_dicts(self):
+        custom = copy.deepcopy(default_config.DEFAULT_CONFIG)
+        custom["data_vendors"]["core_stock_apis"] = "alpha_vantage"
+        custom["tool_vendors"]["get_stock_data"] = "alpha_vantage"
+
+        set_config(custom)
+
+        custom["data_vendors"]["core_stock_apis"] = "yfinance"
+        custom["tool_vendors"]["get_stock_data"] = "yfinance"
+
+        fresh = get_config()
+        self.assertEqual(fresh["data_vendors"]["core_stock_apis"], "alpha_vantage")
+        self.assertEqual(fresh["tool_vendors"]["get_stock_data"], "alpha_vantage")
+
+    def test_partial_nested_update_preserves_existing_defaults(self):
+        set_config(
+            {
+                "data_vendors": {
+                    "core_stock_apis": "alpha_vantage",
+                }
+            }
+        )
+
+        fresh = get_config()
+        self.assertEqual(fresh["data_vendors"]["core_stock_apis"], "alpha_vantage")
+        self.assertEqual(fresh["data_vendors"]["technical_indicators"], "yfinance")
+        self.assertEqual(fresh["data_vendors"]["fundamental_data"], "yfinance")
+        self.assertEqual(fresh["data_vendors"]["news_data"], "yfinance")
+
+    def test_nested_dict_updates_merge_one_level_deep(self):
+        set_config({"tool_vendors": {"get_stock_data": "alpha_vantage"}})
+        set_config({"tool_vendors": {"get_news": "alpha_vantage"}})
+
+        fresh = get_config()
+        self.assertEqual(fresh["tool_vendors"]["get_stock_data"], "alpha_vantage")
+        self.assertEqual(fresh["tool_vendors"]["get_news"], "alpha_vantage")
diff --git a/tradingagents/dataflows/config.py b/tradingagents/dataflows/config.py
index 5819494a3..6f3076aea 100644
--- a/tradingagents/dataflows/config.py
+++ b/tradingagents/dataflows/config.py
@@ -1,6 +1,8 @@
-import tradingagents.default_config as default_config
+from copy import deepcopy
 from typing import Dict, Optional
 
+import tradingagents.default_config as default_config
+
 # Use default config but allow it to be overridden
 _config: Optional[Dict] = None
 
@@ -9,22 +11,31 @@ def initialize_config():
     """Initialize the configuration with default values."""
     global _config
     if _config is None:
-        _config = default_config.DEFAULT_CONFIG.copy()
+        _config = deepcopy(default_config.DEFAULT_CONFIG)
 
 
 def set_config(config: Dict):
-    """Update the configuration with custom values."""
+    """Update the configuration with custom values.
+
+    Dict-valued keys (e.g. ``data_vendors``) are merged one level deep so a
+    partial update like ``{"data_vendors": {"core_stock_apis": "alpha_vantage"}}``
+    keeps the other nested keys from the default; scalar keys are replaced.
+    """
     global _config
-    if _config is None:
-        _config = default_config.DEFAULT_CONFIG.copy()
-    _config.update(config)
+    initialize_config()
+    incoming = deepcopy(config)
+    for key, value in incoming.items():
+        if isinstance(value, dict) and isinstance(_config.get(key), dict):
+            _config[key].update(value)
+        else:
+            _config[key] = value
 
 
 def get_config() -> Dict:
     """Get the current configuration."""
     if _config is None:
         initialize_config()
-    return _config.copy()
+    return deepcopy(_config)
 
 
 # Initialize with default config
diff --git a/tradingagents/graph/trading_graph.py b/tradingagents/graph/trading_graph.py
index 197913e21..949dbf654 100644
--- a/tradingagents/graph/trading_graph.py
+++ b/tradingagents/graph/trading_graph.py
@@ -116,7 +116,9 @@ class TradingAgentsGraph:
             self.conditional_logic,
         )
 
-        self.propagator = Propagator()
+        self.propagator = Propagator(
+            max_recur_limit=self.config.get("max_recur_limit", 100),
+        )
         self.reflector = Reflector(self.quick_thinking_llm)
         self.signal_processor = SignalProcessor(self.quick_thinking_llm)
 
diff --git a/tradingagents/llm_clients/openai_client.py b/tradingagents/llm_clients/openai_client.py
index 354849123..6947ad41e 100644
--- a/tradingagents/llm_clients/openai_client.py
+++ b/tradingagents/llm_clients/openai_client.py
@@ -162,6 +162,12 @@ class OpenAIClient(BaseLLMClient):
                 api_key = os.environ.get(api_key_env)
                 if api_key:
                     llm_kwargs["api_key"] = api_key
+                else:
+                    raise ValueError(
+                        f"API key for provider '{self.provider}' is not set. "
+                        f"Please set the {api_key_env} environment variable "
+                        f"(e.g. add {api_key_env}=your_key to your .env file)."
+                    )
             else:
                 llm_kwargs["api_key"] = "ollama"
         elif self.base_url: