fix(llm_clients): standardize Google API key to unified api_key param

GoogleClient now accepts the unified `api_key` parameter used by
OpenAI and Anthropic clients, mapping it to the provider-specific
`google_api_key` that ChatGoogleGenerativeAI expects. Legacy
`google_api_key` still works for backward compatibility.

Resolves TODO.md item #2 (inconsistent parameter handling).

tests/test_google_api_key.py

@@ -0,0 +1,39 @@
+import unittest
+from unittest.mock import patch
+
+
+class TestGoogleApiKeyStandardization(unittest.TestCase):
+    """Verify GoogleClient accepts unified api_key parameter."""
+
+    @patch("tradingagents.llm_clients.google_client.NormalizedChatGoogleGenerativeAI")
+    def test_api_key_mapped_to_google_api_key(self, mock_chat):
+        from tradingagents.llm_clients.google_client import GoogleClient
+
+        client = GoogleClient("gemini-2.5-flash", api_key="test-key-123")
+        client.get_llm()
+        call_kwargs = mock_chat.call_args[1]
+        self.assertEqual(call_kwargs["google_api_key"], "test-key-123")
+
+    @patch("tradingagents.llm_clients.google_client.NormalizedChatGoogleGenerativeAI")
+    def test_legacy_google_api_key_still_works(self, mock_chat):
+        from tradingagents.llm_clients.google_client import GoogleClient
+
+        client = GoogleClient("gemini-2.5-flash", google_api_key="legacy-key-456")
+        client.get_llm()
+        call_kwargs = mock_chat.call_args[1]
+        self.assertEqual(call_kwargs["google_api_key"], "legacy-key-456")
+
+    @patch("tradingagents.llm_clients.google_client.NormalizedChatGoogleGenerativeAI")
+    def test_api_key_takes_precedence_over_google_api_key(self, mock_chat):
+        from tradingagents.llm_clients.google_client import GoogleClient
+
+        client = GoogleClient(
+            "gemini-2.5-flash", api_key="unified", google_api_key="legacy"
+        )
+        client.get_llm()
+        call_kwargs = mock_chat.call_args[1]
+        self.assertEqual(call_kwargs["google_api_key"], "unified")
+
+
+if __name__ == "__main__":
+    unittest.main()

tradingagents/llm_clients/TODO.md

@@ -5,14 +5,9 @@
 ### 1. `validate_model()` is never called
 - Add validation call in `get_llm()` with warning (not error) for unknown models
 
-### 2. Inconsistent parameter handling
-| Client | API Key Param | Special Params |
-|--------|---------------|----------------|
-| OpenAI | `api_key` | `reasoning_effort` |
-| Anthropic | `api_key` | `thinking_config` → `thinking` |
-| Google | `google_api_key` | `thinking_budget` |
-
-**Fix:** Standardize with unified `api_key` that maps to provider-specific keys
+### 2. ~~Inconsistent parameter handling~~ (Fixed)
+- GoogleClient now accepts unified `api_key` and maps it to `google_api_key`
+- Legacy `google_api_key` still works for backward compatibility
 
 ### 3. `base_url` accepted but ignored
 - `AnthropicClient`: accepts `base_url` but never uses it

tradingagents/llm_clients/google_client.py

@@ -27,10 +27,16 @@ class GoogleClient(BaseLLMClient):
         """Return configured ChatGoogleGenerativeAI instance."""
         llm_kwargs = {"model": self.model}
 
-        for key in ("timeout", "max_retries", "google_api_key", "callbacks", "http_client", "http_async_client"):
+        for key in ("timeout", "max_retries", "callbacks", "http_client", "http_async_client"):
             if key in self.kwargs:
                 llm_kwargs[key] = self.kwargs[key]
 
+        # Unified api_key maps to provider-specific google_api_key
+        if "api_key" in self.kwargs:
+            llm_kwargs["google_api_key"] = self.kwargs["api_key"]
+        elif "google_api_key" in self.kwargs:
+            llm_kwargs["google_api_key"] = self.kwargs["google_api_key"]
+
         # Map thinking_level to appropriate API param based on model
         # Gemini 3 Pro: low, high
         # Gemini 3 Flash: minimal, low, medium, high