feat: add custom Gemini endpoint support

- Add GEMINI_BASE_URL configuration option in .env.example
- Implement custom endpoint support in GeminiModelProvider using HttpOptions
- Update registry to pass base_url parameter to Gemini provider
- Maintain backward compatibility - uses default Google endpoint when not configured

.env.example

@@ -12,6 +12,7 @@
 # Option 1: Use native APIs (recommended for direct access)
 # Get your Gemini API key from: https://makersuite.google.com/app/apikey
 GEMINI_API_KEY=your_gemini_api_key_here
+# GEMINI_BASE_URL=                            # Optional: Custom Gemini endpoint (defaults to Google's API)
 
 # Get your OpenAI API key from: https://platform.openai.com/api-keys
 OPENAI_API_KEY=your_openai_api_key_here

providers/gemini.py

@@ -117,16 +117,26 @@ class GeminiModelProvider(ModelProvider):
     }
 
     def __init__(self, api_key: str, **kwargs):
-        """Initialize Gemini provider with API key."""
+        """Initialize Gemini provider with API key and optional base URL."""
         super().__init__(api_key, **kwargs)
         self._client = None
         self._token_counters = {}  # Cache for token counting
+        self._base_url = kwargs.get('base_url', None)  # Optional custom endpoint
 
     @property
     def client(self):
         """Lazy initialization of Gemini client."""
         if self._client is None:
-            self._client = genai.Client(api_key=self.api_key)
+            # Check if custom base URL is provided
+            if self._base_url:
+                # Use HttpOptions to set custom endpoint
+                from google.genai.types import HttpOptions
+                http_options = HttpOptions(baseUrl=self._base_url)
+                logger.debug(f"Initializing Gemini client with custom endpoint: {self._base_url}")
+                self._client = genai.Client(api_key=self.api_key, http_options=http_options)
+            else:
+                # Use default Google endpoint
+                self._client = genai.Client(api_key=self.api_key)
         return self._client
 
     def get_capabilities(self, model_name: str) -> ModelCapabilities:

providers/registry.py

@@ -93,6 +93,18 @@ class ModelProviderRegistry:
                 api_key = api_key or ""
                 # Initialize custom provider with both API key and base URL
                 provider = provider_class(api_key=api_key, base_url=custom_url)
+        elif provider_type == ProviderType.GOOGLE:
+            # For Gemini, check if custom base URL is configured
+            if not api_key:
+                return None
+            gemini_base_url = os.getenv("GEMINI_BASE_URL")
+            if gemini_base_url:
+                # Initialize with custom endpoint
+                provider = provider_class(api_key=api_key, base_url=gemini_base_url)
+                logging.info(f"Initialized Gemini provider with custom endpoint: {gemini_base_url}")
+            else:
+                # Use default Google endpoint
+                provider = provider_class(api_key=api_key)
         else:
             if not api_key:
                 return None