Add validation on LLM provider param.

proxy/routes/proxy.py

@@ -1,11 +1,32 @@
 """Proxy service to forward requests to the appropriate language model provider"""
 
-from fastapi import APIRouter
+from enum import Enum
+
+from fastapi import APIRouter, HTTPException
 
 proxy = APIRouter()
 
 
+class LLMProvider(str, Enum):
+    """Supported language model providers"""
+
+    OPEN_AI = "openai"
+    ANTHROPIC = "anthropic"
+
+    @classmethod
+    def is_valid(cls, provider: str) -> bool:
+        """Check if a provider is a valid LLM provider"""
+        return provider in {provider.value for provider in cls}
+
+
 @proxy.post("/{username}/{dataset_name}/{llm_provider}")
 async def chat_completion(username: str, dataset_name: str, llm_provider: str):
     """Proxy call to a language model provider"""
+
+    if not LLMProvider.is_valid(llm_provider):
+        raise HTTPException(
+            status_code=400,
+            detail=f"Unsupported LLM provider '{llm_provider}'.",
+        )
+
     return {"message": f"Upload {dataset_name} for {username} to {llm_provider}"}