pre-register nemotron

Signed-off-by: Bryan Bednarski <bbednarski@nvidia.com>

Author: bbednarski9

packages/nvidia_nat_langchain/src/nat/plugins/langchain/llm.py

@@ -169,9 +169,20 @@ async def azure_openai_langchain(llm_config: AzureOpenAIModelConfig, _builder: B
 async def nim_langchain(llm_config: NIMModelConfig, _builder: Builder):
 
     from langchain_nvidia_ai_endpoints import ChatNVIDIA
+    from langchain_nvidia_ai_endpoints._statics import MODEL_TABLE, Model
 
     validate_no_responses_api(llm_config, LLMFrameworkEnum.LANGCHAIN)
 
+    # Pre-register unknown models so ChatNVIDIA skips the /v1/models API
+    # call. This guards against upstream issues such as duplicate entries
+    # in the API response that cause ChatNVIDIA to crash with AssertionError.
+    if llm_config.model_name not in MODEL_TABLE:
+        MODEL_TABLE[llm_config.model_name] = Model(
+            id=llm_config.model_name,
+            model_type="chat",
+            client="ChatNVIDIA",
+        )
+
     # prefer max_completion_tokens over max_tokens
     # verify_ssl is a supported keyword parameter for the ChatNVIDIA client
     client = ChatNVIDIA(