Fix: Bedrock Application Inference ARN breaks Claude Sonnet tools usage (#561)

### Description

This PR fixes the issue when running a agent using tools with
application inference profile of Claude Sonnet 3.7 as input. Note that
using regional inference profile is working well, and only application
inference profile (AIP) will not return any tools use information.

### Root Cause

Langchain needs to identify the model id of the foundation model but
fails to detect the foundation model from the input AIP ARN (e.g.,
`arn:aws:bedrock:us-east-1:111111484058:application-inference-profile/c3myu2h6fllr`),
while regional inference profile contains the foundation model name
`us.anthropic.claude-3-7-sonnet-20250219-v1:0` and can be easily used to
identify the base model id. Therefore, regional inference profile is
working well while AIP is not.

### Solution

To identify the foundation model used in AIP, we need to call Bedrock
`get_inference_profile` control plane
[API](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/bedrock/client/get_inference_profile.html),
and parse the model id from the response.

### Issue 

#535

Author: 0x-fang

libs/aws/langchain_aws/llms/bedrock.py

@@ -591,6 +591,10 @@ class BedrockBase(BaseLanguageModel, ABC):
     """Base class for Bedrock models."""
 
     client: Any = Field(default=None, exclude=True)  #: :meta private:
+    """The bedrock runtime client for making data plane API calls"""
+    
+    bedrock_client: Any = Field(default=None, exclude=True)  #: :meta private:
+    """The bedrock client for making control plane API calls"""
 
     region_name: Optional[str] = Field(default=None, alias="region")
     """The aws region e.g., `us-west-2`. Falls back to AWS_REGION or AWS_DEFAULT_REGION 
@@ -775,6 +779,19 @@ def validate_environment(self) -> Self:
                 service_name="bedrock-runtime",
             )
 
+        # Create bedrock client for control plane API call
+        if self.bedrock_client is None:
+            self.bedrock_client = create_aws_client(
+                region_name=self.region_name,
+                credentials_profile_name=self.credentials_profile_name,
+                aws_access_key_id=self.aws_access_key_id,
+                aws_secret_access_key=self.aws_secret_access_key,
+                aws_session_token=self.aws_session_token,
+                endpoint_url=self.endpoint_url,
+                config=self.config,
+                service_name="bedrock",
+            )
+
         return self
 
     @property
@@ -815,6 +832,16 @@ def _get_provider(self) -> str:
         )
 
     def _get_base_model(self) -> str:
+        # identify the base model id used in the application inference profile (AIP)
+        # Format: arn:aws:bedrock:us-east-1:<accountId>:application-inference-profile/<id>
+        if self.base_model_id is None and 'application-inference-profile' in self.model_id:
+            response = self.bedrock_client.get_inference_profile(
+                inferenceProfileIdentifier=self.model_id
+            )
+            if 'models' in response and len(response['models']) > 0:
+                model_arn = response['models'][0]['modelArn']
+                # Format: arn:aws:bedrock:region::foundation-model/provider.model-name
+                self.base_model_id = model_arn.split('/')[-1]
         return self.base_model_id if self.base_model_id else self.model_id.split(".", maxsplit=1)[-1]
 
     @property

libs/aws/tests/unit_tests/llms/test_bedrock.py

@@ -781,3 +781,61 @@ def test__get_base_model():
         region_name="us-west-2"
     )
     assert llm._get_base_model() == "meta.llama3-8b-instruct-v1:0"
+
+
+@patch("langchain_aws.llms.bedrock.create_aws_client")
+def test_bedrock_client_creation(mock_create_client):
+    """Test that both bedrock-runtime and bedrock clients are created."""
+    mock_runtime_client = MagicMock()
+    mock_bedrock_client = MagicMock()
+    mock_create_client.side_effect = [mock_runtime_client, mock_bedrock_client]
+    
+    llm = BedrockLLM(
+        model_id="meta.llama3-8b-instruct-v1:0",
+        region_name="us-west-2"
+    )
+    
+    # Should create both clients
+    assert mock_create_client.call_count == 2
+    
+    # Check that bedrock-runtime client was created
+    calls = mock_create_client.call_args_list
+    runtime_call = calls[0]
+    assert runtime_call.kwargs["service_name"] == "bedrock-runtime"
+    assert runtime_call.kwargs["region_name"] == "us-west-2"
+    
+    # Check that bedrock client was created
+    bedrock_call = calls[1]
+    assert bedrock_call.kwargs["service_name"] == "bedrock"
+    assert bedrock_call.kwargs["region_name"] == "us-west-2"
+    
+    assert llm.client is mock_runtime_client
+    assert llm.bedrock_client is mock_bedrock_client
+
+
+@patch("langchain_aws.llms.bedrock.create_aws_client")
+def test_get_base_model_with_application_inference_profile(mock_create_client):
+    """Test _get_base_model with application inference profile."""
+    mock_runtime_client = MagicMock()
+    mock_bedrock_client = MagicMock()
+    mock_bedrock_client.get_inference_profile.return_value = {
+        "models": [
+            {"modelArn": "arn:aws:bedrock:us-east-1::foundation-model/anthropic.claude-3-sonnet-20240229-v1:0"}
+        ]
+    }
+    mock_create_client.side_effect = [mock_runtime_client, mock_bedrock_client]
+    
+    llm = BedrockLLM(
+        model_id="arn:aws:bedrock:us-east-1:123456789012:application-inference-profile/my-profile",
+        provider="anthropic",
+        region_name="us-west-2"
+    )
+    
+    result = llm._get_base_model()
+    
+    # Should call get_inference_profile and extract base model
+    mock_bedrock_client.get_inference_profile.assert_called_once_with(
+        inferenceProfileIdentifier="arn:aws:bedrock:us-east-1:123456789012:application-inference-profile/my-profile"
+    )
+    assert result == "anthropic.claude-3-sonnet-20240229-v1:0"
+    assert llm.base_model_id == "anthropic.claude-3-sonnet-20240229-v1:0"