Fix: resolve default region-specific model initialization in default agent settings

Author: cerashdan

src/strands/models/bedrock.py

@@ -29,7 +29,7 @@
 logger = logging.getLogger(__name__)
 
 DEFAULT_BEDROCK_REGION = "us-west-2"
-DEFAULT_BEDROCK_MODEL_ID = "us.anthropic.claude-sonnet-4-20250514-v1:0"
+DEFAULT_BEDROCK_MODEL_ID = "anthropic.claude-sonnet-4-20250514-v1:0"
 
 BEDROCK_CONTEXT_WINDOW_OVERFLOW_MESSAGES = [
     "Input is too long for requested model",
@@ -137,7 +137,11 @@ def __init__(
         # get default model id based on resolved region
         resolved_model_id = self._get_default_model_for_region(resolved_region)
         if resolved_model_id == "":
-            raise ValueError("default model {} is not available in {} region. Specify another model".format(DEFAULT_BEDROCK_MODEL_ID, resolved_region))
+            raise ValueError(
+                "default model {} is not available in {} region. Specify another model".format(
+                    DEFAULT_BEDROCK_MODEL_ID, resolved_region
+                )
+            )
 
         self.config = BedrockModel.BedrockConfig(model_id=resolved_model_id)
         self.update_config(**model_config)
@@ -357,15 +361,18 @@ def _generate_redaction_events(self) -> list[StreamEvent]:
         return events
 
     def _get_default_model_for_region(self, region: str) -> str:
-        client = boto3.client("bedrock", region_name=region)
-        response = client.list_inference_profiles()
-        inferenceProfileSummary = response["inferenceProfileSummaries"]
-        
-        for profile in inferenceProfileSummary:
-            if DEFAULT_BEDROCK_MODEL_ID in profile["inferenceProfileId"]:
-                return profile["inferenceProfileId"]
-
-        return ""
+        try:
+            client = boto3.client("bedrock", region_name=region)
+            response = client.list_inference_profiles()
+            inference_profile_summary = response["inferenceProfileSummaries"]
+
+            for profile in inference_profile_summary:
+                if DEFAULT_BEDROCK_MODEL_ID in profile["inferenceProfileId"]:
+                    return str(profile["inferenceProfileId"])
+
+            return ""
+        except ClientError as e:
+            raise e
 
     @override
     async def stream(

tests/strands/agent/test_agent.py

@@ -211,7 +211,7 @@ def test_agent__init__with_default_model():
     agent = Agent()
 
     assert isinstance(agent.model, BedrockModel)
-    assert agent.model.config["model_id"] == DEFAULT_BEDROCK_MODEL_ID
+    assert agent.model.config["model_id"] and DEFAULT_BEDROCK_MODEL_ID in agent.model.config["model_id"]
 
 
 def test_agent__init__with_explicit_model(mock_model):
@@ -891,7 +891,9 @@ def test_agent__del__(agent):
 def test_agent_init_with_no_model_or_model_id():
     agent = Agent()
     assert agent.model is not None
-    assert agent.model.get_config().get("model_id") == DEFAULT_BEDROCK_MODEL_ID
+    assert agent.model.get_config().get("model_id") and DEFAULT_BEDROCK_MODEL_ID in agent.model.get_config().get(
+        "model_id"
+    )
 
 
 def test_agent_tool_no_parameter_conflict(agent, tool_registry, mock_randint, agenerator):