[Issue 20] Make bedrock model ID configurable

.kiro/steering/python-agent.md

@@ -35,4 +35,14 @@ fileMatchPattern: "agent/**"
 ## Environment
 
 **LOG_LEVEL**: INFO (default), DEBUG, ERROR
+**BEDROCK_MODEL_ID**: Configure Bedrock model (see `DEFAULT_MODEL_ID` in `agentcore_app.py`)
 **AWS regions**: Auto-set by AgentCore Runtime
+
+## Model Selection
+
+**Default Model**: See `DEFAULT_MODEL_ID` constant in `agentcore_app.py`
+
+```python
+def get_model_id() -> str:
+    return os.getenv("BEDROCK_MODEL_ID", DEFAULT_MODEL_ID)
+```

.kiro/steering/tech.md

@@ -39,6 +39,12 @@ pytest && mypy src/ && ruff check --fix . && black .  # Manual validation with f
 
 **Configuration:** All settings in `agent/pyproject.toml` (line length: 100, Python 3.13, strict mode)
 
+## Model Configuration
+
+**BEDROCK_MODEL_ID**: Configure Bedrock model (see `DEFAULT_MODEL_ID` in `agent/src/agentcore_app.py`)
+**Examples**: `us.anthropic.claude-3-5-sonnet-20241022-v2:0`, `us.amazon.titan-text-express-v1`
+**Local**: Set in `.env` file | **Deploy**: CDK environment variables
+
 ## AWS Deployment
 
 **Prerequisites:** Docker running, AWS CLI configured, Bedrock access

DEPLOYMENT.md

@@ -16,6 +16,18 @@ Deploy Strands agent to AWS Bedrock AgentCore Runtime.
 
 The CI/CD pipeline requires OIDC authentication to deploy from GitHub Actions to AWS. Follow the [GitHub documentation for configuring OIDC in AWS](https://docs.github.com/en/actions/how-tos/secure-your-work/security-harden-deployments/oidc-in-aws), then add the role ARN as a repository secret named `AWS_ROLE_TO_ASSUME`.
 
+## Configuration
+
+**Model Selection** (optional): Set `BEDROCK_MODEL_ID` environment variable to use a different Bedrock model. If not provided, defaults to `us.anthropic.claude-sonnet-4-5-20250929-v1:0`.
+
+```bash
+# Local (agent/.env file)
+BEDROCK_MODEL_ID=us.anthropic.claude-3-5-sonnet-20241022-v2:0
+
+# CDK deployment (cdk/.env)
+BEDROCK_MODEL_ID=us.amazon.titan-text-express-v1
+```
+
 ## Local Testing
 
 ```bash

agent/.env.example

@@ -1,3 +1,9 @@
 # Logging Configuration
 # Options: DEBUG, INFO, WARNING, ERROR, CRITICAL
 LOG_LEVEL=INFO
+
+# Bedrock Model Configuration
+# Specify the Amazon Bedrock model ID to use for the agent
+# If not set, uses DEFAULT_MODEL_ID from src/agentcore_app.py
+# For valid model IDs, see: https://docs.aws.amazon.com/bedrock/latest/userguide/model-ids.html
+# BEDROCK_MODEL_ID=your-preferred-model-id

agent/README.md

@@ -9,6 +9,23 @@ python3.13 -m venv .venv && source .venv/bin/activate && pip install -e ".[dev]"
 python src/agentcore_app.py
 ```
 
+## Configuration
+
+**Environment Variables**: The agent automatically loads environment variables from a `.env` file when running locally (requires `python-dotenv` from dev dependencies).
+
+```bash
+# Copy the example and customize
+cp .env.example .env
+
+# Edit .env file
+BEDROCK_MODEL_ID=your-preferred-model-id
+LOG_LEVEL=DEBUG
+```
+
+**Model**: Set `BEDROCK_MODEL_ID` environment variable (see `DEFAULT_MODEL_ID` in `src/agentcore_app.py` for current default)
+
+**Available Models**: See [AWS Bedrock Model IDs documentation](https://docs.aws.amazon.com/bedrock/latest/userguide/model-ids.html)
+
 ## Adding Tools
 
 **Community Tools:**

agent/pyproject.toml

@@ -22,6 +22,7 @@ dev = [
     "ruff>=0.14.9",
     "mypy>=1.19.0",
     "black>=25.12.0",
+    "python-dotenv>=1.0.0",
 ]
 
 [tool.hatch.build.targets.wheel]

agent/src/agentcore_app.py

@@ -10,6 +10,23 @@
 
 from tools import letter_counter
 
+# Load environment variables from .env file for local development
+if os.path.exists(".env"):
+    try:
+        from dotenv import load_dotenv
+
+        load_dotenv()
+    except ImportError:
+        import warnings
+
+        warnings.warn(
+            ".env file found but python-dotenv not installed. "
+            "Install with: pip install python-dotenv",
+            UserWarning,
+            stacklevel=2,
+        )
+
+DEFAULT_MODEL_ID = "us.anthropic.claude-sonnet-4-5-20250929-v1:0"
 log_level = os.getenv("LOG_LEVEL", "INFO").upper()
 
 logging.basicConfig(
@@ -23,9 +40,22 @@
 app = BedrockAgentCoreApp()
 
 
+def get_model_id() -> str:
+    """
+    Get the Bedrock model ID from environment variable or use default.
+
+    Returns:
+        str: The model ID to use for the agent
+    """
+    model_id = os.getenv("BEDROCK_MODEL_ID", DEFAULT_MODEL_ID)
+    logging.info(f"Using Bedrock model: {model_id}")
+    return model_id
+
+
 def get_agent() -> Agent:
-    """Create and return a Strands agent with configured tools."""
-    return Agent(tools=[calculator, current_time, http_request, letter_counter])
+    """Create and return a Strands agent with configured tools and model."""
+    model_id = get_model_id()
+    return Agent(model=model_id, tools=[calculator, current_time, http_request, letter_counter])
 
 
 @app.entrypoint

agent/tests/test_agent.py

@@ -1,6 +1,9 @@
 """Tests for the agent."""
 
-from src.agentcore_app import get_agent
+import os
+from unittest.mock import patch
+
+from src.agentcore_app import DEFAULT_MODEL_ID, get_agent, get_model_id
 
 
 def test_agent_has_tools() -> None:
@@ -10,3 +13,10 @@ def test_agent_has_tools() -> None:
     assert "calculator" in tool_names
     assert "current_time" in tool_names
     assert "letter_counter" in tool_names
+
+
+def test_get_model_id_fallback() -> None:
+    """Test get_model_id returns the default when environment variable is not set."""
+    with patch.dict(os.environ, {}, clear=True):
+        model_id = get_model_id()
+        assert model_id == DEFAULT_MODEL_ID

cdk/.env.example

@@ -0,0 +1,9 @@
+# CDK Deployment Configuration
+
+# Bedrock Model ID for the agent (optional)
+# If not set, the agent will use its DEFAULT_MODEL_ID from agent/src/agentcore_app.py
+# Uncomment and set to override the default model:
+# BEDROCK_MODEL_ID=your-preferred-model-id
+
+# For a complete list of available model IDs, see:
+# https://docs.aws.amazon.com/bedrock/latest/userguide/model-ids.html

cdk/bin/cdk.ts

@@ -1,12 +1,22 @@
 #!/usr/bin/env node
+import * as dotenv from 'dotenv'
+import path from 'path'
 import { App } from 'aws-cdk-lib'
 import { StrandsAgentStack } from '../lib/strands-agent-stack'
 
-const { AWS_DEFAULT_ACCOUNT_ID, AWS_DEFAULT_REGION, CDK_DEFAULT_ACCOUNT, CDK_DEFAULT_REGION } =
-  process.env
+dotenv.config({ path: path.join(__dirname, '../.env') })
+
+const {
+  AWS_DEFAULT_ACCOUNT_ID,
+  AWS_DEFAULT_REGION,
+  CDK_DEFAULT_ACCOUNT,
+  CDK_DEFAULT_REGION,
+  BEDROCK_MODEL_ID,
+} = process.env
 
 const account = CDK_DEFAULT_ACCOUNT ?? AWS_DEFAULT_ACCOUNT_ID
 const region = CDK_DEFAULT_REGION ?? AWS_DEFAULT_REGION
+const bedrockModelID = BEDROCK_MODEL_ID ?? undefined
 
 if (!account || !region) {
   throw new Error(
@@ -19,5 +29,6 @@ if (!account || !region) {
 const app = new App()
 new StrandsAgentStack(app, 'StrandsAgentStack', {
   description: 'Demo template for strands-agents',
+  bedrockModelID,
   env: { account, region },
 })

cdk/lib/strands-agent-stack.ts

@@ -11,8 +11,12 @@ import { Construct } from 'constructs'
 import { Runtime, AgentRuntimeArtifact } from '@aws-cdk/aws-bedrock-agentcore-alpha'
 import * as path from 'path'
 
+interface StrandsAgentStackProps extends StackProps {
+  bedrockModelID?: string | undefined
+}
+
 export class StrandsAgentStack extends Stack {
-  constructor(scope: Construct, id: string, props?: StackProps) {
+  constructor(scope: Construct, id: string, props: StrandsAgentStackProps) {
     super(scope, id, props)
 
     // IAM Role for AgentCore Runtime
@@ -94,6 +98,7 @@ export class StrandsAgentStack extends Stack {
         AWS_REGION: this.region,
         AWS_DEFAULT_REGION: this.region,
         LOG_LEVEL: 'INFO',
+        ...(props.bedrockModelID && { BEDROCK_MODEL_ID: props.bedrockModelID }),
       },
     })
 

cdk/package.json

@@ -29,6 +29,7 @@
     "@types/jest": "^30.0.0",
     "@types/node": "^25.0.2",
     "aws-cdk": "^2.1034.0",
+    "dotenv": "^17.2.3",
     "eslint": "^9.17.0",
     "eslint-config-prettier": "^10.0.1",
     "jest": "^30.2.0",