feat: update runtime client with passthrough

[nborges-aws]

Issue #, if available: Issue #391

Description of changes:

• Add __getattr__ passthrough with accept_snake_case_kwargs to AgentCoreRuntimeClient
• Update __init__ to create cp_client and dp_client boto3 clients
• Control plane allowlisted methods (12):
  • Runtime CRUD: create_agent_runtime, get_agent_runtime, list_agent_runtimes, update_agent_runtime, delete_agent_runtime
  • Endpoint CRUD: create_agent_runtime_endpoint, get_agent_runtime_endpoint, update_agent_runtime_endpoint, delete_agent_runtime_endpoint, list_agent_runtime_endpoints
  • Other: list_agent_runtime_versions, delete_agent_runtime_version
• Data plane allowlisted methods (2):
  • invoke_agent_runtime, stop_runtime_session
• Add *_and_wait polling methods using shared wait_until/wait_until_deleted utilities:
  • create_agent_runtime_and_wait, update_agent_runtime_and_wait, delete_agent_runtime_and_wait
  • create_agent_runtime_endpoint_and_wait, update_agent_runtime_endpoint_and_wait
• Add higher-level orchestration methods:
  • get_aggregated_status — returns runtime + endpoint status in a single call
  • teardown_endpoint_and_runtime — ordered deletion: waits for endpoint deletion then deletes runtime
• All *_and_wait methods accept WaitConfig for configurable polling behavior and apply convert_kwargs for snake_case support
• Existing methods (generate_ws_connection, generate_presigned_url, generate_ws_connection_oauth) are untouched

Test plan

• Unit tests (16 new):
  • Passthrough: CP forwarding, DP forwarding, snake_case conversion, AttributeError on unknown method, CP allowlist contents, DP allowlist contents
  • *_and_wait: create_agent_runtime_and_wait (success + failure), update_agent_runtime_and_wait, delete_agent_runtime_and_wait, update_agent_runtime_endpoint_and_wait
  • Orchestration: get_aggregated_status (success, not found, reraises non-not-found), teardown_endpoint_and_runtime (success, skips missing endpoint)
• Integration tests (10 total):
  • Passthrough (3): list_agent_runtimes, list_agent_runtimes with snake_case, non-allowlisted method raises
  • Runtime + endpoint CRUD (7): create_agent_runtime_and_wait → get_agent_runtime (camelCase + snake_case) → update_agent_runtime_and_wait → create_agent_runtime_endpoint_and_wait → get_aggregated_status (verifies both runtime + endpoint READY) → teardown_endpoint_and_runtime
  • Requires RUNTIME_ROLE_ARN and RUNTIME_S3_CODE_URI environment variables

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[github-actions]

⚠️ Breaking Change Warning

Found 1 potential breaking change(s) in this PR:

�[1msrc/bedrock_agentcore/runtime/agent_core_runtime_client.py�[0m:84: AgentCoreRuntimeClient.region: �[33mAttribute value was changed�[39m: region -> validate_region(region or session.region_name or 'us-west-2')

---

Note: This is an automated static analysis check. Some flagged changes may be intentional.
Please confirm each item is expected and, if so, add a migration note to CHANGELOG.md.

[Hweinstock]

nit: should we call convert_kwargs once and re-use?

[nborges-aws]

yep I'll make this change

[Hweinstock]

would the behavior here be the same if we checked the field on the converted kwargs once?

My current understanding of the flow is we check for agentRuntimeId, then fallback to the converted ones. However, I thought converting it handled it for us here?

[nborges-aws]

You're correct, we can check the converted kwargs once with the same end behavior. I will update

[Hweinstock]

do we still need to validate the region or does boto3 handle this for us? Wondering if this opens us up to poisoning the endpoint? Context: #417

[nborges-aws]

boto3 validates the region for its client creation (raises botocore.exceptions.InvalidRegionError for malicious inputs). Self.region is used to construct the websocket URLs, but that method calls validate_region() internally, so technically we are still fine with this region construction

However, we can validate_region on the __init__ construction for safety. I'll make this change