fix: add known-third-party config for a2a and fix import ordering

Adds [tool.ruff.lint.isort] known-third-party = ["a2a"] so ruff
classifies a2a imports consistently regardless of whether a2a-sdk
is installed in the lint environment.

Author: tejaskash

pyproject.toml

@@ -86,6 +86,9 @@ select = [
 "!src/**/*.py" = ["D"]
 "src/bedrock_agentcore/memory/metadata-workflow.ipynb" = ["E501"]
 
+[tool.ruff.lint.isort]
+known-third-party = ["a2a"]
+
 [tool.ruff.lint.pydocstyle]
 convention = "google"
 

src/bedrock_agentcore/runtime/a2a.py

@@ -177,13 +177,12 @@ def build_a2a_app(
 
     _check_a2a_sdk()
 
-    from starlette.applications import Starlette
-    from starlette.responses import JSONResponse
-    from starlette.routing import Route
-
     from a2a.server.apps import A2AStarletteApplication
     from a2a.server.request_handlers import DefaultRequestHandler
     from a2a.server.tasks import InMemoryTaskStore
+    from starlette.applications import Starlette
+    from starlette.responses import JSONResponse
+    from starlette.routing import Route
 
     runtime_url = os.environ.get(AGENTCORE_RUNTIME_URL_ENV, "http://localhost:9000/")
 

tests/bedrock_agentcore/runtime/test_a2a.py

@@ -2,13 +2,13 @@
 import uuid
 from unittest.mock import patch
 
-from starlette.testclient import TestClient
-
 from a2a.server.agent_execution import AgentExecutor, RequestContext
 from a2a.server.events import EventQueue
 from a2a.server.tasks import InMemoryTaskStore, TaskUpdater
 from a2a.types import AgentCapabilities, AgentCard, AgentSkill, Part, TextPart
 from a2a.utils import new_task
+from starlette.testclient import TestClient
+
 from bedrock_agentcore.runtime.a2a import (
     BedrockCallContextBuilder,
     build_a2a_app,

tests/integration/runtime/test_a2a_integration.py

@@ -9,8 +9,6 @@
 import uuid
 
 import pytest
-from starlette.testclient import TestClient
-
 from a2a.server.agent_execution import AgentExecutor, RequestContext
 from a2a.server.events import EventQueue
 from a2a.server.tasks import TaskUpdater
@@ -24,6 +22,8 @@
 )
 from a2a.utils import new_task
 from a2a.utils.errors import ServerError
+from starlette.testclient import TestClient
+
 from bedrock_agentcore.runtime.a2a import BedrockCallContextBuilder, build_a2a_app