Summary

• add an optional agent_control.integrations.langgraph package with lazy imports and a langgraph extra
• add create_controlled_tool_node(...) using LangGraph's public ToolNode wrapper seams with Agent Control registration, refresh, and policy evaluation
• add a sibling agent_control.integrations.langchain.AgentControlMiddleware for LangChain agent-factory middleware integration, backed by the same shared tool-control runtime
• add focused unit coverage for lazy imports, registration behavior, sync/async execution, and deny/steer handling across both integration surfaces
• add a minimal LangGraph smoke example and setup script for local validation against a live server

Closes #72.

Testing

• uv run --package agent-control pytest sdks/python/tests/test_langgraph_init.py sdks/python/tests/test_langgraph_tool_node.py sdks/python/tests/test_langchain_init.py sdks/python/tests/test_langchain_middleware.py
• make sdk-lint
• make sdk-typecheck
• uv run python -m py_compile examples/langchain/setup_langgraph_toolnode_controls.py examples/langchain/langgraph_toolnode_integration_smoke.py
• uv run ruff check examples/langchain/setup_langgraph_toolnode_controls.py examples/langchain/langgraph_toolnode_integration_smoke.py

Notes

• make sdk-test was not run because the local SDK test harness expects Postgres on localhost:5432.
• LangChain middleware applies when tool execution flows through LangChain's agent factory. Raw StateGraph / ToolNode usage still needs the LangGraph integration surface.