Dependent on : UiPath/uipath-python#1761 for uipath-core package

Summary

Adds a LangChain / LangGraph governance adapter to uipath-langchain. It lets UiPath governance evaluate what a LangChain chain or LangGraph agent does at the model and tool level, and block disallowed actions, without the agent author writing governance code. This package contains only the LangChain-specific bridge.

What it does

• Detects LangChain Runnable and LangGraph CompiledStateGraph objects and wraps them with a governance proxy.
• Hooks the model and tool lifecycle via LangChain's callback system and maps each event to a governance check:

  LangChain event	Governance hook
  on_llm_start / on_chat_model_start	BEFORE_MODEL
  on_llm_end	AFTER_MODEL
  on_tool_start	TOOL_CALL
  on_tool_end	AFTER_TOOL

• Enforces by letting a GovernanceBlockException (raised on a DENY decision) propagate to stop the model call or tool. Any other error in the hook is logged and swallowed, so a governance failure cannot break an otherwise-healthy run.

What it does not do

• Does not fire agent-level boundaries (BEFORE_AGENT / AFTER_AGENT); those are owned by the governance host.
• Does not depend on platform, auth, transport, or runtime internals — only on the shared governance contracts.

Development Package

• Use uipath pack --nolock to get the latest dev build from this PR (requires version range).
• Add this package as a dependency in your pyproject.toml:

[project]
dependencies = [
  # Exact version:
  "uipath-langchain==0.13.19.dev1008995123",

  # Any version from PR
  "uipath-langchain>=0.13.19.dev1008990000,<0.13.19.dev1009000000"
]

[[tool.uv.index]]
name = "testpypi"
url = "https://test.pypi.org/simple/"
publish-url = "https://test.pypi.org/legacy/"
explicit = true

[tool.uv.sources]
uipath-langchain = { index = "testpypi" }

[tool.uv]
override-dependencies = [
    "uipath-langchain>=0.13.19.dev1008990000,<0.13.19.dev1009000000",
]