cap|fence
v0.1 · private betaGitHub

LangGraph Integration

CapFence integrates with LangGraph by wrapping tools before they are passed to graph nodes. Enforcement applies at every tool invocation, including within loops and conditional branches.

Installation

shellscript
pip install "capfence[langchain]"

Wrapping tools for a graph

python
from capfence import CapFenceTool
from langchain.tools import ShellTool
from langgraph.prebuilt import create_react_agent

safe_shell = CapFenceTool(
    tool=ShellTool(),
    agent_id="graph-agent",
    capability="shell.execute",
    policy_path="policies/shell.yaml"
)

# Pass wrapped tools to the graph agent
graph = create_react_agent(model, tools=[safe_shell])

Manual graph nodes

When defining graph nodes manually, gate tool calls within the node function:

python
from capfence import ActionRuntime, ActionEvent
from langgraph.graph import StateGraph

runtime = ActionRuntime.from_policy("policies/shell.yaml")

def tool_node(state):
    command = state["command"]
    
    # Formulate the governed event
    event = ActionEvent.create(
        actor="graph-agent",
        action="execute",
        resource="shell",
        environment="production",
        payload={"command": command}
    )
    
    verdict = runtime.execute(event)
    if not verdict.authorized:
        return {"error": f"Blocked: {verdict.reason}"}
        
    # execute tool
    output = run_shell(command)
    return {"output": output}

builder = StateGraph(MyState)
builder.add_node("tool", tool_node)

Multi-agent graphs

In graphs where one agent hands off to another, propagate the agent lineage:

python
event = ActionEvent.create(
    actor="executor-agent",
    action="write",
    resource="database",
    environment="production",
    payload={"query": sql}
)
verdict = runtime.execute(event)

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