> ## Documentation Index
> Fetch the complete documentation index at: https://ctrlrun.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# LangGraph with interrupt()

> Route a refund's approval through LangGraph's own interrupt(): the operator builds the Control.

A LangGraph agent issues refunds from a node. When the policy says a human must approve, the
request should surface as the graph's own interrupt, where your operators already answer, and
the yes must not be reusable for a different amount. The adapter buys exactly that and nothing
else; `@protect` alone already covers the node.

## The policy

```yaml runnable theme={null}
schema: ctrlrun.policy/v2

actions:
  stripe.refund:
    effect: "refund:{payment_id}"
    rules:
      - when: { amount_gte: 0, amount_lte: 50000 }
        decision: allow
      - decision: approve
```

## The code

This is the adapter's own example. It needs `pip install ctrlrun-langgraph` and a LangGraph
install, which the harness that runs the other recipes does not have; the adapter's tests run
this shape against a real `langgraph` in this repository's CI, and the adapter's README carries
the conformance results.

```python theme={null}
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.graph import START, StateGraph
from langgraph.types import Command

from ctrlrun import Control, InterruptApprovalProvider, Policy, SQLiteStateStore, context, protect
from ctrlrun_langgraph import LangGraphInterrupt

store = SQLiteStateStore(".ctrlrun/state.db")
control = Control(
    Policy.from_file("ctrlrun.yaml"),
    store,
    approvals=InterruptApprovalProvider(store, LangGraphInterrupt(carries_approved_arguments=True)),
)


@protect("stripe.refund", effect="refund:{payment_id}", wait=True, control=control)
def issue_refund(payment_id: str, amount: int) -> str:
    return stripe.Refund.create(payment_intent=payment_id, amount=amount).status


def refund_node(state: dict) -> dict:
    with context(agent="refund-agent"):
        return {"status": issue_refund(payment_id=state["payment_id"], amount=state["amount"])}


graph = StateGraph(dict).add_node("refund", refund_node).add_edge(START, "refund").compile(
    checkpointer=InMemorySaver()
)
config = {"configurable": {"thread_id": "ticket-4471"}}

result = graph.invoke({"payment_id": "txn_2", "amount": 250000}, config)
if "__interrupt__" in result:
    pending = graph.get_state(config).tasks[0].interrupts[0].value
    # `pending` is JSON: request_id, action_id, action, action_hash, arguments, resource,
    # environment, agent, user, created_at, expires_at. Show it to a human.
    result = graph.invoke(
        Command(resume={"approved": True, "approver": "ada@example.com", "arguments": pending["arguments"]}),
        config,
    )
print(result["status"])
```

## What the agent sees

The €2,500 refund interrupts the graph with a payload naming the action and its arguments.
Resuming with `approved: True` and the arguments the human saw runs it once. Resuming with
different arguments is refused with `ApprovalMismatch`, the approval is left grantable, and
nothing runs. Resuming with `approved: False` refuses and records who said no.

## The receipt

The receipt is the same shape as one from `ctrlrun approve`: `approve/committed`, approver
`ada@example.com`. The node ran twice, once to ask and once on resume, so the log holds two
`action_id`s and two approval requests for one refund; the `action_hash` is continuous, which is
why the binding is about content and never about an id.

## When an AMBIGUOUS appears

If Stripe's reply is lost inside the resumed node, the effect is `AMBIGUOUS` and the graph's
retry, or a re-run of the thread, is refused. Resolve it with `ctrlrun resolve refund:txn_2 --committed` or `--failed`; the approval was spent on the execution, so a retry after `--failed`
needs a new interrupt.

## Next

* [Use the LangGraph adapter](/guides/langgraph-adapter): prevention versus attribution, and where LangGraph shows through.
* [Approval binding](/concepts/approval-binding) · [Get started](/get-started/quickstart) · [Why](/why).


## Related topics

- [Cookbook](/cookbook/index.md)
- [Use the LangGraph adapter](/guides/langgraph-adapter.md)
- [FrameworkInterrupt](/reference/api/FrameworkInterrupt.md)
- [Roadmap](/ROADMAP.md)
- [CTRLRun and framework human-in-the-loop](/compare/framework-hitl.md)