langgraph-interrupt-pattern

name	langgraph-interrupt-pattern
description	Use when implementing LangGraph workflows that need to pause for user input or external confirmation before continuing execution

LangGraph Interrupt Pattern

Overview

Pattern for using LangGraph interrupt() to pause graph execution at a node and resume after receiving external input (e.g., user confirmation, selection).

Prerequisites

• A checkpointer must be configured (MemorySaver for dev, AsyncPostgresSaver for production)
• Use a consistent thread_id in the config across stream and resume calls

Pattern

Pausing execution

from langgraph.types import interrupt

def my_node(state):
    # Do work, then pause for input
    user_input = interrupt({
        "reason": "need_selection",
        "options": ["option_a", "option_b"],
        "context": "Choose which path to take"
    })

    # Execution resumes here after user responds
    match user_input.get("action"):
        case "select":
            selected = user_input["selected"]
            return state.model_copy(update={"selected": selected})
        case "skip":
            return state

Resuming execution

from langgraph.types import Command

# Resume the graph with user's response
async for event in graph.astream_events(
    Command(resume={"action": "select", "selected": chosen_item}),
    config={"configurable": {"thread_id": thread_id}},
    version="v2",
):
    # Process streamed events
    pass

Extracting interrupt data from state

state_snapshot = await graph.aget_state(config)

for task in state_snapshot.tasks:
    for intr in task.interrupts:
        payload = intr.value  # The dict passed to interrupt()
        reason = payload.get("reason")
        options = payload.get("options")

Common Mistakes

Mistake	Fix
No checkpointer configured	interrupt() silently fails without a checkpointer
Different thread_id on resume	Must match the original stream's thread_id
Passing full state to astream_events on resume	Pass Command(resume=...) only, not the state
Forgetting to handle the resume value	interrupt() returns whatever was passed in Command(resume=...)