Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://langchain-ai.github.io/langgraphjs/cloud/how-tos/human_in_the_loop_time_travel below:

Time travel using Server API

LangGraph provides the time travel functionality to resume execution from a prior checkpoint, either replaying the same state or modifying it to explore alternatives. In all cases, resuming past execution produces a new fork in the history.

To time travel using the LangGraph Server API (via the LangGraph SDK):

1. Run the graph with initial inputs using LangGraph SDK's @ or @ APIs.
2. Identify a checkpoint in an existing thread: Use @ method to retrieve the execution history for a specific thread_id and locate the desired checkpoint_id. Alternatively, set a breakpoint before the node(s) where you want execution to pause. You can then find the most recent checkpoint recorded up to that breakpoint.
3. (Optional) modify the graph state: Use the @ method to modify the graph’s state at the checkpoint and resume execution from alternative state.
4. Resume execution from the checkpoint: Use the @ or @ APIs with an input of None and the appropriate thread_id and checkpoint_id.

from typing_extensions import TypedDict, NotRequired
from langgraph.graph import StateGraph, START, END
from langchain.chat_models import init_chat_model
from langgraph.checkpoint.memory import InMemorySaver

class State(TypedDict):
    topic: NotRequired[str]
    joke: NotRequired[str]

llm = init_chat_model(
    "anthropic:claude-3-7-sonnet-latest",
    temperature=0,
)

def generate_topic(state: State):
    """LLM call to generate a topic for the joke"""
    msg = llm.invoke("Give me a funny topic for a joke")
    return {"topic": msg.content}

def write_joke(state: State):
    """LLM call to write a joke based on the topic"""
    msg = llm.invoke(f"Write a short joke about {state['topic']}")
    return {"joke": msg.content}

# Build workflow
builder = StateGraph(State)

# Add nodes
builder.add_node("generate_topic", generate_topic)
builder.add_node("write_joke", write_joke)

# Add edges to connect nodes
builder.add_edge(START, "generate_topic")
builder.add_edge("generate_topic", "write_joke")

# Compile
graph = builder.compile()

PythonJavaScriptcURL

from langgraph_sdk import get_client
client = get_client(url=<DEPLOYMENT_URL>)

# Using the graph deployed with the name "agent"
assistant_id = "agent"

# create a thread
thread = await client.threads.create()
thread_id = thread["thread_id"]

# Run the graph
result = await client.runs.wait(
    thread_id,
    assistant_id,
    input={}
)

import { Client } from "@langchain/langgraph-sdk";
const client = new Client({ apiUrl: <DEPLOYMENT_URL> });

// Using the graph deployed with the name "agent"
const assistantID = "agent";

// create a thread
const thread = await client.threads.create();
const threadID = thread["thread_id"];

// Run the graph
const result = await client.runs.wait(
  threadID,
  assistantID,
  { input: {}}
);

Create a thread:

curl --request POST \
--url <DEPLOYMENT_URL>/threads \
--header 'Content-Type: application/json' \
--data '{}'

Run the graph:

curl --request POST \
--url <DEPLOYMENT_URL>/threads/<THREAD_ID>/runs/wait \
--header 'Content-Type: application/json' \
--data "{
  \"assistant_id\": \"agent\",
  \"input\": {}
}"

PythonJavaScriptcURL

# The states are returned in reverse chronological order.
states = await client.threads.get_history(thread_id)
selected_state = states[1]
print(selected_state)

// The states are returned in reverse chronological order.
const states = await client.threads.getHistory(threadID);
const selectedState = states[1];
console.log(selectedState);

curl --request GET \
--url <DEPLOYMENT_URL>/threads/<THREAD_ID>/history \
--header 'Content-Type: application/json'

update_state will create a new checkpoint. The new checkpoint will be associated with the same thread, but a new checkpoint ID.

PythonJavaScriptcURL

new_config = await client.threads.update_state(
    thread_id,
    {"topic": "chickens"},
    checkpoint_id=selected_state["checkpoint_id"]
)
print(new_config)

const newConfig = await client.threads.updateState(
  threadID,
  {
    values: { "topic": "chickens" },
    checkpointId: selectedState["checkpoint_id"]
  }
);
console.log(newConfig);

curl --request POST \
--url <DEPLOYMENT_URL>/threads/<THREAD_ID>/state \
--header 'Content-Type: application/json' \
--data "{
  \"assistant_id\": \"agent\",
  \"checkpoint_id\": <CHECKPOINT_ID>,
  \"values\": {\"topic\": \"chickens\"}
}"

PythonJavaScriptcURL

await client.runs.wait(
    thread_id,
    assistant_id,
    input=None,
    checkpoint_id=new_config["checkpoint_id"]
)

await client.runs.wait(
  threadID,
  assistantID,
  {
    input: null,
    checkpointId: newConfig["checkpoint_id"]
  }
);

curl --request POST \
--url <DEPLOYMENT_URL>/threads/<THREAD_ID>/runs/wait \
--header 'Content-Type: application/json' \
--data "{
  \"assistant_id\": \"agent\",
  \"checkpoint_id\": <CHECKPOINT_ID>
}"

• LangGraph time travel guide: learn more about using time travel in LangGraph.

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4