Claude b1826c112c Make retry policy durable by persisting attempt count and timestamp
Retries were previously entirely in-memory: the attempt counter and
backoff sleep happened inside run_with_retry/arun_with_retry without
any checkpoint writes. If the process crashed mid-retry, the state was
lost and the task would restart from attempt 0 on resume, effectively
ignoring max_attempts across restarts.

This change adds a RETRY special write channel. On each retryable
failure, before sleeping, the retry loop persists (attempt_count,
next_retry_timestamp) to the checkpoint via put_writes. On resume,
the scratchpad restores these values so the retry loop continues
from the correct attempt and honors the remaining backoff time.

Key changes:
- New RETRY constant in _constants.py and checkpoint serde/types
- RETRY added to WRITES_IDX_MAP for checkpoint storage
- PregelScratchpad gains retry_attempt/retry_ts fields
- _scratchpad() in _algo.py extracts RETRY from pending_writes
- _match_writes skips RETRY (like ERROR/INTERRUPT/RESUME)
- output_writes returns early for RETRY (no stream output)
- run_with_retry/arun_with_retry accept put_writes callback,
  restore attempt state from scratchpad, persist before sleep
- Runner passes put_writes to retry functions

https://claude.ai/code/session_01768mrKrVCCtXdJgRNFdWrb
2026-02-07 07:55:53 +00:00
2026-01-09 15:07:12 -05:00

LangGraph Logo

Version Downloads Open Issues Docs

Trusted by companies shaping the future of agents including Klarna, Replit, Elastic, and more LangGraph is a low-level orchestration framework for building, managing, and deploying long-running, stateful agents.

Get started

Install LangGraph:

pip install -U langgraph

Create a simple workflow:

from langgraph.graph import START, StateGraph
from typing_extensions import TypedDict


class State(TypedDict):
    text: str


def node_a(state: State) -> dict:
    return {"text": state["text"] + "a"}


def node_b(state: State) -> dict:
    return {"text": state["text"] + "b"}


graph = StateGraph(State)
graph.add_node("node_a", node_a)
graph.add_node("node_b", node_b)
graph.add_edge(START, "node_a")
graph.add_edge("node_a", "node_b")

print(graph.compile().invoke({"text": ""}))
# {'text': 'ab'}

Get started with the LangGraph Quickstart.

To quickly build agents with LangChain's create_agent (built on LangGraph), see the LangChain Agents documentation.

Core benefits

LangGraph provides low-level supporting infrastructure for any long-running, stateful workflow or agent. LangGraph does not abstract prompts or architecture, and provides the following central benefits:

  • Durable execution: Build agents that persist through failures and can run for extended periods, automatically resuming from exactly where they left off.
  • Human-in-the-loop: Seamlessly incorporate human oversight by inspecting and modifying agent state at any point during execution.
  • Comprehensive memory: Create truly stateful agents with both short-term working memory for ongoing reasoning and long-term persistent memory across sessions.
  • Debugging with LangSmith: Gain deep visibility into complex agent behavior with visualization tools that trace execution paths, capture state transitions, and provide detailed runtime metrics.
  • Production-ready deployment: Deploy sophisticated agent systems confidently with scalable infrastructure designed to handle the unique challenges of stateful, long-running workflows.

LangGraphs ecosystem

While LangGraph can be used standalone, it also integrates seamlessly with any LangChain product, giving developers a full suite of tools for building agents. To improve your LLM application development, pair LangGraph with:

  • LangSmith — Helpful for agent evals and observability. Debug poor-performing LLM app runs, evaluate agent trajectories, gain visibility in production, and improve performance over time.
  • LangSmith Deployment — Deploy and scale agents effortlessly with a purpose-built deployment platform for long running, stateful workflows. Discover, reuse, configure, and share agents across teams — and iterate quickly with visual prototyping in LangGraph Studio.
  • LangChain Provides integrations and composable components to streamline LLM application development.

Note

Looking for the JS version of LangGraph? See the JS repo and the JS docs.

Additional resources

  • Guides: Quick, actionable code snippets for topics such as streaming, adding memory & persistence, and design patterns (e.g. branching, subgraphs, etc.).
  • Reference: Detailed reference on core classes, methods, how to use the graph and checkpointing APIs, and higher-level prebuilt components.
  • Examples: Guided examples on getting started with LangGraph.
  • LangChain Forum: Connect with the community and share all of your technical questions, ideas, and feedback.
  • LangChain Academy: Learn the basics of LangGraph in our free, structured course.
  • Case studies: Hear how industry leaders use LangGraph to ship AI applications at scale.

Acknowledgements

LangGraph is inspired by Pregel and Apache Beam. The public interface draws inspiration from NetworkX. LangGraph is built by LangChain Inc, the creators of LangChain, but can be used without LangChain.

Languages
Python 99.6%
Makefile 0.2%
TypeScript 0.1%