LangChain + MemorySync

Overview

Install langchain-memorysync (Python) or memorysync-langchain (JavaScript) to give any LangChain chain or agent durable memory. The chat history class plugs into RunnableWithMessageHistory, five structured tools let agents store and search memories safely, and both packages run on langchain-core 0.3.x and 1.x.

Setup status and requirements

Supported version

langchain-memorysync 1.0.1 (PyPI) / memorysync-langchain 1.0.0 (npm)

Last setup review

2026-08-22

Permissions

A MemorySync API key with read and write scopes.

Limits

Requires langchain-core 0.3 or newer (Python 3.10+, Node 18+). The delete tool and history clear() need a key with delete permission; anonymous evaluation keys can write and read history but cannot clear it.

Capabilities

• BaseChatMessageHistory implementation for RunnableWithMessageHistory
• Five structured agent tools: add, search, list, update, delete
• Prompt-ready recall context blocks
• Idempotent writes that survive retries
• Per-end-user scoping and read-only mode
• langchain-core 0.3.x and 1.x support in both languages

Quick Start

from langchain_core.runnables.history import RunnableWithMessageHistory
from langchain_memorysync import MemorySyncChatMessageHistory

chain_with_history = RunnableWithMessageHistory(
    chain,
    lambda session_id: MemorySyncChatMessageHistory(session_id=session_id),
    input_messages_key="input",
    history_messages_key="history",
)

Use Cases

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