Bun SQLite Checkpointer

Native SQLite checkpointer for LangGraph using Bun's built-in SQLite implementation.

Installation

bun add @skroyc/bun-sqlite-checkpointer

Requires bun >= 1.0.0.

Quick Start

import { BunSqliteSaver } from "@skroyc/bun-sqlite-checkpointer";
import { createReactAgent } from "@langchain/langgraph/prelanggraph";

// Initialize the saver with an in-memory database
const saver = new BunSqliteSaver(":memory:");

// Or with a persistent database
const saver = new BunSqliteSaver("./checkpoints.db");

// Create your agent with the checkpointer
const agent = createReactAgent({
  llm: model,
  tools: [],
  checkpointSaver: saver,
});

API

BunSqliteSaver

class BunSqliteSaver extends BaseCheckpointSaver<number> {
  constructor(db: Bun.SqliteDb, serde?: SerializerProtocol);
  static fromConnString(connString: string, serde?: SerializerProtocol): BunSqliteSaver;
}

Constructor Parameters

| Parameter | Type | Description | |-----------|------|-------------| | db | Bun.SqliteDb | Bun SQLite Database instance | | serde | SerializerProtocol | Optional custom serializer |

Connection String

Use BunSqliteSaver.fromConnString() for convenience:

// In-memory database
const saver = BunSqliteSaver.fromConnString(":memory:");

// Persistent file
const saver = BunSqliteSaver.fromConnString("./checkpoints.db");

// Read-only in-memory
const saver = BunSqliteSaver.fromConnString(":readonly:");

// Temporary (not persisted)
const saver = BunSqliteSaver.fromConnString(":temp:");

Sharing a Database Connection

import { Database } from "bun:sqlite";

const db = new Database("./shared.db");
const saver = new BunSqliteSaver(db);

Usage with LangGraph

import { BunSqliteSaver } from "@skroyc/bun-sqlite-checkpointer";

const saver = new BunSqliteSaver(":memory:");

// All threads will be persisted automatically
const config = { configurable: { thread_id: "user-123" } };

for await (const event of agent.streamEvents(
  { messages: userInput },
  { ...config, version: "v2" }
)) {
  // Events are checkpointed automatically
}

Database Schema

The checkpointer creates the following tables:

• checkpoints - Stores checkpoint data and metadata
• writes - Stores incremental writes

Requirements

• Bun >= 1.0.0
• @langchain/langgraph-checkpoint >= 1.0.0

License

Apache-2.0