Neo4j Storage for MCP Servers

npm install neo4j-driver

// filepath: /path/to/Neo4jStorage.ts
import neo4j, { Driver, Session } from 'neo4j-driver';

class Neo4jStorage implements MCPStorageProvider {
  private driver: Driver;

  constructor(uri: string, username: string, password: string) {
    this.driver = neo4j.driver(uri, neo4j.auth.basic(username, password));
  }

  async initialize(): Promise<void> {
    const session = this.driver.session();
    try {
      // Create constraints
      await session.run(`
        CREATE CONSTRAINT context_id IF NOT EXISTS
        FOR (c:Context) REQUIRE c.id IS UNIQUE
      `);
    } finally {
      await session.close();
    }
  }

  async storeContext(contextId: string, data: Buffer): Promise<void> {
    const session = this.driver.session();
    try {
      await session.run(`
        MERGE (c:Context {id: $contextId})
        SET c.data = $data,
            c.updatedAt = datetime(),
            c.size = $size
      `, {
        contextId,
        data: data.toString('base64'),
        size: data.length
      });
    } finally {
      await session.close();
    }
  }

  async retrieveContext(contextId: string): Promise<Buffer> {
    const session = this.driver.session();
    try {
      const result = await session.run(`
        MATCH (c:Context {id: $contextId})
        RETURN c.data
      `, { contextId });

      if (result.records.length === 0) {
        throw new Error('Context not found');
      }

      return Buffer.from(result.records[0].get('c.data'), 'base64');
    } finally {
      await session.close();
    }
  }
}