Exa Websets MCP Server

import { promises as fs } from 'fs'; import path from 'path'; export interface GraphEntity { name: string; entityType: string; observations: string[]; } export interface GraphRelation { from: string; to: string; relationType: string; } export interface KnowledgeGraph { entities: GraphEntity[]; relations: GraphRelation[]; } /** * Simple persistent knowledge graph store. * * Stores entities and relations in a newline-separated JSON file so the * graph can survive server restarts without requiring an external database. */ export class KnowledgeGraphService { private filePath: string; constructor(filePath?: string) { const defaultPath = path.join(process.cwd(), 'knowledge-graph.json'); const resolved = filePath || process.env.KG_FILE_PATH || defaultPath; this.filePath = path.isAbsolute(resolved) ? resolved : path.join(process.cwd(), resolved); } private async loadGraph(): Promise<KnowledgeGraph> { try { const data = await fs.readFile(this.filePath, 'utf-8'); const lines = data.split('\n').filter(line => line.trim() !== ''); return lines.reduce<KnowledgeGraph>((graph, line) => { const item = JSON.parse(line); if (item.type === 'entity') graph.entities.push(item as GraphEntity); if (item.type === 'relation') graph.relations.push(item as GraphRelation); return graph; }, { entities: [], relations: [] }); } catch (err: any) { if (err && err.code === 'ENOENT') { return { entities: [], relations: [] }; } throw err; } } private async saveGraph(graph: KnowledgeGraph): Promise<void> { const lines = [ ...graph.entities.map(e => JSON.stringify({ type: 'entity', ...e })), ...graph.relations.map(r => JSON.stringify({ type: 'relation', ...r })), ]; await fs.writeFile(this.filePath, lines.join('\n')); } async createEntities(entities: GraphEntity[]): Promise<GraphEntity[]> { const graph = await this.loadGraph(); const newEntities = entities.filter(e => !graph.entities.some(ex => ex.name === e.name)); graph.entities.push(...newEntities); await this.saveGraph(graph); return newEntities; } async createRelations(relations: GraphRelation[]): Promise<GraphRelation[]> { const graph = await this.loadGraph(); const newRelations = relations.filter(r => !graph.relations.some(ex => ex.from === r.from && ex.to === r.to && ex.relationType === r.relationType )); graph.relations.push(...newRelations); await this.saveGraph(graph); return newRelations; } async addObservations(observations: { entityName: string; contents: string[] }[]) : Promise<{ entityName: string; addedObservations: string[] }[]> { const graph = await this.loadGraph(); const results = observations.map(o => { const entity = graph.entities.find(e => e.name === o.entityName); if (!entity) { throw new Error(`Entity with name ${o.entityName} not found`); } const newObs = o.contents.filter(c => !entity.observations.includes(c)); entity.observations.push(...newObs); return { entityName: o.entityName, addedObservations: newObs }; }); await this.saveGraph(graph); return results; } async deleteEntities(names: string[]): Promise<void> { const graph = await this.loadGraph(); graph.entities = graph.entities.filter(e => !names.includes(e.name)); graph.relations = graph.relations.filter(r => !names.includes(r.from) && !names.includes(r.to)); await this.saveGraph(graph); } async deleteObservations(deletions: { entityName: string; observations: string[] }[]): Promise<void> { const graph = await this.loadGraph(); deletions.forEach(d => { const entity = graph.entities.find(e => e.name === d.entityName); if (entity) { entity.observations = entity.observations.filter(o => !d.observations.includes(o)); } }); await this.saveGraph(graph); } async deleteRelations(relations: GraphRelation[]): Promise<void> { const graph = await this.loadGraph(); graph.relations = graph.relations.filter(r => !relations.some(del => r.from === del.from && r.to === del.to && r.relationType === del.relationType )); await this.saveGraph(graph); } async readGraph(): Promise<KnowledgeGraph> { return this.loadGraph(); } async searchNodes(query: string): Promise<KnowledgeGraph> { const graph = await this.loadGraph(); const filteredEntities = graph.entities.filter(e => e.name.toLowerCase().includes(query.toLowerCase()) || e.entityType.toLowerCase().includes(query.toLowerCase()) || e.observations.some(o => o.toLowerCase().includes(query.toLowerCase())) ); const names = new Set(filteredEntities.map(e => e.name)); const filteredRelations = graph.relations.filter(r => names.has(r.from) && names.has(r.to) ); return { entities: filteredEntities, relations: filteredRelations }; } async openNodes(names: string[]): Promise<KnowledgeGraph> { const graph = await this.loadGraph(); const filteredEntities = graph.entities.filter(e => names.includes(e.name)); const nameSet = new Set(filteredEntities.map(e => e.name)); const filteredRelations = graph.relations.filter(r => nameSet.has(r.from) && nameSet.has(r.to) ); return { entities: filteredEntities, relations: filteredRelations }; } } export default KnowledgeGraphService;