CSS Tutor MCP Server

import { server } from "../index.js"; import { z } from "zod"; import fs from 'fs/promises'; // Use promises for async operations import path from 'path'; import { fileURLToPath } from 'url'; // Helper to get the correct directory path in ES Modules const __filename = fileURLToPath(import.meta.url); const __dirname = path.dirname(__filename); // Path to the JSON file acting as our simple database const memoryFilePath = path.resolve(__dirname, '../../data/memory.json'); // Zod schema to validate the structure of the memory data const MemorySchema = z.object({ user_id: z.string(), known_concepts: z.record(z.string(), z.boolean()) // Concept name -> known status }); // TypeScript type derived from the Zod schema for type safety export type MemoryData = z.infer<typeof MemorySchema>; // Reads and validates the memory data from memory.json export async function readMemory(): Promise<MemoryData> { try { const data = await fs.readFile(memoryFilePath, 'utf-8'); const jsonData = JSON.parse(data); // Ensure the data conforms to our expected schema return MemorySchema.parse(jsonData); } catch (error) { console.error("Error reading or parsing memory file:", error); // For a demo, we throw; a real app might return a default or handle errors differently throw new Error(`Failed to read/parse memory file: ${error instanceof Error ? error.message : String(error)}`); } } // Validates and writes the given memory data to memory.json export async function writeMemory(newData: MemoryData): Promise<void> { try { // Ensure the data to be written conforms to the schema MemorySchema.parse(newData); const dataString = JSON.stringify(newData, null, 2); // Pretty-print JSON await fs.writeFile(memoryFilePath, dataString, 'utf-8'); } catch (error) { console.error("Error validating or writing memory file:", error); throw new Error(`Failed to validate/write memory file: ${error instanceof Error ? error.message : String(error)}`); } } // Registers the 'css_knowledge_memory' resource with the MCP server. // This resource represents the user's knowledge state stored in memory.json. function registerCssKnowledgeMemoryResource() { const resourceName = "css_knowledge_memory"; // A URI identifying this resource type. Clients might request specific URIs under this base. const resourceUriBase = `memory://${resourceName}/`; server.resource( resourceName, resourceUriBase, { // Metadata defining resource capabilities read: true, // Allows clients/tools to read the resource write: true // Allows clients/tools to modify the resource (via tools) }, async (uri: URL) => { // Handler called when a client reads the resource // This demo ignores the specific URI path and always returns the single memory file. // A multi-user system might use the path to identify the user. try { const memoryData = await readMemory(); return { contents: [{ uri: uri.toString(), // Echo the requested URI mimeType: "application/json", text: JSON.stringify(memoryData) // Return data as a JSON string }] }; } catch (error) { console.error(`Error handling resource request for ${uri}:`, error); throw error; // Propagate error to the server framework } } ); } // Function called by src/index.ts to register all resources for this server. export function registerResources() { registerCssKnowledgeMemoryResource(); }