feat(app): reimplement and streamline MCP server creation
- uses reference Typescript MCP servers as basis for redesign - centralises tool registration for different transports, reducing code duplication - implements MCP notifications
This commit is contained in:
Sooty
parent
9a7a9d7fea
commit
95cfd6c2cc
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@ -0,0 +1,340 @@
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import { InMemoryEventStore } from '@modelcontextprotocol/sdk/examples/shared/inMemoryEventStore.js';
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import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
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import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
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import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
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import { isInitializeRequest, SetLevelRequestSchema } from '@modelcontextprotocol/sdk/types.js';
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import { randomUUID } from 'crypto';
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import { Client, GatewayIntentBits } from 'discord.js';
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import { config as dotenvConfig } from 'dotenv';
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import express, { Request, Response } from 'express';
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import { info, Level, setLevel, warning } from './notifications.js';
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import * as schemas from './schemas.js';
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import * as handlers from './tools/tools.js';
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import { createToolContext } from './tools/tools.js';
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// Load environment variables from .env file if exists
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dotenvConfig();
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/**
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* Create and return a configured MCP server wired with the Discord client.
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* The server registers tools programmatically using the handlers and schemas
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* exported from the local modules to avoid a large switch statement.
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*/
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function createMcpServer(client: Client) {
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const server = new McpServer(
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{ name: 'discord-mcp-server', version: '1.0.0' },
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{ capabilities: { tools: {}, logging: {} } }
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);
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// attach the Discord client to the tool context for use in handlers
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const toolContext = createToolContext(client);
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// attach the Discord client to the server for logging purposes
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// The underlying Server type from the SDK doesn't declare a `client` property,
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// so assert to `any` to attach a runtime-only property used by handlers.
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(client as any).server = server.server;
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(server as any).discord = client;
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// Map of tool name to handler + schema. Keep this small and explicit so it's
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// easy to see which handler is wired to which tool. Use the exported
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// Zod schemas from `schemas.ts` where available.
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const toolMap: Array<{ name: string; schema?: any; handler: any }> = [
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{ name: 'discord_login', schema: schemas.DiscordLoginSchema, handler: handlers.loginHandler },
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{ name: 'discord_send', schema: schemas.SendMessageSchema, handler: handlers.sendMessageHandler },
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{ name: 'discord_get_forum_channels', schema: schemas.GetForumChannelsSchema, handler: handlers.getForumChannelsHandler },
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{ name: 'discord_create_forum_post', schema: schemas.CreateForumPostSchema, handler: handlers.createForumPostHandler },
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{ name: 'discord_get_forum_post', schema: schemas.GetForumPostSchema, handler: handlers.getForumPostHandler },
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{ name: 'discord_reply_to_forum', schema: schemas.ReplyToForumSchema, handler: handlers.replyToForumHandler },
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{ name: 'discord_delete_forum_post', schema: schemas.DeleteForumPostSchema, handler: handlers.deleteForumPostHandler },
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{ name: 'discord_create_text_channel', schema: schemas.CreateTextChannelSchema, handler: handlers.createTextChannelHandler },
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{ name: 'discord_delete_channel', schema: schemas.DeleteChannelSchema, handler: handlers.deleteChannelHandler },
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{ name: 'discord_read_messages', schema: schemas.ReadMessagesSchema, handler: handlers.readMessagesHandler },
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{ name: 'discord_get_server_info', schema: schemas.GetServerInfoSchema, handler: handlers.getServerInfoHandler },
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{ name: 'discord_add_reaction', schema: schemas.AddReactionSchema, handler: handlers.addReactionHandler },
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{ name: 'discord_add_multiple_reactions', schema: schemas.AddMultipleReactionsSchema, handler: handlers.addMultipleReactionsHandler },
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{ name: 'discord_remove_reaction', schema: schemas.RemoveReactionSchema, handler: handlers.removeReactionHandler },
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{ name: 'discord_delete_message', schema: schemas.DeleteMessageSchema, handler: handlers.deleteMessageHandler },
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{ name: 'discord_create_webhook', schema: schemas.CreateWebhookSchema, handler: handlers.createWebhookHandler },
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{ name: 'discord_send_webhook_message', schema: schemas.SendWebhookMessageSchema, handler: handlers.sendWebhookMessageHandler },
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{ name: 'discord_edit_webhook', schema: schemas.EditWebhookSchema, handler: handlers.editWebhookHandler },
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{ name: 'discord_delete_webhook', schema: schemas.DeleteWebhookSchema, handler: handlers.deleteWebhookHandler },
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{ name: 'discord_list_servers', schema: schemas.ListServersSchema, handler: handlers.listServersHandler },
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{ name: 'discord_create_category', schema: schemas.CreateCategorySchema, handler: handlers.createCategoryHandler },
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{ name: 'discord_edit_category', schema: schemas.EditCategorySchema, handler: handlers.editCategoryHandler },
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{ name: 'discord_delete_category', schema: schemas.DeleteCategorySchema, handler: handlers.deleteCategoryHandler },
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];
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// Register each tool on the MCP server
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for (const t of toolMap) {
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try {
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server.tool(t.name, t.schema ? t.schema.shape ?? t.schema : undefined, async (args: any) => {
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// Handlers follow the signature: (args, context) => Promise<ToolResponse>
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return await t.handler(args, toolContext);
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});
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} catch (err) {
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// If a particular tool registration fails, log and continue (keeps boot resilient)
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// eslint-disable-next-line no-console
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warning(server.server, `Failed to register tool ${t.name}: ${String(err)}`);
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}
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}
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// Handle logging method separately
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server.server.setRequestHandler(SetLevelRequestSchema, async (request) => {
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const levelParam = request.params.level as Level | undefined;
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const ok = setLevel(levelParam || 'info');
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// Empty result on success, error on failure
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if (!ok) {
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throw { code: -32602, message: 'Invalid log level' };
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}
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return {};
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});
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return server;
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}
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// Helper to create a Discord client with sensible defaults used by the CLI
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function createDiscordClient(token?: string) {
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const client = new Client({ intents: [GatewayIntentBits.Guilds, GatewayIntentBits.GuildMessages, GatewayIntentBits.MessageContent] });
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if (token) {
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client.token = token;
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// Auto-login on startup if token is available
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(async () => {
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try {
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await client.login(token);
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info((client as any).server, 'Successfully logged in to Discord');
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} catch (err: any) {
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if (typeof err.message === 'string' && err.message.includes('Privileged intent provided is not enabled or whitelisted')) {
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warning((client as any).server, 'Discord login failed due to missing privileged intents. Please enable the required intents in the Discord Developer Portal.');
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} else {
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warning((client as any).server, 'Discord login failed: ' + String(err));
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}
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}
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})();
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}
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let clientStatusInterval: NodeJS.Timeout | null = null;
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function logClientState(context: string) {
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// only log if server is attached and connected
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if (!(client as any).server || !(client as any).server.transport) {
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return;
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}
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info((client as any).server, `Discord client state [${context}]: ${JSON.stringify({
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isReady: client.isReady(),
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hasToken: !!client.token,
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user: client.user ? {
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id: client.user.id,
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tag: client.user.tag,
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} : null
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})}`);
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}
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clientStatusInterval = setInterval(() => {
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logClientState("periodic check");
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}, 10000);
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client.on('ready', () => {
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logClientState("on ready event");
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});
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client.on('disconnect', () => {
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logClientState("on disconnect event");
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if (clientStatusInterval) {
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clearInterval(clientStatusInterval);
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clientStatusInterval = null;
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}
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});
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return client;
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}
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// Configuration from command-line arguments or environment variables
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const config = {
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DISCORD_TOKEN: (() => {
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try {
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// First check for command-line argument
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const tokenIndex = process.argv.indexOf('--config');
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if (tokenIndex !== -1 && tokenIndex + 1 < process.argv.length) {
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const configArg = process.argv[tokenIndex + 1];
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if (typeof configArg === 'string') {
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try {
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const parsedConfig = JSON.parse(configArg);
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return parsedConfig.DISCORD_TOKEN;
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} catch (err) {
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// If not valid JSON, try using the string directly
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return configArg;
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}
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}
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}
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// Then try environment variable
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return process.env.DISCORD_TOKEN;
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} catch (err) {
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process.stderr.write('Error parsing configuration: ' + String(err) + '\n');
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return null;
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}
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})(),
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TRANSPORT: (() => {
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// Check for transport type argument
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const transportIndex = process.argv.indexOf('--transport');
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if (transportIndex !== -1 && transportIndex + 1 < process.argv.length) {
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return process.argv[transportIndex + 1];
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}
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// Default to stdio
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return 'stdio';
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})(),
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HTTP_PORT: (() => {
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// Check for port argument
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const portIndex = process.argv.indexOf('--port');
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if (portIndex !== -1 && portIndex + 1 < process.argv.length) {
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return parseInt(process.argv[portIndex + 1]);
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}
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// Default port for MCP
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return 8080;
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})()
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};
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const discord = createDiscordClient(config.DISCORD_TOKEN);
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const server = createMcpServer(discord);
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const app = express();
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app.use(express.json());
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// region MCP Streamable HTTP Transport Handlers
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const transports: { [sessionId: string]: StreamableHTTPServerTransport } = {};
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const mcpPostHandler = async (req: Request, res: Response) => {
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const sessionId = req.headers['mcp-session-id'] as string;
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if (sessionId) {
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process.stderr.write(`Received MCP request for session: ${sessionId}\n`);
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} else {
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process.stderr.write('Request body:' + JSON.stringify(req.body) + '\n');
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}
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try {
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let transport: StreamableHTTPServerTransport;
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if (sessionId && transports[sessionId]) {
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transport = transports[sessionId];
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} else if (!sessionId && isInitializeRequest(req.body)) {
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// New session initialization
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const eventStore = new InMemoryEventStore();
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transport = new StreamableHTTPServerTransport({
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sessionIdGenerator: () => randomUUID(),
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eventStore,
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enableJsonResponse: true, // Enable JSON response mode
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onsessioninitialized: sessionId => {
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// Store the transport by session ID for future requests
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transports[sessionId] = transport;
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process.stderr.write(`Initialized new MCP session: ${sessionId}\n`);
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}
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});
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// Set up onclose handler to clean up transport
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transport.onclose = () => {
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const sid = transport.sessionId;
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if (sid && transports[sid]) {
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delete transports[sid];
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process.stderr.write(`Closed and removed MCP session: ${sid}\n`);
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}
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};
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// Connect the transport to the MCP server before handling the request
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await server.connect(transport);
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await transport.handleRequest(req, res, req.body);
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return;
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} else {
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// Invalid request without session ID
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res.status(400).json({
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jsonrpc: "2.0",
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error: { code: -32000, message: "Invalid or missing MCP session ID." },
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id: req.body.id || null
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});
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return;
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}
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// Handle the request with the existing transport - no need to reconnect
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await transport.handleRequest(req, res, req.body);
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} catch (err) {
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process.stderr.write('Error handling MCP request: ' + String(err) + '\n');
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if (!res.headersSent) {
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res.status(500).json({
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jsonrpc: "2.0",
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error: { code: -32000, message: "Internal server error." },
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id: req.body.id || null
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});
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}
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}
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};
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// Handle GET requests for SSE streams (using built-in support from StreamableHTTP)
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const mcpGetHandler = async (req: Request, res: Response) => {
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const sessionId = req.headers['mcp-session-id'] as string | undefined;
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if (!sessionId || !transports[sessionId]) {
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res.status(400).send('Invalid or missing session ID');
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return;
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}
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// Check for Last-Event-ID header for resumability
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const lastEventId = req.headers['last-event-id'] as string | undefined;
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if (lastEventId) {
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process.stderr.write(`Client reconnecting with Last-Event-ID: ${lastEventId}\n`);
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} else {
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process.stderr.write(`Establishing new SSE stream for session ${sessionId}\n`);
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}
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const transport = transports[sessionId];
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await transport.handleRequest(req, res);
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};
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// Handle DELETE requests for session termination (according to MCP spec)
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const mcpDeleteHandler = async (req: Request, res: Response) => {
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const sessionId = req.headers['mcp-session-id'] as string | undefined;
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if (!sessionId || !transports[sessionId]) {
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res.status(400).send('Invalid or missing session ID');
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return;
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}
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process.stderr.write(`Received session termination request for session ${sessionId}\n`);
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try {
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const transport = transports[sessionId];
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await transport.handleRequest(req, res);
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} catch (error) {
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process.stderr.write('Error handling session termination:' + String(error) + '\n');
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if (!res.headersSent) {
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res.status(500).send('Error processing session termination');
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}
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}
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};
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// endregion
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// Handle both Stdio and HTTP transports based on configuration
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if (config.TRANSPORT.toLowerCase() === 'http') {
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// HTTP transport endpoints
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app.post('/mcp', mcpPostHandler);
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app.get('/mcp', mcpGetHandler);
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app.delete('/mcp', mcpDeleteHandler);
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const port = config.HTTP_PORT || 8080;
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app.listen(port, error => {
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if (error) {
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process.stderr.write('Error starting MCP HTTP server: ' + String(error) + '\n');
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process.exit(1);
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}
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process.stderr.write(`MCP Streamable HTTP Server listening on port ${port}\n`);
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});
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// Handle server shutdown
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process.on('SIGINT', async () => {
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process.stderr.write('Shutting down server...\n');
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// Close all active transports to properly clean up resources
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for (const sessionId in transports) {
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try {
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process.stderr.write(`Closing transport for session ${sessionId}\n`);
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await transports[sessionId].close();
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delete transports[sessionId];
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} catch (error) {
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process.stderr.write(`Error closing transport for session ${sessionId}:` + String(error) + '\n');
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}
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}
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process.stderr.write('Server shutdown complete\n');
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process.exit(0);
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});
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} else {
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// Stdio transport
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const transport = new StdioServerTransport();
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await server.connect(transport);
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process.stderr.write('MCP Stdio Server started. Awaiting messages...\n');
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}
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@ -0,0 +1,45 @@
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import { Server } from '@modelcontextprotocol/sdk/server'
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export type Level = 'debug' | 'info' | 'notice' | 'warning' | 'error' | 'critical' | 'alert' | 'emergency';
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const levelPriority: Record<Level, number> = {
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debug: 0,
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info: 1,
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notice: 2,
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warning: 3,
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error: 4,
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critical: 5,
|
||||||
|
alert: 6,
|
||||||
|
emergency: 7,
|
||||||
|
};
|
||||||
|
|
||||||
|
export let currentLevel: Level = 'info';
|
||||||
|
|
||||||
|
export function setLevel(level: Level) {
|
||||||
|
if (!levelPriority.hasOwnProperty(level)) return false;
|
||||||
|
currentLevel = level;
|
||||||
|
return true;
|
||||||
|
}
|
||||||
|
|
||||||
|
export function log(server: Server, message: string, level: Level = 'info') {
|
||||||
|
if (levelPriority[level] < levelPriority[currentLevel]) return;
|
||||||
|
server.sendLoggingMessage(
|
||||||
|
{
|
||||||
|
level: level,
|
||||||
|
logger: 'mcp-discord',
|
||||||
|
data: { text: message },
|
||||||
|
}
|
||||||
|
);
|
||||||
|
}
|
||||||
|
|
||||||
|
export function info(server: Server, message: string) {
|
||||||
|
log(server, message, 'info');
|
||||||
|
}
|
||||||
|
|
||||||
|
export function warning(server: Server, message: string) {
|
||||||
|
log(server, message, 'warning');
|
||||||
|
}
|
||||||
|
|
||||||
|
export function error(server: Server, message: string) {
|
||||||
|
log(server, message, 'error');
|
||||||
|
}
|
||||||
Loading…
Reference in New Issue