Add HTTP/SSE transport with graceful degradation for public deployment
New Features: - HTTP/SSE server (server-http.js) for network access - Express-based web server with MCP SSE transport - Rate limiting (50 req/min per IP) - Request timeouts (30s) - Concurrent request limiting (max 10) - Circuit breaker pattern for failure handling - Memory monitoring (450MB threshold) - Gzip compression for responses - CORS support for cross-origin requests - Health check endpoint (/health) Infrastructure: - Updated package.json with new dependencies (express, cors, compression, rate-limit) - New npm script: start:http for HTTP server - Comprehensive deployment guide (DEPLOYMENT.md) - Updated README with deployment instructions Graceful Degradation: - Automatically rejects requests when at capacity - Circuit breaker opens after 5 failures - Memory-aware request handling - Per-IP rate limiting to prevent abuse The original stdio server (index.js) remains unchanged for local use. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
Lee Hanken
779
server-http.js
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779
server-http.js
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@@ -0,0 +1,779 @@
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#!/usr/bin/env node
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import express from 'express';
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import cors from 'cors';
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import compression from 'compression';
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import rateLimit from 'express-rate-limit';
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import { Server } from '@modelcontextprotocol/sdk/server/index.js';
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import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';
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import {
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CallToolRequestSchema,
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ListToolsRequestSchema,
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ListResourcesRequestSchema,
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ReadResourceRequestSchema,
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} from '@modelcontextprotocol/sdk/types.js';
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import HPRDataLoader from './data-loader.js';
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// Configuration
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const PORT = process.env.PORT || 3000;
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const MAX_CONCURRENT_REQUESTS = 10;
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const REQUEST_TIMEOUT_MS = 30000;
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const RATE_LIMIT_WINDOW_MS = 60000; // 1 minute
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const RATE_LIMIT_MAX_REQUESTS = 50; // 50 requests per minute per IP
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const MEMORY_THRESHOLD_MB = 450;
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const CIRCUIT_BREAKER_THRESHOLD = 5;
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const CIRCUIT_BREAKER_TIMEOUT_MS = 60000;
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// Initialize data loader
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console.error('Loading HPR knowledge base data...');
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const dataLoader = new HPRDataLoader();
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await dataLoader.load();
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console.error('Data loaded successfully!');
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// Circuit Breaker class for graceful degradation
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class CircuitBreaker {
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constructor(threshold = CIRCUIT_BREAKER_THRESHOLD, timeout = CIRCUIT_BREAKER_TIMEOUT_MS) {
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this.failures = 0;
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this.threshold = threshold;
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this.timeout = timeout;
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this.state = 'CLOSED'; // CLOSED, OPEN, HALF_OPEN
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this.nextAttempt = Date.now();
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}
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async execute(fn) {
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if (this.state === 'OPEN') {
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if (Date.now() < this.nextAttempt) {
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throw new Error('Service temporarily unavailable. Please try again later.');
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}
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this.state = 'HALF_OPEN';
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}
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try {
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const result = await fn();
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if (this.state === 'HALF_OPEN') {
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this.state = 'CLOSED';
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this.failures = 0;
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}
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return result;
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} catch (error) {
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this.failures++;
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if (this.failures >= this.threshold) {
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this.state = 'OPEN';
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this.nextAttempt = Date.now() + this.timeout;
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console.error(`Circuit breaker opened after ${this.failures} failures`);
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}
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throw error;
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}
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}
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reset() {
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this.failures = 0;
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this.state = 'CLOSED';
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}
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}
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const circuitBreaker = new CircuitBreaker();
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// Request timeout wrapper
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function withTimeout(promise, timeoutMs = REQUEST_TIMEOUT_MS) {
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return Promise.race([
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promise,
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new Promise((_, reject) =>
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setTimeout(() => reject(new Error('Request timeout')), timeoutMs)
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),
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]);
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}
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// Concurrent request limiter
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let activeRequests = 0;
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function checkConcurrency() {
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if (activeRequests >= MAX_CONCURRENT_REQUESTS) {
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throw new Error('Server at capacity. Please try again later.');
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}
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}
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// Memory monitoring
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let memoryWarning = false;
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function checkMemory() {
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const usage = process.memoryUsage();
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const heapUsedMB = usage.heapUsed / 1024 / 1024;
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if (heapUsedMB > MEMORY_THRESHOLD_MB) {
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if (!memoryWarning) {
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console.error(`High memory usage: ${heapUsedMB.toFixed(2)}MB`);
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memoryWarning = true;
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}
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throw new Error('Server under high load. Please try again later.');
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} else if (memoryWarning && heapUsedMB < MEMORY_THRESHOLD_MB * 0.8) {
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memoryWarning = false;
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}
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}
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setInterval(() => {
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const usage = process.memoryUsage();
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const heapUsedMB = usage.heapUsed / 1024 / 1024;
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console.error(`Memory: ${heapUsedMB.toFixed(2)}MB, Active requests: ${activeRequests}`);
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}, 30000);
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// Helper function to strip HTML tags
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function stripHtml(html) {
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return html
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.replace(/<[^>]*>/g, '')
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.replace(/ /g, ' ')
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.replace(/</g, '<')
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.replace(/>/g, '>')
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.replace(/&/g, '&')
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.replace(/"/g, '"')
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.trim();
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}
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// Helper to format episode for display
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function formatEpisode(episode, includeNotes = false) {
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const host = dataLoader.getHost(episode.hostid);
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const seriesInfo = episode.series !== 0 ? dataLoader.getSeries(episode.series) : null;
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let result = `# HPR${String(episode.id).padStart(4, '0')}: ${episode.title}
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**Date:** ${episode.date}
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**Host:** ${host?.host || 'Unknown'} (ID: ${episode.hostid})
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**Duration:** ${Math.floor(episode.duration / 60)}:${String(episode.duration % 60).padStart(2, '0')}
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**Tags:** ${episode.tags}
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**License:** ${episode.license}
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**Downloads:** ${episode.downloads}
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## Summary
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${episode.summary}`;
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if (seriesInfo) {
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result += `\n\n## Series
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**${seriesInfo.name}**: ${stripHtml(seriesInfo.description)}`;
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}
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if (includeNotes && episode.notes) {
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result += `\n\n## Host Notes\n${stripHtml(episode.notes)}`;
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}
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return result;
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}
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// Create MCP server factory
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function createMCPServer() {
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const server = new Server(
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{
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name: 'hpr-knowledge-base',
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version: '1.0.0',
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},
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{
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capabilities: {
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tools: {},
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resources: {},
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},
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}
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);
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// List available resources
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server.setRequestHandler(ListResourcesRequestSchema, async () => {
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return {
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resources: [
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{
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uri: 'hpr://stats',
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mimeType: 'text/plain',
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name: 'HPR Statistics',
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description: 'Overall statistics about the HPR knowledge base',
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},
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{
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uri: 'hpr://episodes/recent',
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mimeType: 'text/plain',
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name: 'Recent Episodes',
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description: 'List of 50 most recent HPR episodes',
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},
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{
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uri: 'hpr://hosts/all',
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mimeType: 'text/plain',
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name: 'All Hosts',
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description: 'List of all HPR hosts',
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},
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{
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uri: 'hpr://series/all',
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mimeType: 'text/plain',
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name: 'All Series',
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description: 'List of all HPR series',
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},
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],
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};
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});
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// Read a resource
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server.setRequestHandler(ReadResourceRequestSchema, async (request) => {
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const uri = request.params.uri;
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if (uri === 'hpr://stats') {
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const stats = dataLoader.getStats();
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return {
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contents: [
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{
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uri,
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mimeType: 'text/plain',
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text: `# Hacker Public Radio Statistics
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**Total Episodes:** ${stats.totalEpisodes}
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**Total Hosts:** ${stats.totalHosts}
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**Total Comments:** ${stats.totalComments}
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**Total Series:** ${stats.totalSeries}
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**Transcripts Available:** ${stats.totalTranscripts}
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**Date Range:** ${stats.dateRange.earliest} to ${stats.dateRange.latest}
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Hacker Public Radio is a community-driven podcast released under Creative Commons licenses.
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All content is contributed by the community, for the community.`,
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},
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],
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};
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}
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if (uri === 'hpr://episodes/recent') {
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const recent = dataLoader.searchEpisodes('', { limit: 50 });
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const text = recent.map(ep => {
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const host = dataLoader.getHost(ep.hostid);
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return `**HPR${String(ep.id).padStart(4, '0')}** (${ep.date}) - ${ep.title} by ${host?.host || 'Unknown'}`;
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}).join('\n');
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return {
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contents: [
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{
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uri,
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mimeType: 'text/plain',
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text: `# Recent Episodes\n\n${text}`,
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},
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],
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};
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}
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if (uri === 'hpr://hosts/all') {
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const hosts = dataLoader.hosts
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.filter(h => h.valid === 1)
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.map(h => {
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const episodeCount = dataLoader.getEpisodesByHost(h.hostid).length;
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return `**${h.host}** (ID: ${h.hostid}) - ${episodeCount} episodes`;
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})
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.join('\n');
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return {
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contents: [
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{
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uri,
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mimeType: 'text/plain',
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text: `# All HPR Hosts\n\n${hosts}`,
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},
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],
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};
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}
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if (uri === 'hpr://series/all') {
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const series = dataLoader.series
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.filter(s => s.valid === 1 && s.private === 0)
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.map(s => {
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const episodeCount = dataLoader.getEpisodesInSeries(s.id).length;
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return `**${s.name}** (ID: ${s.id}) - ${episodeCount} episodes\n ${stripHtml(s.description)}`;
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})
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.join('\n\n');
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return {
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contents: [
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{
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uri,
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mimeType: 'text/plain',
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text: `# All HPR Series\n\n${series}`,
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},
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],
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};
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}
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throw new Error(`Unknown resource: ${uri}`);
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});
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// List available tools
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server.setRequestHandler(ListToolsRequestSchema, async () => {
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return {
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tools: [
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{
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name: 'search_episodes',
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description: 'Search HPR episodes by keywords in title, summary, tags, or host notes. Can filter by host, series, tags, and date range.',
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inputSchema: {
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type: 'object',
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properties: {
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query: {
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type: 'string',
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description: 'Search query (searches title, summary, tags, and notes)',
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},
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limit: {
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type: 'number',
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description: 'Maximum number of results to return (default: 20)',
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},
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hostId: {
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type: 'number',
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description: 'Filter by host ID',
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},
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seriesId: {
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type: 'number',
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description: 'Filter by series ID',
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},
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tag: {
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type: 'string',
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description: 'Filter by tag',
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},
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fromDate: {
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type: 'string',
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description: 'Filter episodes from this date (YYYY-MM-DD)',
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},
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toDate: {
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type: 'string',
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description: 'Filter episodes to this date (YYYY-MM-DD)',
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},
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},
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required: [],
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},
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},
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{
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name: 'get_episode',
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description: 'Get detailed information about a specific HPR episode including transcript if available',
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inputSchema: {
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type: 'object',
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properties: {
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episodeId: {
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type: 'number',
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description: 'Episode ID number',
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},
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includeTranscript: {
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type: 'boolean',
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description: 'Include full transcript if available (default: true)',
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},
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includeComments: {
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type: 'boolean',
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description: 'Include community comments (default: true)',
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},
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},
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required: ['episodeId'],
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},
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},
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{
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name: 'search_transcripts',
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description: 'Search through episode transcripts for specific keywords or phrases',
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inputSchema: {
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type: 'object',
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properties: {
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query: {
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type: 'string',
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description: 'Search query to find in transcripts',
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},
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limit: {
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type: 'number',
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description: 'Maximum number of episodes to return (default: 20)',
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},
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contextLines: {
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type: 'number',
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description: 'Number of lines of context around matches (default: 3)',
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},
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},
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required: ['query'],
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},
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},
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{
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name: 'get_host_info',
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description: 'Get information about an HPR host including all their episodes',
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inputSchema: {
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type: 'object',
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properties: {
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hostId: {
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type: 'number',
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description: 'Host ID number',
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},
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hostName: {
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type: 'string',
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description: 'Host name (will search if hostId not provided)',
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},
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includeEpisodes: {
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type: 'boolean',
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description: 'Include list of all episodes by this host (default: true)',
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},
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},
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required: [],
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},
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},
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{
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name: 'get_series_info',
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description: 'Get information about an HPR series including all episodes in the series',
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inputSchema: {
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type: 'object',
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properties: {
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seriesId: {
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type: 'number',
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description: 'Series ID number',
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},
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},
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required: ['seriesId'],
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},
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},
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],
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};
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});
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// Handle tool calls
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server.setRequestHandler(CallToolRequestSchema, async (request) => {
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const { name, arguments: args } = request.params;
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try {
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if (name === 'search_episodes') {
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const results = dataLoader.searchEpisodes(args.query || '', {
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limit: args.limit || 20,
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hostId: args.hostId,
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seriesId: args.seriesId,
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tag: args.tag,
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fromDate: args.fromDate,
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toDate: args.toDate,
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});
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const text = results.length > 0
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? results.map(ep => formatEpisode(ep, false)).join('\n\n---\n\n')
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: 'No episodes found matching your search criteria.';
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return {
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content: [
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{
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type: 'text',
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text: `# Search Results (${results.length} episodes found)\n\n${text}`,
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},
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],
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||||
};
|
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}
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|
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if (name === 'get_episode') {
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const episode = dataLoader.getEpisode(args.episodeId);
|
||||
|
||||
if (!episode) {
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text: `Episode ${args.episodeId} not found.`,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
let text = formatEpisode(episode, true);
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||||
|
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// Add transcript if requested and available
|
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if (args.includeTranscript !== false) {
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const transcript = dataLoader.getTranscript(args.episodeId);
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||||
if (transcript) {
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text += `\n\n## Transcript\n\n${transcript}`;
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||||
} else {
|
||||
text += `\n\n## Transcript\n\n*No transcript available for this episode.*`;
|
||||
}
|
||||
}
|
||||
|
||||
// Add comments if requested
|
||||
if (args.includeComments !== false) {
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||||
const comments = dataLoader.getCommentsForEpisode(args.episodeId);
|
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if (comments.length > 0) {
|
||||
text += `\n\n## Comments (${comments.length})\n\n`;
|
||||
text += comments.map(c =>
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||||
`**${c.comment_author_name}** (${c.comment_timestamp})${c.comment_title ? ` - ${c.comment_title}` : ''}\n${c.comment_text}`
|
||||
).join('\n\n---\n\n');
|
||||
}
|
||||
}
|
||||
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
if (name === 'search_transcripts') {
|
||||
const results = dataLoader.searchTranscripts(args.query, {
|
||||
limit: args.limit || 20,
|
||||
contextLines: args.contextLines || 3,
|
||||
});
|
||||
|
||||
if (results.length === 0) {
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text: `No transcripts found containing "${args.query}".`,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
const text = results.map(result => {
|
||||
const { episode, matches } = result;
|
||||
const host = dataLoader.getHost(episode.hostid);
|
||||
|
||||
let episodeText = `# HPR${String(episode.id).padStart(4, '0')}: ${episode.title}
|
||||
**Host:** ${host?.host || 'Unknown'} | **Date:** ${episode.date}
|
||||
|
||||
**Matches found:** ${matches.length}
|
||||
|
||||
`;
|
||||
|
||||
matches.forEach(match => {
|
||||
episodeText += `### Line ${match.lineNumber}
|
||||
\`\`\`
|
||||
${match.context}
|
||||
\`\`\`
|
||||
|
||||
`;
|
||||
});
|
||||
|
||||
return episodeText;
|
||||
}).join('\n---\n\n');
|
||||
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text: `# Transcript Search Results (${results.length} episodes)\n\nSearching for: "${args.query}"\n\n${text}`,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
if (name === 'get_host_info') {
|
||||
let host;
|
||||
|
||||
if (args.hostId) {
|
||||
host = dataLoader.getHost(args.hostId);
|
||||
} else if (args.hostName) {
|
||||
const hosts = dataLoader.searchHosts(args.hostName);
|
||||
host = hosts[0];
|
||||
}
|
||||
|
||||
if (!host) {
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text: 'Host not found.',
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
let text = `# ${host.host}
|
||||
|
||||
**Host ID:** ${host.hostid}
|
||||
**Email:** ${host.email}
|
||||
**License:** ${host.license}
|
||||
**Profile:** ${stripHtml(host.profile)}
|
||||
`;
|
||||
|
||||
if (args.includeEpisodes !== false) {
|
||||
const episodes = dataLoader.getEpisodesByHost(host.hostid);
|
||||
text += `\n**Total Episodes:** ${episodes.length}\n\n## Episodes\n\n`;
|
||||
|
||||
// Sort by date (newest first)
|
||||
episodes.sort((a, b) => b.date.localeCompare(a.date));
|
||||
|
||||
text += episodes.map(ep =>
|
||||
`**HPR${String(ep.id).padStart(4, '0')}** (${ep.date}) - ${ep.title}\n ${ep.summary}`
|
||||
).join('\n\n');
|
||||
}
|
||||
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
if (name === 'get_series_info') {
|
||||
const series = dataLoader.getSeries(args.seriesId);
|
||||
|
||||
if (!series) {
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text: `Series ${args.seriesId} not found.`,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
const episodes = dataLoader.getEpisodesInSeries(args.seriesId);
|
||||
|
||||
let text = `# ${series.name}
|
||||
|
||||
**Series ID:** ${series.id}
|
||||
**Description:** ${stripHtml(series.description)}
|
||||
**Total Episodes:** ${episodes.length}
|
||||
|
||||
## Episodes in Series
|
||||
|
||||
`;
|
||||
|
||||
// Sort by date
|
||||
episodes.sort((a, b) => a.date.localeCompare(b.date));
|
||||
|
||||
text += episodes.map((ep, index) => {
|
||||
const host = dataLoader.getHost(ep.hostid);
|
||||
return `${index + 1}. **HPR${String(ep.id).padStart(4, '0')}** (${ep.date}) - ${ep.title} by ${host?.host || 'Unknown'}\n ${ep.summary}`;
|
||||
}).join('\n\n');
|
||||
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text,
|
||||
},
|
||||
],
|
||||
};
|
||||
}
|
||||
|
||||
throw new Error(`Unknown tool: ${name}`);
|
||||
} catch (error) {
|
||||
return {
|
||||
content: [
|
||||
{
|
||||
type: 'text',
|
||||
text: `Error: ${error.message}`,
|
||||
},
|
||||
],
|
||||
isError: true,
|
||||
};
|
||||
}
|
||||
});
|
||||
|
||||
return server;
|
||||
}
|
||||
|
||||
// Create Express app
|
||||
const app = express();
|
||||
|
||||
// Enable CORS
|
||||
app.use(cors());
|
||||
|
||||
// Enable compression
|
||||
app.use(compression());
|
||||
|
||||
// Rate limiting
|
||||
const limiter = rateLimit({
|
||||
windowMs: RATE_LIMIT_WINDOW_MS,
|
||||
max: RATE_LIMIT_MAX_REQUESTS,
|
||||
message: 'Too many requests from this IP, please try again later.',
|
||||
standardHeaders: true,
|
||||
legacyHeaders: false,
|
||||
});
|
||||
|
||||
app.use(limiter);
|
||||
|
||||
// Health check endpoint
|
||||
app.get('/health', (req, res) => {
|
||||
const usage = process.memoryUsage();
|
||||
const heapUsedMB = usage.heapUsed / 1024 / 1024;
|
||||
|
||||
res.json({
|
||||
status: 'ok',
|
||||
memory: {
|
||||
used: `${heapUsedMB.toFixed(2)}MB`,
|
||||
threshold: `${MEMORY_THRESHOLD_MB}MB`,
|
||||
},
|
||||
activeRequests,
|
||||
circuitBreaker: circuitBreaker.state,
|
||||
});
|
||||
});
|
||||
|
||||
// SSE endpoint for MCP
|
||||
app.get('/sse', async (req, res) => {
|
||||
try {
|
||||
// Check system health
|
||||
checkMemory();
|
||||
checkConcurrency();
|
||||
|
||||
activeRequests++;
|
||||
console.error(`New SSE connection. Active requests: ${activeRequests}`);
|
||||
|
||||
// Create a new MCP server instance for this connection
|
||||
const server = createMCPServer();
|
||||
|
||||
// Create SSE transport
|
||||
const transport = new SSEServerTransport('/message', res);
|
||||
|
||||
// Connect server with timeout and circuit breaker
|
||||
await withTimeout(
|
||||
circuitBreaker.execute(() => server.connect(transport)),
|
||||
REQUEST_TIMEOUT_MS
|
||||
);
|
||||
|
||||
// Handle connection close
|
||||
req.on('close', () => {
|
||||
activeRequests--;
|
||||
console.error(`SSE connection closed. Active requests: ${activeRequests}`);
|
||||
});
|
||||
|
||||
} catch (error) {
|
||||
activeRequests--;
|
||||
console.error('SSE connection error:', error.message);
|
||||
|
||||
if (!res.headersSent) {
|
||||
res.status(503).json({
|
||||
error: error.message,
|
||||
circuitBreaker: circuitBreaker.state,
|
||||
});
|
||||
}
|
||||
}
|
||||
});
|
||||
|
||||
// POST endpoint for MCP messages
|
||||
app.post('/message', express.json(), async (req, res) => {
|
||||
try {
|
||||
// SSE transport handles this internally
|
||||
res.status(200).send();
|
||||
} catch (error) {
|
||||
console.error('Message error:', error.message);
|
||||
res.status(500).json({ error: error.message });
|
||||
}
|
||||
});
|
||||
|
||||
// Error handling middleware
|
||||
app.use((err, req, res, next) => {
|
||||
console.error('Express error:', err);
|
||||
res.status(500).json({
|
||||
error: 'Internal server error',
|
||||
message: err.message,
|
||||
});
|
||||
});
|
||||
|
||||
// Start server
|
||||
app.listen(PORT, () => {
|
||||
console.error(`HPR Knowledge Base MCP Server running on http://localhost:${PORT}`);
|
||||
console.error(`SSE endpoint: http://localhost:${PORT}/sse`);
|
||||
console.error(`Health check: http://localhost:${PORT}/health`);
|
||||
console.error(`Configuration:`);
|
||||
console.error(` - Max concurrent requests: ${MAX_CONCURRENT_REQUESTS}`);
|
||||
console.error(` - Request timeout: ${REQUEST_TIMEOUT_MS}ms`);
|
||||
console.error(` - Rate limit: ${RATE_LIMIT_MAX_REQUESTS} requests per ${RATE_LIMIT_WINDOW_MS / 1000}s`);
|
||||
console.error(` - Memory threshold: ${MEMORY_THRESHOLD_MB}MB`);
|
||||
});
|
||||
|
||||
// Graceful shutdown
|
||||
process.on('SIGTERM', () => {
|
||||
console.error('SIGTERM received, shutting down gracefully...');
|
||||
process.exit(0);
|
||||
});
|
||||
|
||||
process.on('SIGINT', () => {
|
||||
console.error('SIGINT received, shutting down gracefully...');
|
||||
process.exit(0);
|
||||
});
|
||||
Reference in New Issue
Block a user