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- const crypto = require('crypto');
- const http = require('http');
- const fs = require('fs');
- const path = require('path');
- // ========== WebSocket Protocol (RFC 6455) ==========
- const OPCODES = { TEXT: 0x01, CLOSE: 0x08, PING: 0x09, PONG: 0x0A };
- const WS_MAGIC = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';
- function computeAcceptKey(clientKey) {
- return crypto.createHash('sha1').update(clientKey + WS_MAGIC).digest('base64');
- }
- function encodeFrame(opcode, payload) {
- const fin = 0x80;
- const len = payload.length;
- let header;
- if (len < 126) {
- header = Buffer.alloc(2);
- header[0] = fin | opcode;
- header[1] = len;
- } else if (len < 65536) {
- header = Buffer.alloc(4);
- header[0] = fin | opcode;
- header[1] = 126;
- header.writeUInt16BE(len, 2);
- } else {
- header = Buffer.alloc(10);
- header[0] = fin | opcode;
- header[1] = 127;
- header.writeBigUInt64BE(BigInt(len), 2);
- }
- return Buffer.concat([header, payload]);
- }
- function decodeFrame(buffer) {
- if (buffer.length < 2) return null;
- const secondByte = buffer[1];
- const opcode = buffer[0] & 0x0F;
- const masked = (secondByte & 0x80) !== 0;
- let payloadLen = secondByte & 0x7F;
- let offset = 2;
- if (!masked) throw new Error('Client frames must be masked');
- if (payloadLen === 126) {
- if (buffer.length < 4) return null;
- payloadLen = buffer.readUInt16BE(2);
- offset = 4;
- } else if (payloadLen === 127) {
- if (buffer.length < 10) return null;
- payloadLen = Number(buffer.readBigUInt64BE(2));
- offset = 10;
- }
- const maskOffset = offset;
- const dataOffset = offset + 4;
- const totalLen = dataOffset + payloadLen;
- if (buffer.length < totalLen) return null;
- const mask = buffer.slice(maskOffset, dataOffset);
- const data = Buffer.alloc(payloadLen);
- for (let i = 0; i < payloadLen; i++) {
- data[i] = buffer[dataOffset + i] ^ mask[i % 4];
- }
- return { opcode, payload: data, bytesConsumed: totalLen };
- }
- // ========== Configuration ==========
- const PORT = process.env.BRAINSTORM_PORT || (49152 + Math.floor(Math.random() * 16383));
- const HOST = process.env.BRAINSTORM_HOST || '127.0.0.1';
- const URL_HOST = process.env.BRAINSTORM_URL_HOST || (HOST === '127.0.0.1' ? 'localhost' : HOST);
- const SESSION_DIR = process.env.BRAINSTORM_DIR || '/tmp/brainstorm';
- const CONTENT_DIR = path.join(SESSION_DIR, 'content');
- const STATE_DIR = path.join(SESSION_DIR, 'state');
- let ownerPid = process.env.BRAINSTORM_OWNER_PID ? Number(process.env.BRAINSTORM_OWNER_PID) : null;
- const MIME_TYPES = {
- '.html': 'text/html', '.css': 'text/css', '.js': 'application/javascript',
- '.json': 'application/json', '.png': 'image/png', '.jpg': 'image/jpeg',
- '.jpeg': 'image/jpeg', '.gif': 'image/gif', '.svg': 'image/svg+xml'
- };
- // ========== Templates and Constants ==========
- const WAITING_PAGE = `<!DOCTYPE html>
- <html>
- <head><meta charset="utf-8"><title>Brainstorm Companion</title>
- <style>body { font-family: system-ui, sans-serif; padding: 2rem; max-width: 800px; margin: 0 auto; }
- h1 { color: #333; } p { color: #666; }</style>
- </head>
- <body><h1>Brainstorm Companion</h1>
- <p>Waiting for the agent to push a screen...</p></body></html>`;
- const frameTemplate = fs.readFileSync(path.join(__dirname, 'frame-template.html'), 'utf-8');
- const helperScript = fs.readFileSync(path.join(__dirname, 'helper.js'), 'utf-8');
- const helperInjection = '<script>\n' + helperScript + '\n</script>';
- // ========== Helper Functions ==========
- function isFullDocument(html) {
- const trimmed = html.trimStart().toLowerCase();
- return trimmed.startsWith('<!doctype') || trimmed.startsWith('<html');
- }
- function wrapInFrame(content) {
- return frameTemplate.replace('<!-- CONTENT -->', content);
- }
- function getNewestScreen() {
- const files = fs.readdirSync(CONTENT_DIR)
- .filter(f => f.endsWith('.html'))
- .map(f => {
- const fp = path.join(CONTENT_DIR, f);
- return { path: fp, mtime: fs.statSync(fp).mtime.getTime() };
- })
- .sort((a, b) => b.mtime - a.mtime);
- return files.length > 0 ? files[0].path : null;
- }
- // ========== HTTP Request Handler ==========
- function handleRequest(req, res) {
- touchActivity();
- if (req.method === 'GET' && req.url === '/') {
- const screenFile = getNewestScreen();
- let html = screenFile
- ? (raw => isFullDocument(raw) ? raw : wrapInFrame(raw))(fs.readFileSync(screenFile, 'utf-8'))
- : WAITING_PAGE;
- if (html.includes('</body>')) {
- html = html.replace('</body>', helperInjection + '\n</body>');
- } else {
- html += helperInjection;
- }
- res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
- res.end(html);
- } else if (req.method === 'GET' && req.url.startsWith('/files/')) {
- const fileName = req.url.slice(7);
- const filePath = path.join(CONTENT_DIR, path.basename(fileName));
- if (!fs.existsSync(filePath)) {
- res.writeHead(404);
- res.end('Not found');
- return;
- }
- const ext = path.extname(filePath).toLowerCase();
- const contentType = MIME_TYPES[ext] || 'application/octet-stream';
- res.writeHead(200, { 'Content-Type': contentType });
- res.end(fs.readFileSync(filePath));
- } else {
- res.writeHead(404);
- res.end('Not found');
- }
- }
- // ========== WebSocket Connection Handling ==========
- const clients = new Set();
- function handleUpgrade(req, socket) {
- const key = req.headers['sec-websocket-key'];
- if (!key) { socket.destroy(); return; }
- const accept = computeAcceptKey(key);
- socket.write(
- 'HTTP/1.1 101 Switching Protocols\r\n' +
- 'Upgrade: websocket\r\n' +
- 'Connection: Upgrade\r\n' +
- 'Sec-WebSocket-Accept: ' + accept + '\r\n\r\n'
- );
- let buffer = Buffer.alloc(0);
- clients.add(socket);
- socket.on('data', (chunk) => {
- buffer = Buffer.concat([buffer, chunk]);
- while (buffer.length > 0) {
- let result;
- try {
- result = decodeFrame(buffer);
- } catch (e) {
- socket.end(encodeFrame(OPCODES.CLOSE, Buffer.alloc(0)));
- clients.delete(socket);
- return;
- }
- if (!result) break;
- buffer = buffer.slice(result.bytesConsumed);
- switch (result.opcode) {
- case OPCODES.TEXT:
- handleMessage(result.payload.toString());
- break;
- case OPCODES.CLOSE:
- socket.end(encodeFrame(OPCODES.CLOSE, Buffer.alloc(0)));
- clients.delete(socket);
- return;
- case OPCODES.PING:
- socket.write(encodeFrame(OPCODES.PONG, result.payload));
- break;
- case OPCODES.PONG:
- break;
- default: {
- const closeBuf = Buffer.alloc(2);
- closeBuf.writeUInt16BE(1003);
- socket.end(encodeFrame(OPCODES.CLOSE, closeBuf));
- clients.delete(socket);
- return;
- }
- }
- }
- });
- socket.on('close', () => clients.delete(socket));
- socket.on('error', () => clients.delete(socket));
- }
- function handleMessage(text) {
- let event;
- try {
- event = JSON.parse(text);
- } catch (e) {
- console.error('Failed to parse WebSocket message:', e.message);
- return;
- }
- touchActivity();
- console.log(JSON.stringify({ source: 'user-event', ...event }));
- if (event.choice) {
- const eventsFile = path.join(STATE_DIR, 'events');
- fs.appendFileSync(eventsFile, JSON.stringify(event) + '\n');
- }
- }
- function broadcast(msg) {
- const frame = encodeFrame(OPCODES.TEXT, Buffer.from(JSON.stringify(msg)));
- for (const socket of clients) {
- try { socket.write(frame); } catch (e) { clients.delete(socket); }
- }
- }
- // ========== Activity Tracking ==========
- const IDLE_TIMEOUT_MS = 30 * 60 * 1000; // 30 minutes
- let lastActivity = Date.now();
- function touchActivity() {
- lastActivity = Date.now();
- }
- // ========== File Watching ==========
- const debounceTimers = new Map();
- // ========== Server Startup ==========
- function startServer() {
- if (!fs.existsSync(CONTENT_DIR)) fs.mkdirSync(CONTENT_DIR, { recursive: true });
- if (!fs.existsSync(STATE_DIR)) fs.mkdirSync(STATE_DIR, { recursive: true });
- // Track known files to distinguish new screens from updates.
- // macOS fs.watch reports 'rename' for both new files and overwrites,
- // so we can't rely on eventType alone.
- const knownFiles = new Set(
- fs.readdirSync(CONTENT_DIR).filter(f => f.endsWith('.html'))
- );
- const server = http.createServer(handleRequest);
- server.on('upgrade', handleUpgrade);
- const watcher = fs.watch(CONTENT_DIR, (eventType, filename) => {
- if (!filename || !filename.endsWith('.html')) return;
- if (debounceTimers.has(filename)) clearTimeout(debounceTimers.get(filename));
- debounceTimers.set(filename, setTimeout(() => {
- debounceTimers.delete(filename);
- const filePath = path.join(CONTENT_DIR, filename);
- if (!fs.existsSync(filePath)) return; // file was deleted
- touchActivity();
- if (!knownFiles.has(filename)) {
- knownFiles.add(filename);
- const eventsFile = path.join(STATE_DIR, 'events');
- if (fs.existsSync(eventsFile)) fs.unlinkSync(eventsFile);
- console.log(JSON.stringify({ type: 'screen-added', file: filePath }));
- } else {
- console.log(JSON.stringify({ type: 'screen-updated', file: filePath }));
- }
- broadcast({ type: 'reload' });
- }, 100));
- });
- watcher.on('error', (err) => console.error('fs.watch error:', err.message));
- function shutdown(reason) {
- console.log(JSON.stringify({ type: 'server-stopped', reason }));
- const infoFile = path.join(STATE_DIR, 'server-info');
- if (fs.existsSync(infoFile)) fs.unlinkSync(infoFile);
- fs.writeFileSync(
- path.join(STATE_DIR, 'server-stopped'),
- JSON.stringify({ reason, timestamp: Date.now() }) + '\n'
- );
- watcher.close();
- clearInterval(lifecycleCheck);
- server.close(() => process.exit(0));
- }
- function ownerAlive() {
- if (!ownerPid) return true;
- try { process.kill(ownerPid, 0); return true; } catch (e) { return e.code === 'EPERM'; }
- }
- // Check every 60s: exit if owner process died or idle for 30 minutes
- const lifecycleCheck = setInterval(() => {
- if (!ownerAlive()) shutdown('owner process exited');
- else if (Date.now() - lastActivity > IDLE_TIMEOUT_MS) shutdown('idle timeout');
- }, 60 * 1000);
- lifecycleCheck.unref();
- // Validate owner PID at startup. If it's already dead, the PID resolution
- // was wrong (common on WSL, Tailscale SSH, and cross-user scenarios).
- // Disable monitoring and rely on the idle timeout instead.
- if (ownerPid) {
- try { process.kill(ownerPid, 0); }
- catch (e) {
- if (e.code !== 'EPERM') {
- console.log(JSON.stringify({ type: 'owner-pid-invalid', pid: ownerPid, reason: 'dead at startup' }));
- ownerPid = null;
- }
- }
- }
- server.listen(PORT, HOST, () => {
- const info = JSON.stringify({
- type: 'server-started', port: Number(PORT), host: HOST,
- url_host: URL_HOST, url: 'http://' + URL_HOST + ':' + PORT,
- screen_dir: CONTENT_DIR, state_dir: STATE_DIR
- });
- console.log(info);
- fs.writeFileSync(path.join(STATE_DIR, 'server-info'), info + '\n');
- });
- }
- if (require.main === module) {
- startServer();
- }
- module.exports = { computeAcceptKey, encodeFrame, decodeFrame, OPCODES };
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