const express = require('express');
const http = require('http');
const WebSocket = require('ws');
const chokidar = require('chokidar');
const fs = require('fs');
const path = require('path');
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 SCREEN_DIR = process.env.BRAINSTORM_DIR || '/tmp/brainstorm';
if (!fs.existsSync(SCREEN_DIR)) {
fs.mkdirSync(SCREEN_DIR, { recursive: true });
}
// Load frame template and helper script once at startup
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 = ``;
// Detect whether content is a full HTML document or a bare fragment
function isFullDocument(html) {
const trimmed = html.trimStart().toLowerCase();
return trimmed.startsWith('', content);
}
// Find the newest .html file in the directory by mtime
function getNewestScreen() {
const files = fs.readdirSync(SCREEN_DIR)
.filter(f => f.endsWith('.html'))
.map(f => ({
name: f,
path: path.join(SCREEN_DIR, f),
mtime: fs.statSync(path.join(SCREEN_DIR, f)).mtime.getTime()
}))
.sort((a, b) => b.mtime - a.mtime);
return files.length > 0 ? files[0].path : null;
}
const WAITING_PAGE = `
Brainstorm Companion
Brainstorm Companion
Waiting for Claude to push a screen...
`;
const app = express();
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });
const clients = new Set();
wss.on('connection', (ws) => {
clients.add(ws);
ws.on('close', () => clients.delete(ws));
ws.on('message', (data) => {
const event = JSON.parse(data.toString());
console.log(JSON.stringify({ source: 'user-event', ...event }));
// Write user events to .events file for Claude to read
if (event.choice) {
const eventsFile = path.join(SCREEN_DIR, '.events');
fs.appendFileSync(eventsFile, JSON.stringify(event) + '\n');
}
});
});
// Serve newest screen with helper.js injected
app.get('/', (req, res) => {
const screenFile = getNewestScreen();
let html;
if (!screenFile) {
html = WAITING_PAGE;
} else {
const raw = fs.readFileSync(screenFile, 'utf-8');
html = isFullDocument(raw) ? raw : wrapInFrame(raw);
}
// Inject helper script
if (html.includes(' ')) {
html = html.replace('', `${helperInjection}\n`);
} else {
html += helperInjection;
}
res.type('html').send(html);
});
// Watch for new or changed .html files
chokidar.watch(SCREEN_DIR, { ignoreInitial: true })
.on('add', (filePath) => {
if (filePath.endsWith('.html')) {
// Clear events from previous screen
const eventsFile = path.join(SCREEN_DIR, '.events');
if (fs.existsSync(eventsFile)) fs.unlinkSync(eventsFile);
console.log(JSON.stringify({ type: 'screen-added', file: filePath }));
clients.forEach(ws => {
if (ws.readyState === WebSocket.OPEN) {
ws.send(JSON.stringify({ type: 'reload' }));
}
});
}
})
.on('change', (filePath) => {
if (filePath.endsWith('.html')) {
console.log(JSON.stringify({ type: 'screen-updated', file: filePath }));
clients.forEach(ws => {
if (ws.readyState === WebSocket.OPEN) {
ws.send(JSON.stringify({ type: 'reload' }));
}
});
}
});
server.listen(PORT, HOST, () => {
console.log(JSON.stringify({
type: 'server-started',
port: PORT,
host: HOST,
url_host: URL_HOST,
url: `http://${URL_HOST}:${PORT}`,
screen_dir: SCREEN_DIR
}));
});