serve.js

const http = require('http'), fs = require('fs'), path = require('path');
const PORT = 8180;
const ROOT = __dirname;
const MODEL_DIR = path.join(ROOT, 'model_splits');

const MIME = {
  '.html': 'text/html', '.js': 'text/javascript', '.mjs': 'text/javascript',
  '.json': 'application/json', '.gguf': 'application/octet-stream',
  '.wasm': 'application/wasm', '.css': 'text/css',
};

http.createServer((req, res) => {
  if (req.method === 'OPTIONS') {
    res.writeHead(200, {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'GET,HEAD',
      'Cross-Origin-Embedder-Policy': 'require-corp',
      'Cross-Origin-Opener-Policy': 'same-origin',
    });
    return res.end();
  }

  let p = decodeURIComponent(req.url.split('?')[0]);
  if (p === '/') p = '/index.html';

  let fp;
  if (p.startsWith('/model/')) {
    fp = path.join(MODEL_DIR, p.slice('/model/'.length));
  } else {
    fp = path.resolve(ROOT, '.' + p);
  }

  fs.stat(fp, (e, st) => {
    if (e) { res.writeHead(404); return res.end('not found: ' + p); }
    const total = st.size;
    const range = req.headers.range;
    const ct = MIME[path.extname(fp)] || 'application/octet-stream';

    const headers = {
      'Content-Type': ct, 'Accept-Ranges': 'bytes',
      'Access-Control-Allow-Origin': '*',
      'Cross-Origin-Embedder-Policy': 'require-corp',
      'Cross-Origin-Opener-Policy': 'same-origin',
    };

    if (range) {
      const m = range.match(/bytes=(\d+)-(\d*)/);
      if (m) {
        const start = parseInt(m[1]);
        const end = m[2] ? parseInt(m[2]) : total - 1;
        headers['Content-Range'] = `bytes ${start}-${end}/${total}`;
        headers['Content-Length'] = end - start + 1;
        res.writeHead(206, headers);
        return fs.createReadStream(fp, { start, end }).pipe(res);
      }
    }

    headers['Content-Length'] = total;
    res.writeHead(200, headers);
    fs.createReadStream(fp).pipe(res);
  });
}).listen(PORT, () => {
  console.log(`SmolLM2-360M WebGPU on http://localhost:${PORT}`);
  console.log(`Model splits: ${MODEL_DIR}`);
  try {
    const files = fs.readdirSync(MODEL_DIR).filter(f => f.endsWith('.gguf'));
    console.log(`Split files: ${files.length}`);
  } catch(e) { console.log('No model_splits dir yet'); }
});