Function downloadFile

browse/src/security-classifier.ts:138–171

(url: string, dest: string)

// ─── Model download + staging ────────────────────────────────

export async function downloadFile(url: string, dest: string): Promise<void> {
  const res = await fetch(url);
  if (!res.ok || !res.body) {
    throw new Error(`Failed to fetch ${url}: ${res.status} ${res.statusText}`);
  }
  const tmp = `${dest}.tmp.${process.pid}`;
  const writer = fs.createWriteStream(tmp);
  // @ts-ignore — Node stream compat
  const reader = res.body.getReader();
  try {
    let done = false;
    while (!done) {
      const chunk = await reader.read();
      if (chunk.done) { done = true; break; }
      writer.write(chunk.value);
    }
    await new Promise<void>((resolve, reject) => {
      writer.end((err?: Error | null) => (err ? reject(err) : resolve()));
    });
    fs.renameSync(tmp, dest);
  } catch (err) {
    // Drop the half-written tmp so we don't ship a truncated model file to
    // a retry's renameSync. Wait for the writer to close fully before
    // unlinking: Node's createWriteStream lazily opens the FD and flushes
    // buffered writes during destroy(), so a naive unlinkSync hits ENOENT
    // first and the writer re-creates the file on the next tick.
    await new Promise<void>((resolve) => {
      writer.once('close', () => resolve());
      writer.destroy();
    });
    try { fs.unlinkSync(tmp); } catch { /* nothing to clean */ }
    throw err;
  }
}

async function ensureTestsavantStaged(onProgress?: (msg: string) => void): Promise<void> {
  mkdirSecure(path.join(TESTSAVANT_DIR, 'onnx'));