Function downloadVideoBody

packages/cli/src/capture/mediaCapture.ts:233–273

(
  srcUrl: string,
  filename: string,
  videosDir: string,
)

 */
// fallow-ignore-next-line complexity
async function downloadVideoBody(
  srcUrl: string,
  filename: string,
  videosDir: string,
): Promise<string | null> {
  if (isPrivateUrl(srcUrl)) return null; // cheap pre-check; safeFetch re-checks every hop
  let ext = "";
  try {
    ext = extname(new URL(srcUrl).pathname).toLowerCase();
  } catch {
    return null;
  }
  if (!DOWNLOADABLE_VIDEO_EXTS.has(ext)) return null; // streaming manifest / unknown — leave on origin
  try {
    // safeFetch resolves redirects manually and re-runs isPrivateUrl on each
    // Location hop, so a public URL cannot 30x to an internal/metadata host.
    const res = await safeFetch(srcUrl, {
      signal: AbortSignal.timeout(120000), // up to ~75 MB on a slow link; aborts cleanly → still-frame fallback
      headers: { "User-Agent": "HyperFrames/1.0" },
    });
    if (!res || !res.ok || !res.body) return null;
    const ct = (res.headers.get("content-type") || "").toLowerCase();
    if (ct && !ct.startsWith("video/") && !ct.includes("octet-stream")) return null;
    const declared = Number(res.headers.get("content-length") || 0);
    if (declared && declared > MAX_VIDEO_BYTES) return null; // too big — leave on origin
    // Stream with a hard cap; a chunked response has no Content-Length to trust.
    const chunks: Buffer[] = [];
    let total = 0;
    for await (const chunk of res.body as unknown as AsyncIterable<Uint8Array>) {
      total += chunk.length;
      if (total > MAX_VIDEO_BYTES) return null; // abort oversized stream — no partial file written
      chunks.push(Buffer.from(chunk));
    }
    if (total < 1024) return null; // too small to be a real video (likely an error blob)
    const safe = /\.[a-z0-9]+$/i.test(filename) ? filename.replace(/[^\w.-]/g, "_") : `video${ext}`;
    writeFileSync(join(videosDir, safe), Buffer.concat(chunks));
    return `assets/videos/${safe}`;
  } catch {
    return null;
  }
}

/** A <video> descriptor scanned from the DOM (rich: has rect + nearby text). */
interface VideoDescriptor {