VP9-alpha detection (shouldUseVp9AlphaDecoder -> extractMediaMetadata)
spawns ffprobe with no timeout. For the new remote http(s) fallback that
ran before the bounded extractVideoFrameToBuffer, so a stalled remote host
could wedge `hyperframes snapshot` in ffprobe before the 30s extract timer
ever started. Probe only local files; for remote URLs skip it (pass false).
Local alpha behavior is unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
`hyperframes snapshot` works around Chrome-headless's inability to seek
`<video>` elements by extracting a frame via FFmpeg and injecting it as an
overlay. That path only resolved `<video src>` to a project-LOCAL file and
skipped everything else — so a composition whose embedded `<video>` points
at a remote http(s) URL (e.g. an S3-hosted clip embedded by an upstream
agent) rendered as a blank box in every snapshot, while `render` (which
plays the element in-browser) showed it fine.
Add a remote fallback: when the src doesn't resolve to a project-local file
but is an http(s) URL, pass the absolute URL straight to FFmpeg (it reads
http(s) input directly). Local-first is preserved (fast, sandboxed); the
existing 30s extract timeout bounds remote fetches.
Verified on a real composition: remote-src snapshot was blank, local-src
rendered; `ffmpeg -ss N -i <https-url> -frames:v 1` extracts in ~0.5s.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
