- Wait until the picker movie's file size stops changing before
staging it, so a movie whose final bytes are still being flushed is
never copied truncated (which produced drafts without a thumbnail
and unplayable previews).
- Log the whole camera video path (pickup size, staging result,
analyze outcome, thumbnail decode) under the video-preview os_log
category for fast on-device diagnosis.
- Cover the video analysis pipeline with a simulator test that
generates an HEVC QuickTime movie and asserts duration plus JPEG
thumbnail, and guard the diagnostics in Scripts/verify.sh.
