Track records now carry the source blob's byte size on muxlTrack and per-track duration on commonMetadata; the video record's duration is required so it's always populated. Pulls size from publishParams and durationMS from the gstreamer probe, both shared across every track of a single MUXL container. Indexer drops its nil-check on Video.Duration since the lexicon now mandates it. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>