Collapse one-word and very short caption carry-over fragments so reprocessed YouTube transcripts do not retain residual prefix chains.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Normalize incremental backend hypothesis chains before persistence and ignore stale or replayed webhook callbacks so duplicate transcript text does not survive ingest.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>