merge_scenes never reassigned playback_sources → ON DELETE CASCADE dropped them
with the absorbed scene. Cross-source (canonical) merges rarely had tube playback
so it hid, but tube-dup merges silently LOST playback links. Add _move_playback_sources
(global unique (origin,page_url) guarantees no collision on reassign).
+ merge_exact_title_duration.py: catches missing-merge dupes bulk_dedup misses
(same performer + identical normalized title + identical duration_sec, no phash).
Bad Bella had 25 such pairs (bug-report ef92809d "duplikat, te same miniatury").
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
