Diagnosis: individual tiles flickered when their stream died and mpv
relaunched (confirmed via status: a PID dropping to 0 and coming back).
The restarted window mapped at the video's native size wherever sway
dropped it, and the corrective loop only snapped it into its cell on the
next tick — up to 2s later on the relaxed cadence.
Fix, at the source instead of racing the map:
- Pre-install a per-slot for_window rule (matched on each mpv's unique
window title, anchored so slot-1 never matches slot-10) so sway
positions and sizes the window synchronously the moment it maps.
- Pass --geometry=WxH per tile so mpv opens at the tile size rather
than resizing itself to the video's native size on load.
The placeLoop remains as a corrective backstop for mid-life drift.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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