Splitting or closing a panel changes the stride, which renumbers every
step, so the slides are rebuilt -- and the rebuild threw away the panes
along with them. Every video on screen was fetched and buffered again to
show what it was already showing.
The panes are now set aside by video id first, and whoever needs that
video next takes the pane that already has it: the same element, the
same stream, the frames it had already decoded. It all happens in one go
without yielding, so a pane is never out of the document long enough to
be paused for it. Panes the new layout has no place for are torn down as
before -- they are holding a stream open.
Pane tools are rebindable for the same reason: a reused pane comes back
under a different node in the tree, and its old buttons would otherwise
split and close the one it left.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MPZFnNdHbPGDTqQUNiE4ZN
adb254c20b