Now-playing pager without a feedback loop

The pager is a two-way binding: it slides when the player advances, and it seeks when the user settles on another page. Each direction writes what the other watches — keep one quiet at a time.

Traps

The in-progress-scroll flag is true for programmatic animation too. It is the obvious way to mean "the user is dragging" and it is wrong: the pager sets it identically for a drag and for the animate-to-page call your own follow effect just made, so it blocks the follow while it runs. Use a flag you own: