Every Images card's overlay starts with the concept's "Select <filename>"
checkbox before the star. Checked image keys form the page's selection,
kept across Load more, infinite scroll and bounded re-mounting and cleared
whenever the collection is replaced. The #bulkbar between the filter row
and the gallery shows "N selected" with Set category, Export metadata and
Clear (the first two are wired by the next tasks); Clear empties it.
The interim D8 star rule is removed, and the concept comparison now
measures the overlay with its checkbox and the bar with one card checked.
Vito Sansevero
d7f1b9987f