Faster Stitched Plate Sprites

Previously, a stitched plate sprite was only built the first time someone loaded the plate page after imaging finished, so the first viewer had to wait. Now, as soon as all of a plate's well images are ready, the stitched sprite packs automatically in the background — so the plate view is ready the moment you open it.

Details

• If a well image changes after packing started, only the affected size is retried — its sibling size still completes on time
• A verification step confirms each well image is current before it's packed, so a stitched sprite never silently shows outdated imagery