Favourites & notes
Hearting picks and leaving per-photo retouching notes.
When an album is in Proofing, the client picks the photos they want and can attach a retouching note to each — exactly the selection that comes back to you on the photographer side.
Hearting favourites
In the album grid, the client taps the heart on any photo to mark it a favourite. Tapping again removes it. Picks save instantly (no "submit" step) and are tied to that client's email, so two clients on the same album keep separate lists.

Retouching notes
The Selections page lists everything the client has hearted. Next to each photo there's a note field — "please remove the sign in the background", "crop to portrait", and so on. They write their notes and click Save.

Those favourites and notes show up against the album in your proofing view, so you edit exactly what the client asked for.
Picking needs Proofing to be on
The heart buttons only appear while the album is in the Proofing phase. Before that (In review) there's nothing to select; after it (Editing/ Delivered) the selection is locked in as the brief for your edit.