The reply that stays put
Sending a reply no longer nudges the thread, and delivery no longer redraws your bubble. Holding a photo now keeps you in the viewer instead of throwing a reaction picker on top.
You quote a message, type a line, and hit send. The quoted bar clears before your bubble lands, and the rows above it stay exactly where they were. When the checkmark arrives, the bubble is the same bubble, with no flicker and no reorder. On a phone, press and hold a photo and the viewer keeps its ground instead of throwing reactions over it.
Credit goes to xHeaven, who rebuilt the thread's moving parts. The reply bar folds over 300 milliseconds on a grid row when you cancel, and sending clears it before the outgoing bubble is inserted. Each message keeps one identity from pending to delivered, so the delivery update has nothing to replace. Reaction chips get 2 pixels of clearance above and 4 below without making a message taller. A finger hold waits 420 milliseconds. A second finger cancels it, and a double tap within 300 milliseconds and 24 pixels still leaves a heart. On phones, the empty composer's placeholder now truncates to one line while a real draft still wraps.
One catch. The photo viewer now swallows the hold. A press that begins inside it no longer opens reactions, so you have to close the viewer and hold the image in the thread to react.