1702
When the user taps the add-to-watchlist button, the plus ('+') icon smoothly morphs into a checkmark ('✓'). The vertical and horizontal strokes of the plus sign dynamically shift, rotate, and resize to form the checkmark with a subtle springy bounce. Tapping it again reverses the animation, morphing the checkmark back into a plus sign. This fluid vector transition provides clear, delightful feedback without changing the button's overall container size.
