Make actions feel like they happened
The feedback that stops people clicking twice.
Here's my interface: <paste> Every action should visibly acknowledge itself. Add: - Immediate press feedback on buttons — within one frame. - A loading state on anything asynchronous, on the element that was clicked, not a full-page overlay. - A clear success state that lasts long enough to notice. - Smooth transitions on things that appear and disappear, so nothing pops into existence. Rules: nothing over 200ms, nothing that delays the actual action, and everything respects prefers-reduced-motion. Tell me which of my actions currently give no feedback at all.
Any action with no acknowledgement gets clicked again. That's how one order becomes three, and it's an interface bug rather than a user error.