Lessons

Alpine x-transition + tw-animate-css exit animations flash at the end

• Symptom: a modal/overlay fades out, then flashes fully visible for 1-2 frames before it disappears.
• Cause: animate-out keyframes default to animation-fill-mode: none. The element snaps back to its natural state when the keyframe ends. Alpine hides the element (display: none) only after its own timer (read from transition-duration), which starts ~2 rAF later than the animation. The gap shows the element at full opacity.
• Rule: every x-transition:leave that uses tw-animate-css animate-out MUST also include fill-mode-forwards.
• Rule: when a user reports UI flicker, check ALL layers of the animation stack (state reset timing, spinner flash, keyframe fill mode, focus restore) before you report the fix as complete. My first fix covered state reset and spinner only; the fill-mode snap was the visible one.