v151 · css · native runtime proof

Native scroll re-entry lab

Run the real named timeline-trigger + animation-trigger path used by the WPT. Enter the trigger range, let the animation finish, leave, then re-enter. Chrome 151 should keep the animation finished instead of rewinding it.

Checking the exact named-trigger syntax…

Scroll down to the blue trigger range
Named trigger sourcetimeline-trigger: --reentry view() 60px 120px
Continue past the trigger, then return
target
Waiting for capability check…
  1. Enter: target plays toward the enlarged state.
  2. Finish: force the native CSS animation to its end for a deterministic check.
  3. Exit + re-enter: record whether the finished animation restarted.

Exact CSS under test

.subject {
  timeline-trigger: --reentry view() 60px 120px;
}
.target {
  animation: grow 900ms ease-out both;
  animation-trigger: --reentry play;
}

references