diff --git a/tests/Browser/CarouselTest.php b/tests/Browser/CarouselTest.php
index d6e0fe01..500618a3 100644
--- a/tests/Browser/CarouselTest.php
+++ b/tests/Browser/CarouselTest.php
@@ -170,14 +170,18 @@ it('brings a partly hidden item into focus when it is pressed, and leaves an ope
 it('scrolls instantly and leaves every item unmasked under reduced motion', function () {
     // A click, then a separate read-only assertScript: assertScript retries its whole expression
     // on a false result (this file's own comment above), and a click inside it would fire again on
-    // every retry, drifting the carousel one further item each time and never recovering.
+    // every retry, drifting the carousel one further item each time and never recovering. Whether
+    // the row had arrived is read in the same task as the click, against the slot size measured
+    // before it, and kept, so a retry cannot turn a smooth scroll that finishes later into a pass:
+    // under reduced motion it must be instant. (The row re-measures its slot a frame later, so the
+    // assertion below reads a fresh size rather than this one.)
     $page = carouselShowcase(['reducedMotion' => 'reduce']);
 
-    $page->script(onCarousel(0, 'root.querySelector(\'[aria-label="Next"]\').click()'));
+    $page->script(onCarousel(0, 'root.querySelector(\'[aria-label="Next"]\').click(); window.__arrivedAtOnce = at(1)'));
 
     $page->assertScript(onCarousel(0, <<<'JS'
         await pause(50)
-        return at(1) && items.every((_, i) => inset(i) === 0)
+        return window.__arrivedAtOnce === true && at(1) && items.every((_, i) => inset(i) === 0)
             && items.every((item) => Math.abs(item.getBoundingClientRect().width - size) < 1.5)
         JS));
 });