310211 2026-03-18 13:56:40 -0700 [macOS] imported/w3c/web-platform-tests/webvtt/rendering/cues-with-video/processing-model/selectors/cue/background_shorthand_css_relative_url.html is a flaky image diff 2026-04-06 12:27:01 -0700 1 1 1 Unclassified WebKit New Bugs WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 d_delatoba d_delatoba webkit-bot-watchers-bugzilla webkit-bug-importer oldest_to_newest 2191447 0 d_delatoba 2026-03-18 13:56:40 -0700 imported/w3c/web-platform-tests/webvtt/rendering/cues-with-video/processing-model/selectors/cue/background_shorthand_css_relative_url.html is a flaky image diff on macOS HISTORY: https://results.webkit.org/?suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fwebvtt%2Frendering%2Fcues-with-video%2Fprocessing-model%2Fselectors%2Fcue%2Fbackground_shorthand_css_relative_url.html DIFF: https://build.webkit.org/results/Apple-Tahoe-Debug-AppleSilicon-WK2-Tests/309478@main%20(1348)/imported/w3c/web-platform-tests/webvtt/rendering/cues-with-video/processing-model/selectors/cue/background_shorthand_css_relative_url-diffs.html IMAGES: See attached. REPRODUCTION: I was able to reproduce this on macOS Tahoe Release and Debug with the following: run-webkit-tests --no-build --no-retry --no-show-results --exit-after-n-failures=1 --expect-pass --iterations=469 --force -f --debug imported/w3c/web-platform-tests/webvtt/rendering/cues-with-video/processing-model/selectors/cue/background_shorthand_css_relative_url.html I am going to mark expectations as imageOnlyFailure Pass while this pends investigation 2191449 1 webkit-bug-importer 2026-03-18 13:56:51 -0700 <rdar://problem/172860387> 2191451 2 d_delatoba 2026-03-18 14:00:14 -0700 Test gardening pull request: https://github.com/WebKit/WebKit/pull/60882 2191455 3 ews-feeder 2026-03-18 14:06:35 -0700 Test gardening commit 309501@main (ca7657d68d24): <https://commits.webkit.org/309501@main> Reviewed commits have been landed. Closing PR #60882 and removing active labels. 2191466 4 d_delatoba 2026-03-18 14:37:01 -0700 The test is flaky because the onplaying event handler called takeScreenshot() immediately after pausing the video. This results in a blank screenshot (no cue text visible) compared against the reference that always shows the text due to video rendering times being slower on debug and release builds under load. The fix is to add a 10ms delay before the screenshot. 2191472 5 d_delatoba 2026-03-18 14:39:49 -0700 Pull request: https://github.com/WebKit/WebKit/pull/60886 2197335 6 ews-feeder 2026-04-06 12:26:59 -0700 Committed 310661@main (c580efceede5): <https://commits.webkit.org/310661@main> Reviewed commits have been landed. Closing PR #60886 and removing active labels.