test(scroll): de-flake invariant-1 by measuring anchor drift from the DOM#968
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mremond wants to merge 2 commits into
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test(scroll): de-flake invariant-1 by measuring anchor drift from the DOM#968mremond wants to merge 2 commits into
mremond wants to merge 2 commits into
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…virt map Retry-absorbed webkit flake persisted because Assertion B derived drift from __fluuxGetVirtOffset: during the re-assert loop that map can report a stale pre-prepend offset for a sustained window while scrollTop already reflects the added batch, yielding a ~2880-3034px phantom drift that isn't on screen. A second trigger was the demo mount blowing the 60s per-test budget on a slow webkit runner. - Measure the anchor row's own getBoundingClientRect().top vs its captured before-position — the layout truth the user sees, which can't go stale like the offset map. waitForAnchorSettled polls that DOM offset until quiet. - Raise the per-test timeout to 120s so slow webkit demo-boot proceeds instead of failing the mount wait (retry no longer needed for that path). - Drop the now-unused virt-offset path; keep the engine-specific tolerance. Full scroll suite 48 passed locally (chromium + webkit); invariant-1 12/12 across repeats.
The DOM-based drift measurement fixed the anchor-drift flake, but invariant-1 still retry-flaked on one run purely at the demo mount: waitForSelector hit its own 45s ceiling when a loaded webkit runner took >45s to boot the bundle + run the stress seeding. The per-test budget is 120s, so lift the mount wait to 90s (leaving ~30s for the body) — a slow boot now proceeds instead of burning a retry. Pure boot-time headroom; no scroll-logic change.
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Follow-up to #966. That PR reduced but didn't eliminate the retry-absorbed webkit flake in scroll
invariant-1.Root cause: Assertion B derived drift from
__fluuxGetVirtOffset. During the prepend re-assert loop that offset map can report a stale pre-prepend value for a sustained window whilescrollTopalready reflects the added batch, producing a ~2880–3034px phantom drift that isn't visible on screen. A second trigger was the demo mount blowing the 60s per-test budget on a slow webkit runner.getBoundingClientRect().topvs its captured before-position — the layout truth the user actually sees, which can't go stale like the offset map.waitForAnchorSettledpolls that DOM offset until quiet.Verified locally: full scroll suite 48 passed (chromium + webkit), invariant-1 green across repeats.