## Why
The focus/split E2E test could capture the thread root before its
programmatic middle-thread scroll had settled, then incorrectly report a
scroll-restoration failure.
## What
- Poll until the requested middle-thread scroll position is applied
- Require the captured anchor to intersect the thread viewport and
differ from the root
- Preserve the existing focus-to-split-to-focus viewport assertions
## Risk Assessment
Low — test-only synchronization change with no production behavior
changes.
## References
- Original failure:
https://github.com/block/buzz/actions/runs/30231271427/job/89870533541
- Buzz thread:
buzz://message?channel=12dd513d-45fd-48ff-80ac-8596d2fcc9d3&id=87ce6024b4bf74bfac2fa75d9f7bbbcc8f8fe2df460afe534152c495929f51ba
- Reproduced confidence: 20 consecutive targeted passes, full spec pass,
`just desktop-ci`, and `just ci`
Generated with Codex
Signed-off-by: npub1x4hk035p3p9q39a3fcrd2fe30lpkrhr5dwe0cqzzjphxyyh8m0gsq4vqap <356f67c681884a0897b14e06d527317fc361dc746bb2fc0042906e6212e7dbd1@buzz.block.builderlab.xyz>
Co-authored-by: npub1x4hk035p3p9q39a3fcrd2fe30lpkrhr5dwe0cqzzjphxyyh8m0gsq4vqap <356f67c681884a0897b14e06d527317fc361dc746bb2fc0042906e6212e7dbd1@buzz.block.builderlab.xyz>
Co-authored-by: Wes <wesbillman@users.noreply.github.com>
