## Summary
- make Virtua the sole prepend geometry/correction owner by accumulating
active prepend ResizeObserver corrections from the live DOM offset
- retire prepend reconciliation on ordinary reader wheel input, while
preserving it for Ctrl+wheel browser zoom
- remove Buzz's competing three-second semantic-anchor watcher and
corrective `scrollBy` loop
- keep ESM/CJS Virtua patch behavior equivalent and update the patch
lock hash
## Why
Buzz admitted prepended rows using seeded estimates, then Virtua
received multiple measurement corrections for the same transaction. Each
correction was based on the same stale model offset, so a later write
replaced an earlier correction instead of accumulating it. In the
reproduced first page, that resurrected 452px of anchor drift; the
app-level watcher merely corrected the lost virtualizer write afterward.
This fixes the correction inside Virtua and deletes the competing app
writer, following the single-owner geometry invariant used by Berd
rather than copying its spacer implementation.
## Validation
- watcher-off desktop virtualization matrix: 11/11 passed, including 15
cascading prepends, continued wheel input, detached rich-row growth,
channel switching, bottom follow, and buffered live arrivals
- focused cascading prepend/Ctrl+wheel regression passed
- desktop typecheck passed
- desktop unit suite passed: 3,495 tests
- Biome passed on changed desktop files
- `git diff --check` clean
## Manual behavior
Load older history repeatedly while scrolling upward, then wheel
downward during/after a prepend. The visible anchor should stay within
the existing 5px contract during reconciliation, and deliberate reader
movement should not be pulled back. Ctrl+wheel during the prepend commit
must not cancel reconciliation.
---------
Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@sprout-oss.stage.blox.sqprod.co>
Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@buzz.block.builderlab.xyz>
