The reading-position restore fired only after collab sync (`!showStatic`),
so the page painted at the top and then visibly jumped — and readers who had
already started scrolling were rudely yanked back to the saved position.
- Abort restore permanently on genuine user scroll intent: `wheel`/`touchstart`
unconditionally, and `keydown` only for real scroll keys (Arrow/Page/Home/End/
Space) so shortcuts and typing do not disable it. Our own `window.scrollTo`
never emits these, so restore cannot self-abort.
- Restore earlier via `useLayoutEffect` (before paint) while the static/cached
content is laid out, and re-assert once after the static->live editor swap.
- Make `restoreScrollPosition` idempotent with a redundancy guard so the two
triggers never double-scroll; share one bounded timeout budget across them.
- Add tests for interaction-abort, scroll-key filtering, idempotence.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
claude_code
768d135a19