Root cause (confirmed via Chrome DevTools on the live app): the reading-position
restore jittered on reload — it landed at the saved spot, jumped to the top, then
back. The jump was NOT a height collapse: the title editor auto-focuses ~300ms
after mount, and TipTap's focus scrolls the focused node into view. Since the
title sits at the top of the page, that yanked window scroll to the top.
Minimal fix (the fast restore mechanism is left unchanged):
- Focus the title with { scrollIntoView: false } so placing the caret no longer
moves the viewport.
- Skip the title auto-focus entirely when a saved reading position will be
restored (otherwise the caret lands in the now-off-screen title). Exported
hasSavedReadingPosition() as the single source of truth.
- Extracted the decision into a testable useTitleAutofocus hook (which also adds
a clearTimeout cleanup, fixing a pre-existing uncancelled/destroyed-editor
timer), and covered it + hasSavedReadingPosition with unit tests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The prior test guarded a verbatim MIRROR of the two scroll-restore useLayoutEffect
blocks — the reviewer proved removing '&& editor' from the real page-editor.tsx left
the test green (a copy, not the original). Extract the wiring into an exported
useScrollRestoreOnSwap(pageId, editor, showStatic) hook (the two effects verbatim +
useScrollPosition inside; F1 budget logic untouched), call it once from page-editor.tsx
(replacing the removed useScrollPosition call + both effects), and rewrite the test to
render the REAL hook — deleting the mirror and the false 'regresses in lockstep' comment
(F2-doc). Non-vacuity proven: removing '&& editor' from the real hook reddens the guard
test.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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>
Review round 1 on the scroll-position feature:
- F1: add two tests for the hook's subtlest invariants — (a2) the restore
target is captured synchronously at mount and survives a fresh scroll@0
overwriting storage on load (a regression moving the capture into an effect
would now fail); (a3) restore runs at most once per mount even when called
again (the wiring effect can re-run).
- F2: log instead of silently swallowing sessionStorage errors in
readStorage/writeStorage (AGENTS.md "errors must never be swallowed" rule);
no user notification since a missed scroll restore is not actionable.
- F3: document the hard dependency on PageEditor remounting per page
(key={page.id}) at the refs declaration — the per-mount refs are not reset
on an in-place pageId change, so removing that key would break restore on
the 2nd page.
vitest 9/9, tsc 0, eslint 0.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Adds useScrollPosition(pageId): saves window.scrollY to sessionStorage
(key gitmost:scroll-position:<pageId>) on throttled scroll / pagehide /
visibilitychange / cleanup, capturing the previously-saved value
synchronously at mount before any handler can overwrite it with the fresh 0.
restoreScrollPosition() (wired in page-editor.tsx to fire once the live
content is laid out, !showStatic && editor) yields to a #hash anchor, then
polls the document height and scrolls to the saved Y once the content is
tall enough, with a 5s timeout clamped to the max reachable position. All
storage access is try/caught so a disabled/quota'd Storage never breaks the
page. The in-flight restore poll is held in a ref and cancelled on unmount,
so a fast SPA navigation can't scroll the next page. closes#266
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
claude_code
agent_coder