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>
claude_code