- A page's live read claims its turn before cancelling the old one, so
  two refreshes at once start one watcher, not two.
- An image still uploading keeps the unsaved mark: it is not stale.
- The sync button shows the deleted-page notice if it mounts while one
  is already waiting.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>