When TTS playback crosses a section boundary, the page would stay on
the last page of the previous chapter while audio continued reading
the next chapter — leaving the user stuck behind the "back-to-TTS"
button.
Two compounding issues since the paginator adjacent-section preloading
landed:
1. `handleSectionChange` called `view.renderer.goTo(resolved)` without
awaiting. `TTSController.#initTTSForSection` does
`await this.onSectionChange?.(sectionIndex)` precisely so the view
can finish navigating before audio of the new section starts, but
the missing await defeated that contract.
2. `handleHighlightMark` returned silently on a cross-section
mismatch (`viewSectionIndex !== ttsSectionIndex`), so when the
renderer.goTo above completed only partially — which can happen on
the new paginator when the target section is already loaded as an
adjacent view and the post-goTo state appears reused without a
visible page flip — there was no second chance to drag the view to
the TTS cfi.
Fix:
- Await `view.renderer.goTo` in `handleSectionChange`.
- In `handleHighlightMark`, run the cross-section branch *before* the
`followingTTSLocationRef` check and call `view.goTo(cfi)` directly,
stamping `sectionChangingTimestampRef` so the back-to-TTS button
stays suppressed while progress.location catches up. Skip only when
the user is actively selecting text.
Adds unit tests covering both the cross-section navigation path and
the in-section scrollToAnchor path.
Roy Zhu
fed8ab7b67