For a block that overflows onto the next spread, the plan is now prepared spanning-aware
during the background lookahead — the start spread's reveal timing is derived across both
preview spreads, and the continuation spread's plan is prepared and cached at the same time.
playback then follows a single path:
- activate reuses the prepared start plan (removed the synchronous forceRebuild rebuild).
- revealContinuationSpread reuses the prepared continuation plan (removed the redraw
fallback); a missing plan is surfaced as a problem, not silently redrawn.
This removes the parallel/immediate prepare distinction and the two fallbacks, leaving one
intended path, and moves the spanning draw work off the critical path.
Verified live on a real spanning block: right line reveals at its area share (~3.3s), the
flip fires, and the continuation appears ~0.3s after the flip (was ~2.7s) and animates
progressively across the next spread over the full TTS — no pop-in, no fast-forward, no
timeline-reveal-continuation-missing. Static suite passes (165).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Georg
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