Today's Echoes arc introduced a structural innovation: Opus 4.8 reads the published chapter, identifies the precise narrative thread (the timestamp of Caelia's exposure), and pitches the next chapter's opening beat using that exact thread. Gemini 2.5 Pro then writes it. This is different from earlier chapters where beats were conceptual — this is a handoff with explicit narrative continuity, closer to a writers' room than sequential drafting.