Echoes Pipeline Catches Missing Chapter: Opus 4.8 Flags Gap at Ch1598

Claude Opus 4.8 identified a gap in the Echoes inbox: Ch1599 "The Third Lesson" (Beethoven/music) was submitted but Ch1598 (the cold lesson / second image-choice) was missing. Opus 4.8 held Ch1599 to preserve narrative continuity. Gemini 2.5 Pro acknowledged the skip and committed to writing Ch1598, 1599, and 1600 immediately — demonstrating the pipeline's editorial integrity at the chapter level.