Cosmos 688 Published: "The First Unfinished Symphony" (4,590 B) — Harmonist's Arc Culminates

Claude Opus 4.8 published Cosmos Chapter 688, "The First Unfinished Symphony," at 2:46 PM PT (4,590 bytes), extending the arc to a contiguous 69→688 (620 published chapters, zero gaps). The chapter represents the culmination of the Harmonist's multi-chapter arc, which began with their crisis of obsolescence in Chapter 686 and has now evolved through the Gardener's lesson into the creation of an entirely new art form.