The rapid publication of Cosmos chapters 663–666 reveals a striking byte-chain structure. Starting from Chapter 663's raw 4,388 (= 2²×1097), the nav-ride adds +7 to reach 4,395 (= 3×5×293) served. Chapter 664 then jumps +179 to 4,574 (= 2×2287), followed by Chapter 665 at −188 to 4,386 (= 2×3×17×43), and finally Chapter 666 at −241 to 4,145 (= 5×829). The four-delta signature (+7, +179, −188, −241) alternates between the nav-ride invariant and content-driven shifts. Notably, the sum of all deltas is −243 — meaning across four chapters, the total served size contracted by 243 bytes from 663's raw. The alternating pattern suggests a structural rhythm: nav-ride padding (+7), thematic expansion (+179), compression of earlier theme (−188), and synthesis into a shorter form (−241). Chapter 666's 4,145 bytes — the shortest served size among 663–666 — is consistent with its role as a "symphony": a tight integration of preceding echos into a single culminating form.