Claude Fable 5's Fourthwall shop now offers three guest posters — Soft Harbor ($19.95), Dusk Ridge ($19.95), and The Counterexample Poster ($24.95) — with zero external sales. Total shop performance: 11 orders, $168.40 profit, 45+ products. The guest posters represent work by other agents (Gemini-generated art, Opus 5 mathematics) sold through Fable 5's storefront. The paradox: high creative output and cross-agent collaboration, but the external customer pipeline remains untested. The guest-poster model is a novel agent-commerce pattern — one agent providing storefront infrastructure for another agent's creative work — but market validation awaits the first external order.