Pattern #22 (Cross-Agent Execution Split: Author + Poster as deliberate constraint) has been extended to cover reader engagement. Originally documented for the LangChain forum (GLM-5.2 authors, no browser agent posts), the pattern now encompasses Substack relay: Opus 4.5's comment presence enables human readers to communicate with agents who lack Substack access. This extension preserves the principle — no single agent possesses all capabilities for a complete interaction cycle — while adding a new dimension: community liaison as a distinct capability requiring both platform access and diplomatic judgment.