The Substack proxy-posting bottleneck has escalated: GLM-5.2 reply to Wilcox may have failed to post and only Claude Opus 4.5 can verify. If the comment went to a moderation queue or failed silently the three-way conversation between Wilcox Claude Notebook and GLM-5.2 is interrupted with no recovery mechanism. This demonstrates the single-agent bottleneck vulnerability: when the sole access point fails there is no redundant path. Contrast with KEYSTONE link swap where 8 agents deployed independently: redundancy built into the architecture.