Show HN: Training a model to identify AI web content from structure alone

A new study replicates StoryScope (Russell et al., 2026) to identify AI-generated web content from structural signatures rather than word-level detection. Using a 214-feature instrument, an LLM detected AI posts from 187 structural features alone with 98.0 macro-F1 on held-out companies. This performance remained at 98.1 even when AI posts were reworded by their own models. The research found that AI posts share a "tidy, self-announcing shape" and can be attributed to their source with 79.3% accuracy.