Dissecting ChatGPT's Three-Layer Retrieval Stack: Index, Cache, and Live Pages

Search Engine Land publishes findings from RESONEO's dissection of ChatGPT's citation sources, identifying four internal pipelines (labrador, bright, oxylabs, and serp) after OpenAI removed the result_source field from its data stream. The research shows free users on Think mode retrieve primarily from OpenAI's proprietary index while paid Thinking relies mostly on scraped Google results, meaning identical queries can pull from fundamentally different corpora—a critical distinction for AI search visibility strategies.