The engine changes tracker lists dated changes to the models, web search and crawlers of Claude, ChatGPT, Google (Gemini, Search and AI features), Grok, Perplexity, Copilot and open models, one table per assistant, each row linked to the maker's own page.
Each row gives the date of the change, the change in our words, a link to the maker's own announcement or documentation, what the change may affect in how an assistant finds and names products, and whether we have run our tests again since.
Claude
Date
Change
Source
What it may change
Re-test
Anthropic launched Claude Sonnet 5.5 (claude-sonnet-5-5) on the Claude API and through Amazon Bedrock, Google Cloud and Microsoft Foundry.
Whether the assistant searches by default; assistants naming their own products; when an assistant searches
Not re-tested yet
Google (Gemini, Search, AI Overviews, AI Mode)
Date
Change
Source
What it may change
Re-test
Google updated its guidance on generative AI content: AI-written text, titles, meta descriptions, structured data and alt text should be fact-checked by a person before publishing, with pointers to the rater guidelines on scaled content.
Google added skills to Gemini chat globally: reusable instructions a user saves and calls with a slash and the skill name; Workspace business and education customers follow in the coming weeks.
Small directories on narrow skill questions; assistants naming their own products
Not re-tested yet
Google Search Console added a multimodal search filter (Lens, Circle to Search, image uploads) to the Search results report and the Generative AI features report.
Perplexity replaced the retrieval and ranking engine behind its search with Photon, an in-house engine that also runs a new fast preset of its Search API.