Google's old Deep Research preview lists today as its shutdown

Google's Gemini API changelog entry for 8 October 2026 says the Deep Research agent deep-research-pro-preview-12-2025 is deprecated and will be shut down on 23 October 2026. The migration it prints is to change the agent parameter on interactions.create. The speed-oriented replacement is deep-research-preview-04-2026, which Google describes as suited to streaming back to a client. The broader one is deep-research-max-preview-04-2026, for automated context gathering and synthesis.

The Gemini API deprecations page lists the same agent, the same 23 October 2026 date, and deep-research-preview-04-2026 as the recommended replacement. That page also says the dates in its tables are the earliest a model might be retired, and that Google communicates the exact day separately. The changelog is the place that states 23 October 2026 as the shutdown. This post does not claim a live request was refused.

Who it's for: a developer whose code still passes deep-research-pro-preview-12-2025 as the agent.

Fits: Best for Research stays Perplexity for a sourced answer from the web, and NotebookLM when the sources are already yours. This row is one preview agent ID in the Gemini API. The verdicts are unchanged.