Google's current Gemini Apps help page lists Auto as the default for personal accounts without an AI plan. Google says most prompts go to Flash-Lite, while those needing deeper reasoning may go to Flash or Pro. The page does not date the addition of Auto.
The page says model-availability changes start taking effect October 9 for free users. AI Plus subscribers receive their timing by email. Its availability table lists:
| Google AI Plan | Available Models |
|---|---|
| Without a plan | Auto (default) |
AI Plus | Flash-Lite, Flash |
AI Pro | Flash-Lite, Flash, Pro |
AI Ultra | Flash-Lite, Flash, Pro |
Auto routing is conditional access, rather than unrestricted manual Pro selection. For available models, Google offers low, medium and high effort levels; higher effort uses more allowance.
If smart model selection is disabled, free-account chats use Flash-Lite for all responses.