I selected a Gemini model in Settings, Test says "Key works", but generating an outline fails and the error names a different model. Is BookyAI ignoring my selection?

No, your selected model is always tried first. What you are seeing is this: some Gemini models, such as gemini-3.1-pro-preview, have no free tier on Google's side, so on a free API key Google rejects every request to them. BookyAI then tries its other Gemini models, and in version 1.9.17 the error message could name one of those instead of your selected model, and the Test button said "Key works" because another model had answered. To write again right away: open Settings, "AI engines", "Gemini", set "Gemini model" to "Automatic (rotation)" or to a Flash model such as gemini-3.5-flash, and try again. If you tried many times in one day, the free daily quota of your key may be used up; it resets at midnight Pacific time. To use a Pro model, enable billing for your key in Google AI Studio. From version 1.9.18 BookyAI says this itself: the error names your selected model and the real reason in plain words, with Google's own message, the Test line says which model answered and warns in amber when it is not the one you selected, and BookyAI only rotates through the models your key really has.