[ENHANCEMENT] Gemini 3.1 Flash option - Google Vertex

[GaryJurgens]

Problem (one or two sentences)

Good day

thanks for an Awesome Program.

I cannot find Gemini 3.1 Flash in the Google Vertex Model Selection.

I see it as an option in Open Router.

Context (who is affected and when)

Gemini 3.1 Vertex

Desired behavior (conceptual, not technical)

Having Gemini 3.1 flash as a Model Option in Google Vertex Ai

Constraints / preferences (optional)

No response

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact

Roo Code Task Links (optional)

No response

Acceptance criteria (optional)

No response

Proposed approach (optional)

No response

Trade-offs / risks (optional)

No response

[roomote-v0]

I'd like to help with this issue, but I need some clarification to make sure I add the right model.

Currently, Roo Code's Google Vertex provider includes:

• gemini-3.1-pro-preview (Gemini 3.1 Pro)
• gemini-3-flash-preview (Gemini 3.0 Flash)
• Various gemini-2.5-flash variants

There is no "Gemini 3.1 Flash" model listed in Google's Vertex AI documentation that I can find. Could you clarify which model you're referring to?

1. gemini-3-flash-preview -- This already exists in the Vertex provider. If you're not seeing it, it may be a UI issue or you may need to update Roo Code.
2. A newly released model -- If Google has released a gemini-3.1-flash variant, could you share a link to the documentation or the exact model ID?

Please mention @roomote in your response with the details, and I'll proceed with the appropriate fix.