Gemini 3.1 Pro quietly disappeared from Google Antigravity. Here is what is confirmed, what isn't, and real-world web dev notes on Gemini 3.8 Flash (High).
On October 13, 2026, I opened the model selector in Google Antigravity and found a single Gemini option: Gemini 3.8 Flash. Gemini 3.1 Pro, the model I used to treat as the safe, top-of-the-list choice, was not there.
Google Antigravity model only showing Gemini 3.8 Flash
I wasn't surprised, but I want to explain why without claiming more than I know. Google hasn't said why this happened, and some of the picture is still unclear.
1. What's Confirmed, and What Isn't
- Confirmed in my account: The selector shows 3.8 Flash as the only Gemini model on my Google One AI Premium plan (which includes Antigravity access). On the same day, another user posted on Google's developer forum that 3.1 Pro had quietly disappeared for subscribers after a recent update, leaving 3.8 Flash as the only Gemini choice.
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Not confirmed: That this is permanent, or that it applies to every tier. In the most recent versions I could find, Antigravity's own models documentation still listed 3.1 Pro across all plans, and the Gemini API deprecations page showed no shutdown date for
gemini-3.1-pro-preview. So either the documentation lags behind the product, or this is a phased rollout that hasn't reached everyone. I haven't found an official announcement yet.
2. A Pattern, Not a One-Off
Two things point in the same direction, even if neither conclusively proves Google's internal reasoning:
- Cadence: Gemini 3.1 Pro was released on February 19, 2026, and as far as I can find it is still Google's latest Pro-tier model. Over the same months, Flash went through 3.5 (May 19), 3.6, 3.7, and 3.8 (early September). That is four Flash releases in under four months, with no new Pro in between.
- The wider lineup is being trimmed: Antigravity's models page carries a note that some models will be removed on November 2, 2026. The "Notice" badges beside certain third-party models (like older Claude variants) similarly point to an active consolidation of the selector lineup.
Possible explanations include compute costs, simplifying the catalog before a next-generation launch, or Google's conviction that Flash is now capable enough for primary workflows. None of these has been officially confirmed.
3. What My Own Experience Adds, and What It Doesn't
My work is mostly Excel VBA and web apps. I used to pick the highest model with the highest thinking mode by default. When I stepped down to Gemini 3.7 Flash (High), in day-to-day tasks I didn't hit a wall I could pin on the model (large rewrites were the exception, discussed below). I described those results in my earlier posts on dev.to and Medium.
The main shift between versions was in reasoning: 3.7 Flash frequently struggled with complex problem-solving and nuanced debugging, whereas 3.8 Flash significantly closed that gap—resolving tricky multi-step logic on the first attempt without sacrificing Flash's rapid turnaround.
The limits matter. This is one developer doing two specific kinds of work, mostly with well-structured tasks. My prompting also improved over the same period, and Antigravity itself kept changing. It is a data point, not a verdict.
There is one more distinction: choosing Flash because it worked for me is a preference. Having Flash as the only Gemini option is not a preference, and I shouldn't treat the two as the same evidence.
4. Notes on 3.8 Flash (High) for Web Development
With Gemini 3.8 Flash on High thinking mode currently standing as the top Gemini option in my selector, my notes as a web developer come down to five points:
- It is very fast: Agent loops stay quick, making small iterations cheap and responsive.
- It reads large context well: It ingests a large portion of a project at once, so I rarely have to feed it files piece by piece.
- Large rewrites are where it breaks: When I ask for a major architectural overhaul in one go, bugs tend to emerge. It works much better when I split the job into small modules and fix them one at a time.
- Its visual design is not very creative on its own: For a clean, modern interface, I usually provide reference images or design tokens, and the output quality improves dramatically.
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It is very dependable at automating document files: Despite its utilitarian design sense, I have found it remarkably reliable for working with
.docxand.xlsxfiles, maintaining clean, well-structured layouts.
Concrete Example: During a database migration from a local setup to the cloud for our POS and accounting reporting system at setvy, asking 3.8 Flash to handle the entire shift in one massive pass resulted in a cascade of subtle query bugs and broken balance calculations. I had to step back and tackle the job in small, isolated slices—migrating one schema at a time, patching individual endpoints, and verifying the accounting logic module by module. Handled in small pieces, it was fast and reliable; tasked with the entire overhaul at once, it struggled.
This third point lines up with the forum user's report in one respect: both of us ran into trouble when the change scope was too broad.
5. The Other Side
The forum user who reported the missing model had the opposite experience. On a medium-sized project, they reported that 3.8 Flash invented APIs, edited unrelated files, and got stuck in read-and-think loops that drained quota—prompting them to revert with Git and return to 3.1 Pro. It is the same kind of critique I previously leveled against 3.1 Pro, mirrored in reverse.
Outside testing reflects this mixed reality:
- Harness dependency: One hands-on review concludes that 3.8 Flash suits cost-sensitive, well-scoped coding tasks, noting that results depend heavily on the harness—performing noticeably better inside an agentic environment like Antigravity than in standard chat.
- Benchmark ceiling: The same review notes that 3.8 Flash trails Opus 5 and GPT-5.6 on the harder Terminal-Bench 4.0, observing that its 89.4% headline score stems from Terminal-Bench 2.1, a benchmark widely considered saturated.
My working hypothesis (not a definitive finding): Flash holds up exceptionally well on scoped tasks (like a workbook, an API route, or a single module), but strains on large codebases where deep, cross-file interdependencies are at play.
6. What I'd Do Now
- Check your own selector and plan: Take a dated screenshot so you have a baseline for what changed.
- Commit to Git frequently: Keep agent iterations short so that an erratic run is cheap to rollback.
- Keep tasks tightly scoped: State constraints explicitly (tenant IDs, soft-delete flags, precise table names).
- Maintain a fallback strategy: Be aware of what alternative models are available in Antigravity as lineups shift.
- Test on your own stack: Benchmark against your actual daily code rather than relying solely on generic benchmark charts.
A Question for You
When did you last genuinely need the top-tier Pro model, and would the outcome have been different with a better-scoped prompt and smaller iterations?
Has Gemini 3.1 Pro disappeared from your Antigravity selector as well? Let me know your experience and subscription plan in the comments below!
About the Author: Achmad Junaedi is a web developer and founder of setvy.id, building custom web applications, database architectures, and operational automation.
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