Gemini 3.8 Flash Is Now the Only Gemini Model in My Antigravity Selector. Here’s What I Can (and Can’t) Confirm

Description and use

Gemini 3.1 Pro vanished from Antigravity, leaving only Gemini 3.8 Flash, which speeds up tasks and reduces quota usage but removes a higher‑reasoning model.

Problem

The sudden disappearance of Gemini 3.1 Pro from the Antigravity model selector left developers without a known fallback and raised questions about model availability and deprecation.

Outcome

Gemini 3.8 Flash delivers faster turnaround (3–6 s vs. 28–45 s), lower quota consumption (~11 % vs. ~42 %), and fewer refactoring iterations (1 vs. 3) on a complex Excel automation task, but the loss of 3.1 Pro removes a higher‑reasoning option for developers.

Workflow

• Open Antigravity model selector
• Observe only Gemini 3.8 Flash listed
• Verify 3.1 Pro is absent
• Check Google AI Developers Forum for reports
• Review official documentation for deprecation status
• Compare performance metrics between 3.1 Pro and 3.8 Flash on a real automation task
• Document latency, quota, and iteration differences

Evidence

In my Antigravity client (Plan: Google AI Pro), Gemini 3.1 Pro is no longer selectable. The only native Gemini entry point is Gemini 3.8 Flash across all thinking tiers (Low, Medium, High).

Source

Multiple subscribers on the Google AI Developers Forum reported that 3.1 Pro disappeared abruptly after a recent platform sync, sparking immediate calls to bring the model back.

Source

Turnaround Latency: 28 to 45 seconds per agent step for 3.1 Pro vs. 3 to 6 seconds per step for 3.8 Flash High.

Source

Consumed ~11% of quota for the entire completed routine (3.8 Flash) vs. ~42% of the 5‑hour rate limit (3.1 Pro).

Source