Google I/O 2026: Gemini 3.5 Flash GA, Antigravity 2.0 + CLI + SDK, and Managed Agents in the Gemini API

Google’s I/O 2026 (May 20, 2026) leaned heavily on developer-facing AI releases. The three changes that matter most for teams building or evaluating AI coding tools: Gemini 3.5 Flash going GA, Antigravity expanding into a desktop app + CLI + SDK, and Managed Agents landing in the Gemini API. (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

If you’ve been tracking Google Antigravity since its 1.22.2 release or comparing against the Gemini API May 2026 updates, this is the biggest single-day delta of the year.

Gemini 3.5 Flash is GA

Google released Gemini 3.5 Flash as the first model in its new 3.5 series. It’s available through Google Antigravity, the Gemini API, Google AI Studio, and Android Studio. (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

On benchmarks, Google says 3.5 Flash outperforms Gemini 3.1 Pro on:

• Terminal-Bench 2.1: 76.2%
• GDPval-AA: 1656 Elo
• MCP Atlas: 83.6%

Google’s positioning: “What used to take a developer days or an auditor weeks, 3.5 Flash can now help complete in a fraction of the time, often at less than half the cost of other frontier models.” (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

For builders, the practical read is that a Flash-class model is now competitive on agentic coding workloads where Pro-class capacity used to be required.

Antigravity expands into a desktop app, CLI, and SDK

Antigravity evolved from a single product into a platform with three interfaces: (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

• Antigravity 2.0 — a desktop application for parallel multi-agent orchestration.
• Antigravity CLI — terminal-based agent creation without a graphical interface.
• Antigravity SDK — “programmatic access to the same agent harness powering Google’s products that’s co-optimized for our Gemini models.”

Google also added native voice support for Gemini audio models in Antigravity, plus tighter integrations with Android, Firebase, and Google AI Studio. (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

For teams already on Antigravity, the CLI and SDK are the more durable announcements — they let you build Antigravity into pipelines, agents, and other products instead of staying inside the IDE.

Managed Agents in the Gemini API

Google introduced Managed Agents in the Gemini API: a single API call provisions a remote environment where agents can: (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

• Reason, plan, and call tools using the agent harness.
• Execute code and manage files in an isolated sandbox.
• Browse the web to fetch and process live data.

Custom agent extension is supported through markdown files — specifically AGENTS.md and SKILL.md. That’s a notable convergence: those filenames are already familiar from the broader agent-tooling ecosystem, and Google adopting them lowers the friction to port custom agents across platforms.

Pricing and plan updates

Two pricing notes from the same keynote: (https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)

• New $100/mo AI Ultra plan with 5× higher usage limits and 20TB of cloud storage.
• Google AI Pro now includes YouTube Premium Lite (an $8.99/mo bundle value).
• AI Studio offers the first two app deployments to Google Cloud at no cost.

Why this matters

Three takeaways for teams building or evaluating AI coding stacks:

1. A Flash-class model is now agent-grade. With 3.5 Flash outperforming 3.1 Pro on Terminal-Bench 2.1 at lower cost, the cost ceiling for serious agent workloads drops.
2. Antigravity is now a platform. The SDK + CLI make it integratable into existing build/agent pipelines rather than only an IDE.
3. Managed Agents shorten the “stand up a sandboxed agent” path from weeks of infra work to a single API call — and align on the same AGENTS.md / SKILL.md files other agent ecosystems are converging on.

Sources

• Google Blog — “Google I/O 2026: all our announcements”: https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/