Preface¶

At Google I/O 2026, Google performed another major integration of its developer terminal tooling lineup: the brand new Antigravity CLI was officially launched, sharing the same Agent Harness as the desktop Antigravity 2.0. At the same time, the Gemini CLI for individual users will cease service on June 18, 2026.

If you have gotten used to using Gemini CLI in your terminal to write code, look up documentation, and run Agent tasks over the past year, you need to understand more than just “a simple name change” — Google is consolidating terminals, desktop IDEs, and cloud Harness under the single Antigravity Agent-first platform. This article cross-verifies information based on the Google Developers Blog official announcement, the Antigravity official blog, and the Google I/O 2026 announcement roundup to help you quickly grasp the full context of this migration.

Why the Change: From Single Agent to Multi-Agent Orchestration¶

Gemini CLI was released in 2025. Official data shows its GitHub repository has accumulated over 100,000 stars, more than 6,000 merged PRs, and hundreds of community contributors, proving that the “terminal + Agent” model works. However, as developer needs evolve, a single Agent running sequentially in the terminal can no longer cover complex engineering scenarios.

In its May 19, 2026 announcement, Google clearly stated that users now need multiple Agents to collaborate with each other, splitting tasks and processing them in parallel; terminal tools must share a unified backend with desktop IDEs and cloud Harness. Therefore, Google has focused its efforts on the Antigravity platform — which includes the server-side Harness, the desktop application Antigravity 2.0, and the new terminal entry point Antigravity CLI.

To put it simply: It’s not that Gemini CLI was poorly made, but that Google has chosen to unify all developer touchpoints with a more powerful Harness.

What Is Antigravity CLI?¶

Antigravity CLI is the lightest terminal entry point in the Google Antigravity ecosystem, with the command line alias agy. Its official positioning is to call, monitor, and interact with Antigravity Agents in the terminal, with no GUI, focusing on speed and low overhead.

The relationship with Antigravity 2.0 can be summarized in three points:
1. Shared Agent Harness: Core Agent capability improvements will benefit both the CLI and desktop versions simultaneously, eliminating the need for separate iterations by two teams.
2. Shared Settings: Configurations such as Agent permissions are synchronized across both ends, eliminating the need for repeated setup.
3. Session Import: Conversations initiated in the CLI can be pulled up via Antigravity 2.0’s @conversation dropdown menu, making it easy to switch from the terminal to the graphical interface to continue working.

Under the hood, Antigravity CLI has been rewritten in Go language (Gemini CLI was based on TypeScript/Node), which the official says makes it faster. It also supports asynchronous background workflows — tasks such as large-scale refactoring and multi-topic research can run in the background without blocking the current terminal session.

Core Capabilities: Agent Skills, MCP, and Multi-Agent¶

Antigravity CLI retains the most critical capabilities of Gemini CLI, with extensions at the Harness layer. The officially confirmed retained features include:

Capability	Description
Agent Skills	Reusable skill modules, supports migration from Gemini CLI
Hooks	Insert custom logic at key points in the Agent lifecycle
Subagents	Sub-agents used for task decomposition and parallel processing
Extensions → Plugins	Original Gemini CLI extensions now exist as Antigravity plugins

Regarding MCP (Model Context Protocol) integration, Antigravity CLI will automatically detect the local Gemini CLI directory during installation and migrate pre-configured MCP Servers. For users migrating from Gemini CLI, Skills, Agent configurations, and gemini.md project memory files will remain compatible.

Multi-Agent orchestration is a joint selling point of Antigravity 2.0 and the CLI. The Google I/O 2026 announcement mentions that the new Harness introduces primitives such as subagents, hooks, and asynchronous task management, and comes preloaded with the Gemini 3.5 Flash model — jointly optimized with the Harness — which is Google’s current flagship combination in the CLI coding Agent space.

It is worth noting that the official also acknowledged that Antigravity CLI will not be 1:1 feature-aligned with Gemini CLI at launch, and some edge capabilities are still being completed. Community feedback can be submitted via the Antigravity CLI forum.

Gemini 3.5 Flash: Default Model and Harness Collaboration¶

Gemini 3.5 Flash was launched alongside Google I/O 2026, and has been adopted as the default Flash series model across the entire Antigravity platform (including the CLI). The official has provided several reference metrics targeted at Agent and coding scenarios:
- Terminal-Bench 2.1: 76.2%
- GDPval-AA: 1656 Elo
- MCP Atlas: 83.6%

The Antigravity blog further explained that Gemini 3.5 Flash has undergone co-optimization with the Agent Harness; in Antigravity, Flash inference speed is typically around 4x faster than comparable cutting-edge models, and up to 12x faster under limited-time optimization. For long-chain Agent tasks, latency accumulates with each step, and Flash’s speed advantage is highly noticeable in terminal interaction scenarios.

If your task requires higher complexity, you can switch to other available models such as Gemini 3.1 Pro via the /model command within the CLI — Flash is the default, but you are not locked into a single model.

Timeline: Who Should Migrate, Who Can Wait¶

This is the most important section for developers, please match it with your account type:

Individual Users (Free / Google AI Pro / Ultra)¶

Starting May 19, 2026: Antigravity CLI is open for download by all users.
Starting June 18, 2026: Gemini CLI and the Gemini Code Assist IDE extension will cease service for individual accounts; Gemini Code Assist for GitHub will also stop accepting new installations, and will cease service within the following weeks.

Enterprise Users¶

If your organization uses a Gemini Code Assist Standard / Enterprise license, or uses Gemini Code Assist for GitHub via Google Cloud, your access rights will remain unchanged. Gemini CLI can still be used with paid Gemini and Gemini Enterprise Agent Platform API Keys, and will continue to receive the latest Gemini model updates. Enterprise users can also experience Antigravity CLI using their Google Cloud projects immediately.

Open Source Repositories¶

The Gemini CLI repository will remain open source under the Apache 2.0 license. Google stated that it will continue to maintain model updates and security fixes for enterprise customers; but for individual subscription users, the “official entry point” on the terminal side has switched to Antigravity CLI.

Migration Guide: Installation and Configuration Import¶

1. Install Antigravity CLI¶

Select the corresponding command for your platform (source: Google official migration instructions and GitHub Discussion #28017):

macOS / Linux:

curl -fsSL https://antigravity.google/cli/install.sh | bash

Windows PowerShell:

irm https://antigravity.google/cli/install.ps1 | iex

Windows Command Prompt:

curl -fsSL https://antigravity.google/cli/install.cmd -o install.cmd && install.cmd && del install.cmd

After installation is complete, run agy in the terminal to start it.

2. Automatically Migrate Gemini CLI Configuration¶

The installation program will detect the local Gemini CLI directory and attempt to import:
- Skills: Custom and installed skills
- MCP Servers: Model Context Protocol service configurations
- Agents: Existing Agent configuration files
- Memory: Project memory files such as gemini.md

3. Import Gemini CLI Extensions as Plugins¶

If you have previously installed Gemini CLI extensions, you can convert them to Antigravity plugins with one command:

agy plugin import gemini

4. Further Reading¶

Antigravity CLI Official Documentation (includes slash commands, keyboard shortcuts, and settings)
Gemini CLI → Antigravity CLI Migration Guide (Google Developers documentation site)

If you encounter issues such as MCP Servers being visible in the UI but Agents unable to call them, or subscription quotas not being mapped correctly during the migration, there are already extensive community discussions. It is recommended to first check the official FAQ and submit feedback on the forum with specific environment details.

Google’s Agent Terminal Strategy: A Visual Overview¶

Combining the above information, Google’s 2026 developer Agent layout is roughly as follows:

┌─────────────────────────────────────────────────────┐
│              Google Antigravity Platform           │
│  ┌──────────────┐  ┌──────────────┐  ┌────────────┐ │
│  │ Antigravity  │  │ Antigravity  │  │ Antigravity│ │
│  │ CLI (agy)    │  │ 2.0 Desktop App │  │ SDK        │ │
│  │ Terminal / TUI │  │ GUI / Multi-Agent │  │ Programmatic Access │ │
│  └──────┬───────┘  └──────┬───────┘  └─────┬──────┘ │
│         └─────────────────┼─────────────────┘       │
│                    Shared Agent Harness                │
│              (Subagents / Hooks / Async Tasks)         │
│                           │                          │
│              Gemini 3.5 Flash (Default, Co-Optimized)       │
└─────────────────────────────────────────────────────┘
         ▲                              │
         │ Ceases Service on 2026-06-18           │ Enterprise/API Key Users
         │                              ▼
   Gemini CLI (Individual Users)          Gemini CLI Remains Available

The strategic intent is clear:
1. One Harness, Multiple Touchpoints: CLI for speed, desktop for full functionality, SDK for programmatic access, with consistent underlying capabilities.
2. Model and Harness Co-Optimization: Gemini 3.5 Flash is not simply “hooked up” to the CLI, but deeply tuned for Agent workflows.
3. Embrace MCP and Skills Ecosystem: Expand the Agent tool surface via standardized protocols to reduce vendor lock-in.
4. Focus on Multi-Agent: Upgraded from the single-Agent interaction of Gemini CLI to orchestratable and parallelizable Agent teams.

In terms of the competitive landscape, Antigravity CLI has become another heavyweight player in the CLI coding Agent space alongside OpenAI Codex CLI, Anthropic Claude Code, and others. The difference lies in Google’s emphasis on Harness + proprietary model + desktop/cloud integration, rather than just being an open-source terminal tool.

Final Notes¶

The retirement of Gemini CLI marks that Google’s developer tools have entered a new phase: moving from “shoving Gemini into the terminal” to “reconstructing Agent workflows centered around the Antigravity Harness”. For individual developers, June 18 is the hard deadline; for enterprise users, the transition period is relatively lenient, but the unified direction of Antigravity is already clear.

If you are already using Gemini CLI, it is recommended to complete the agy installation and agy plugin import gemini as soon as possible, and verify that Skills and MCP configurations are working properly; if you rely on Google AI Pro/Ultra subscription quotas, you also need to check the official documentation to confirm the authentication and quota paths under the new CLI. Antigravity CLI is still in rapid iteration, and if you encounter experience issues, feel free to provide feedback to the community — Google itself acknowledges that this migration requires joint polishing with developers.

References:
- Introducing Google Antigravity CLI
- Transitioning Gemini CLI to Antigravity CLI
- 100 things we announced at Google I/O 2026
- Gemini 3.5 Flash in Google Antigravity

Gemini CLI Steps Down, Antigravity CLI Takes Over: A Comprehensive Guide to Google's Agent Terminal Strategy