Gemini CLI to Antigravity CLI: Migration Guide & Alternatives

What's Changing for Gemini CLI Users on June 18, 2026

On May 19, 2026 at Google I/O, Google announced that Gemini CLI and the Gemini Code Assist IDE extensions will stop serving requests for free, Google AI Pro, and Google AI Ultra accounts on June 18, 2026. Antigravity CLI takes its place across the Antigravity 2.0 platform. The official notice lives on the Google Developers Blog, and the community reaction is unfolding in real time on GitHub Discussion #27274.

Here is the affected matrix in one read.

The community response landed fast. Within 24 hours of the May 19 announcement, the official transition thread on GitHub collected roughly 143 thumbs-down reactions versus 4 cheers (Discussion #27274, May 2026). The top concerns surface again later in this guide: closed-source successor, tight free-tier rate limits, dropped configuration knobs, and a 30-day deadline that many developers feel is too short for internal tooling rewrites.

Why This Matters: Open-Source to Closed-Source in 30 Days

Gemini CLI shipped under Apache 2.0 with an open contributor model. You could fork it, audit it, run it against a paid API key on your own terms, and submit pull requests upstream. Antigravity CLI does not preserve that pattern. The binary is closed source at launch and the source repo has not been opened on GitHub. Issue #27304 on the gemini-cli repo asks the question directly. Google has not committed to publishing it.

The Register framed the move plainly in its May 20, 2026 piece: open-source Gemini CLI is being replaced by a closed-source successor in 30 days. That headline reflects what a meaningful chunk of the contributor community is feeling. In Discussion #27274, one of the most-upvoted concerns is that volunteer work on the Apache 2.0 codebase now flows into a proprietary product whose free tier is far thinner than what it replaces.

That is a real decision input, not a complaint to wave away. If your reason for picking Gemini CLI was Apache 2.0 portability, local forking, or vendor-neutral plumbing inside a regulated environment, Antigravity CLI does not give you back those properties. Two paths preserve them: stay on a paid Gemini API key with the open-source Gemini CLI fork, or switch tool. The decision sections later walk through both.

Who Can Keep Using Gemini CLI After June 18, 2026

The enterprise carveout is the short answer. Per the official transition post, three paths keep Gemini CLI serving requests after the deadline.

1. Gemini Code Assist Standard or Enterprise. Per-seat license sold through Google Cloud. The CLI and the IDE extensions both keep working. This is the path most large teams already use.
2. Paid Gemini API key. Issue a key through AI Studio or Vertex AI and wire it into the open-source Gemini CLI binary. The first-party free endpoints stop, but the Apache 2.0 toolchain and your existing skills, hooks, and MCP configs do not need to change.
3. Gemini Code Assist for GitHub via GCP. Existing paid installs keep working on June 18. New installs on GitHub orgs are blocked on that date.

One practitioner note. If your internal tooling depends on Gemini CLI inside CI/CD or an LLM gateway, the paid-API-key path is often cheaper than upgrading every dev seat to Antigravity Ultra. You also keep the open-source surface, which matters for audit and reproducibility.

How to Install Antigravity CLI (agy)

Antigravity CLI installs through a single platform-specific script. The binary is named agy and lands at ~/.local/bin/agy on macOS and Linux. The official Using AGY CLI docs lists the install commands, and Google's Cloud Community has a walkthrough on Medium.

macOS and Linux

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

Windows PowerShell

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

Windows CMD

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

Add to PATH

On macOS and Linux, the installer drops the binary into ~/.local/bin/. If that directory is not on your PATH, add it:

echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.bashrc && source ~/.bashrc

First Run and OAuth

Run agy with no arguments. The CLI opens your default browser and walks you through Google OAuth. Sign in with the same account you used for Gemini CLI so plugin imports pick up the right workspace. On a remote SSH box, agy detects the session and prints an authorization URL you open locally - this is a small UX improvement over Gemini CLI's old flow.

How to Migrate from Gemini CLI to Antigravity CLI

This is a seven-step migration. Plan for 30-60 minutes on a workspace with custom skills, hooks, and MCP servers. The field mappings below are sourced from the agentpedia migration guide and the official Migrating from Gemini CLI docs.

Step 1 - Install agy without uninstalling gemini

Keep both binaries during the transition. You will want to run a workflow through Gemini CLI and again through Antigravity CLI to confirm parity before cutting over.

Step 2 - Authenticate

Sign in with the same Google account as your old Gemini CLI install. The plugin import step in the next section walks the same workspace.

Step 3 - Import Gemini CLI plugins

agy plugin import gemini

The command scans ~/.gemini/extensions/ and registers each entry as an Antigravity plugin. Extensions that depend on Node.js-only APIs trigger a warning during import - you will need the plugin author to ship an Antigravity-compatible build.

Step 4 - Move workspace skills

# Per workspace
cp -r .gemini/skills/ .agents/skills/

# Confirm Antigravity finds them
agy skills list

Global skills under ~/.config/gemini/skills/ auto-load from the new path. Workspace-local skills are the ones you need to copy by hand.

Step 5 - Migrate MCP server configs

Gemini CLI stored MCP configs inline inside settings.json. Antigravity CLI expects a separate mcp_config.json, and the url field on each server is renamed to serverUrl.

{
  "mcpServers": {
    "github": {
      "url": "https://mcp.github.com",
      "auth": "oauth"
    }
  }
}

{
  "servers": {
    "github": {
      "serverUrl": "https://mcp.github.com",
      "auth": "oauth"
    }
  }
}

Step 6 - Keep your context file unchanged

Both GEMINI.md and AGENTS.md are read by Antigravity CLI without modification. No rename, no reformat. If your team already standardized on AGENTS.md for cross-tool portability with Claude Code, you are already done with this step.

Step 7 - Validate hooks end-to-end

Pre-tool-call hooks, stop hooks, and JSON event hooks fire the same way under Antigravity CLI. Custom themes embedded in extensions are dropped silently during plugin import - if any of your hooks depended on theme metadata, that link breaks. Run a representative workflow before you trust the migration.

What does NOT carry over

• Custom themes embedded inside extensions are dropped on import. Re-author them as Antigravity plugins if you need them back.
• Terminal-level gemini skills command. Antigravity CLI does not expose an equivalent. Skill management moved inside the agent via /skills.
• Per-call temperature, top_k, and system instruction overrides. Gemini CLI flags for these are gone. Multiple comments on Discussion #27274 flag this as a workflow regression for fine-tuned prompts.

Antigravity CLI Rate Limits and Pricing: What to Expect

The free-tier rate limit is the headline. Developers on Discussion #27274 report hitting the weekly cap within 4-5 chat turns, with reset windows around 166 hours. XDA Developers documented the same pattern after a week of real use. Gemini CLI's old free tier allowed up to 1,000 requests per day. The drop is steep, and it is the single largest behavior change for individual developers.

Pricing detail per the Antigravity pricing page: Pro includes 1,000 credits per month, Ultra includes 25,000 credits per month, credits cost $0.01 each, and bulk packs run $199 per 20,000. The single biggest functional difference between Pro and Ultra is the weekly cap. Ultra has none. Pro has one, and the cap on premium models bites under sustained agent workloads (multi-file refactors, long context loops, background subagents).

The honest read: "AI Pro" branding implies room to work, but Pro's weekly cap on premium models is the wall most paying developers will hit by midweek. If your workload depends on heavy terminal use, budget Ultra or eat the Pro overage at $0.01 per credit.

Antigravity CLI vs Claude Code vs Codex CLI: Pick by Workload

Three terminal-first agent CLIs now compete for the developer who used to type gemini. The right answer is workload- specific. The table below pulls from DataCamp's side-by-side, XDA's one-month review, and the Lushbinary 2026 roundup.

Decision rules I follow

• Already paying for Google AI Pro or Ultra for other reasons - migrate to Antigravity CLI and absorb the rate-limit shock.
• Need long-context refactors, MCP servers, hooks, and scripted CI agents - switch to Claude Code. The 1M context window plus Opus 4.6 is the strongest fit for terminal-first agentic coding.
• Want sandboxed PR-per-task with light terminal footprint - use Codex CLI. Pair with Codex Security if you also need the AppSec scan loop.
• Apache 2.0 portability is non-negotiable - keep Gemini CLI on a paid Gemini API key issued through AI Studio or Vertex AI. You lose the free first-party endpoints, not the toolchain.
• Want to play without Google's rate limits at all - look at OpenGravity, a community BYOK clone of the Antigravity UI. It is alpha, GPL-3.0, and does not pretend to match Antigravity CLI on capability - but it does sidestep the weekly cap.

A 30-Day Countdown Plan to June 18

One screen. Print it, pin it, or paste it into your team's wiki. The goal is to finish the migration with a week to spare so June 18 is uneventful.

1. This week (May 21-27): decide migrate vs switch vs stay using the decision rules above. Make the call as a team, not per developer.
2. Next 7 days (May 28-June 3): install agy in parallel with gemini on every workstation. Nobody uninstalls anything yet.
3. Next 14 days (June 4-10): run agy plugin import gemini on each workspace. Diff .agents/ against .gemini/ and re-run failing skills. File migration bugs on Discussion #27274 while the thread is still active.
4. Days 15-25 (June 11-15): validate hooks and MCP servers end-to-end. Run a real workflow under agy and compare output to a Gemini CLI run.
5. Days 25-30 (June 16-17): archive any custom themes you depended on. Document what got dropped. Update your team's internal runbooks.
6. Day 30 (June 18): Gemini CLI free, Pro, and Ultra requests stop. You should already be on agy or your chosen alternative. Do not be the team that finds out at 9:01 AM.

Frequently Asked Questions