Gemini CLI Is Dead: 15-Minute Migration to Antigravity CLI Before June 18

TL;DR — Google is sunsetting Gemini CLI on June 18, 2026. After that date, gemini commands return HTTP 410 and your CI breaks. The replacement is Antigravity CLI (av), which keeps most of the same surface but moves auth, configuration, and a handful of commands. This guide is the 15-minute migration path for engineers who use Gemini CLI in scripts, agents, or CI pipelines today.

Why Gemini CLI Is Being Shut Down

Google announced the Gemini CLI deprecation on May 8, 2026, with a hard cutover on June 18, 2026. The replacement, Antigravity CLI, consolidates Google's developer-side AI tooling — Gemini models, Vertex AI agents, and the new Antigravity multi-agent runtime — under one binary. Existing Gemini CLI installs will receive a deprecation warning on every invocation until the deadline; after that, the auth endpoint returns 410 Gone and every command fails.

If you have ever scripted gemini chat, gemini generate, or gemini agents run into a CI job, a Makefile, or a Claude Code / Cursor hook, this affects you. The good news: most of the migration is automatic.

The Migration in 4 Steps

Step 1: Install Antigravity CLI

# macOS / Linux
curl -fsSL https://antigravity.dev/install.sh | sh

# Windows (PowerShell)
iwr -useb https://antigravity.dev/install.ps1 | iex

# Verify
av --version

The new binary is av (short for "antigravity"). It coexists with gemini during the deprecation window, so you can migrate gradually.

Step 2: Authenticate

Antigravity CLI uses the same Google account but a new OAuth scope. Re-auth once:

av auth login

For CI / service accounts, swap the environment variable:

Old keys are honored until June 18, but Antigravity will warn on every invocation. Rotate now.

Step 3: Rewrite Your Commands

Most subcommands map 1:1 with one rename. Here is the side-by-side:

The big rename to watch: agents is now agent (singular). That breaks scripted invocations. Grep your repo before pushing.

# Find lingering Gemini CLI references in your repo
grep -rn "gemini " --include="*.sh" --include="*.yml" --include="*.yaml" --include="Makefile"

Step 4: Update CI Pipelines

GitHub Actions, GitLab CI, and CircleCI all need a workflow tweak. The most common Gemini CLI step:

# Old — Gemini CLI in GitHub Actions
- name: Run Gemini agent
  run: gemini agents run code-review --diff "${{ github.event.pull_request.diff_url }}"
  env:
    GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}

Migrates to:

# New — Antigravity CLI in GitHub Actions
- name: Install Antigravity CLI
  run: curl -fsSL https://antigravity.dev/install.sh | sh

- name: Run Antigravity agent
  run: av agent run code-review --diff "${{ github.event.pull_request.diff_url }}"
  env:
    AV_API_KEY: ${{ secrets.AV_API_KEY }}

If you templatized the binary name with a CI variable ($AI_CLI gemini), this is a one-line change.

Breaking Changes to Watch

Most of the migration is mechanical, but four behaviors actually changed:

1. 01Default model. Gemini CLI defaulted to gemini-1.5-pro. Antigravity defaults to gemini-3-pro (the model Google announced alongside Antigravity). If your prompts were tuned against 1.5, pin the model explicitly with --model gemini-1.5-pro.
2. 02Streaming output format. Gemini CLI's --stream emitted plain text deltas. Antigravity emits SSE-formatted events by default. If you piped gemini chat --stream into another tool, add --stream-format=plain to keep the old behavior.
3. 03Agent state directory. Was ~/.gemini/agents/. Now ~/.antigravity/agents/. The first av agent run migrates state automatically, but --state-dir overrides break.
4. 04Exit codes. Gemini CLI exited 0 on tool-use failures. Antigravity exits non-zero. If your CI swallowed errors silently, this will catch them — and your green builds may suddenly turn red. That is intended.

Migration Verification Script

Save this as verify-av-migration.sh and run it before the June 18 deadline. It exits non-zero if any Gemini CLI reference remains:

#!/usr/bin/env bash
set -euo pipefail

# Check binary
if ! command -v av >/dev/null; then
  echo "✗ Antigravity CLI not installed" && exit 1
fi

# Check auth
av auth status >/dev/null || { echo "✗ Not authenticated"; exit 1; }

# Check repo for stale references
LEFTOVERS=$(grep -rn "gemini " --include="*.sh" --include="*.yml" --include="*.yaml" --include="Makefile" . || true)
if [[ -n "$LEFTOVERS" ]]; then
  echo "✗ Found stale Gemini CLI references:"
  echo "$LEFTOVERS"
  exit 1
fi

# Check env vars
[[ -n "${AV_API_KEY:-}" ]] || { echo "✗ AV_API_KEY not set"; exit 1; }

echo "✓ Antigravity migration verified"

Wire this into your CI as a job that runs daily through June 17. It catches the migration debt before the shutdown does.

Common Migration Gotchas

• MCP servers that wrapped gemini will fail silently. If you wired Gemini CLI as a tool inside a Model Context Protocol server, the spawn command must be rewritten. For background on MCP tool servers in general, see my Model Context Protocol production guide.
• Pinned versions. gemini@2.x was the LTS line. Antigravity starts at 1.0 — there is no av@2.x. Update version pins.
• Brew formula moved. brew install gemini-cli is gone. Use brew install antigravity-cli. The old formula will be marked disabled after May 30.
• Vertex AI auth tokens. If you used gemini auth print-token to mint Vertex tokens, the equivalent is av auth token --vertex.

Why This Migration Matters Beyond One CLI Tool

The Gemini → Antigravity rename is more than a binary swap. It signals Google consolidating its developer-AI surface into a single multi-agent runtime, the same direction Anthropic took with Claude Opus 4.7 and OpenAI took with Agents SDK. Single-purpose CLIs are losing ground to unified agent runtimes that ship models, tools, eval harnesses, and observability under one binary.

If you maintain dev tooling that wraps an AI vendor's CLI, expect this same migration pattern from every major provider over the next 18 months. The lesson: keep your AI CLI invocation behind a thin wrapper in your codebase. The next rename will hurt less.

Bottom Line

Gemini CLI shuts down June 18, 2026. Antigravity CLI is a near-drop-in replacement, but four breaking behaviors (default model, streaming format, state dir, exit codes) catch teams who run the rename mechanically. Migrate this week. Wire the verification script into CI. Pin your model. Done.