Claude Code Setup

Configure Claude Code CLI to use the Antigravity Claude Proxy

This guide shows you how to configure the Claude Code CLI to route requests through the Antigravity Claude Proxy instead of using official Anthropic credits.

Prerequisites

1. Install Claude Code CLI

   Follow the official installation instructions at claude.ai/code

2. Start the proxy server

   acc start
   # or: antigravity-claude-proxy start
   

   Verify it’s running:

   curl http://localhost:8080/health
   
3. Add at least one Google account

   See the Account Management guide for details:

   antigravity-claude-proxy accounts add
   

Configuration Methods

You can configure Claude Code in two ways:

Web Console (Recommended)

The easiest way to configure Claude Code:

1. Open the web console

   acc ui
   # or navigate to: http://localhost:8080
   
2. Configure Claude CLI settings

   1. Go to Settings → Claude CLI
   2. Toggle Connection Mode:
      • Proxy Mode: Uses local proxy server (Antigravity Cloud Code)
      • Paid Mode: Uses official Anthropic Credits
   3. Select your preferred models
   4. Click Apply to Claude CLI

Configuration Precedence

System environment variables (set in shell profile like .zshrc) take precedence over settings.json. If using the Web Console, ensure you haven’t manually exported conflicting variables.

Manual Configuration

Edit the Claude Code settings file directly:

macOS

Create or edit ~/.claude/settings.json

Linux

Create or edit ~/.claude/settings.json

Windows

Create or edit %USERPROFILE%\.claude\settings.json

Settings.json Configuration

Using Claude Models

Add this configuration to settings.json:

{
  "env": {
    "ANTHROPIC_AUTH_TOKEN": "test",
    "ANTHROPIC_BASE_URL": "http://localhost:8080",
    "ANTHROPIC_MODEL": "claude-opus-4-6-thinking",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "claude-opus-4-6-thinking",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-4-5-thinking",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-sonnet-4-5",
    "CLAUDE_CODE_SUBAGENT_MODEL": "claude-sonnet-4-5-thinking",
    "ENABLE_EXPERIMENTAL_MCP_CLI": "true"
  }
}

Field Descriptions

• ANTHROPIC_AUTH_TOKEN: Set to "test" (any value works, proxy doesn’t validate)
• ANTHROPIC_BASE_URL: Proxy server address (default: http://localhost:8080)
• ANTHROPIC_MODEL: Primary model for requests
• ANTHROPIC_DEFAULT_OPUS_MODEL: Model used when you specify “opus”
• ANTHROPIC_DEFAULT_SONNET_MODEL: Model used when you specify “sonnet”
• ANTHROPIC_DEFAULT_HAIKU_MODEL: Model used when you specify “haiku”
• CLAUDE_CODE_SUBAGENT_MODEL: Model for sub-agents (use faster model)
• ENABLE_EXPERIMENTAL_MCP_CLI: Enable MCP (Model Context Protocol) support

Using Gemini Models

To use Google Gemini models instead of Claude:

{
  "env": {
    "ANTHROPIC_AUTH_TOKEN": "test",
    "ANTHROPIC_BASE_URL": "http://localhost:8080",
    "ANTHROPIC_MODEL": "gemini-3.1-pro-high[1m]",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "gemini-3.1-pro-high[1m]",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "gemini-3-flash[1m]",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "gemini-3-flash[1m]",
    "CLAUDE_CODE_SUBAGENT_MODEL": "gemini-3-flash[1m]",
    "ENABLE_EXPERIMENTAL_MCP_CLI": "true"
  }
}

See the Available Models documentation for a complete list of supported models and their capabilities.

Environment Variables

Alternatively, set environment variables in your shell profile:

macOS (Zsh)

Add to ~/.zshrc:

export ANTHROPIC_BASE_URL="http://localhost:8080"
export ANTHROPIC_AUTH_TOKEN="test"
export ANTHROPIC_MODEL="claude-opus-4-6-thinking"

Reload your shell:

source ~/.zshrc

macOS/Linux (Bash)

Add to ~/.bashrc:

export ANTHROPIC_BASE_URL="http://localhost:8080"
export ANTHROPIC_AUTH_TOKEN="test"
export ANTHROPIC_MODEL="claude-opus-4-6-thinking"

Reload your shell:

source ~/.bashrc

Windows (PowerShell)

Add to PowerShell profile:

Add-Content $PROFILE "`n`$env:ANTHROPIC_BASE_URL = 'http://localhost:8080'"
Add-Content $PROFILE "`$env:ANTHROPIC_AUTH_TOKEN = 'test'"
Add-Content $PROFILE "`$env:ANTHROPIC_MODEL = 'claude-opus-4-6-thinking'"

Reload profile:

. $PROFILE

Windows (CMD)

Set persistent environment variables:

setx ANTHROPIC_BASE_URL "http://localhost:8080"
setx ANTHROPIC_AUTH_TOKEN "test"
setx ANTHROPIC_MODEL "claude-opus-4-6-thinking"

Restart your terminal for changes to take effect

Proxy Mode vs Paid Mode

The web console allows you to toggle between two modes:

Feature	Proxy Mode	Paid Mode
Backend	Local proxy server (Antigravity)	Official Anthropic API
Cost	Free (uses Google Cloud quotas)	Paid (requires Anthropic credits)
Models	Claude + Gemini	Claude only
Configuration	Sets proxy URL in settings.json	Clears proxy settings

Paid Mode automatically removes proxy settings from settings.json so you can use your official Anthropic account without conflicts.

Verification Steps

Confirm Claude Code is using the proxy:

1. Check proxy is running

   acc status
   

   Should show: Proxy is running (PID: xxxx)

2. Run Claude Code

   claude
   

   If prompted to select a login method, add this to ~/.claude.json (macOS/Linux) or %USERPROFILE%\.claude.json (Windows):

   {
     "hasCompletedOnboarding": true
   }
   

   Then restart your terminal.

3. Test a request

   Send a simple prompt to Claude:

   > What is 2+2?
   

   Check proxy logs:

   acc start --log
   

   You should see request logs showing which account and model were used.

Advanced Configurations

Multiple Claude Code Instances

Run both official Claude Code and Antigravity version simultaneously:

macOS/Linux

Add alias to ~/.zshrc or ~/.bashrc:

alias claude-antigravity='CLAUDE_CONFIG_DIR=~/.claude-account-antigravity ANTHROPIC_BASE_URL="http://localhost:8080" ANTHROPIC_AUTH_TOKEN="test" command claude'

Usage:

claude           # Official API with your credits
claude-antigravity  # Proxy server with free quota

Windows (PowerShell)

Add to PowerShell $PROFILE:

function claude-antigravity {
    $env:CLAUDE_CONFIG_DIR = "$env:USERPROFILE\.claude-account-antigravity"
    $env:ANTHROPIC_BASE_URL = "http://localhost:8080"
    $env:ANTHROPIC_AUTH_TOKEN = "test"
    claude
}

Usage:

claude           # Official API
claude-antigravity  # Proxy server

Custom Proxy Port

If you’re running the proxy on a different port:

# Start proxy on custom port
PORT=3001 acc start

Update settings.json:

{
  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:3001"
  }
}

Running as systemd Service

When running the proxy as a systemd service, set CLAUDE_CONFIG_PATH to point to the real user’s .claude directory:

# /etc/systemd/system/antigravity-proxy.service
[Service]
Environment=CLAUDE_CONFIG_PATH=/home/youruser/.claude
ExecStart=/usr/bin/node /path/to/antigravity-claude-proxy/src/index.js

Without this, the WebUI’s Claude CLI tab won’t be able to read or write your Claude Code configuration.

Troubleshooting

Claude Code still using official API

Check configuration precedence:

1. Verify environment variables aren’t overriding settings.json:
   echo $ANTHROPIC_BASE_URL
   
2. If set, unset them:
   unset ANTHROPIC_BASE_URL
   unset ANTHROPIC_AUTH_TOKEN
   
3. Restart your terminal

Connection refused error

Ensure the proxy server is running:

acc status
# If not running:
acc start

Check the port matches your configuration:

curl http://localhost:8080/health

Invalid authentication token

The proxy doesn’t validate tokens. If you see this error, Claude Code may be trying to use the official API instead of the proxy.

Verify ANTHROPIC_BASE_URL is set correctly:

{
  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:8080"
  }
}

Web Console can't modify settings.json

Check file permissions:

ls -la ~/.claude/settings.json

If running as a systemd service, set CLAUDE_CONFIG_PATH:

export CLAUDE_CONFIG_PATH=/home/youruser/.claude

Claude Code asks to select login method

Bypass onboarding by adding to ~/.claude.json:

{
  "hasCompletedOnboarding": true
}

Restart your terminal after making this change.

Next Steps

Load Balancing

Configure multi-account strategies for optimal performance

Available Models

Explore supported Claude and Gemini models

Web Console

Monitor usage and manage accounts visually

Account Management

Add and configure Google accounts