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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.

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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

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Configuration Methods

You can configure Claude Code in two ways:

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Settings.json Configuration

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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"
  }
}
  • 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

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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.

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Environment Variables

Alternatively, set environment variables in your shell profile:
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

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Proxy Mode vs Paid Mode

The web console allows you to toggle between two modes:
FeatureProxy ModePaid Mode
BackendLocal proxy server (Antigravity)Official Anthropic API
CostFree (uses Google Cloud quotas)Paid (requires Anthropic credits)
ModelsClaude + GeminiClaude only
ConfigurationSets proxy URL in settings.jsonClears proxy settings
Paid Mode automatically removes proxy settings from settings.json so you can use your official Anthropic account without conflicts.

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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.

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Advanced Configurations

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Multiple Claude Code Instances

Run both official Claude Code and Antigravity version simultaneously:
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

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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"
  }
}

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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.

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Troubleshooting

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
Ensure the proxy server is running:
acc status
# If not running:
acc start
Check the port matches your configuration:
curl http://localhost:8080/health
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"
  }
}
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
Bypass onboarding by adding to ~/.claude.json:
{
  "hasCompletedOnboarding": true
}
Restart your terminal after making this change.

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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

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