Available Models

Claude and Gemini models supported by Antigravity Claude Proxy

Antigravity Claude Proxy provides access to both Claude and Gemini models through a unified Anthropic-compatible API.

Claude Models

Claude models are accessed through the proxy using Anthropic’s API format. All Claude models support extended thinking capabilities.

claude-opus-4-6-thinking

Most Capable Model

Claude Opus 4.6 with extended thinking capabilities. Best for complex reasoning tasks and challenging problems.

• Extended thinking output
• Highest capability tier
• Best for multi-step reasoning

claude-sonnet-4-5-thinking

Balanced Performance

Claude Sonnet 4.5 with extended thinking. Excellent balance of speed and capability.

• Extended thinking output
• Fast response times
• Ideal for general coding tasks

claude-sonnet-4-5

Standard Model

Claude Sonnet 4.5 without thinking output. Fastest response times for straightforward tasks.

• No thinking blocks
• Maximum speed
• Best for simple operations

Claude Thinking Models

Claude thinking models include an internal reasoning process before generating their final response:

• signature field: Claude uses the signature field on thinking blocks for multi-turn conversations
• Thinking blocks: Extended reasoning is included in the response as separate content blocks
• Cache support: Thinking signatures are cached for conversation continuity

Gemini Models

Gemini models provide high-performance alternatives with Google’s latest AI technology. All Gemini models version 3+ include thinking capabilities.

gemini-3.1-pro-high

High Performance Tier

Gemini 3.1 Pro High with advanced thinking. Best for demanding workloads.

• Extended thinking via thoughtSignature
• High quota allocation
• Best for production use

gemini-3.1-pro-low

Balanced Tier

Gemini 3.1 Pro Low with thinking support. Good balance of performance and quota.

• Extended thinking support
• Moderate quota allocation
• General purpose use

gemini-3-flash

Fast Responses

Gemini 3 Flash with thinking. Optimized for speed and efficiency.

• Quick response times
• Extended thinking included
• Ideal for rapid iteration

Gemini Thinking Models

Gemini models (version 3 and higher) support thinking capabilities:

• thoughtSignature field: Gemini uses the thoughtSignature field on functionCall parts
• Automatic detection: Models with “thinking” in the name or version 3+ are treated as thinking models
• Signature caching: thoughtSignature values are cached for 2 hours
• Fallback handling: If Claude Code strips the signature, the proxy restores it from cache or uses a sentinel value

Model Selection in Claude Code

Configure your Claude Code CLI to use specific models:

Configuration File

Edit ~/.claude/settings.json:

{
  "ANTHROPIC_BASE_URL": "http://localhost:8080",
  "ANTHROPIC_AUTH_TOKEN": "test",
  "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"
}

Environment Variables

Set environment variables before launching Claude Code:

export ANTHROPIC_BASE_URL="http://localhost:8080"
export ANTHROPIC_AUTH_TOKEN="test"
export ANTHROPIC_MODEL="gemini-3.1-pro-high"
claude

WebUI Presets

Use the Web Console to generate pre-configured settings:

1. Open the WebUI at http://localhost:8080
2. Navigate to Settings → Claude CLI
3. Select a preset (Claude Thinking or Gemini 1M)
4. Click Save to ~/.claude/settings.json

Model Naming Conventions

The proxy uses consistent naming patterns for model identification:

Thinking vs Non-Thinking

Pattern	Type	Example
Contains thinking	Thinking model	claude-sonnet-4-5-thinking
Version 3+ (Gemini)	Thinking model	gemini-3-flash
No thinking + version 2.x or older	Standard model	claude-sonnet-4-5

Model Family Detection

The proxy automatically detects model families:

• Claude family: Model name contains claude
• Gemini family: Model name contains gemini

// Example model family detection
getModelFamily('claude-opus-4-6-thinking')  // Returns 'claude'
getModelFamily('gemini-3-flash')            // Returns 'gemini'

Context Window Limits

Gemini models have a maximum output token limit of 16,384 tokens. The proxy automatically enforces this limit.

Quota and Rate Limits

Each model has different quota allocations based on your subscription tier:

• Ultra tier: Highest quota limits across all models
• Pro tier: Moderate quota limits
• Free tier: Basic quota limits

Check your current quota in the Web Console under Models or via the /account-limits API endpoint.

Cross-Model Conversations

When switching between Claude and Gemini models mid-conversation, thinking signatures may be incompatible and will be dropped automatically.

The proxy handles cross-model scenarios:

1. Signature validation: Checks if cached signatures match the target model family
2. Automatic cleanup: Drops incompatible signatures when switching families
3. Recovery mechanism: Injects synthetic messages to close interrupted tool loops

Best Practices

• Stick to one family: Use either Claude or Gemini for the entire conversation
• Use fallback strategically: Enable fallback only when needed to maintain signature compatibility
• Monitor model switches: Check logs for signature cleanup warnings

Testing Models

The proxy includes test utilities for each model family:

# Test Claude models
npm run test:signatures

# Test Gemini models
npm run test:crossmodel

# Test all models
npm test

Default test models:

• Claude: claude-sonnet-4-5-thinking
• Gemini: gemini-3-flash