Antigravity + Gemini CLI OAuth Plugin for Opencode

Enable Opencode to authenticate against Antigravity (Google's IDE) via OAuth so you can use Antigravity rate limits and access models like gemini-3-pro and claude-opus-4-5-thinking with your Google credentials.

What You Get

• Claude Opus 4.5, Sonnet 4.5 and Gemini 3 Pro/Flash via Google OAuth
• Multi-account support — add multiple Google accounts, auto-rotates when rate-limited
• Dual quota system — access both Antigravity and Gemini CLI quotas from one plugin
• Thinking models — extended thinking for Claude and Gemini 3 with configurable budgets
• Google Search grounding — enable web search for Gemini models (auto or always-on)
• Auto-recovery — handles session errors and tool failures automatically
• Plugin compatible — works alongside other OpenCode plugins (oh-my-opencode, dcp, etc.)

Installation

Option A: Let an LLM do it

Paste this into any LLM agent (Claude Code, OpenCode, Cursor, etc.):

Install the opencode-antigravity-auth plugin and add the Antigravity model definitions to ~/.config/opencode/opencode.json by following: https://raw.githubusercontent.com/NoeFabris/opencode-antigravity-auth/dev/README.md

Option B: Manual setup

1. Add the plugin to ~/.config/opencode/opencode.json:

   {
     "plugin": ["opencode-antigravity-auth@latest"]
   }

   Want bleeding edge features? Use opencode-antigravity-auth@beta instead.

2. Login with your Google account:

   opencode auth login

3. Add models — copy the full configuration below

4. Use it:

   opencode run "Hello" --model=google/antigravity-claude-sonnet-4-5-thinking --variant=max

Step-by-Step Instructions

1. Edit the OpenCode configuration file:

   • Linux/Mac: ~/.config/opencode/opencode.json
   • Windows: %APPDATA%\opencode\opencode.json

2. Add the plugin to the plugins array:

   {
     "plugin": ["opencode-antigravity-auth@latest"]
   }

3. Add the model definitions from the Full models configuration section

4. Set provider to "google" and choose a model

Verification

opencode run "Hello" --model=google/antigravity-claude-sonnet-4-5-thinking --variant=max

Models

Model Reference

Antigravity quota (Claude + Gemini 3):

| Model | Variants | Notes | |-------|----------|-------| | antigravity-gemini-3-pro | low, high | Gemini 3 Pro with thinking | | antigravity-gemini-3-flash | minimal, low, medium, high | Gemini 3 Flash with thinking | | antigravity-claude-sonnet-4-5 | — | Claude Sonnet 4.5 | | antigravity-claude-sonnet-4-5-thinking | low, max | Claude Sonnet with extended thinking | | antigravity-claude-opus-4-5-thinking | low, max | Claude Opus with extended thinking |

Gemini CLI quota (separate from Antigravity):

| Model | Notes | |-------|-------| | gemini-2.5-flash | Gemini 2.5 Flash | | gemini-2.5-pro | Gemini 2.5 Pro | | gemini-3-flash-preview | Gemini 3 Flash (preview) | | gemini-3-pro-preview | Gemini 3 Pro (preview) |

Using variants:

opencode run "Hello" --model=google/antigravity-claude-sonnet-4-5-thinking --variant=max

For details on variant configuration and thinking levels, see docs/MODEL-VARIANTS.md.

Add this to your ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-antigravity-auth@latest"],
  "provider": {
    "google": {
      "models": {
        "antigravity-gemini-3-pro": {
          "name": "Gemini 3 Pro (Antigravity)",
          "limit": { "context": 1048576, "output": 65535 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] },
          "variants": {
            "low": { "thinkingLevel": "low" },
            "high": { "thinkingLevel": "high" }
          }
        },
        "antigravity-gemini-3-flash": {
          "name": "Gemini 3 Flash (Antigravity)",
          "limit": { "context": 1048576, "output": 65536 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] },
          "variants": {
            "minimal": { "thinkingLevel": "minimal" },
            "low": { "thinkingLevel": "low" },
            "medium": { "thinkingLevel": "medium" },
            "high": { "thinkingLevel": "high" }
          }
        },
        "antigravity-claude-sonnet-4-5": {
          "name": "Claude Sonnet 4.5 (Antigravity)",
          "limit": { "context": 200000, "output": 64000 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        },
        "antigravity-claude-sonnet-4-5-thinking": {
          "name": "Claude Sonnet 4.5 Thinking (Antigravity)",
          "limit": { "context": 200000, "output": 64000 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] },
          "variants": {
            "low": { "thinkingConfig": { "thinkingBudget": 8192 } },
            "max": { "thinkingConfig": { "thinkingBudget": 32768 } }
          }
        },
        "antigravity-claude-opus-4-5-thinking": {
          "name": "Claude Opus 4.5 Thinking (Antigravity)",
          "limit": { "context": 200000, "output": 64000 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] },
          "variants": {
            "low": { "thinkingConfig": { "thinkingBudget": 8192 } },
            "max": { "thinkingConfig": { "thinkingBudget": 32768 } }
          }
        },
        "gemini-2.5-flash": {
          "name": "Gemini 2.5 Flash (Gemini CLI)",
          "limit": { "context": 1048576, "output": 65536 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        },
        "gemini-2.5-pro": {
          "name": "Gemini 2.5 Pro (Gemini CLI)",
          "limit": { "context": 1048576, "output": 65536 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        },
        "gemini-3-flash-preview": {
          "name": "Gemini 3 Flash Preview (Gemini CLI)",
          "limit": { "context": 1048576, "output": 65536 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        },
        "gemini-3-pro-preview": {
          "name": "Gemini 3 Pro Preview (Gemini CLI)",
          "limit": { "context": 1048576, "output": 65535 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        }
      }
    }
  }
}

Multi-Account Setup

Add multiple Google accounts for higher combined quotas. The plugin automatically rotates between accounts when one is rate-limited.

opencode auth login  # Run again to add more accounts

For details on load balancing, dual quota pools, and account storage, see docs/MULTI-ACCOUNT.md.

Plugin Compatibility

@tarquinen/opencode-dcp

DCP creates synthetic assistant messages that lack thinking blocks. List this plugin BEFORE DCP:

{
  "plugin": [
    "opencode-antigravity-auth@latest",
    "@tarquinen/opencode-dcp@latest"
  ]
}

oh-my-opencode

Disable built-in auth and override agent models in oh-my-opencode.json:

{
  "google_auth": false,
  "agents": {
    "frontend-ui-ux-engineer": { "model": "google/antigravity-gemini-3-pro" },
    "document-writer": { "model": "google/antigravity-gemini-3-flash" },
    "multimodal-looker": { "model": "google/antigravity-gemini-3-flash" }
  }
}

Tip: When spawning parallel subagents, enable pid_offset_enabled: true in antigravity.json to distribute sessions across accounts.

Plugins you don't need

• gemini-auth plugins — Not needed. This plugin handles all Google OAuth.

Configuration

Create ~/.config/opencode/antigravity.json for advanced settings:

{
  "$schema": "https://raw.githubusercontent.com/NoeFabris/opencode-antigravity-auth/main/assets/antigravity.schema.json",
  "quiet_mode": false,
  "debug": false
}

| Option | Default | What it does | |--------|---------|--------------| | quiet_mode | false | Hide toast notifications | | debug | false | Enable debug logging | | session_recovery | true | Auto-recover from tool errors | | auto_resume | true | Auto-send "continue" after recovery | | web_search.default_mode | "off" | Google Search grounding: "auto" or "off" |

For all options, see docs/CONFIGURATION.md.

Environment variables:

OPENCODE_ANTIGRAVITY_DEBUG=1 opencode   # Enable debug logging
OPENCODE_ANTIGRAVITY_DEBUG=2 opencode   # Verbose logging

Troubleshooting

See the full Troubleshooting Guide for solutions to common issues including:

• Auth problems and token refresh
• "Model not found" errors
• Session recovery
• Gemini CLI permission errors
• Safari OAuth issues
• Plugin compatibility
• Migration guides

Documentation

• Configuration — All configuration options
• Multi-Account — Load balancing, dual quota pools, account storage
• Model Variants — Thinking budgets and variant system
• Troubleshooting — Common issues and fixes
• Architecture — How the plugin works
• API Spec — Antigravity API reference

Support

If this plugin helps you, consider supporting its maintenance:

Credits

• opencode-gemini-auth by @jenslys
• CLIProxyAPI

License

MIT License. See LICENSE for details.

Intended Use

• Personal / internal development only
• Respect internal quotas and data handling policies
• Not for production services or bypassing intended limits

Warning

By using this plugin, you acknowledge:

• Terms of Service risk — This approach may violate ToS of AI model providers
• Account risk — Providers may suspend or ban accounts
• No guarantees — APIs may change without notice
• Assumption of risk — You assume all legal, financial, and technical risks

Disclaimer

• Not affiliated with Google. This is an independent open-source project.
• "Antigravity", "Gemini", "Google Cloud", and "Google" are trademarks of Google LLC.