This repository, `opencode-antigravity-auth`, is a plugin designed to bridge the gap between the Opencode CLI and Google's Antigravity platform, enabling users to leverage Antigravity's features and access advanced language models like Gemini 3 Pro and Claude Opus 4.5 using their existing Google credentials. The primary purpose of this plugin is to provide a seamless authentication experience, allowing Opencode users to bypass the limitations of standard API access and benefit from the rate limits and model availability offered by Antigravity.

The core functionality of the plugin revolves around OAuth authentication with Google. This allows users to log in with their Google accounts and gain access to the specified models. A key feature is the ability to utilize Antigravity's quota system, which is crucial for accessing the more powerful and often rate-limited models. The plugin supports models such as `gemini-3-pro`, `gemini-3-flash`, `claude-sonnet-4-5`, and `claude-opus-4-5`, including variants with extended "thinking" capabilities, enhancing the models' reasoning and problem-solving abilities.

A significant advantage of this plugin is its multi-account support. Users can add multiple Google accounts, and the plugin automatically rotates between them when one account reaches its rate limit. This feature helps to maximize usage and avoid interruptions. Furthermore, the plugin offers a dual quota system, allowing access to both Antigravity and Gemini CLI quotas, providing flexibility and redundancy. It also incorporates Google Search grounding, enabling web search functionality for Gemini models, enhancing their ability to provide up-to-date and relevant information.

The plugin is designed to be user-friendly, offering multiple installation methods. Users can either leverage an LLM agent to install and configure the plugin automatically or follow a manual setup process. The manual setup involves adding the plugin to the Opencode configuration file and logging in with a Google account. The repository provides clear instructions and model configurations, making it easy for users to get started.

However, the repository also includes a crucial warning regarding Google's Terms of Service. The use of this plugin may potentially violate these terms, and users are cautioned about the risk of account bans or shadow bans. The repository strongly recommends using established Google accounts that are not critical for essential services and avoiding the creation of new accounts specifically for this plugin.

Beyond the core functionality, the repository provides comprehensive documentation, including troubleshooting guides and configuration options. It addresses common issues such as authentication problems, 403 permission errors, and model not found errors. The documentation also covers multi-account setup, session recovery, and integration with other Opencode plugins like `oh-my-opencode` and `@tarquinen/opencode-dcp`. The plugin offers various configuration options, including settings for model behavior, account rotation strategies, and quota protection mechanisms. These settings allow users to customize the plugin's behavior to suit their specific needs and usage patterns. The repository also provides guidance on migrating accounts between machines and handling OAuth callback issues. In essence, this repository provides a powerful tool for Opencode users to access advanced language models through Google's Antigravity platform, while also acknowledging and addressing potential risks and providing comprehensive support.