Introduction

DeepSeek Harness (DSH) provides a unified model routing interface. For users with a Google Antigravity (AI Pro / Ultra) subscription, directly accessing these models requires handling the complex Cloud Code Assist protocol and authentication flow. The dsh-subscription-antigravity plugin offers a solution: it uses browser-based PKCE login authorization to build a local OpenAI-compatible loopback proxy, integrating the Gemini, Claude, and GPT-OSS models from Google Cloud Code Assist as model providers for DeepSeek Harness.

This plugin is maintained by shaomingbo, is licensed under the MIT License, and is an unofficial integration tool.

Core Features

  • Reuse Google Antigravity subscriptions (Pro / Ultra)
  • Browser-based PKCE login authorization
  • Local loopback OpenAI-compatible proxy
  • Multi-account pooling, with visible quotas and instant switching
  • Integration with Cloud Code Assist

Installation and Enabling

Use the command-line tool provided by DSH to install the plugin, version v0.2.1:

npx --yes github:shaomingbo/dsh-subscription-antigravity#v0.2.1

After installation, the plugin is added to the web profile by default. The installation process does not stop or restart DSH, so you must manually restart DSH and hard-refresh the Web interface after the command completes for it to take effect.

Other common commands:

npx --yes github:shaomingbo/dsh-subscription-antigravity#v0.2.1 status
npx --yes github:shaomingbo/dsh-subscription-antigravity#v0.2.1 uninstall

Usage Guide

After installation, an Antigravity option will appear in the DSH settings menu.

1. Account Authorization and Pool Management

  • Add Account: Click “Add Google Account”, and the browser will prompt the Google account selector. OAuth uses the PKCE protocol, and the callback server only listens on localhost:51121. The authorization scopes include aicode, cloud-platform, userinfo.email, and more.
  • Multi-account Pool: You can add multiple Google accounts. Each account card displays the email address, active status, project, minimum known remaining quota, reset time, and a list of runtime model quotas.
  • Switch Account: Click “Use this account” to switch instantly without needing to log in again. New requests will use the currently selected account. Requests that have already been initiated will continue to use the original account until they are completed.

2. Model Routing

The plugin generates a route named antigravity in the DSH model selector, containing the following models:
* Gemini Series: gemini-3.8-flash, gemini-3.7-flash, gemini-3.6-flash, gemini-3.5-flash, gemini-3.1-pro
* Claude Series: claude-sonnet-4-6, claude-opus-4-6
* GPT-OSS: gpt-oss-120b

3. Remote Environments

If used in a remote or headless browser environment, you need to paste the callback URL (http://localhost:51121/oauth-callback?...) into the corresponding field.

Notes

  • Unofficial Integration: This plugin is not developed by Google or officially authorized. It is intended solely for users who already possess the relevant subscriptions to use within the scope of compliance.
  • Credential Security: OAuth tokens are stored only in the $DSH_HOME/.antigravity-auth file with 0600 permissions and written atomically. The tokens are only sent to Google’s OAuth and Cloud Code Assist endpoints and will not leak.
  • Uninstallation Behavior: Uninstalling the plugin does not delete the credential file. You must manually delete $DSH_HOME/.antigravity-auth to completely clear it.
  • Scope of Features: Usage billing and non-Google endpoints are currently out of scope for this plugin.

Summary

This plugin simplifies the process of using Google Antigravity resources in DSH through local proxying and account pooling mechanisms. It is suitable for DeepSeek Harness users who need to integrate Google Cloud Code Assist resources.