opencode-antigravity-auth README

The project's README from github.com/NoeFabris/opencode-antigravity-auth. As one markdown file: README.md.

Antigravity + Gemini CLI OAuth Plugin for Opencode

npm version npm beta npm downloads License: MIT X (Twitter)

Enable Opencode to authenticate against Antigravity (Google's IDE) via OAuth so you can use Antigravity rate limits and access models like gemini-3.1-pro and claude-opus-4-6-thinking with your Google credentials.

What You Get

⚠️ Terms of Service Warning — Read Before Installing

[!CAUTION] Using this plugin (and any proxy for Antigravity) violates Google's Terms of Service. A number of users have reported their Google accounts being banned or shadow-banned (restricted access without explicit notification).

By using this plugin, you acknowledge:

  • This is an unofficial tool not endorsed by Google
  • Your account may be suspended or permanently banned
  • You assume all risks associated with using this plugin

Installation

For Humans

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 — choose one:

    • Run opencode auth login → Google → OAuth with Google (Antigravity) → select "Configure models in opencode.json" (auto-configures all models)
    • Or manually copy the full configuration below

  4. Use it:

    opencode run "Hello" --model=google/antigravity-claude-opus-4-6-thinking --variant=max
For LLM Agents

Step-by-Step Instructions

  1. Edit the OpenCode configuration file at ~/.config/opencode/opencode.json

    Note: This path works on all platforms. On Windows, ~ resolves to your user home directory (e.g., C:\Users\YourName).

  2. Add the plugin to the plugin array

  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-opus-4-6-thinking --variant=max

Models

Model Reference

Antigravity quota (default routing for Claude and Gemini):

Model Variants Notes
antigravity-gemini-3-pro low, high Gemini 3 Pro with thinking
antigravity-gemini-3.1-pro low, high Gemini 3.1 Pro with thinking (rollout-dependent)
antigravity-gemini-3-flash minimal, low, medium, high Gemini 3 Flash with thinking
antigravity-claude-sonnet-4-6 — Claude Sonnet 4.6
antigravity-claude-opus-4-6-thinking low, max Claude Opus 4.6 with extended thinking

Gemini CLI quota (separate from Antigravity; used when cli_first is true or as fallback):

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)
gemini-3.1-pro-preview Gemini 3.1 Pro (preview, rollout-dependent)
gemini-3.1-pro-preview-customtools Gemini 3.1 Pro Preview Custom Tools (preview, rollout-dependent)

Routing Behavior:

  • Antigravity-first (default): Gemini models use Antigravity quota across accounts.
  • CLI-first (cli_first: true): Gemini models use Gemini CLI quota first.
  • When a Gemini quota pool is exhausted, the plugin automatically falls back to the other pool.
  • Claude and image models always use Antigravity. Model names are automatically transformed for the target API (e.g., antigravity-gemini-3-flash → gemini-3-flash-preview for CLI).

Using variants:

opencode run "Hello" --model=google/antigravity-claude-opus-4-6-thinking --variant=max

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

Full models configuration (copy-paste ready)

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-3.1-pro": {
          "name": "Gemini 3.1 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-4-6": {
          "name": "Claude Sonnet 4.6 (Antigravity)",
          "limit": { "context": 200000, "output": 64000 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        },
        "antigravity-claude-opus-4-6-thinking": {
          "name": "Claude Opus 4.6 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"] }
        },
        "gemini-3.1-pro-preview": {
          "name": "Gemini 3.1 Pro Preview (Gemini CLI)",
          "limit": { "context": 1048576, "output": 65535 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        },
        "gemini-3.1-pro-preview-customtools": {
          "name": "Gemini 3.1 Pro Preview Custom Tools (Gemini CLI)",
          "limit": { "context": 1048576, "output": 65535 },
          "modalities": { "input": ["text", "image", "pdf"], "output": ["text"] }
        }
      }
    }
  }
}

Backward Compatibility: Legacy model names with antigravity- prefix (e.g., antigravity-gemini-3-flash) still work. The plugin automatically handles model name transformation for both Antigravity and Gemini CLI APIs.

Multi-Account Setup

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

opencode auth login  # Run again to add more accounts

Account management options (via opencode auth login):

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

Troubleshooting

Quick Reset: Most issues can be resolved by deleting ~/.config/opencode/antigravity-accounts.json and running opencode auth login again.

Configuration Path (All Platforms)

OpenCode uses ~/.config/opencode/ on all platforms including Windows.

File Path
Main config ~/.config/opencode/opencode.json
Accounts ~/.config/opencode/antigravity-accounts.json
Plugin config ~/.config/opencode/antigravity.json
Debug logs ~/.config/opencode/antigravity-logs/

Windows users: ~ resolves to your user home directory (e.g., C:\Users\YourName). Do NOT use %APPDATA%.

Custom path: Set OPENCODE_CONFIG_DIR environment variable to use a custom location.

Windows migration: If upgrading from plugin v1.3.x or earlier, the plugin will automatically find your existing config in %APPDATA%\opencode\ and use it. New installations use ~/.config/opencode/.

Multi-Account Auth Issues

If you encounter authentication issues with multiple accounts:

  1. Delete the accounts file:
    rm ~/.config/opencode/antigravity-accounts.json
  2. Re-authenticate:
    opencode auth login

403 Permission Denied (rising-fact-p41fc)

Error:

Permission 'cloudaicompanion.companions.generateChat' denied on resource 
'//cloudaicompanion.googleapis.com/projects/rising-fact-p41fc/locations/global'

Cause: Plugin falls back to a default project ID when no valid project is found. This works for Antigravity but fails for Gemini CLI models.

Solution:

  1. Go to Google Cloud Console
  2. Create or select a project
  3. Enable the Gemini for Google Cloud API (cloudaicompanion.googleapis.com)
  4. Add projectId to your accounts file:
    {
  "accounts": [
    {
      "email": "[email protected]",
      "refreshToken": "...",
      "projectId": "your-project-id"
    }
  ]
}

Note: Do this for each account in a multi-account setup.

Gemini Model Not Found

Add this to your google provider config:

{
  "provider": {
    "google": {
      "npm": "@ai-sdk/google",
      "models": { ... }
    }
  }
}

Gemini 3 Models 400 Error ("Unknown name 'parameters'")

Error:

Invalid JSON payload received. Unknown name "parameters" at 'request.tools[0]'

Causes:

Solutions:

  1. Update to latest beta:

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

  2. Disable MCP servers one-by-one to find the problematic one

  3. Add npm override:

    { "provider": { "google": { "npm": "@ai-sdk/google" } } }

MCP Servers Causing Errors

Some MCP servers have schemas incompatible with Antigravity's strict JSON format.

Common symptom:

Invalid function name must start with a letter or underscore

Sometimes it shows up as:

GenerateContentRequest.tools[0].function_declarations[12].name: Invalid function name must start with a letter or underscore

This usually means an MCP tool name starts with a number (for example, a 1mcp key like 1mcp_*). Rename the MCP key to start with a letter (e.g., gw) or disable that MCP entry for Antigravity models.

Diagnosis:

  1. Disable all MCP servers in your config
  2. Enable one-by-one until error reappears
  3. Report the specific MCP in a GitHub issue

"All Accounts Rate-Limited" (But Quota Available)

Cause: Cascade bug in clearExpiredRateLimits() in hybrid mode (fixed in recent beta).

Solutions:

  1. Update to latest beta version
  2. If persists, delete accounts file and re-authenticate
  3. Try switching account_selection_strategy to "sticky" in antigravity.json

Session Recovery

If you encounter errors during a session:

  1. Type continue to trigger the recovery mechanism
  2. If blocked, use /undo to revert to pre-error state
  3. Retry the operation

Using with Oh-My-OpenCode

Important: Disable the built-in Google auth to prevent conflicts:

// ~/.config/opencode/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" }
  }
}

Infinite .tmp Files Created

Cause: When account is rate-limited and plugin retries infinitely, it creates many temp files.

Workaround:

  1. Stop OpenCode
  2. Clean up: rm ~/.config/opencode/*.tmp
  3. Add more accounts or wait for rate limit to expire

OAuth Callback Issues

Safari OAuth Callback Fails (macOS)

Symptoms:

  • "fail to authorize" after successful Google login
  • Safari shows "Safari can't open the page"

Cause: Safari's "HTTPS-Only Mode" blocks http://localhost callback.

Solutions:

  1. Use Chrome or Firefox (easiest): Copy the OAuth URL and paste into a different browser.

  2. Disable HTTPS-Only Mode temporarily:

    • Safari > Settings (⌘,) > Privacy
    • Uncheck "Enable HTTPS-Only Mode"
    • Run opencode auth login
    • Re-enable after authentication
Port Conflict (Address Already in Use)

macOS / Linux:

# Find process using the port
lsof -i :51121

# Kill if stale
kill -9 <PID>

# Retry
opencode auth login

Windows (PowerShell):

netstat -ano | findstr :51121
taskkill /PID <PID> /F
opencode auth login
Docker / WSL2 / Remote Development

OAuth callback requires browser to reach localhost on the machine running OpenCode.

WSL2:

  • Use VS Code's port forwarding, or
  • Configure Windows → WSL port forwarding

SSH / Remote:

ssh -L 51121:localhost:51121 user@remote

Docker / Containers:

  • OAuth with localhost redirect doesn't work in containers
  • Wait 30s for manual URL flow, or use SSH port forwarding

Configuration Key Typo: plugin not plugins

The correct key is plugin (singular):

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

Not "plugins" (will cause "Unrecognized key" error).

Migrating Accounts Between Machines

When copying antigravity-accounts.json to a new machine:

  1. Ensure the plugin is installed: "plugin": ["opencode-antigravity-auth@beta"]
  2. Copy ~/.config/opencode/antigravity-accounts.json
  3. If you get "API key missing" error, the refresh token may be invalid — re-authenticate

Known Plugin Interactions

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

Configuration

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

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

Most users don't need to configure anything — defaults work well.

Model Behavior

Option Default What it does
keep_thinking false Preserve Claude's thinking across turns. Warning: enabling may degrade model stability.
session_recovery true Auto-recover from tool errors
cli_first false Route Gemini models to Gemini CLI first (Claude and image models stay on Antigravity).

Account Rotation

Your Setup Recommended Config
1 account "account_selection_strategy": "sticky"
2-5 accounts Default ("hybrid") works great
5+ accounts "account_selection_strategy": "round-robin"
Parallel agents Add "pid_offset_enabled": true

Quota Protection

Option Default What it does
soft_quota_threshold_percent 90 Skip account when quota usage exceeds this percentage. Prevents Google from penalizing accounts that fully exhaust quota. Set to 100 to disable.
quota_refresh_interval_minutes 15 Background quota refresh interval. After successful API requests, refreshes quota cache if older than this interval. Set to 0 to disable.
soft_quota_cache_ttl_minutes "auto" How long quota cache is considered fresh. "auto" = max(2 × refresh interval, 10 minutes). Set a number (1-120) for fixed TTL.

How it works: Quota cache is refreshed automatically after API requests (when older than quota_refresh_interval_minutes) and manually via "Check quotas" in opencode auth login. The threshold check uses `soft_quot

opencode-antigravity-auth (NoeFabris/opencode-antigravity-auth)

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10.9K ·GitHub
Opencode-antigravity-auth
archived
What is this?It's an OpenCode plugin that authenticates via Google OAuth against Antigravity (Google's IDE), letting OpenCode use Antigravity's quota to run models like Gemini 3.1 Pro and Claude Opus 4.6-thinking under your own Google account instead of a separate API key.
Is this a standalone app or just an OpenCode add-on?It's only a plugin you add to OpenCode's config array — it doesn't run on its own and is meant to sit alongside other OpenCode plugins.
How do I install and configure it?Add the plugin to the plugin array in ~/.config/opencode/opencode.json, run 'opencode auth login' → Google → OAuth with Google (Antigravity), then pick 'Configure models in opencode.json' to auto-add all the model definitions.
Do I need a Google Cloud API key, or just my Google account?No separate API key is required for normal use — you log in with your Google account via OAuth, and can add multiple accounts for more combined quota. You only need to create a Google Cloud project with the Gemini API enabled if you hit a specific 403 error on Gemini CLI models.
Does using this violate Google's Terms of Service?Yes — the README explicitly warns this violates Google's ToS, and some users have had their Google accounts banned or shadow-banned for using it.
Does setup differ between Windows, macOS, and Linux?The config path is identical on every OS (~/.config/opencode/, including on Windows where ~ still resolves to the user's home folder), though OAuth callbacks need extra steps on Safari/macOS, WSL2, SSH, and inside Docker.
Where are my Google credentials stored?OAuth account data is stored locally in a JSON file inside your OpenCode config folder, not sent anywhere else by the plugin.
What models can I actually access through this?Claude Opus 4.6 / Sonnet 4.6 and Gemini 3.1 Pro / Flash via the Antigravity quota, plus Gemini 2.5 and 3 Pro/Flash via the separate Gemini CLI quota, with automatic fallback between the two pools when one runs out.
How does multi-account rotation work?You add several Google accounts and the plugin automatically rotates between them when one is rate-limited, using a sticky, hybrid, or round-robin strategy depending on how many accounts you have.
Is this project still actively maintained?The repository is marked archived on GitHub, so although the README documents an actively evolving plugin with a beta channel, it's no longer getting new work from this repo.
What happens if an MCP server breaks this plugin?Antigravity's strict schema validation can choke on malformed MCP tool schemas (for example tool names starting with a digit); the fix is to disable MCP servers one by one or rename the offending tool key until the error disappears.
What are similar projects?9router, Antigravity, casbin-gateway, opencodex, paragravity, LibreChat, context-mode, nobuzz
Which topics is it in?multi-account, llm-proxy, rate-limiting, antigravity, ide, google, opencode, oauth, authentication, gemini, deprecated, plugin
Creator
NoeFabris
Size
1.2 MB
Stars
10.9K
Updated
CommitAug 27Releasev1.6.0Feb 20
Age
10mo
Commits · 90 Days