npm package: @shaywong/opencode-antigravity-auth
Description: Google Antigravity IDE OAuth auth plugin for Opencode - access Gemini 3 Pro and Claude 4.5 using Google credentials
Author: noefabris
Latest version: 1.3.2-beta.2

# Antigravity + Gemini CLI OAuth Plugin for Opencode

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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.

Fork notice: This project is based on https://github.com/NoeFabris/opencode-antigravity-auth and modified by @shaywong. License: MIT (see `LICENSE`).

## 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.)

---

<details open>
<summary><b>⚠️ Terms of Service Warning — Read Before Installing</b></summary>

> [!CAUTION]
> Using this plugin may violate Google's Terms of Service. A small number of users have reported their Google accounts being **banned** or **shadow-banned** (restricted access without explicit notification).
>
> **High-risk scenarios:**
> - 🚨 **Fresh Google accounts** have a very high chance of getting banned
> - 🚨 **New accounts with Pro/Ultra subscriptions** are frequently flagged and banned
>
> **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
>
> **Recommendation:** Use an established Google account that you don't rely on for critical services. Avoid creating new accounts specifically for this plugin.

</details>

---

## Installation

<details open>
<summary><b>For Humans</b></summary>

**Option A: Let an LLM do it**

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

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

**Option B: Manual setup**

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

   ```json
   {
     "plugin": ["@shaywong/opencode-antigravity-auth@latest"]
   }
   ```

   > Want bleeding-edge features? Use `@shaywong/opencode-antigravity-auth@beta` instead.

2. **Login** with your Google account:

   ```bash
   opencode auth login
   ```

3. **Add models** — copy the [full configuration](#models) below

4. **Use it:**

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

</details>

<details>
<summary><b>For LLM Agents</b></summary>

### 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](#models) section

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

### Verification

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

</details>

---

## 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:**
```bash
   opencode run "Hello" --model=antigravity/antigravity-claude-sonnet-4-5-thinking --variant=max
```

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

<details>
<summary><b>Full models configuration (copy-paste ready)</b></summary>

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

```json
{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["@shaywong/opencode-antigravity-auth@latest"],
  "provider": {
    "antigravity": {
      "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"] }
        }
      }
    }
  }
}
```

</details>

---

## Multi-Account Setup

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

```bash
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](docs/MULTI-ACCOUNT.md).

---

## Troubleshoot

> **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%`.

---

### Multi-Account Auth Issues

If you encounter authentication issues with multiple accounts:

1. Delete the accounts file:
   ```bash
   rm ~/.config/opencode/antigravity-accounts.json
   ```
2. Re-authenticate:
   ```bash
   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](https://console.cloud.google.com/)
2. Create or select a project
3. Enable the **Gemini for Google Cloud API** (`cloudaicompanion.googleapis.com`)
4. Add `projectId` to your accounts file:
   ```json
   {
     "accounts": [
       {
         "email": "your@email.com",
         "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:

```json
{
  "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:**
- Tool schema incompatibility with Gemini's strict protobuf validation
- MCP servers with malformed schemas
- Plugin version regression

**Solutions:**
1. **Update to latest beta:**
   ```json
   { "plugin": ["@shaywong/opencode-antigravity-auth@beta"] }
   ```

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

3. **Add npm override:**
   ```json
   { "provider": { "antigravity": { "npm": "@ai-sdk/google" } } }
   ```

---

### MCP Servers Causing Errors

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

**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](https://github.com/shay-wong/opencode-antigravity-auth/issues)

---

### "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:

```json
// ~/.config/opencode/oh-my-opencode.json
{
  "google_auth": false,
  "agents": {
  "frontend-ui-ux-engineer": { "model": "antigravity/antigravity-gemini-3-pro" },
  "document-writer": { "model": "antigravity/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

<details>
<summary><b>Safari OAuth Callback Fails (macOS)</b></summary>

**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

</details>

<details>
<summary><b>Port Conflict (Address Already in Use)</b></summary>

**macOS / Linux:**
```bash
# Find process using the port
lsof -i :51121

# Kill if stale
kill -9 <PID>

# Retry
opencode auth login
```

**Windows (PowerShell):**
```powershell
netstat -ano | findstr :51121
taskkill /PID <PID> /F
opencode auth login
```

</details>

<details>
<summary><b>Docker / WSL2 / Remote Development</b></summary>

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:**
```bash
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

</details>

---

### Configuration Key Typo: `plugin` not `plugins`

The correct key is `plugin` (singular):

```json
{
  "plugin": ["@shaywong/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": ["@shaywong/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](docs/MULTI-ACCOUNT.md).

---

## Plugin Compatibility

### @tarquinen/opencode-dcp

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

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

### oh-my-opencode

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

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

```json
{
  "$schema": "https://raw.githubusercontent.com/shay-wong/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 |
| `web_search.default_mode` | `"off"` | Gemini Google Search: `"auto"` or `"off"` |

### 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` |

### Rate Limit Scheduling

Control how the plugin handles rate limits:

| Option | Default | What it does |
|--------|---------|--------------|
| `scheduling_mode` | `"cache_first"` | `"cache_first"` = wait for same account (preserves prompt cache), `"balance"` = switch immediately, `"performance_first"` = round-robin |
| `max_cache_first_wait_seconds` | `60` | Max seconds to wait in cache_first mode before switching accounts |
| `failure_ttl_seconds` | `3600` | Reset failure count after this many seconds (prevents old failures from permanently penalizing accounts) |

**When to use each mode:**
- **cache_first** (default): Best for long conversations. Waits for the same account to recover, preserving your prompt cache.
- **balance**: Best for quick tasks. Switches accounts immediately when rate-limited for maximum availability.
- **performance_first**: Best for many short requests. Distributes load evenly across all accounts.

### App Behavior

| Option | Default | What it does |
|--------|---------|--------------|
| `quiet_mode` | `false` | Hide toast notifications |
| `debug` | `false` | Enable debug logging |
| `auto_update` | `true` | Auto-update plugin |

For all options, see [docs/CONFIGURATION.md](docs/CONFIGURATION.md).

**Environment variables:**
```bash
OPENCODE_ANTIGRAVITY_DEBUG=1 opencode   # Enable debug logging
OPENCODE_ANTIGRAVITY_DEBUG=2 opencode   # Verbose logging
```

---

## Troubleshooting

See the full [Troubleshooting Guide](docs/TROUBLESHOOTING.md) 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](docs/CONFIGURATION.md) — All configuration options
- [Multi-Account](docs/MULTI-ACCOUNT.md) — Load balancing, dual quota pools, account storage
- [Model Variants](docs/MODEL-VARIANTS.md) — Thinking budgets and variant system
- [Troubleshooting](docs/TROUBLESHOOTING.md) — Common issues and fixes
- [Architecture](docs/ARCHITECTURE.md) — How the plugin works
- [API Spec](docs/ANTIGRAVITY_API_SPEC.md) — Antigravity API reference

---

## Support

If this plugin helps you, consider supporting its maintenance:

[![ko-fi](https://ko-fi.com/img/githubbutton_sm.svg)](https://ko-fi.com/S6S81QBOIR)

---

## Credits

- [opencode-gemini-auth](https://github.com/jenslys/opencode-gemini-auth) by [@jenslys](https://github.com/jenslys)
- [CLIProxyAPI](https://github.com/router-for-me/CLIProxyAPI)

## License

MIT License. See [LICENSE](LICENSE) for details.

<details>
<summary><b>Legal</b></summary>

### 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.

</details>