opencode-antigravity-auth/README.md

# 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-3.1-pro` and `claude-opus-4-6-thinking` with your Google credentials.

## What You Get

- **Claude Opus 4.6, Sonnet 4.6** and **Gemini 3.1 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 (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
>

</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 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`:

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

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

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

   ```bash
   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](#models) below

4. **Use it:**

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

</details>

---

## 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:**
```bash
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](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": ["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.

</details>

---

## Multi-Account Setup

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

```bash
opencode auth login  # Run again to add more accounts
```

**Account management options (via `opencode auth login`):**
- **Configure models** — Auto-configure all plugin models in opencode.json
- **Check quotas** — View remaining API quota for each account
- **Manage accounts** — Enable/disable specific accounts for rotation

For details on load balancing, dual quota pools, and account storage, see [docs/MULTI-ACCOUNT.md](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:
   ```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": ["opencode-antigravity-auth@beta"] }
   ```

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

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

---

### MCP Servers Causing Errors

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

**Common symptom:**
```bash
Invalid function name must start with a letter or underscore
```

Sometimes it shows up as:
```bash
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](https://github.com/NoeFabris/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": "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

<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": ["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](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": [
    "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": "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 optional settings:

```json
{
  "$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_quota_cache_ttl_minutes` to determine cache freshness - if cache is older, the account is considered "unknown" and allowed (fail-open). When ALL accounts exceed the threshold, the plugin waits for the earliest quota reset time (like rate limit behavior). If wait time exceeds `max_rate_limit_wait_seconds`, it errors immediately.

### 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 file logging (`~/.config/opencode/antigravity-logs/`) |
| `debug_tui` | `false` | Show debug logs in the TUI log panel (independent from `debug`) |
| `auto_update` | `true` | Auto-update plugin |

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

**Environment variables:**
```bash
OPENCODE_CONFIG_DIR=/path/to/config opencode  # Custom config directory
OPENCODE_ANTIGRAVITY_DEBUG=1 opencode         # Enable debug file logging
OPENCODE_ANTIGRAVITY_DEBUG=2 opencode         # Verbose debug file logging
OPENCODE_ANTIGRAVITY_DEBUG_TUI=1 opencode     # Enable TUI log panel debug output
```

---

## 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 saves you time, consider supporting its development:

[![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>