Antigravity + Gemini CLI OAuth Plugin for Opencode

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-4-6-thinking with your Google credentials.

What You Get

Claude Opus 4.6, Sonnet 4.6 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>⚠️ Terms of Service Warning — Read Before Installing</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>For Humans</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

Add the plugin to ~/.config/opencode/opencode.json:
```
{
  "plugin": ["opencode-antigravity-auth@latest"]
}
```
Want bleeding-edge features? Use opencode-antigravity-auth@beta instead.
Login with your Google account:
```
opencode auth login
```
Add models — choose one:
- Run opencode auth login → select "Configure models in opencode.json" (auto-configures all models)
- Or manually copy the full configuration below

Use it:

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

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

Step-by-Step Instructions

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).
Add the plugin to the plugin array
Add the model definitions from the Full models configuration section
Set provider to "google" and choose a model

Verification

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:

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.

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

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.

</details>

Multi-Account Setup

Add multiple Google accounts for higher combined quotas. 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):

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.

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%.

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:

Delete the accounts file:

rm ~/.config/opencode/antigravity-accounts.json

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:

Go to Google Cloud Console
Create or select a project
Enable the Gemini for Google Cloud API (cloudaicompanion.googleapis.com)

Add projectId to your accounts file:

{
  "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:

{
  "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:

Update to latest beta:

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

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

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:

Disable all MCP servers in your config
Enable one-by-one until error reappears
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:

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

Session Recovery

If you encounter errors during a session:

Type continue to trigger the recovery mechanism
If blocked, use /undo to revert to pre-error state
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:

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

OAuth Callback Issues

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

Use Chrome or Firefox (easiest): Copy the OAuth URL and paste into a different browser.
Disable HTTPS-Only Mode temporarily:
- Safari > Settings (⌘,) > Privacy
- Uncheck "Enable HTTPS-Only Mode"
- Run opencode auth login
- Re-enable after authentication

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

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

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

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):

{
  "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:

Ensure the plugin is installed: "plugin": ["opencode-antigravity-auth@beta"]
Copy ~/.config/opencode/antigravity-accounts.json
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

gemini-auth plugins — Not needed. This plugin handles all Google OAuth.

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_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.

Environment variables:

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 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 — All configuration options
Multi-Account — Load balancing, dual quota pools, account storage
Model Variants — Thinking budgets and variant system
Troubleshooting — Common issues and fixes
Architecture — How the plugin works
API Spec — Antigravity API reference

Support

If this plugin helps you, consider supporting its maintenance:

Credits

License

MIT License. See LICENSE for details.

<details> <summary>Legal</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>

AI Architecture Analysis

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Repository Summary (README)

Antigravity + Gemini CLI OAuth Plugin for Opencode

What You Get

Installation

Step-by-Step Instructions

Verification

Models

Model Reference

Multi-Account Setup

Troubleshoot

Configuration Path (All Platforms)

Multi-Account Auth Issues

403 Permission Denied (rising-fact-p41fc)

Gemini Model Not Found

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

MCP Servers Causing Errors

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

Session Recovery

Using with Oh-My-OpenCode

Infinite .tmp Files Created

OAuth Callback Issues

Configuration Key Typo: plugin not plugins

Migrating Accounts Between Machines

Known Plugin Interactions

Plugin Compatibility

@tarquinen/opencode-dcp

oh-my-opencode

Plugins you don't need

Configuration

Model Behavior

Account Rotation

Quota Protection

Rate Limit Scheduling

App Behavior

Troubleshooting

Documentation

Support

Credits

License

Intended Use

Warning

Disclaimer

403 Permission Denied (`rising-fact-p41fc`)

Infinite `.tmp` Files Created

Configuration Key Typo: `plugin` not `plugins`