opencode-antigravity-auth

The plugin intercepts requests to generativelanguage.googleapis.com and performs several transformations to make them compatible with the Antigravity API and Claude models:

1. Model Detection: Identifies if the model is Claude or Gemini.
2. Thinking Configuration: Adds thinkingConfig for supported thinking models.
3. Thinking Stripping: Removes all thinking blocks from outgoing requests to prevent signature corruption.
4. Tool Normalization: Converts tools into functionDeclarations[].
5. Schema Cleaning: Sanitizes JSON Schemas by removing unsupported fields like const, $ref, $defs, default, examples, $schema, and title. Note that const: "value" is transformed into enum: ["value"].
6. ID Assignment: Assigns IDs to tool calls using FIFO matching.
7. Request Wrapping: Wraps the payload into the format { project, model, request: {...} }.

Once your runner status shows as "Idle" (green) in your GitHub Repository settings, update your workflow file (e.g., .github/workflows/issue-triage.yml) to target the self-hosted runner.

Use the runs-on key to specify the runner. You can use a generic label or a specific label if you have multiple self-hosted runners.

runs-on: self-hosted
# or specifically:
# runs-on: [self-hosted, pi]

OpenCode's variant system allows you to dynamically configure thinking budgets without needing separate model definitions for every level. When a model has variants defined in its configuration, you can select a specific variant using the --variant flag in the CLI. This passes the providerOptions to the plugin to set the thinking configuration.

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

When using oh-my-opencode, you must disable the built-in Google authentication to prevent conflicts. You should also override the agent models in your oh-my-opencode.json file.

Example configuration for ~/.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" }
  }
}

To install the plugin, add it to the plugin array in your OpenCode configuration file located at ~/.config/opencode/opencode.json. You can use the @latest tag for stable releases or @beta for bleeding-edge features.

After adding the plugin, run the login command to authenticate with your Google account:

opencode auth login

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

If you encounter authentication issues, the quickest fix is to delete the existing accounts file and re-authenticate using the CLI.

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

The plugin includes regression tests that consume API quota. Use these commands to verify functionality:

• --sanity: Runs 7 tests (approx. 5 min).
• --heavy: Runs 4 tests (approx. 30 min).
• --dry-run: Lists available tests without running them.

npx tsx script/test-regression.ts --sanity      # 7 tests, ~5 min
npx tsx script/test-regression.ts --heavy       # 4 tests, ~30 min
npx tsx script/test-regression.ts --dry-run     # List tests

If the OAuth process fails because the port is already in use, kill the process occupying port 51121.

### macOS/Linux
```bash
lsof -i :51121
kill -9 <PID>
opencode auth login

Windows

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

Use these pre-configured JSON objects based on your requirements:

1 Account (Preserve prompt cache):

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

2-3 Accounts (Smart rotation):

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

3+ Accounts / Parallel Agents (Maximum throughput):

{
  "$schema": "https://raw.githubusercontent.com/NoeFabris/opencode-antigravity-auth/main/assets/antigravity.schema.json",
  "account_selection_strategy": "round-robin",
  "switch_on_first_rate_limit": true,
  "pid_offset_enabled": true
}

After setting up the runner, you must authenticate tools like gh copilot and other AI utilities by running the auth-pi-tools.sh script (found in the scripts/ folder of this repository).

# On your Pi
chmod +x auth-pi-tools.sh
./auth-pi-tools.sh

Follow the interactive login flows to complete authentication.

Google enforces strict quotas. If you experience hanging prompts or 403 errors, follow these steps:

• Wait it out: Stop using the account for 24-48 hours.
• Warm up accounts: Log in to Antigravity IDE and run simple prompts (e.g., "Hello") to reset internal flags.
• Reduce volume: Use shorter sessions and avoid parallel subagents.
• Fail fast: Set max_rate_limit_wait_seconds: 0 to avoid infinite retries.