The core technical problem: Google subsidizes Antigravity tokens via aggressive prompt caching optimized for their own clients. Third-party tools break those cache hit rates, potentially increasing serving costs 5-10x per request.

That's a legitimate economic concern. But the enforcement is indefensible — zero-tolerance instant bans on paying subscribers with no warning, no graduated response, and near-zero support.

Anthropic had the same problem with Claude Code third-party tools. They communicated first, flagged it, gave people time to adjust. That's how you enforce policy without torching customer trust.

If the penalty for a gray-area OAuth usage is an instant ban with no appeal, the platform isn't buildable.