How to Elegantly Monitor Google Antigravity Model Usage on macOS

The release of the Google Antigravity (AGY) SDK has unlocked a new paradigm in software engineering: autonomous AI agents and multi-agent systems. As a developer, I am now spinning up fleets of subagents to research, code, and debug. But with this incredible power comes a very practical challenge: monitoring API costs.

When your agents are autonomously parallelizing tasks and invoking heavy models, your API quota can deplete faster than expected. The traditional solution—refreshing the Google Cloud Console dashboard or constantly running verbose CLI commands—disrupts your flow.

You need real-time, unobtrusive visibility into your usage.

Enter the native macOS menu bar app.

The Case for Native over Web Wrappers

When building developer tools for macOS, the instinct is often to reach for Electron or Tauri to build a cross-platform web app. However, a menu bar app needs to be invisible until you need it. It must consume negligible battery, minimal RAM, and blend seamlessly into the macOS aesthetic.

This is why native SwiftUI is the superior choice. A native app integrates flawlessly with the system, utilizing core frameworks for networking and secure storage while keeping the memory footprint in the low megabytes.

Case Study: GravityQuota

To solve the API monitoring problem, I built GravityQuota—a lightweight, native macOS menu bar application designed specifically to track Google Antigravity SDK API usage in real-time.

Live App Demo

Check out this quick 20-second walkthrough to see how GravityQuota functions in real-time:

Here is how the app runs natively in the macOS menu bar, giving you a zero-click experience to view your remaining quotas and budgets instantly:

GravityQuota illustrates three key principles of modern independent macOS development:

1. Local-First Privacy

For developers, API keys are the keys to the kingdom. Users rightly distrust apps that require pasting sensitive credentials into forms that might phone home. GravityQuota is built with a strictly local-first architecture.

Your Google Antigravity API key is stored securely in the native macOS Keychain. The app communicates directly with the Google Cloud Billing and Antigravity APIs. There is no middleman, no analytics tracking, and absolutely no telemetry. The only network requests made are to Google's official endpoints.

2. Native SwiftUI Architecture

Written entirely in Swift and SwiftUI, GravityQuota takes full advantage of modern Apple frameworks. The menu bar extra updates dynamically, providing a quick glance at your daily or monthly spend. Clicking the icon reveals a beautifully crafted native popover with historical charts, usage by subagent, and proactive budget alerts. Because it’s native, it feels like a natural extension of macOS rather than a bolted-on widget.

3. Independent Distribution: Cloudflare R2 + Sparkle

Publishing to the Mac App Store (MAS) offers discoverability, but it also enforces strict sandboxing rules that can cripple developer tools. Furthermore, the review process can slow down the deployment of critical bug fixes.

For GravityQuota, I opted for the independent route. I distribute the application using Sparkle, the gold standard for macOS software updates. Sparkle provides a seamless, App Store-like update experience—notifying users of new versions, presenting release notes, and securely installing updates via EdDSA signatures.

To host the app binaries and the Sparkle appcast XML, I utilize Cloudflare R2. Unlike traditional AWS S3, Cloudflare R2 offers zero egress fees, which is a game-changer for independent developers distributing software globally. R2 is fast, reliable, and keeps distribution costs incredibly low, even as the user base scales.

The Future of Developer Tooling

The transition towards agentic workflows demands tools that keep pace with autonomous systems. GravityQuota demonstrates that solving these niche developer problems doesn't require massive frameworks or centralized infrastructure.

By leveraging native SwiftUI, secure local storage, and cost-effective independent distribution channels like Cloudflare R2 and Sparkle, independent developers can build professional-grade macOS applications outside the walled garden of the App Store.

If you are developing with the Google Antigravity SDK and want to keep your API costs in check without breaking your flow, give GravityQuota a try. It’s a testament to the power of native development and the vibrant ecosystem of independent Mac software.