A weekend with Antigravity: 17,000 Lines of Code in < 48 Hours

This weekend, I didn't just code. I accelerated.

I spent the last 48 hours pair-programming with Antigravity, an advanced AI coding assistant. We took a legacy JavaScript codebase—riddled with global variables, monolithic files, and "spaghetti" dependencies—and transformed it into a modern, service-oriented architecture.

The results go beyond just "helper" status. The metrics suggest a level of productivity that warps the traditional time-cost equation of software development.

This app started out in 2024 as a scrappy concept, MVP, rapidly coded as a single index.html file with inline vanilla Javascript & CSS code - messy spaghetti code that grew and grew, until this weekend when I decided to just stop, refactor and clobber all technical debt. The goal? To experience the full journey of coding with AI and improve the code over time, to eventually get a "modern" app deployed. This code was touched by many AI hands: GPT-o1, Gemini, Claude, Codex 5.1, and also my manual tweaks here and there. 

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The Analytics: Friday to Sunday

Let's look at the raw data from git. This represents activity from Friday, December 5th, to Sunday evening, December 7th.

• Commits: 60 (non-merges)
• Files Changed: 89
• Lines Added: 10,468
• Lines Deleted: 6,755
• Total Code Churn: ~17,223 lines

17,000 lines of code touched in one weekend.

The Narrative: Deconstructing the Monolith

When we started on Friday, the application was held together by window objects. Functions were exposed globally, state was scattered across main.js and utils.js, and components were tightly coupled to the DOM via inline onclick handlers.

Here is the story of our weekend, told through the commit log:

1. The Purge of Globals: We began by hunting down window. dependencies. One by one, we replaced fragile global state with rigid, testable Singletons and Services.
2. Breaking main.js: We took the 1,000+ line main.js file and chopped it up. We extracted logic into dedicated domains: PlanningService, AIService, SystemService, and NotificationManager.
3. Refactoring the UI: We implemented a VIEW_REGISTRY pattern, moving away from ad-hoc function calls to structured Class-based component management.
4. Safety Check-ins: You see this pattern in the logs constantly: "Safety checkin - refactoring...". We moved fast, but we didn't break things. The AI allowed me to make sweeping architectural changes with the confidence that I wasn't leaving behind broken references.

The "Antigravity" Effect: AI vs. Human Effort

How long would this have taken a human developer working alone?

The Human Estimate:

To touch 89 files and rewrite the core architecture of an application requires immense cognitive load.

• Day 1-3: Reading code, mapping dependencies, planning the refactor safe-zones.
• Day 4-8: Executing the refactor file-by-file. Manually checking imports. Wrangling with loads of ReferenceError
• Day 9-10: Regression testing. Realizing you broke the "Save" button because it relied on a global variable you deleted three days ago.

Conservative Estimate: 2 Weeks (1 Sprint) of full-time, focused work.

The Antigravity Reality:

We did it in 14.7 hours.

I analyzed the timestamps of every commit. Our total active coding time—the actual time spent typing, refactoring, and verifying—was less than 15 hours.

• Saturday: ~5 hours of strategic refactoring.
• Sunday: ~9.5 hours of high-intensity execution.

The AI didn't just "autocomplete" lines. It understood the architectural intent. When I said "Refactor this to use a Singleton pattern", it didn't just write a class; it found every usage of the old global variable across 20 files and updated them instantly. It remembered the context I would have forgotten.

This wasn't just faster coding. It was higher leverage coding. I spent my weekend making high-level architectural decisions, while Antigravity handled the thousands of lines of execution required to make those decisions reality.

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Conclusion

If this weekend proved anything, it's that the metric for "developer productivity" is changing. We aren't limited by typing speed or syntax recall anymore. We are limited only by our ability to describe the architecture we want.

My small experiment shows a software engineer would've saved two weeks of work in 15 hours! 

Did I waste my weekend coding with AI? Maybe...but I'm learning a ton and having fun coding after a very long time...it's like I'm back to my early teenage days of losing myself inside the machine...