Refactoring Legacy Code with Antigravity: A Survival Guide

We all have that one repo.
Written 5 years ago. No documentation. Variable names like `x` and `temp`. Touching it feels like defusing a bomb.

Google Antigravity is your bomb disposal robot.

Here is how to use it to modernize legacy code without breaking production.

1. The “Explain” Agent

Before you change anything, you need to understand it.
Spawn an Explainer Agent:
> “Analyze the `process_payment` function in `legacy_billing.py`. Explain the logic in plain English and generate a flowchart.”

Antigravity reads the spaghetti code and produces a clear explanation and a Mermaid diagram. Now you know what it does.

2. Generating Tests (Safety Net)

Refactoring without tests is suicide.
Spawn a Tester Agent:
> “Write a comprehensive test suite for `legacy_billing.py`. Cover all edge cases. Do not modify the code yet, just write tests that pass against the current implementation.”

This creates a “Golden Master” test suite. It ensures that whatever you do next, the behavior remains the same.

3. The “Refactor” Agent

Now, the fun part.
> “Refactor `legacy_billing.py`.
> 1. Rename variables to be descriptive.
> 2. Extract the tax calculation into a separate function.
> 3. Add type hints.
> 4. Ensure all tests still pass.”

Antigravity performs the surgery. It runs the tests after every change. If a test fails, it reverts and tries again.

4. CodeMender for Cleanup

Once the big refactor is done, turn on CodeMender.
It will scan the new code for:
* Unused imports.
* Inefficient loops.
* Security vulnerabilities.

It's like having a janitor polish the floor after the construction crew leaves.

Conclusion

Legacy code doesn't have to be a nightmare. With Antigravity, you can turn a “Do Not Touch” module into a modern, maintainable component in an afternoon.

At BYS Marketing, we specialize in “AI-Assisted Modernization,” helping companies rescue their technical debt.

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Stuck with a legacy codebase?
Contact BYS Marketing. We can modernize your systems without the risk.