The Complete Guide to PR Compare and Side-by-Side AI Analysis

Reviewing a Pull Request on GitHub is usually a linear process: you look at the lines added and the lines removed. But when reviewing code heavily driven by AI, this flat view isn't enough.

You need to understand the *trajectory* of the code.

VibeFix's **PR Compare** feature fundamentally changes how pull requests are reviewed by introducing contextual, side-by-side intelligence analysis.

## The Core Concept: The Quality Delta

When a PR is opened, VibeFix doesn't just scan the new code. It performs a complete analysis of the affected files in the `main` branch (the "Before") and compares them against the proposed changes (the "After").

We calculate the **Quality Delta**—the exact numerical shift in the Vibe Score.

- **Positive Delta (+5):** The contributor refactored slop, improved naming, or abstracted repetition.

- **Negative Delta (-12):** The contributor pasted 400 lines of raw Cursor output without cleaning it up.

## The Side-by-Side View

In the VibeFix dashboard, you can open the PR Compare view. Instead of just seeing red and green text, you see:

1. **Entropy Shifts:** A visual map showing how the complexity of the file changed. Did the developer introduce a "God Component"? The heat map will show it immediately.

2. **Signature Detection Overlay:** VibeFix highlights specific blocks of code and tags them with their identified "Neural DNA" pattern (e.g., *Excessive Class Generation*, *Hallucinated Commenting*).

## Enforcing Standards

By making the Quality Delta visible, teams can establish firm ground rules. "We do not merge PRs that have a negative impact delta greater than 2."

This shifts the culture from "ship as fast as the AI can type" to "ship fast, but leave the codebase cleaner than you found it."