> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentastic.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Diff Viewer: compare and review code changes

> The Diff Viewer shows your code changes with syntax highlighting in unified or side-by-side layout, making it easy to review before committing or merging.

The Diff Viewer gives you a clear picture of every change in your working directory or between branches. Use it to inspect what an AI agent has written, compare your feature branch against `main`, or review staged changes before committing — all with syntax highlighting and a navigable file list.

## Opening the Diff Viewer

### From Source Control

<Steps>
  <Step title="Open the Source Control Navigator">
    Click the Source Control icon in the sidebar or press `Cmd+3`.
  </Step>

  <Step title="Click a modified file">
    Select any file from the changed files list. Its diff opens in the editor area.
  </Step>
</Steps>

Staged and unstaged changes are shown in separate sections of the file list.

### From the Command Palette

<Steps>
  <Step title="Open the Command Palette">
    Press `Cmd+Shift+P`.
  </Step>

  <Step title="Type diff or compare">
    Filter results to find the comparison you want.
  </Step>

  <Step title="Select a comparison">
    Press `Enter` to open it.
  </Step>
</Steps>

## View modes

Toggle between the two display modes using the button in the toolbar.

### Unified view

A single-column layout similar to GitHub's diff display. Both the old and new versions of a file appear in one scrollable column:

* Added lines have a **green** background.
* Removed lines have a **red** background.
* Unchanged context lines appear without a background.
* Line numbers from both the old and new file are shown side by side.

Best for: quick reviews, smaller changesets, and reading changes linearly.

### Side-by-side view

A two-column layout showing the original and modified versions simultaneously:

* **Left column** — the original file.
* **Right column** — the modified file.
* Corresponding changes are aligned horizontally so you can compare them directly.

Best for: large refactors, moved code, and situations where you need to compare the before and after in detail.

## Color coding

| Color            | Meaning                |
| ---------------- | ---------------------- |
| Green background | Line was added         |
| Red background   | Line was removed       |
| No highlight     | Unchanged context line |

## Navigating diffs

### File list

The left panel lists all changed files. Each entry shows:

* The file path
* A change summary (`+additions / -deletions`)
* A status icon indicating the type of change

| Icon | Status   | Meaning                   |
| ---- | -------- | ------------------------- |
| M    | Modified | File has changes          |
| A    | Added    | New file                  |
| D    | Deleted  | File was removed          |
| R    | Renamed  | File was moved or renamed |

Use these controls to move through the file list:

| Action                     | How                      |
| -------------------------- | ------------------------ |
| Navigate between files     | `Up` / `Down` arrow keys |
| Open a file in the editor  | `Enter`                  |
| Show or hide the file list | Click the sidebar toggle |

### Within a single diff

* Scroll to move through the diff.
* Changes are grouped into hunks, separated by context dividers.
* Click a line number to jump directly to that line in the editor.

## Comparing branches

When you open a branch comparison, the Diff Viewer shows:

* **Base branch** — the target (e.g., `main`).
* **Head branch** — your feature branch.
* All commits between the two branches.
* The complete unified diff across all changed files.

The title bar displays the comparison: for example, `feature-x vs main`.

## Integration with Code Review

The Diff Viewer and [Code Review](/features/code-review) work together:

<Steps>
  <Step title="Review your changes visually">
    Open the Diff Viewer to confirm the diff is what you expect.
  </Step>

  <Step title="Click Code Review">
    Press the **Code Review** button in the toolbar. The AI agents analyze the same diff you're viewing.
  </Step>

  <Step title="Read the feedback">
    Agent output appears in terminal tabs. Address the suggestions, then re-check the diff.
  </Step>
</Steps>

## Keyboard shortcuts

| Action              | Shortcut             |
| ------------------- | -------------------- |
| Navigate files      | `Up` / `Down`        |
| Open file in editor | `Enter`              |
| Toggle file list    | Click sidebar toggle |

<Tip>
  Use the side-by-side view when reviewing refactored code. It makes it easy to spot relocated blocks and verify that logic was preserved.
</Tip>

<Tip>
  The file list summary gives you additions and deletions at a glance, so you can prioritize which files to review first.
</Tip>