Meld 3-Way Merge for VS Code

Boost developer productivity with an intuitive layout, clear connections, and automated resolutions that standard git tools miss.

This extension brings the power of Meld's intuitive frontend diff viewer and advanced auto-merge heuristics directly into Visual Studio Code. If you're looking for a dedicated 3-way merge tool and superior Git merge conflict resolution, this Visual Studio Code Git extension provides an unmatched developer experience.

Table of Contents

• Alpha Release Notice
• Installation
• Why Use This?
• Features
• How It Works
• How to Use the Extension
• Configuration Settings
• Developer Setup
• Credits
• License
• Feedback & Support

⚠️ Alpha Release Notice

This extension is currently in alpha.

While the core Meld algorithms have been carefully ported and tested, the VS Code UI integration is under active development. Features may be incomplete, behavior may change without notice, and bugs are expected.

Please review your merges carefully and report any bugs you find!

Use at your own discretion.

Installation

As this extension is currently in Alpha, it may not be published to the public VS Code Marketplace.

Currently, you must download the .vsix file from the GitHub Releases page and install it manually:

1. Download the latest meld-auto-merge*.vsix file.
2. In VS Code, open the Extensions view (Ctrl+Shift+X).
3. Click the "..." menu in the top-right corner.
4. Select Install from VSIX...
5. Locate the downloaded file and click Install.

Why Use This?

VS Code's built-in Git conflict resolution is excellent, but its standard interface can sometimes be visually noisy and challenging to navigate during complex merges:

Standard VS Code 3-way view.

Even the improved built-in 3-way view can still feel less intuitive than dedicated desktop tools like Meld:

Improved VS Code 3-way view.

Meld for VS Code provides a cleaner, dedicated 3-way merge editor modeled right after the Meld application. Beyond the improved UI, it brings Meld's highly-tuned conflict resolution algorithm that is capable of:

• Resolving changes separated by whitespace.
• Handling complex insert/delete overlaps with unambiguous resolutions.
• Automatically interpolating conflict blocks to find common ground.

The end result? An intuitive merge experience that handles the tedious work for you.

Conflict resolution made intuitive – Meld resolves conflicts automatically when VS Code cannot.

Features

🔀 3-Way Merge Editor

A seamless, visually distinct 3-way merge interface opening directly inside your editor for any conflicted files. See local, base, and remote versions side-by-side with clear connections to the merged output.

✨ Auto-Merge Conflicted Files

Manually trigger auto-merge at any time via the Command Palette: "Meld: Auto-Merge Current File". This extracts the LOCAL, BASE, and REMOTE versions via Git and runs them through the Meld AutoMergeDiffer, applying the highly-optimized merged result to your editor.

🛠️ Quality of Life Git Tools (Source Control UI)

The extension contributes a Meld Conflicted Files view to the native Source Control (SCM) panel, displaying all current conflicts. Each file has inline actions:

• 🚀 Checkout Conflicted (-m): Quickly reset a botched merge attempt in the active file back to its original conflicted state with git checkout -m. (Asks for confirmation)
• 🧠 Rerere Forget File: Tell Git to forget any automatically recorded resolution for the file using git rerere forget. (Asks for confirmation)
• ✅ Smart Git Add: A safer git add that verifies absolutely no conflict markers (<<<<<<<) remain in the file before staging it.
• 🔀 Open 3-Way Merge Editor: Opens the file in the custom Meld 3-way setup.

How It Works

To ensure maximum performance and zero external dependencies, we have ported Meld's core Python logic to pure TypeScript.

This includes:

• myers.ts: A high-performance O(NP) diff algorithm with Meld's custom k-mer inline matching.
• diffutil.ts: Advanced sequence management and chunk tracking.
• merge.ts: The 3-way merge logic and powerful AutoMergeDiffer heuristics.

The logic runs entirely within the VS Code extension host process—no Python installation or background daemons required.

How to Use the Extension

From the Source Control Tab

1. Open a project that currently has Git merge conflicts.
2. Click on the Source Control icon in your Activity Bar (or press Ctrl+Shift+G).
3. Under the standard "Source Control" view, you will see a new collapsible section titled Meld Merge : Conflicted Files.
4. Expanding this tab will show a list of all files currently marked as conflicted.
5. Hover over any conflicted file in this list to reveal its inline action buttons:
   • 🔀 Open Custom Merge (Meld: Open Custom Merge): Opens the file in the dedicated 3-way interactive Meld interface.
   • 🚀 Checkout Conflicted (-m): Quickly resets any botched manual merge attempts in the file back to its original raw conflicted state via git checkout -m.
   • 🧠 Rerere Forget File: Discards any saved git-rerere resolutions for the file.
   • ✅ Git Add Resolved: A "smart add" button that verifying absolutely no conflict markers (<<<<<<<, ======, >>>>>>>) remain in the text before safely staging the file.

From the Command Palette (Ctrl+Shift+P)

If you already have a conflicted file actively open in your regular VS Code editor:

1. Press Ctrl+Shift+P (or Cmd+Shift+P on Mac) to open the Command Palette.
2. Type Meld: Open Custom Merge and hit Enter.
3. The custom 3-way merge viewer will open up immediately for that file.
4. (Optional) Alternatively, you can run the Meld: Auto-Merge Current File command to bypass the UI entirely and let Meld's highly optimized algorithm attempt to resolve the merge automatically.

Configuration Settings

You can customize the extension using the following VS Code settings (accessible via File > Preferences > Settings):

Theme Colors

All diff highlight colors are fully themeable via the workbench colorCustomizations setting in your settings.json:

Example settings.json snippet to tweak colors:

"workbench.colorCustomizations": {
    "meldMerge.diffConflictBackground": "#ff00001a",
    "meldMerge.diffInsertBackground": "#00ff001a"
}

Developer Setup

To run this extension locally:

1. Clone the repository and open the root folder in VS Code.
2. Install dependencies:

   npm install
   

3. Compile the extension:

   npm run compile
   

4. Launch: Press F5 to open an "Extension Development Host" window with the extension loaded.

Testing & Packaging

We use Jest to verify the TypeScript port against Meld's original Python logic:

npm test         # run unit tests
npm run lint     # lint and format check
npm run compile  # type-check
npx vsce package # build the .vsix

Credits

This VS Code extension is authored and maintained by Pyarelal Knowles, 2026.

It is a port of the Meld visual diff and merge tool, originally written in Python. All credit for the core algorithm design, advanced diffing heuristics, and 3-way merge logic and fantastic UI belongs to the original Meld developers. This extension aims to bring their hard work and excellent merge experience into the VS Code ecosystem.

License

GPL Version 2; see LICENSE.

Feedback & Support

If you encounter a bug, have a feature request, or just want to share feedback, please file an issue on our GitHub repository at:
https://github.com/pknowles/meld/issues