Claude Arc Patch

Make the official Claude Chrome Extension work in Arc Browser.

The Problem

Claude's Chrome extension uses the chrome.sidePanel API to display a sidebar panel. Arc Browser doesn't support this API, so the extension fails to load its UI.

The Solution

This patcher copies the official Claude extension and applies minimal patches to make it work in Arc:

• Floating sidebar panel injected into web pages via a content script (replaces the unsupported sidePanel API)
• Service worker patch that monkey-patches chrome.sidePanel calls and routes icon clicks to the floating panel
• Tab context patch that fixes chrome.tabs.query so Claude can identify the active tab from within the iframe
• Inline script extraction to comply with Manifest V3 CSP requirements

No original Claude extension code is modified. Only additional files are injected.

Installation

Prerequisites

• Arc Browser installed
• Claude Chrome Extension installed in Chrome (needed as source files)

Steps

1. Clone this repo

   git clone https://github.com/quardianwolf/claude-arc-patch
   cd claude-arc-patch

2. Run the patcher

   ./patch.sh

   The script auto-detects the Claude extension installed in Chrome. If it can't find it, provide the path manually:

   ./patch.sh /path/to/claude/extension/directory

3. Load in Arc

   • Go to arc://extensions
   • Enable Developer mode (top right toggle)
   • Click Load unpacked
   • Select the claude-arc-patched folder
   • Disable the original Claude extension in Chrome to avoid conflicts

4. If macOS blocks the script

   xattr -cr /path/to/claude-arc-patch
   bash patch.sh

Usage

• Click the extension icon in Arc's toolbar to toggle the Claude sidebar
• Cmd+E (Mac) / Ctrl+E (Windows) to toggle the sidebar
• Click the X button on the sidebar header to close it

How It Works

File	Purpose
patch.sh	Copies the official extension and applies all patches
floating-panel.js	Content script that creates a sidebar panel on web pages
sw-patch.js	Service worker patch: monkey-patches sidePanel API, handles icon clicks and keyboard shortcuts
arc-tabs-patch.js	Patches chrome.tabs.query so the sidepanel can find the active tab from an iframe context
theme-init.js	Extracted inline script for dark/light mode (CSP compliance)

Architecture

                  Arc Browser
                  +--------------------------+
                  |  Web Page                |
                  |  +--------------------+  |
  Icon click /    |  | floating-panel.js  |  |
  Cmd+E           |  | (content script)   |  |
       |          |  |                    |  |
  sw-patch.js --->|  |  +-------------+  |  |
  (service worker)|  |  | sidepanel   |  |  |
                  |  |  | .html       |  |  |
                  |  |  | (iframe)    |  |  |
                  |  |  +-------------+  |  |
                  |  +--------------------+  |
                  +--------------------------+

Troubleshooting

Panel not showing:

• Make sure the extension is enabled at arc://extensions
• Refresh the page (Cmd+R)
• Check console for errors (Cmd+Option+I)

Login issues:

• Make sure you're logged into Claude in Chrome first
• The patched extension shares the same authentication

Shortcut not working:

• Cmd+E only works after the page has loaded
• Check arc://extensions/shortcuts for conflicts with other extensions

"Operation not permitted" when running patch.sh:

xattr -cr /path/to/claude-arc-patch

Security

• No original Claude extension code is modified
• Only additional patch files are injected
• All code is open source and auditable
• The extension ID is preserved, so authentication continues to work
• No data is collected or sent externally

Updating

When Claude releases a new extension version:

1. Update the Claude extension in Chrome
2. Re-run ./patch.sh
3. Reload the extension in Arc (arc://extensions > reload icon)

Contributing

Pull requests welcome. Please keep patches minimal and focused on Arc compatibility.

License

MIT - see LICENSE

Disclaimer

This project is not affiliated with Anthropic. Claude is a trademark of Anthropic, PBC.